Remediation of PFAS in wastewater & landfill leachates w/boron‐doped diamond electrodes

Hello and welcome to today’s seminarI’m Beth Meschewski – senior scientific specialist at the Illinois SustainableTechnology Center (ISTC) and seminar co-organizer. Today’s seminar is the lastone in our spring 2019 series. Watch for more information on the fall series inlate summer. A few housekeeping items before we get started: I’d like to remindour audience members here to please silence electronic devices as we arerecording today’s seminar. We will also hold all questions until the end atwhich time I’ll bring around this microphone so that those on line canhear your questions. For those on line you can type in your questions at anytime in the GoToWebinar toolbar and we’ll answer those at the as well. Andwith that, I’m very pleased to welcome today’s speaker: Corey Rusinek. Corey is ascientist at Michigan State University (MSU) Fraunhofer [pronounced: Frown-hoofer] Center for Coatings and Diamond Technologies. He earned his bachelor’s degree in chemistry at CaseWestern Reserve University and his PhD in electroanalytical chemistry at the University of Cincinnati.Some projects that he’s conducted at the Center include Per- and polyfluoroalkyl substances (PFAS) [PFAS pronounced P Fas] remediation in wastewater, wearable sensors for measurements of lead in sweat, and neurotransmitter detection with diamondmicrofibers. The Fraunhofer Center is a non-profit research and development (R&D) organization that bridges the research gap between academia and industry. Please join me inwelcoming Corey. [applause] [Cory] Thank You Beth and thanks for the invitation and hosting metoday. I really enjoyed it so far. I think we have some nice synergies. We might beable to find some future collaboration on a few different fronts.But with thatbeing said, I’m gonna speak today about our PFAS remediation project and someof the activities that we have going on. This will be a little bit more of asurvey of competing technologies and where we believe electrochemical oxidation with Boron-doped Diamond (BDD) electrodes fits in this fieldand then I’m going to show some data and some other things that we’re working onthat are sort of in concurrent to the research we’re doing here.So before Iget into that, I just want to give a brief background about the MSUFraunhofer Center and the dynamic of Fraunhofer whether that’s in Germany orin the United States (U.S.) in general. This is Germany. Each one of these [green squares on map] is a different location where there is a Fraunhofer Institute. There’s 67 institutes inGermany. There’s a few in other countries around Europe. There’s some of the United Kingdom (UK), Australia, and what have you. This says 23,000 staff but there’sactually 25,000 staff now in Fraunhofer. The Fraunhofer society in Germany orThe Fraunhofer-Gesellschaft touts themselves as the largest applied R&D organization in Europe. Each research institute has its own specific purposesimilar to our model here, which we’ll get to in a second.Here’s a number of different applications of various Institute’s ofwhat they work on.It’s a very widespread research focus amongst allthese different institutes. This elaborates on a little bit more.Here it shows where a lot of institutes are located around the worldand then here we have the Fraunhofer USA, which is made up of about six or sevenresearch centers as I’ll show here. Most of which are on the campus of auniversity. We have one on the University of Connecticut, University of Delaware, Boston University, and then we’re located in East Lansing on the campus ofMichigan State University. We’re the Center for Coatings and DiamondTechnologies.Fraunhofer USA has a similar model to thestructure in Germany where each of the centers has their own specific researchpurpose. But the primary goal is to bridge the gap between industry andacademic research. Fraunhofer is a non-profit organization, so they’re notcommercializing technology rather being the vehicle that takes something fromthe benchtop into industry where it can then be commercialized. We do a variety of different things whether that’s industry projects,government projects, offer goods and services, and things like that. As you’llsee, our headquarters is also located in Plymouth Michigan they’re not affiliatedwith a university. Not all of the centers are associated with auniversity. But I would say that our relationship with MSU with our Center isprobably the closest knit of all the centers that work with University. Toelaborate on that a little bit more, I think this is a little bit hard to seeon the right but essentially the model is at the MSU Fraunhofer Center, we haveabout 18 full-time Fraunhofer USA staff primarily which are German nationals andthen we have about 8 to 10 faculty at Michigan State that are directlyintegrated into the center.Each of them have a research group of PhDstudents, undergraduate students, what have you, and sometimes projectsare led by MSU and then there’s a subcontractor Fraunhofer or vice versabut really we have Fraunhofer staff working with basically PhD studentsundergraduate students and faculty so it helps bridging this gapbetween academic and industry research. Helps the students get an understandingof what they’re doing and how they could actually apply it, but at the same timekeep it fundamental and basic enough that they’re executing research that isthesis caliber let’s say.Our primary technology fields are in diamond technologies, on coding technologies – kind of gives it away in the name of theCenter. Since 2016 and 2017, we’ve added these systems and devices groupsthree dimensional (3D) printing. Systems and devices we’re actually building, a microwave-assisted chemical vapor deposition reactors. We want to become the national diamond fab [fabrication] in the future. A core expertise will be in the development of new systems andimproving on our current reactor design and such things like that. We also, since 2017, we actually have a 3D printing group that focuses on printing metals for engine components, things like that. I think I will skip to the next slide. These areour core competences. We have two primary groups that are – one – focusing on physical vapor deposition (PVD) and another focusing onchemical vapor deposition (CVD).Our physical vapor deposition group has alot of our industry customers. This technology is a little bit more maturethan a lot of our CVD technologies, which are still more funded by hardcore R&Dwhether that’s for industry or for government. But the PVD group – this overhere on the right are end mills. This is a very, very common thingin our lab. We have a number of companies that send us cutting tools and mills, allthese things, to deposit our diamond-like carbon coating on them to improvecorrosion and wear resistance. They have other projects where they’ve done anti-reflective windows and a number of other things. The other group primarily focus is on chemical vapor deposition. I’ll show in the next couple slides whatone of these groups does and that’s in the fabrication and development ofsingle crystal diamond plates and electrodes and things, diodes transistorsfor high-power high-temperature electronics.And then you split off intopolycrystalline diamond growth. This is where we get into this electricchemical engineering and analysis, where we use these electrodes for wastewatertreatment; we develop sensors; things like that. This image on the bottom right hereshows a silicon wafer that we that we deposited diamond on and then structuredall these individual little sensors. This is something that we very commonlydo and there’s some pretty robust capabilities with respect to microfabrication, especially micro fabrication of diamond.Here is one of theinteresting single-crystal of diamonds. If you ask my colleague for growing diamonds for gemstones, it makes their blood boil. but actually one of our largest competitors was recently bought by DeBeers so they’re going to switch to doing laboratory-grown diamonds. Andthat’s actually you can grow them with higher purity than what you can get outof the Earth’s worth considering. But nonetheless, we’ve had a few one-off type projects from like the MSU Foundation they wanted the Sparty head diamond. You can add different process gases when you grow diamond use impurities tochange the color.While we use boron-doped diamond like I’m going to show for the rest of this presentation, when you grow single crystal boron-doped diamond it’sblue when you don’t add any pure boron or another impurity into single crystaldiamond it’s clear sometimes it’s yellow from the nitrogen content. But in general,this was a single-crystal diamond layer that was grown with no doping orimpurity.Then we sort of structured a layer on top and then deposited borondoped diamond and deposited a little Sparty head on top of there and thenactually this one is a little bit different where we actually irradiatedthe S to make it green inside the single-crystal diamond. So this has beensome interesting stuff! I don’t work on these things but I just wanted to showwe do some pretty wild things with diamonds. It might not be as exciting here asit is at MSU since it’s a competitor I suppose. But this could be an I [meaning block I from U of Illinois logo]. It could be. Anyway so now we can get into a little bit more of the details here.I want to go relatively briefly through what are PFAS, where do they come from,some of the transport exposure pathways, health effects. That’s not really a partthat we’re involved in but I just wanted to touch on that a little bit.Like I said, I’m going to talk about other remediation technology someadvantages and pitfalls things like that and then really spend a lot of time onelectrochemical oxidation and the and the analytical challenges associatedwith this problem. A lot of my slides deal with what’s going on in Michigan. I can give you guys a little more of a backgroundwhat’s going on there. But nonetheless, the folks out in Parchment, which is innear Kalamazoo, haven’t been able to drink their water for quite some timethis is in September 6 [2018]. So since last fall they haven’t beenable to drink the water due to high PFAS concentrations. Here’s anotherthing about Michigan’s next water crisis.There’s them finding it in New York andlandfill sites. Huge issues around airports and air force baseslike I’ll talk about. Here’s contamination in El Paso County Colorado. And then here at the end of September, there is a Senate subcommittee and thishas actually led by Senator Gary Peters, who is our district senator inMid-Michigan and he is really leading the charge at the federal level on raisingPFAS awareness. He’s doing a lot of great things and we’ve interfacedwith his team quite a bit in the last couple of months. So what are PFAS? They’re man-made chemicals that were used for a whole slew ofadvantageous things. One of my colleagues who’s a professor at MSU told me thisinteresting story in the 70s when he purchased a Gore-Tex jacket because itwas just the greatest thing on earth and he wore it for decades and now here youcome to find out that for the reasons, I mean Gore-Tex is great because it’s waterrepellent, but there’s perfluorinated chemicals associated withGore-Tex.There’s always these advantages and disadvantages. Butprimarily we’ve got nonstick coatings, water stain resistant coatings,firefighting foams, vapor suppressants – something to get into a little bitmore in detail. But I really just want to use this slide to mention this here. One additional challenge with PFAS and giving presentations and talking with people is that the nomenclature sort of be ambiguous and I commonly find people calling PFAS – PFOS [pronounced P Faws; full name is perfluorooctanesulfonic acid] which is fine, but at the same time PFOS is an actural PFAS.So that’s what can make this a little confusing. We have the perfluorocarboxylic [acids] which is here – PFOA. You have this carbon-fluorine chain here and you have a carboxylicacid at the end and then the perfluorosulfonates, which is sort of similarstuff we have a sulfonic acid group. These are referred to as the perfluoroalkyl acids. All of these are PFAS. I’m going to talk about precursorcompounds but I’m going to commonly say perfluoroalkyl acids or perfluorocarboxylics or things like that. So I just wanted to set everybody straight on the nomenclature that at least I’m going to use in this presentation. So whatmakes these things so strong? Well, fluorine is the most electronegativeatom on the periodic table; so loves its electrons. Carbon is sort ofelectronegative in its own right. When you have this carbon-fluorine bondit forms these partial charges and when you get formation of partial charges,that’s when the bond shrinks and then become stronger, which makes it moreresistant to oxidation, things like that.Now, right here, we have perfluorobutanoic acid, one of the perfluorocarboxylics. And the reason that I want to just show this is, and I know that some people call it thehydrophilic head and hydrophobic tail but for this presentationwe’re gonna go with hydrophobic head and hydrophilic tail. so I mean here is thehydrophobic head – this bulky carbon-fluorine – and then the hydrophilic tail isthe acid group. But I just want to keep this in mind for some of the absorptivebased technologies that I’m going to talk about.I sort of went over thisalready about what they were good for but as you can see you know this waterproofing of shoes and boots. I’ll talk about why that has now led to a landfill that we’re working with, has a lot of waste from thewaterproofing industry, couches, carpets. Here talks about the jackets. I actuallyread a paper recently where they studied the air quality and sporting goodsstores that had a lot of Gore-Tex jackets and sure enough there’s perfluoronated chemicals in the air. It’s astounding! Food packaging primarily popcorn bags,nonstick coatings. When Teflon came out and there’s all these greatadvantageous properties of Teflon, but PFAS, specific PFOA, is aprecursor to Teflon production. So that’s a pitfall there. These aqueous film forming foams [AFFF – said as A triple F]. These are the most efficient firefighters that exist. There’s 600 sites that have been classified as fire crash trainingsites by the defense environmental restoration program.Which means thatthese are primarily Air Force bases and DoD [Department of Defense] owned sites where they used AFFF on a regular basis for decades. Here’s some this is a little brief overview ofthe health effects. Like I said I’m we’re not really into this but just to kind ofshow. These are a number of different health effects that that one can have. The effects that PFAS can have on pregnant women is fairly astounding and the effects that can have on birth defects. There’s actually a documentary on Netflix about that [referring to “The Devil We Know”]. But really the the reason that they havethis health advisory at 70 parts per trillion is because these bioaccumulate.I think there’s still some ambiguity on where these bioaccumulate; whether it’sin just the fat or the liver or what-have-you. But the reason this is solow is because these bioaccumulate just stick in your body for so long.And this is the EPA health advisory for only PFOA and PFOS.They’re working to lower this actually.In Michigan the drinking water limitsare now 12 and 11 parts per trillion for PFOA and PFOS. For waters that are used as a drinking water source, I believe it’s 400 parts per trillion (PPT)for PFOA and it’s still 12 PPT for PFOS. But for water sources that are not used fordrinking water for PFOA, I think it’s actually up to two parts per billion (PPB). Or no, sorry! It’s actually 12 parts per billion of the limit in waters thataren’t used for drinking water in the state of Michigan. As I’ll show, we’renot going after drinking water analyses so it kind of made things a little biteasier on us, but I’m not quite sure that 12 PPB in the environment is stillgood. But it’s worth considering that this action limit or advisorylevel is 215 times lower than the action limit for lead. Lead has a half life inyour body of 28 days and then you essentially metabolize it and excrete it.Granite it wreaks havoc on your body for those 28 days but nonetheless you dometabolize it and that’s where this discrepancy comes in is because PFASbioaccumulates so readily.This shows just the widespread drinking water contamination. A lot here in the East and Midwest where we’ve had youknow chemical industry and things like that especially out here in Californiaas you can see they don’t have much industry here in the western UnitedStates so there’s not really PFAS contamination, let’s say. But nonetheless,this is very widespread and it’s probably, I mean this is a couple yearsold, I’m sure there’s a bit more now. So where do they come from? I mean thisisn’t just specifically to Michigan but I just did I did put just sites inMichigan. So with respect to vapor suppressant, the automotive, automobile,industry in Michigan is very robust. I will elaborate on this in asecond, but essentially it’s when they’re etching plastics todeposit chrome and things like you have in the inside of your car there is amixture of acids that I’ll talk about that it’s particularly bad for you andthere’s vapors for essence you need to put on top to blanket the vapors.Waterproofing the Wolverine shoe company or Wolverine Worldwide Tannery in Grand Rapids used Scotchgard, 3M Scotchgard, primary ingredient is PFOS to waterproof their boots for the longesttime.Dump their waste into a landfill in Kent County. And then firefighting films.I already mentioned the 600 sites. But we do have the Wurtsmith AirForce Base up in sort of northeastern Michigan where I’ll show some plots ofpretty widespread contamination around that site. This is used as amodel site for PFAS contamination for a lot of people with big research around thecountry. So vapor suppressants. I mentioned how you have all thesechrome-plated plastic in your car. There’s a lot of surface finishingcompanies in Michigan that do work for the automobile industry or motorcycles,things like that. They use a mixture of sulfuric and chromic acid in theetching process and the vapors that come off of this bath of concentrated acidswill melt your mucous membrane. If you breathe it in, you’ll die shortlythereafter. So what they do is you need a vapor suppressant blanket on top ofthese baths of chromic and sulfuric acid so that you don’t breathe the vapors inand as such PFAS are remarkable vapor suppressants.We’ve met with a couple ofcompanies that switched to non-PFAS-containing vapor suppressants, but reallyit’s just also a perfluoronated chemical where there’s maybe four, eight, or sixhydrogens (H) where four, eight, or six fluorines should be and when you’ve got quite anoxidative environment right here. They’re finding that in there effluentsthat there’s PFOS in there. Well it’s okay yeah because this is a fairlyoxidative environment you might be breaking down something and then justkicking off the H and replacing it with fluorine and then you’re transforming itinto a PFOS in the end. That’s another challenge for these forspecifically the surface finishing and vapor suppressant industry, let’s say. Also I’m in Mount Pleasant, about an hour north of Lansing, and thisis also an issue at some of these old refineries where they use vaporsuppressants on top of, throughout, the oil refining process tokeep it from igniting so there’s some concerns up in an in Mount Pleasant aswell.So waterproofing. I already mentioned that Scotchgard produced by 3M was used to waterproof boots at Wolverine. They, likeI said, have dumped their waste into the Rockford landfill. That’s why Rockford, Michigan has fairly robust contamination. I’ll show that in a few slides. Butnonetheless that’s contaminated groundwater and subsequently thedrinking water. So now, last January, they’re getting sued; Wolverine is gettingsued by Michigan and then you see here five months later:’oh yeah!’ Wolverine wants 3M to pay for it.It’s this cyclic thing.When actually in 3M’s defense, they did stop making PFOA and PFOS in theearly 2000s and they did provide a lot of information abouttheir animal testing to certain companies that were using their productsand then that’s sort of up to the companies, I suppose, atthat point. But nonetheless, this is a real common and seeing thisstuff anymore. This is Rockford Michigan. So as you can see here’s the landfill site and this is just all of the contaminated waterwaterways. And I actually was giving this presentation, I used this slide, at apresentation at MSU and one of the students that was there, I can’t remember I thinkshe lived like in this neighborhood or something like that and they knew allabout it, especially when you’re in Michigangiving these talks these things sort of hit home with some people. AndGrand Rapids is a great place to live. It’s a great city but thiscontamination is everywhere. The Wurtsmith air force base. I think I’lljust go through this next one. Here’s the air force base.[Corey holding up hand to mimic shape of Michigan] If you look at Michigan as your hand, it [Wurtsmith] sort of likemiddle way up your index finger. Here’s Van Etten Lake [blue middle of slide] and here’s the Wurtsmith air force base [south west of lake]. When they built the air force base as far as I know they thought that if they contaminated anything, it would just get Van Etten Lake and they would delude it and wouldn’t go any further. But here you see these plumes have reached Lake Huron [right of slide]. So they didn’t really look beyond VanEtten Lake for some of those PFAS and then when you started digging a bit, thisis where they’re finding these. All these green dots are residential wells. So as you can see all thesepeople around this base are contaminated with with fairly significant levels. Imean, even this light color here; that’s what 51 to 300 PPT.Up here you get upinto a thousand to five thousand [PPT]. The people around here are very concernedI’ve went and had a meeting with the superintendent of the City of Oscoda, orOscoda Township, and there they’re working to implement activated carbon; Ithink that actually they have already. As I’ll talk about in a little bit there’s some pitfalls that go on with that as well.I also want to mention PFAS and landfills and landfill leachate.Specifically because our, and I’ll get to this when we start talking about ourtechnology. We have found two niches that we think are most applicable and one isin landfills and landfill leachate. This was a paper that was published Ibelieve in – yeah 2013 – by a number of groups, Morton Barlaz – a big guy inlandfills at NC [North Carolina] State and then here’s Jennifer field who’s an analyticalfaculty out at Oregon State University and she’s done a lot of work in PFASanalyses.But nonetheless, they estimated 61.1 million meters cubed of leachatethat’s been sent to a wastewater treatment plant; 79 percent is inlandfills in wet climates. In Michigan we’re sort of like a wet / dry climatedepending on the time of year. But nonetheless, they also estimated 560 to 640 kilograms of PFAS were sent to these wastewater treatment plants fromleachates. You got your traditional activated carbon and thingsthat has a lot of issues with a landfill leachate because there are alot of other co-contaminants a lot of organic load and things like that. Butfor the same reason that activated carbon has some issues capturing shortchain PFAS is the same reason that these landfill liners have a troublecapturing short chain PFAS.The leachates that we’ve looked at we’veseen a lot of short stuff, short chain carboxylates and sulfonates because these are a little bit easier to sneak through these landfill liners. I saw this on a poster that you guys [meaning ISTC] have as well. It’s a great figure. This shows you where all of the contamination can come from. There’s a few lakes in Michigan where we can’t eat the fish there’s a few counties where you can’t eat the deer. All stemming fromPFAS contamination. This is something I’ve pulled off MDEQ [now EGLE – MI Department of Environment, Great Lakes, and Energy] that shows us an additional water cycle and how it can get out into the rivers and the groundwater and be transported to a variety of differentlocations.At the end of 2000/2002, 3M phased out production of PFOAand PFOS. Eight other major chemical manufacturers committed to doing this by2015, however we’re still just talking about PFOA and PFOS. What was the solution then? ‘okay well let’s make Gen X that’s just C6.’ That’s been the workaround of the regulations is, let’s just get aroundthis by shortening the chain and then continuing. Down in North Carolina,Chemours, which is a spin-off of when Dow and DuPont merged, and sure enough theycontinue to make Gen X.And actually, DuPont manufactured their own PFOS andPFOA after 3M stopped making it. It’s worth considering. But nonetheless, toelaborate on that, this says 400 plus. You can read other people say a thousand plus. I mean there are hundreds if not thousands of precursorcompounds. As it says here, there’s a specific lack of understanding on thetransformation pathways of these. A huge issue for us, since we do destruction and we do defluorination, is trying to close thisfluorine mass balance. Several times you can see where in literature, and we’ve had this happen to us, where we get more fluorine back than wethought was in there. And that’s because the analytical methods we use; theycan’t measure. I mean they’re still carbon-fluorine and here’s N. Sothis could be four, six, eight, whatever but you have these amine groups here andthese can be transformed depending on the environment into a more recalcitrantperfluoroalkyl acid. So that’s why you’ll see some people willmeasure something in the influent of a plant and then the effluent will behigher and they don’t understand why will you know you didn’t look at allthese.Throughout your processes when you’re treating water you’re mosttransforming them into a more recalcitrant PFAA. This is somethingthat we’re attempting to tackle and look into to try and close thefluorine mass balanced. This is one of the major hurdles and this issue ingeneral is understanding how much fluorine you’ve got in a givensample. I just wanted to say there are thousands of perfluorinated precursor. They call this the dark matter. Here’s all the stuff we knowabout [outside ring] and then this big vortex of precursors that we don’t really knowanything about.To talk a little bit about remediation technologies, I’m gonna focus quite a bit on activated carbon and ion exchange and then talk aboutsome locations where they’re implemented and some promising results that havebeen reported. Some other technologies and UV methods whether that’s oxidative or reductive. I am not really going to talk about thermal treatment orreverse osmosis because I kind of wanted to spend a lot more time on that on theEO [electrochemical oxidation]. I think with a quick check at the clock, I will go through this a bit quickly. This is an activated carbon matrix. Activated carbon relies on chemicaladsorption to remediate PFAS, let’s say. But then this has the sort of mezzopores – up here – that kind of sneaked down into these micro pores. And because thisrelies solely on essentially the hydrophobicity of the PFAS,that’s why you can have some difficulties of short chains because theshorter chains are less hydrophobic than the long chain and typically the longchains are higher in concentration so if you have a short chain that’s absorbedthe likelihood of a longer chain coming and kicking it off and it’s sneakingthrough this micro pore is quite high.That’s why you’ll see breakthroughcurves, which I’ll show, of a shorter chain PFAS on activated carbon arerelatively poor. Long chain it’s okay. But that’s one of the reason that you can have some issues with the shorter chains like the four, five chain carboxylates andsulfonates. Ion exchange gives you an added advantage and remember I said thishydrophobic head hydrophobic tail so the activated carbon is really gearedtowards that hydrophobic head but with ion exchange that you can synthesize orfabricate resins that have of dual sites.You can have the crosslink that can adsorb the hydrophobic portion but then you canalso have a cation exchange or an anion exchange resin that canelectrostatically attract that acid group. So you’ve sort of double yourcapacity and then you intrinsically eliminate this issue ofone chain length being more hydrophobic than the other because youcan get a bi-electrostatic attraction. That’s some of the advantages ofusing ion exchange – that you have this dual capability. A Brita filter isactually a combination of both ion exchange resin and activated carbon.However this ion exchange resin doesn’t have this dual – because there’s a lot of different types of resins – but unfortunately a Brita filterwill not get the PFAS out for you.But I just wanted you to know this is acombination of activated carbon and ion exchange resin. To elaborate on IX [ion exchange] a little more, Emerging Contaminants Treatment Technologies – they’re located inMaine and they’ve designed this Sorbix Pure [trademark] IX resin and this is thebest absorptive technology that I have seen to date. It has this dual site. I’m not sure exactly what they use obviously; it’s proprietary. Let’s put it this way the country of Australia flies massive – I can’tremember the type of plane – it’s huge cargo planes to Maine to pick upshipping containers of this resin and they fly it back to Australia and thenthey implement in Melbourne. They are treating several million gallons per day with this stuff. Trouble is the resins made in China nowso it’s gotten more expensive because you’ve got to some import tax and so there’s some interest in being able to regenerate the resin and not just take it out and burnit. That’s where we sort of come in. And I’ll talk about that in a second.Here’s some other this is a system where They did a pilot scale test.Ibelieve this says in Austria. They also did this I think the data meant to show is actually from Air Force Base in New England area. But nonetheless, they stoodup activated carbon and ion exchange against one another. Here’s abreakthrough curve. You have bed volumes, whichessentially the absorptive capacity. Then here at the top thisis the influence. So they had about 10 PPB Here’s PFOA [limit in red dash]. So the blue and the yellow are 2.5 and 5 empty bed contact time. That’s essentially how long the the water was in contact with the activated carbon orthe resin. But as you can see the five-minute empty bed contact time onthe resin, you get over 10,000 bed volumes. You look at activated carbonthat’s practically 2,000. So you’ve increased this by a factor offive before you get breakthrough with PFOA. PFOS looks even better. Here isactivated carbon breaking through in about 1,000-2,000 bedvolumes again. Here’s at 2.5-minute empty bed contact time withthe resin. Again got about 10,000 of it. And then they didn’t even getbreakthrough of PFOS with this resin.Now I don’t think I putthe shorter chain compounds in there. This resin does have a little bit of anissue with PFBA. So the perfluorobutanoic acid. the four chain carboxylate. That’s one Achilles heel of this is that the four chain carboxylateis a little bit of a an issue for them. I’m not an ion-exchange expert soI’m not exactly sure why that is but it is something that they showed and inthis paper here. Like I said, what happens when saturation occurs. If forGAC [granular activated carbon – pronounced gak] you take it out and burn it – you incinerate it. Typically that’s done at 800 to 850 degrees C for normal saturated activated carbon but for PFAScontaminated GAC, you got a jack that up a few a hundred degrees C extra. nowthere is again a little bit of ambiguity on the pollution of PFAS in the air.I saw a study, I think it was in the Netherlands, where they studied the gasescoming out of an incinerator and they still found PFOA and PFOS in there.I read a paper where they were finding PFAS in the blood of polar bears at the North Pole. so they think that there’s some transport in the air from these incinerating processes. So it’s not quiteas advantageous, let’s say. But with IX you can regenerate it by adding a solvent-brine mixture. So essentially you add, commonly it’s a methanol and sodium chloride where the methanol will desorb everything thatwas chemically absorbed of the resin. The sodium chloride kicks out all of theelectrostatically attracted PFAS you might have in there. And then so as an example, let’s say you have 100,000 gallons of water. You treat itwith your resin. Your resin is saturated. You run your solvent-brine mixture throughand then you come out with let’s say five hundred gallons of of this solvent-brine concentrated PFAS mixture. Common practice is to distill the solventback off so you can reuse it and you’re left with a couple hundred gallons ofvery concentrated, very salty, PFAS waste, which is called a ‘still bottom.’ And that’s again where our technology comes and I’ll talk aboutthat in a second.Here’s actually another paper published where they they actuallytook these regenerate concentrates and they used, they degraded PFOA and PFOSover time. As you can see this is in milligrams per liter. So this is amillion times more concentrated than the PPT levels that were talking about fordrinking water. So I think I’m gonna skip this just because for the sake of time. Ithink I’ll go through this relatively quickly as well and just highlight thefact that this is extremely difficult to analyze. And this is sort of a bottleneckfor a lot of people and that you can either do EPA method 537 [PFAS detection in drinking water], you can ASTM D7979 [other aqueous media], all of which need a triple quad mass spec. Sometimes they need time-of-flight mass spectrometer. A lot of expensiveinstrumentation, but that’s the only instrumentation that canget down this low. So you don’t really have a choice at least for currenttechnology.This sample analysis can be… We’ve gotten $250 to $400 todo a total organic fluorine. it’s even more than this. So this is abig bottleneck for a lot of people, but I’m not gonna get into the nitty-gritty.Another thing we can do is since we do de-fluorination,we can use fluoride ion selective electrodes at higher concentrations as away to indirectly monitor our PFAS degradation. We did this for a few ofthe figures that I’m going to show. It’s $900 for one ion selective electrode [ISE] prob that we can use for a few months before you have to buy a new one but that’s still a little bit more cost-effective. Thedownside is that we don’t get this extra layer of information about the mechanism and and what sort of PFAS we might be making in solutionbased on our degradation processes.I’ll just highlight this. EPA method 537 getsyou about 14 to 17. The modified will get you 20 to 25 and then ASTMmethod can get you 35 to 40. The trouble is a lot of the ASTM methodsthey use direct injection. So they don’t really do a bona fide extractionprocedure before they send the solution through the to the mass spec. As I’llshow, our process these require a degree of conductivity and we are making ionsas we treat so direct injection is sort of a nightmare with our samples. Okay; sonow we can get into the good stuff. [mumbling] We’re using electrochemical oxidation. What this shows here in the top right and Istill have electrochemical advanced oxidation, which is the generation ofhydroxyl radicals or some sort of oxidizing agent that we can generate atthe electrode surface.I’ll talk about the ambiguity of how theprocesses go for PFAS. We have an anode and cathode or a seriesof anodes and cathodes in solution and we’re applying a high voltage or highcurrent through the surface. In our space high voltage high current may be 5, 10, 15 volts and then maybe, depending on the size ofthe electrodes, maybe 5 to 10 amps. We’re talking like anywhere from 10 to 150 milliamps per centimeter squared iswhere we’re actually operating. I just have organics here.Organics are real common for traditional wastewater treatment. Anorganic will interact with the electrode surface, whether that’s direct throughdirect electron transfer at the electrode surface or we can generatehydroxyl radicals at the anode surface and that can go scavenge an organiccontaminant and then effectively oxidize it or mineralize it into its components,which is CO2 [carbon dioxide] and water In the case of PFAS, we got CO2, water,and fluoride ions.That’s an advantage of this technology is that it is destructive. You could do mineralization. However, if you look hereat the cathode reaction, it’s kind of hard to see, but we are making hydrogengas. So we generate about 0.4 liters of hydrogen per amp hours. So this is a onething to consider is that we do generate significant hydrogen especially whenwe’re using diamond cathodes. Diamond is a very – this reaction occurs veryfrequently on diamond. But again I sort of talked about hydroxyl radicals alittle bit but we don’t always – there’s some ambiguity in the literature as whetheryou need hydroxyl radicals or not. The hydroxyl radical is themost powerful oxidant that one can generate compared to even ozone, bleach,hydrogen peroxide, things like that.But again there’s not always that we have to use hydroxyl radicals. But nonetheless, it’s crucial that anything we’re tryingto oxidize gets very, very close to the electrode surface I’m talking nanometermaybe it’s sub-nanometer distances from the electrode surface. Because even ifwe’re generating a hydroxyl radical these are so reactive that the lifetimeis that’s few nanoseconds. So you’ve got to get these to the electrode surface inorder to actually have something occur. I’ll talk about that. I think I’ll gothrough this…I’ll just breeze through this but essentially, for traditional wastewater treatment, if youknow the molecule that you’re after, you can actually do a series of calculationsto determine the COD – the chemical oxygen demand – that you have and you canactually do a number of calculations where you say okay I want to go fromthis COD level to this COD level and we can actually calculate the theoreticalcharge that we need and then we can actually calculate the actual area thatwe might need.I’m not going to go through this for the sake of time. Butnonetheless, for traditional wastewater treatment practices, when you know thecontaminant that you have and it’s not PFAS, you can actually do thesecalculations. For PFAS, unfortunately, of course you can’t. Just ingeneral it’s a nice little tool to have. This kind of elaborates on this need toget things very close to the electrode surface.This is a model that wasdeveloped by – I’m forgetting his first name, his last name is Comninellis [meaning Christos Comninellis] but he’s done a lot of theoretical work in wastewater treatment and electrochemicaloxidation. But here you have COD. So this is basically the amount of oxidative -the amount of oxidation that we need in order to reduce what sort of contaminantwe have in solution. Here’s current density on the Y [axis]. And so you have this mass transport and current limited region. Unfortunately for PFAS, because the concentrations are so low – see this is ingrams per liter so we are one billion times lower than this – so we’re almostalways in the mass transport limited region. We’ve had to do someinnovative thinking with our reactor design to ensure that we’re getting downto these low levels and this is also why we’re going after two specific nicheapplications that I’ll talk about. There’s some ambiguity in the literatureas to whether you need hydroxyl radicals or not.Here’s one specifically thatshows that it’s a direct electron transfer process to get it started andthen you need the hydroxyl radical to get an intermediate andthat’s how you cause defluorination. Like I said, we’ve done these experimentswith hydroxyl radical scavengers and we still get good degradation but thenthere’s other folks that report things contradictory to that. And so if there’ssome other people that contradict. so it’s a little bitdifficult in this area to go off of literature. And again, I really personallythink that it stems from the variability and analytical that one group might useto the next; I think that’s really the big issue. But we’re using boron-dopeddiamond. So the reason the boron-doped diamond is so advantageous is that ithas the highest oxygen over potential of any electrode material that one can use.It’s a wide bandgap p-type semiconductor, so it’s great anode material. Here, thisis just a voltage current plot.You can see platinum, gold, glassy carbon,and diamond. Each time this current increases here, that’s the oxygen overpotential where you’ll begin to do this reaction right here and as you can seethat does not occur on diamond till beyond about two volts. Now if we were toscan even further you would see that this really jumps up and actually it’scalled what’s called the Tafel slope of this oxygen over potential. That can give you some interesting information about the efficiency of hydroxyl radical production should we need that. But nonetheless, we have a lotof control over the growth process. These are boron-doped diamond films. Each one of these in this micro crystalline film, these areindividual diamond grains that you can see here. This is a very dense coatingsabout 5 to 10 micrometers thick on primarily metal niobium substrates forthis application.But we can also make nano crystalline diamonds. So this scaleright here, this is one micron [right gray] – this is 5 microns [left gray]. You can’t even see the crystalliteshere [right gray]. But the reason we don’t use nanocrystalline diamond for this isthat each time a diamond crystal grain meets another diamond crystal brainthat’s where SP2 hybridized-carbon hides. We want SP3 hybridized-carbon because SP2 hybridized carbons is glassy carbon. We need the advantages ofdiamond. So if we have nanocrystalline diamond, We have a significant amountmore crystallites therefore more grain boundaries, more SP2.So when we go pushing this voltage current up, we just etch the SP2 to carbon dioxide for the samereasons that we can oxidize an organic contaminant. We try and – I won’t reallygo into the doping procedure and all that – but we gear ourprocesses towards high SP3 content. [mumbling] I think I’ll gothrough this relatively quickly as well. But essentially if we take methane gas,hydrogen gas, and diborane, under specific reactor conditions. Here’s amicrowave CVD reactor. We essentially add microwave power and we created a plasma where we ionize these process gases and then we will getdiamond growth. So this is one way via microwave assisted CVD. The growthrates are quicker and faster in microwave CVD. However, the substrates can only be up to six inches in diameter. This is very this is excellent for someof our micro fabricated sensors and things like that we use microwaveassisted CVD. But for this for PFAS and coding these electrode use hot filamentCVD, which is essentially like a gigantic toaster, which I’ll show right here.So wehave these tungsten filaments that are heated to a well above 2400 degreesCelsius and that’s what ionize is the process gasses and then you get diamond growth down here. In this system we could do 4 six inch wafers at once if we wantedto but in this case we do plates and things like that. So that’s why this is alittle bit more advantageous even though the growth rates are a little bitslower. Here is our laboratory scale system that we use at the current moment.We part we collaborate very closely with our Fraunhofer spin-off in Germany – Condias.There a very close colleague of a number of my colleagues. But essentially,we have these two reactors. We have a parallel plate reactor, and we have thisflow through reactor. And I can show the pieces of the flow through reactor. Butthis is really for high concentration. When I say high concentrations we’retalking like hundreds of milligrams per liter. This is probably true fortraditional wastewater treatment. We don’t really use this for any of the PFASbecause that mass transport is not great in a parallel plate reactor. This is whenwe’re in the current limited region, where we have so manythings oxidize and not enough current to supply, we’ll go with the parallel platereactors so we have more area. For something where we’re always in the mass transfer limited region, we use this flow through reactor so we increase thelikelihood of getting something to the electrode surface. This is a colleague ofmine as well at CDM Smith – Charles Schaefer.He’s had some SERDP [Strategic Environmental Research and Development Program – pronounced Sir-Dip] projects. He’s done a number of work in PFAS remediation using our electrodes. I will say he’s probably got even more experience using our electrodes for thisthan we do because he’s been doing it for quite some years. But he’s alsoinvestigating these transformation pathways. We’re proposing somethings where we might be able to use electrochemical oxidation to transformthe precursors into the more recalcitrant compounds and then ramp upthe current density and remediate them at the end. Kind of get to get two birdswith one stone. But here’s some of our data. PFOA on this slide. PFOS on thenext slide. So like I said before I get into this, we are after two applications.We are not treating groundwater plumes.We’re not treating drinking water andwe’re not an end of pipe treatment method at a wastewater treatment plant.If you look at this graph, here’s 50 milliamps per centimeter squared. In anhour, we’ve taken it from 6 ppm down below 1 ppm. So we run these tests forjust about another half hour to 45 minutes, we can effectively get all of this out.However, if you look at 50, this says watts per liter because thisis just a one hour test for these calculations – 88 watts per liter. If you extrapolate that up to 41 million gallons, we are talking about 13.74 gigawatts. That would need per day to power a reactor to clean 41 million gallons of water. That’s notgonna happen! So we immediately wrote all that off; that’s not something wherewe’re going to be able to fix. So we thought ‘okay where is this technology the best for, its in high solution complexity low solution volume.’ So that’swhere we get into reject solutions for reverse osmosis.Those regeneratesolutions that I spoke about for ion exchange because these technologies canhandle millions and millions and millions of gallons and if you were be able toregenerate them more often and destroy it with electrochemical oxidationbecomes a little bit more viable on a large scale or in landfill leachate. Like,we’re working with the city of Grand Rapids. They treat anywhere from 50 to 250 thousand gallons per day. We think 50 maybe 100 a little bit above that thousand gallons per day is anattainable thing as a primary treatment option but we still have to vet thetechnologies. We’ve got a lot of other organic load, ammonia.As I’ll show, that’ll be not necessarily interference but it’ll just eat up sites for oxidation ofPFAS. What we are trying to do: Since we can’t use this experimentalmodel like I showed, we had to somehow do this experimentally. So we when we didthese tests of varied current density, we found in the first 15 minutes there wasan advantage of using a higher current density like 50 milliamps for centimetersquared. But then we looked at the slopes of all the lines or the rate constantsof the lines thereafter and they were all similar. So we thought, ‘okay well whydon’t we just use the high current density for the first 15 minutes andthen reduce the current density thereafter and see what we get.’ And sureenough if we run this 50 million per centimeter squared for 15 minutes reduceit to 5 for the remainder of the time, we have about twice as much PFOA left afterone hour. If we run it for a half hour longer we get below this and we’resaving about 5x on the energy.Even though this still is toomuch to do as an end of pipe treatment we still want to design a way where wecan save as much energy as possible. For PFOS, we did the same thing but we found that 10 milliamps per centimeter squared was actually just as efficient as 50 sowe didn’t really go through this whole rigmarole of mixed current densitiescombined current density. What we’ve move forward with now is we either apply 10 milliamps per centimeter squared for our treatment or we do ourcombined 50 and 5. Here is a comparison of measurements done with a fluoride ISE and then done by LCMS. Michigan State doesn’t have a lot of robustcapabilities in PFAS analysis.So we can only measure a PFOA; so that’s why wecould only do PFOA for this one. Here this is 1, 5, 10, 25, 50, and 50 and 5 [top left to bottom right]. We thought that even though our LCMS measurement is only going to giveus the PFOA, we thought, ‘well if we reference that against our fluoridemeasurements, we know that we’re probably generatingshort chains.’ Because if we don’t get all the fluoride back, we know we still havecomplex fluoride but the LCMS will tell us actually where the PFOA is at.Andso as you can see once we get down into 25, 50, there’s no PFOA remaining.But as you can see by at ISE, there is some PFOA remaining. So that’s where wethought for the first time, ‘okay we’re probably generating some short chains.’And then at the same time, we also verified this with our 50 and 5. Again, ifwe run this for another half hour, we get down to where we need to at 50. Butnonetheless, we went a little bit further and we did the EPA 537 method. That’swhat this data shows here. We started with 2 ppm of PFOA. This was a more of aregenerate style solution; so that was a little bit more concentrated. And within4 hours we’ve taken it from 2 ppm down to 2 ppb. Again, this is water that wouldnot be used as a drinking water source the limit in Michigan is 12 ppb. So thisis good enough for use – for that specific application or niche – in the state ofMichigan.As you can see down here at the bottom, Here is 7, 6, & 5 of thecarboxylate. So in a half hour we generated about 15 to 20 ppb of thoseand then again by 4 hours those were completely gone. This was a good resultin that we were able to remediate the short chains as well but the detectionlimits for this method were about 8 ppt. So that’s where we thought in our flowthrough system maybe we do have efficient enough mass transport becausewe would have seen these if they were still there. So that was one sort ofpromising thing and we’ve done a lot other experiments. We’ve workedwith leachates unfortunately I thought I would have the sample analysis backbefore I came – that was my hope – but I still haven’t gotten the results back yet.Butwe’ve done a lot of our mixed current densities and things like that and inlandfill leachate is doing 24-hour experiments and this shows that thecolor is changing. Tt doesn’t really do much for you with respect to PFAS but Ishould have an update for that relatively soon; so I apologize aboutthat. But these are two separate experiments. And this data is actually detachment from one another. This was a wastewater sample. These are the leachatesamples. I think for the sake of time, I’ll go through this a little bit quickly as well. Nonetheless MSU is one of the only universities doesn’t send their food waste to a landfill or animal waste – well I mean they basically put the animal waste in here. And this is a massive anaerobic digester that they have. And they have a solar-powered unit across the street where they havetheir an anaerobic digester, they have an electric coagulation system to remove some solids.And then they have an RO. Through this process they were ableremove everything except the ammonia. That’s when they came knocking on ourdoor to see if we could remove the ammonia and so we did this in poultryplot processing water. As you can see here, here’s as a function of currentdensity and these poultry processing waters. Here we start out with totalammonia nitrogen, total nitrogen [TN]. As you can see they are – almost all thenitrogen in there is ammonia and then this is a function of currentdensity and so as you can see once we get up to 50 and 75 that’s where wereally can remove a hundred percent of the ammonia. But as you can see, we’veconverted about twenty percent of it to nitrate. We did nitrite andnitrate measurements and it was exclusively this remaining TN was allnitrate, which is okay for this process and what they were doing because theywere using for irrigation water so that was okay.Here’s so some model reactions.But nonetheless, like I said, this is not, as I’ll talk about in a second -electrochemical oxidation is not selective, which is sort of a blessingand a curse. It’s a blessing that and a leachate, we could get rid of theammonia and the PFAS but it’s also a curse in that we make some toxicbyproducts that I’ll talk about. One last thing is, we’re also – this is sort ofnewer data – but we’re also working on 1,4 dioxane, which is another emergingcontaminant. We’ve done current density studies. As you can see it really – even at10 – within I think a little less than four hours, we’ve completely remediateremediated the 1,4 dioxane. We’re also sticking at high levels, aswell, because I in exchange is very efficient at moving 1,4 dioxane.We canregenerate it in the same manner that you do for PFAS. So we’re looking at 1,4dioxane as well. And the reason that is: Here’s the cityof Ann Arbor. There is a massive 1,4 dioxane plum in Washtenaw County inMichigan. So this is also a significant concern in the state and again we’reworking with – we’ve interface with Senator Peters team about 1,4 dioxane and primarily about PFAS but this is another thing that’s on our radar.Okay; so limitations and concerns: This blessing and a curse thing – so when we have chloride in solution, depending on the current density, usually people sayyou need hydroxyl radicals to do this but we make perchlorate. So that’s one -and that’s actually at a specific Achilles heel of diamond in this method.Other materials like mixed metal oxides are specifically Magnli phase titaniumoxide is probably the biggest competitor to boron-doped diamond. You do notgenerate perchlorate with Ti407. However Ti407 has some issues treatingshorter chain compounds.So every single one of these technologies has its ownlittle Achilles heel/advantage to think of things like that. So this is gonna bea big a big puzzle. And I already talked about the energy consumption. And then,like I said, for ammonia we do convert it to nitrate, which could be a problemfor a wastewater treatment plant. So in conclusion. [mumbling] iI conclusion no treatment option is going to be the sole treatment option for PFAS. This is goingto be a puzzle of multiple treatment technologies that are going to be usedto solve this issue. I talked about EO. We’re going for low volume highconcentration or complex matrices. Still have a lot of research to do in healthconcerns, toxicity, fate and transport, etc… Senator Gary Peters is really leadingthe push at the federal level. And I said in Michigan – actually this says “arecoming” – but this recently they changed this. Like I said the Brita won’t quitedo the trick to get it out of your water at home.But there is now NSF certifiedtechnology – I’m forgetting the name of the company – it’s about 200 or 250dollars on Amazon and that is certified by NSF to remove PFOA in PFOS. So on thelighter side of things, we’ve been in the news a little bit. Whether that’s a good ora bad thing, I gave a talk at the MSU Bioeconomy Institute. Here’s us the GrandHaven Tribune. Bill Huizenga endorsed us in one of his speeches; we didn’t evenknow. So that was interesting. He’s a congressman in Michigan. This is a MSU’s article. And then we have some of the bad ones. These were all good, but thenthis is a guy on NPR who I remember I said diamond crystal grains because I was talking about this; he reported diamond crystal brains! so that was notideal. So we stopped with him. And then here’s these folks I interviewed withthis guy; I said exactly what I said you guys were after these two nishaapplications – we’re going after wastewater complex samples – and then they run astory that night on NBC grand rapids toxic tap water! And then it says ‘MSU’s PFAS pulverizer is cleaning water.’ And this guy had the perfect, perfect news anchor kind of like narrator voice.[Cory speaking in a dramatic lower octave voice] so him just like talking about the PFAS pulverizer! [Cory talking in normal voice] It’s classic you can look it up and watch it. It’s hilarious! It’s not funny because he misreported what we said. But it’salso – it’s ridiculous in all reality. But nonetheless, just at the end of lastmonth in chemical and engineering news this woman Kerri Jansen did an articleof “Forever Chemicals No More?” This is the best PFAS related article that Ihave read from a scientific merit point of view that a reporter asked person did.She did for different destructive technologies.We were interviewed for theelectrochemical part. There’s some other: There’s some plasma trees an things going on at Clarkson University in New York. There’s other people workingon destructive technologies. We’re not the only ones using electrochemicaloxidation. we’re not the only ones that make diamond electrodes. We’re justhappened to be good at it and we’re applying it to this. So I want to make it -we’re not really we’re not reinventing the wheel here but at the same time thisisn’t something that we just cooked up in our lab and invented there’s otherpeople working on this. So with that I’ll acknowledge mycolleagues. This is my graduate student Mary [left]. This is all this work has been doneby her. This is Vanessa [right]. She’s a new graduate student finishing her firstyear. That’s sort of getting into this as well. Some of my other colleagues andstudents and then an environmental consulting firm we’ve worked on it’shelped provide us with with real samples to work with.And then the folks at MSU’s communications and brand strategy. Because without them, I wouldn’t reallygotten the word out and since then we’ve gotten a contract from the City of GrandRapids to look into electrochemical oxidation in landfill leachate and theysaw this article and approached us. While I was very apprehensive about doing this news article, [mumbling – comprehensible] it’s more or less. So with that that being said, thank you. I appreciate it. Sorry, I have a tendency to talk longer than that a lot of time that I’mgiven I think I did it again but I hope you enjoyed it and I’m happy to take anyquestions. [applause] [Beth] thanks for a great presentation. [Beth] Before we take questionsin the room, I’ll just remind our online audience that you could type in yourquestions through the GoToWebinar toolbar and I will read those to ourspeakers.Okay questions from our audience? [audience member 1] Actually, I have two questions for you. First thing is: have you tried to calculate the Faraday efficiency byexcluding the water oxidation reaction? [Cory] By excluding a water oxidation? [audience member 1] Yes, becauseunder the high potential or the high current density you canavoid the water oxidation. we then have only the currentdensities – is the mixture of the water oxidation plus the PFAS oxidation, right? [Cory]Yeah, that’s a good point. I can’t say that that’s something that we’ve done. Wedid try and calc. We did a number of experiments to try and calculate theFaraday efficiency and we did not have much success. But no I don’t think we didn’t probably differentiate between the wateroxidation reaction. Perhaps that is something that we should look into. [audience member 1] And the second question is: I’d be worried about electrolyte oxidation status under the high potential.Forexample, like if you are using the sodium sulfate or the sodium perchlorate as your electrolyte. So then under the high potential, is there any chance toget sulfates ions to decomposed, more oxidized? [Cory] Yeah so I mean that’s – to dowhat’s called the total oxidizable precursor assay, which is how you can get.So if you combine the mass spec measurement with total organic fluorineand then the total oxidizable precursor assay, that’s the way to closethis fluorine mass balanced and really get the full idea.Trouble is top assay is700 bucks [$700]. POF is 700 bucks and then you got the the analyses. But what they do inthe total oxidize will precursor assay is they rely on that breakdown ofsulfate to make peroxidesulfuric acid or persulphate and that… [audience member 1] based on the standard reduction potential? [Cory] Yeah right. and so we believe that in sodium sulfate we’re making persulphate as well. We haven’t really had any issues with, let’s say, breakingdown electrolyte, let’s say, we thought. That’s why with some of thesecompanies that were working with doing the regenerate solutions, they all wantto use sodium chloride because it’s the most efficient but we’resitting there thinking like, ‘well… how about sodium hydroxide, sodium sulfate.’ So we’ve had some success. I didn’t say… This was internally fundedfor 16 months and we spent a lot of time on the interface of niobium and diamondbecause you have to pretreat the niobium substrate very, very intricately or elseyou won’t get good adhesion. So we have to etch the substrates in a veryspecific way so we don’t get oxide formation or else that’s wherewe get delamination.A lot of our timewas spent optimizing the coding so I wouldn’t say that we… We’re still learninga lot ourselves. We don’t have all of the questions answered by any stretch ofthe imagination. Like I said, this is stuff that we’re still learning as wellbecause we really focused a lot on developing the reactor and the codingand stuff like that. And we can always talk some more as well.[audience member 2] Do you have any idea what the costs would be on like a per gallon basis? [Cory] a per gallon basis…The issue with that is that, we don’t know yet what currentdensity we need to use.So it’s really difficult to say. I can say that thatsystem that I showed there is about $60,000 from justoff the shelf, let’s say, and a little under half of that is all tied up in theelectrodes. So you’re talking for that big parallel plate reactor and thisother reactor were on the order of $10,000 to $15,000 in just the electrodes.So what we’ve designed – not designed. We’ve sort of specked out a pilot scalesystem where the electrode area will be maybe ten times larger and that’s againthe larger we get the more expensive they get because in diamondunfortunately the more space you take up in the reactor it’s more expensive it gets. So actually make larger substrates actually more expensive on aper unit basis. So the the pilot scale system we free is about $160,000 and thatcan do ten thousand liters but again over half of that’s tied up in theelectrodes and that doesn’t count the energy costs as well.So like I said, thisisn’t cheap. This is not cheap; absolutely, it’s not cheap! But I don’thave a bona fide number for you just because the we don’t know what currentsthat we actually are gonna and that because at 50 milliamps or 100 millionper centimeter squared the lifetime of the electrodes is a heck of a lotdifferent than a 10 so like and then you start bringing that in the equation okaywell can I get if i’m at ten can I have a five-year investment on my electrodesversus two years.So this is all so many moving parts, like i said, that we’re stilllearning a lot ourselves. [audience member 3] So you mentioned your process is mass transfer limited. Isn’t possible to fabricate a slurry instead ofa flow through or a flow by electrode to have a slurry offlow electrodes? That’s what’s done, for example, in capacitive DNA gene transfer.[Cory] yeah, hmm… let’s see here. The trouble is is that we’re sort of limited in the substrate geometries that wecan coat. That’s another sort of disadvantage of diamond is that we canonly grow on a certain number of substrates because they had the very lowthermal expansion coefficient and so we have the even machining these flowthrough electrodes is a little bit of a challenge I suppose that would bepossible, though. That would be interesting. I guess I don’t know as muchabout things like that so it’s something.[audience member 3] You can get to the nanoscale level that create these small spheres. [talking over each other] [Cory] we get a lot of people who ask us about diamond powder to increase surface area to sort of mitigate this and in full disclosure we’ve grownfreestanding diamond films and then we’ve detonated them or we’ve giventhem to people to detonate because nano diamonds in general thataren’t doped are used for a lot of drug delivery processes.And usually peoplejust take undoped diamond and they just detonate it and they make nano diamonds.You have a little bit of a difficulty and I think you know like 10 to 60micron crystallite sizes. But that is something that we’re we’re trying wehave a prototype reactor fixture for that hot filament system that will itsort of comes out like this and it’ll rotate and we could put diamond powderin and coat it with boron don’t diamond overtop. But it’s… the hot filament CVDthose those filaments I said are 2400 degree C so trying to find the rightmaterials that we’ve I could; we’ve given it a shot a couple times and it’s achallenge.But nobody can provide that so that’s why we’re sort of looking towardsthis boron-doped diamond as we get asked a lot for powder for that exactapplication. And we get into these sort of issues sometimes wheresomebody comes and wants something like that and they want… they’re gonnago write a proposal or something to kind get funded both like well actually wewant to write the proposal. So sometimes we have to turn people away because theywanted to do things that we want to do [Cory laughing.] That’s why we’re really open to collaboration. I’ve said it to anumber of you guys here is that we don’t really like to be a provider of material -although we can – then that’s sometimes that’s all people want andthat’s fine. But most of the time we like to develop it in some sort of way thatit can be a collaborative efforts where we’ve got some flexibility. Wecan change doping; you can use different crystallite sizes; you can dodifferent film thicknesses; all these different things.Noteverybody wants that flexibility but that’s sort of where we try and gearthese things as towards a collaborative effort where we can do some developmentand some knowledge sharing and things like that. So that’s kind of how we rigthese projects. [Beth] Do we have one last question from the room? [audience member 4] I have a quick question. Do you know what is the cost of water treatments with the sorbates ion-exchange that was made? [Cory] So I do know a ballpark, that resin is between $400 and $425 per cubic foot. That’s the only number I can probably give. And Idon’t think it was cheaper but then they I think they outsourced it to China orso and now they have to pay the import tax.[audience member 4] And are you thinking along the lines of using like hybrid technology? Like on the front end orhighly-concentrated, you can use the electrolytic oxidation? And on theback and instead of taking the current too high you can – once you treat it tocertain level you can use the ion exchange? [Cory] Yeah, that’s another thing and especially working with the City of Grand Rapids, we’re trying – if with the leachates we’retrying to say okay does the EO need to be in front like as it comes off of thetank and then we can have something behind it that could remove any residualPFAS or any byproducts that we make. That’s goes back tothat sort of puzzle thing. So we’ve actually thought of anadsorbent then the EO and then another adsorbent. so that’s sort ofwe’re at at the current moment because the comment, even with ion exchangethe after they regenerate it, they make that still bottom. They’ll throw it in asuper adsorbent and then just toss it back in the landfill or incinerate it.But that’s where we could use that super absorbent still after ourtreatment process because we might go to rig it to remove the perchlorate,things like that.That’s good back to thissort of puzzle thing. It’s certainly a – like I said – we’re open to collaborate. We’re looking for partners still and a lot ofthis stuff. So we’re very open to collaborating. [Beth] Okay, great! Thank you! If you guys think of a question later on I think it’s okay to contact you [meaning Cory]? [Cory] 100 percent! Like I said I welcome the invitation isopen for you guys to come check out our facility up in East Lansing and MSU andget a tour and see all the capabilities that we have.I told a few peoplehere that it’s – but we always find it best when – obviously weknow what we do. we know the applications were after and we think we can provide youwith something. But you might come there and see that you know we’ve got allthese other capabilities and you think, ‘okay well that would work.’ And like Isaid there’s eight different groups that are doing different things and you mightfind something with another group.You’re more than welcome; feel free to reach out anytime. [Beth] Great! Thank you! [applause].

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