Progress 09/01/20 to 08/31/23
Outputs
Target Audience:Pani Clean is dedicated to engaging a diverse array of target audiences throughout our project. Our focus is not limited to professionals and organizations in the water treatment sector, such as nitrate treatment facilities and potential Original Equipment Manufacturers (OEMs). We are also dedicated to connecting with wider community segments by establishing networks through direct engagement and by participating in industry events, including the Water Environment Federation's Technical Exhibition and Conference (WEFTEC), The Water Council (TWC), and the Ammonia Energy Association (AEA). Our outreach involves building relationships with potential partners in water technology and collaborating with government entities. A key example of this is our interaction with the local nitrate removal facilities in Nebraska and Iowa, and the Government of India for the Jal Jeevan Mission, particularly in areas like Rajasthan, where nitrate levels in water often exceed 1000 ppm due to heavy fertilization. Additionally, our initiatives specifically target groups that are socially, economically, or educationally disadvantaged. This approach ensures that our solutions are accessible to those most impacted by nitrate pollution, thereby promoting inclusive and effective water treatment strategies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two chemical engineering graduate students were part of this project, with one hired full-time to serve as the CTO for Pani Clean. The graduate students involved in this project participated in workshop-type group meetings every week, where students were trained to disseminate their weekly research findings in the form of presentations. They also participate in the Venture School program provided by the John Papajohn Entrepreneurial Center (JPEC) at the University of Iowa. How have the results been disseminated to communities of interest?We have actively engaged with communities significantly affected by nitrate contamination. Our outreach has extended to nitrate treatment facilities, rural areas, users of private wells, and various water-centric organizations like the Community Water Center in California. These efforts aim to enhance public awareness and understanding of nitrate issues and to inform communities about the technologies available for addressing these challenges. Additionally, we emphasize the potential for cost-effective solutions, such as converting nitrates into ammonia at a low cost. Our goal is not only to mitigate the impact of nitrates but also to spark interest in science, technology, and the humanities, especially among those who might not typically be exposed to such research activities. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
(i) Synthesize cost-effectivecatalytic materials and demonstrate improved performance for nitrate reduction compared to catalysts synthesized in Phase I; Task 1: Synthesize and characterize metal alloy catalysts with varying Pd content During the initial phase of the project, our research team experimented with a metal alloy deposited on a carbon electrode substrate. This combination proved effective in reducing nitrate pollution in water. However, a significant challenge was the high cost due to the substantial amount of novel metal used. A preliminary technoeconomic assessment revealed that reducing the novel metal content to less than 0.125 mg per square centimeter could maintain performance while achieving a cost reduction of over 30%. This would lower the capital expenditure from $1.36 to $0.89 for every 1,000 gallons of treated water. In Phase II, ourteam discovered that using metal content on a three-dimensional metal electrode substrate was as effective for nitrate reduction as the previous alloy systems on carbon electrodes. By switching to a newer metal system on metal electrodes, the need for costly novel metal was eliminated without compromising performance in nitrate reduction. Our team experimented with different deposition strategies and found the most optimal catalyst deposition parameters based on nitrate reduction performance. Comparisons were made between the catalyst deposits on metal electrodes and those on carbon electrodes. The metal-on-metal electrode displayed a superior ability to reduce nitrates, achieving a higher rate of nitrate reduction and nearly 100% current efficiency. Additionally, the durability of the metal-on-metal electrodes was tested over approximately 100 hours of operation with the efficiency increased after this prolonged use. This research successfully met its key objectives. Reducing the novel metal content to less than 0.125 mg/cm2. and demonstrating over 90% efficiency in nitrate reduction and maintaining stable catalytic activity after 100 hours of operation. The shift to the optimized metallic system proved to be a significant advancement in reducing nitrate pollution in water, offering both economic and environmental benefits. Task 2: Nitrate reduction in a continuous mode using a small-scale commercial electrolyzer The main objective of this part of the project was to test the selected catalysts from an earlier task using a commercially available small-scale electrolyzer. This was done to understand how fluids move through the system and to identify any electrical inefficiencies. This information would help design larger and more efficient electrolyzers in a future task. However, due to delays caused by COVID-19, the team could not get the small electrolyzer initially planned to use.During this delay, our team creatively adapted a larger, 64-square-centimeter unit andproved successful. We were able to continuously reduce nitrate pollution in water, converting over 90% of the nitrates into ammonia and nitrogen. Importantly, more than 70% of the converted nitrates turned into ammonia, showing that the adapted system worked very efficiently. (ii)Investigate potential-dependent corrosion tolerance of the catalyst using electroanalytical and spectroscopy tools and optimize catalyst formulations based on the results; Task 3: Examine loss in catalyst activity using in situ electrochemical approaches Task 4: Examine reaction intermediates to determine corrosion mechanism and product selectivity using in situ operando spectroscopic technique The project involved using an advanced spectroscopy tool for tasks 3 and 4, which is atechniqueto study materials by observing how they interact with light.The aim was to identify certain molecules and reaction stages on the catalyst surfaces when electricity was applied. By doing this, we were able to identifythe exact reaction mechanisms and how the products varied under different conditions. Especially on the mechanism of nitrates converting into nitrogen or ammonia and the certain intermediate stages in the nitrate reduction process. These stagesindicate how the catalyst preferred to convert nitrates either into nitrogen or ammonia.This information is crucial in evaluating the efficiency of the catalysts and how they perform under different conditions. (iii) Testing of the synthesized catalystsfor their nitrate conversion efficiency, freshwater recovery, and durabilityfor continuous removal and conversion of nitrates in different feed water sources in lab-scale and industrial-scale relevant reactors; and Task 5: Design and construct lab-scale and mini-industrial scale hybrid ED/EL unit This task involved creating a small laboratory-sized unit, specifically designed for removing nitrate pollution from water and converting it into nitrogen gas. This unit had an area of 64 square centimeters and was used for carrying out the initial tests in task 2. The knowledge and experience gained from designing, building, and operating this small reactor were crucial. We planned to use this experience to construct a much larger, mini-industrial scale reactor with an area of 1600 square centimeters, more suitable for practical, real-world applications. As for the results, ourteam was successful in building the smaller 64-square-centimeter reactor. This reactor was capable of integrating complex components like three-dimensional electrodes, membranes for separation, and lines for feeding in electrolyte and nitrate-rich water. It also had a special setup for collecting and analyzing the end products. The insights and learnings from this smaller reactor were then used to redesign and construct the larger 1600-square-centimeter reactor. Task 6: Performance evaluation of the lab and industrial scale ED/EL cell for nitrate removal in different feed waters Our team worked on improving a process to remove nitrates from water, using the best catalyst they had developed earlier. We tested this catalyst on large electrodes and integrated it into a laboratory-scale unit designed for both electrodialysisand electrolysis. We first tried this in a small, 64 square-centimeter reactor with water containing high levels of nitrates. The results were promising and managed to remove over 99% of the nitrates in just over an hour for nitrates in all ranges of 20~164 ppm. In the larger unit, 1600 square centimeter reactor, we achieved more than 90% nitrate removal in only 5 minutes for the same nitrate levels tested in the small unit. The >90% conversion was observed for continuous 2 hours of operations. Further tests were done using waters that simulated real water chemistries. The system performed well in these tests, with no decrease in nitrate removal or conversion rates. An actual brine sample from the nitrate treatment facility in Hastings, NE, was tested and we achieved over 90% efficiency in both removing nitrates and converting a significant portion into ammonia. An important part of this project was to design the system ensuring the feasibility of fitting all components within a consumer-acceptable form factor. The design includes all necessary parts: the combined electrodialysis/electrolysis unit, tanks for storing clean and contaminated water, pumps, valves, flow meters, and pressure gauges. The design was translated into a real, functional unit. This unit was connected to a solar-powered console, making the entire operation run on solar energy. iv) Performing a full-fledged techno-economic analysis to identify pathways for commercialization. Task7: Technoeconomic analysis An extensive techno-economic analysis was conducted to explore ways to reduce the cost of metal-on-metal electrodes and to assess the economic viability of producing ammonia from nitrates. This involved calculating the leveled cost of ammonia (LCOA) generated from water contaminated with various concentrations of nitrates.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:Pani Clean has been continuing its efforts as reported in Year 1 of this grant, including forming networks with potential OEM and contract manufacturers by directly contacting the companies or visiting their exhibit booths at the Water Environment Federation's Technical Exhibition and Conference (WEFTEC). Pani Clean has also been working with Larta consultants to identify the immediate market segments. Additionally, Pani Clean has soformed good relationships with Partners from consultant companies in MENA regionwith expertisein management consulting and water technologies to establishpartnerships and possible Joint ventures in the region. Changes/Problems:Due to COVID, we had delays starting with Task2 which had a trickle effect completing all our tasks in two years. We have asked for a no-cost extension to complete the remaining (50%) of Task 6 and Task 7. What opportunities for training and professional development has the project provided?Silimar to year 1,two chemical engineering graduate students were part of this proposal, with one hired full time to serve as CTO for Pani Clean. The graduate students involved in this project participated in workshop-type group meetings every week, where students were trained to disseminate their weekly research findings in a form of presentations. How have the results been disseminated to communities of interest?One paper on theoperando spectroscopy to monitor nitrate reaction products is being revised for submission. What do you plan to do during the next reporting period to accomplish the goals?We have asked a no-cost extension to complete Task6 and Task 7. In Task 6,we will demonstrate mini-industrial scale ED/EL unit for continuous nitrate removal and conversion and evaluate its performance metrics. In Task 7,we will conclude TEA modeling with a sensitivity analysis to clarify necessary cost/performance metrics to commercialize this process
Impacts
What was accomplished under these goals?
This project had 7 R&D tasks spread across 2 years. In year 1,we completed Tasks 1, 4 and 5. In this project report, we accomplushed Task 2, Task 3, completed 50% of Task 6 and Task 7. Task 2:In this task, we proposed to assemble and test 5 cm2 electrodes in continuous electrolyzer mode using catalysts prepared through Tasks 1 and evaluate their performance and durability for nitrate conversion in model nitrate-rich waters. A 5 cm2 (active electrode area) electrolyzer was built and re-engineered to perform nitrate reduction in a continuous mode. We perofrmed electrochemical evaluation, includingpolarization curves as a function of nitrate concentration, constant potential and constant current eletrolysis, and investigated product distribution ratios as a function of potential and time. We also investigated the effect of catalyst/substrate interaction on product selectivity and current yield. Task 3: In this task, the goal was to examine the loss in mass and intrinsic activity of the catalyst using in situ electrochemical approaches. We performed electrochemical active surface area measurements of the catalyst as a function of operational time and observed no changes to the intrinsic activity of the catalyst or drop in surface area. The ICP measurements did not show any loss of catalyst mass after continuous operation of the catalyst in model-nitrate waters. Task 6: In this task, the goal was to evaluate lab and mini-industrial scale ED/EL cell for nitrate removal in different feed waters. The best-in-class nitrate reduction catalyst was integrated to lab and mini-industrial scale ED/EL unit. The overall goal here was to understand the effect of system size on nitrate treatment performance for wider market adoption. The effect of water composition and nitrate concentration on the ED/EL unit performance was investigated. Different feed water chemistries were selected based on the US brackish water data published by the Department of Interior.We completed assessment of the nitrate removal and conversion in different feed water chemistries for lab scale unit. We are currently working on assesing the nitrate removal and conversion efficacy in industrial scale unit. We have requested a no-cost extension for completing Task 6. Task 7: In this task, the goal was to complete the technoeconomic analysis using the data derived from the Tasks 2, 5, and 6. We designed a conceptual engineering process model to performTEA for three commercial applications: (1) To treat nitrate-rich tile drainage; (ii) To treat nitrate contaminated community water systems ; (iii) Nitrate treatment for POU application. We are currently gathering relevant data from Task 6 which will then serve as input for Task 7.We have requested a no-cost extension for completing Task 7.
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:Pani Clean has contacted various end customers and customer-facing entities by participating in the NSF I-CORPS program. We achieved over 110 interviews with end-users (farmers, well owners), water facility managers, large corporate managers, etc. This has given us a good understanding of the product requirements for potential users - cheap, easy operation, and low maintenance should be met to have a viable product. Our consultant in Larta is also proactively assisting the process by offering suggestions for exhibitions, conferences, and regulators to reach out for collecting helpful information on the product requirements. Pani Clean has actively been forming networks with potential OEM and contract manufacturers by directly contacting the companies or visiting their exhibit booths at the Water Environment Federation's Technical Exhibition and Conference (WEFTEC). We formed good relationships with potential OEM partners such as Snow Pure technologies, and contract manufacturers. Changes/Problems:For this interim report, the goals were to complete R&D Tasks 1 and 2 and to initiate Task 5. However, due to COVID-19, there were delays with procuring the commercial electrolyzer needed for Task 2 and we were unable to complete it by the end of Year 1. We currently have the commercial electrolyzer and anticipate completing Task 2 by the end of Q1 Year 2. However, during this downtime, we worked on Tasks 4, 5, and 6. We completed Task 4 and Task 5 which had initially planned date of completion during Year 2. What opportunities for training and professional development has the project provided?Two chemical engineering graduate students are part of this proposal, with one hired as a research intern for Pani Clean. The graduate students involved in this project participated in workshop-type group meetings every week, where students were trained to disseminate their weekly research findings in a form of presentations. How have the results been disseminated to communities of interest?Two manuscripts - one on the application of operando spectroscopy to monitor nitrate reaction products and the other on the initial proof of concept on the hybrid ED/EL unit for nitrate capture and conversion - are in preparation for publication in peer-reviewed journals What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we aim to complete testing the catalyst in a commercial small-scale electrolyzer and apply the best-in-class catalyst to demonstrate the hybrid ED/EL process in a mini-industrial scale unit. We will also complete a preliminary technoeconomic analysis for our process. For the mini-industrial scale reactor, we will evaluate the effect of feed water chemistries on nitrate capture and conversion efficiencies.
Impacts
What was accomplished under these goals?
Task 1: Synthesis and performance characterization ofthe proprietary catalyst using a batch reactor. While the focus of the task was to reduce the noble metal content in the proprietary alloy catalyst, we serendipitously discovered that an earth-abundant catalyst deposited on high surface area metal support can achieve nitrate conversion with selectivity >95%, far exceeding our prior reports. These catalysts when tested in a beaker cell showed no degradation for nitrate conversion after 100 hours of operation. Thus, achieving all proposed milestones for this task. Task 2: Nitrate reduction in a continuous mode using a commercialelectrolyzer. In this task, we proposed to reengineer a commercially availablewater electrolyzer for continuous nitrate reduction studies. However, due to COVID-19, we had a delay with the purchase of the commercial electrolyzer unit. We recently acquired the electrolyzer unit and are in the process of reengineering the design to test the activity, selectivity, and durability of the catalysts identified from Task 1 in continuous mode. Task 4: Examine reaction intermediates to determine product selectivity using in situ operando technique. This task was initially designed to be carried out in year 2 but was moved to year 1 to make up for the electrolyzer downtime in Task 2. Using in-situ and operandospectroscopywe determined the reaction intermediates on catalyst surfaces under operation conditions. Notably, we observed that different electrochemical voltages yielded different surface adsorbates with catalyst favoring nitrogen and ammonia formation when operated at large overpotentials and nitrite at low overpotentials. The above finding illustrates that by careful tuning of the applied potential, the same catalyst can be tailored to yield different nitrate reduction products. We successfully achieved the milestone associated with this task. Task 5: Design and construct a large lab-scale hybrid ED/EL unit. In this task, we first designed and built a large lab-scalehybrid electrodialysis/electrolyzer unit for nitrate removal and its subsequent conversion to nitrogen. The experience gained by building, troubleshooting, and running a large lab-scalereactor will then be used to build a mini-industrial scale reactor. The large lab-scalereactor was successfully constructed with the capability for integrating proprietary electrodes and catalysts with electrolyte feed, nitrate-rich water feed, and purge line for product collection and analysis. A preliminary HAZOP analysis was also performed on the system design. Tests of the flow properties and total cell resistancewere measured with total cell resistance <10 Ohm cm2. Thereby, successfully achieving Milestone 6. Task 6: Performance evaluation of the lab-scale ED/EL cell for nitrate removal in different feed waters. This task, like Tasks 4 and 5 was started earlier to make up for the electrolyzer downtime in Task 2. The best-in-class nitrate reduction catalyst was deposited on large area proprietaryelectrodesand integrated into a lab-scale ED/EL unit. The integrated electrodes were then first tested to evaluate their performance in model nitrate-rich waters. We successfully were able to recover >95% nitrate from nitrate-rich waters and were able to convert >60% of them. We are currently optimizing the catalyst loading for the lab-scale unit to achieve >90% nitrate conversion in model nitrate-rich water and in waters that simulates real water chemistries.
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