Progress 02/01/24 to 01/31/25
Outputs
Target Audience: 1. Research institutions and companies engaged in drinking water/wastewater treatment research 2. Ordinary citizens who are interested in impact of emerging contaminants and remediation technologies Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project in this period has provided training and professional development for 1 PhD studentand oneundergraduate researchers. How have the results been disseminated to communities of interest? The results have been disseminated to the communities of interest through conference presentations at the University of Idaho Institute for Health in the Human Ecosystem Annual Research Symposium, ASABE 116th Annual International Meeting, and a journal article in Separation and Purification Technology. What do you plan to do during the next reporting period to accomplish the goals? There is work and rebudget needed for finishing the Objective 2 to elucidate the mechanism of effective remediation PFOS by the improved continuous flow liquid-phase plasma discharge (CFLPPD) process designed for on-farm use.
Impacts
What was accomplished under these goals?
To evaluate the effect of heavy metal in water on the removal of PFAS, the novel continuous liquid phase plasma discharge (CFLPPD) reactor was investigated on the removal of cobalt (II) from water first. It was found that besides the efficient removal of cobalt, cobalt oxide (Co3O4) particles were produced as a byproduct. Independent and significant processing parameters, i.e., applied power and liquid flow rate, were evaluated to achieve maximal removal of cobalt by the CFLPPD treatment. The optimal conditions for the 93% maximum removal efficiency of cobalt were found to be 300 W applied power and 50 ml/min liquid flow rate at 25 min of treatment time. After 25 minutes of treatment, particle deformation was observed. Removal of cobalt followed the first-order kinetics for all experimental cases. Based on the obtained electrical data at different applied powers, increases in applied power resulted in an increase of discharge power. The energy efficiency for the maximal removal under optimal conditions was calculated as 27.44 g kW-1h-1. OES analysis and scavenger test results showed that superoxide and hydroxyl radicals played a significant role in the removal mechanism of cobalt from water by the CFLPPDtreatment. The obtained particles of Co3O4 during the removal process were more crystalline after calcination, which had an average particle size of 2.75 µm. According to the particle characteristics, the produced Co3O4 can be applied as a catalyst for many applications. Comparisons with other conventional methods and plasma treatments indicated that our CFLPPD reactor examined in this study was a robust and highly efficient method for cobalt removal from water. Since the CFLPPDprocess did not require any additional chemicals and carrier gas to achieve high removal and energy efficiencies, it is considered economically feasible when scaled up for industrial applications. A mixed solution of cobalt, PFOA, and PFOS will be in tested to evaluate the effect of heavy metal on PFAS removal by CFLPPD.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
Mohotti, D., MM. Hossain, R. Ndeddy Aka, A. Mukhtar, N. Holloway, *S. Wu. 2024. Evaluating a green liquid phase plasma discharge process and working mechanism for remediating cobalt contamination in water. Separation and Purification Technology, 354(3):128940.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
D. Mohotti, MM. Hossain, Y. Yuan, R. Robi, S. Wu. Evaluating a Green Liquid Phase Plasma Discharge Process and The Mechanism for Remediating Cobalt Contamination in Water. University of Idaho Institute for Health in the Human Ecosystem Annual Research Symposium, April 8, 2024.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
A. Nasir, Rivera, C., E. Agyekum-Oduro, S. Saqib, D. Mohotti, S. Deng, S. Wu. 2023. Evaluating A Continuous Liquid-phase Plasma Discharge Process for Destroying PFAS in Water. ASABE 117th Annual International Meeting. Paper#: 2401483. Anaheim, CA. July 28-31, 2024.
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Progress 02/01/23 to 01/31/24
Outputs
Target Audience: Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project in this period has provided training and professional development for 1 Postdoc, 1 PhD student, and 1undergraduate researcher. How have the results been disseminated to communities of interest? The results have been disseminated to the communities of interest through conference presentations at the University of Idaho Institute for Health in the Human Ecosystem Annual Research Symposium, ASABE 116th Annual International Meeting, and a journal article in Water Research. What do you plan to do during the next reporting period to accomplish the goals?Work for Objectives 1 and 2 on PFOS is still ongoing. The similarity and differencein degradation and defluorination efficiency and pathways compared with PFOA due to the structural difference of functional group will be revealed with more tests and trials.
Impacts
What was accomplished under these goals?
This year, under Objective 2, further evaluation of CLPD for PFOA removal and defluorination revealed very promising features of CLPD in treating PFAS and the degradation pathway. Comparing the performance of PFOA destruction at different applied power levels selected to ensure stable CLPD discharge with or without gas, the two CLPD conditions with argon gas at either 100 Watt or 200 Watt achieved very high and similar PFOA removal (93.6% vs. 92.4%) but very distinct defluorination rate (59.7% vs. 87.7%) and degraded PFAS byproducts after 1 hour treatment, while at 300 Watt without gas only 62.8% PFOA removal and defluorination but with fluoride ions (F-) as the only degraded products and no fluorinated byproducts. These results indicated that power and carrier gas play significant roles for the PFOA decomposition pathways. The addition of gas may enhance the levels of the reactive species (can be seen in the optical emission spectroscopy (OES) profiles)accelerate the PFOA removal, but also trigger the C-C scission pathway to form shorter-chain byproducts. However, higher power at 300 W without gas induces slightly higher voltageand much higher discharge current and power, indicated by the extended voltage measured with a small capacitor and calculated from the Lissajous plot, respectively. This may create more energetic electrons in the aqueous phase for exclusive defluorination pathway which has never been reported in literature and may only be possible with CLPD. Complete defluorination is expected to be achieved with longer treatment time. The ratio of oxidative species to reductive species in the CLPD may also have a significant impact on the PFAS degradation pathway. Seen from the comparison of OES profiles, The CLPD condition at 300W with no gas clearly showed a low OH radical to Hβ (an indicator of electron density) ratio which may be the reason behind no C-C cleavage. The potential for controlling PFAS degradation and defluorination pathways by manipulating CLPD operational conditions for quantitative defluorination with no degraded short-chain PFAS is very promising. Work on PFOS is still ongoing with the highest removal achieving 82%. Thesimilarity and differencein degradation and defluorination pathways with PFOA will be revealed with more tests and trials.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Nasir, A., Z. Warren, C. Rivera, S. Wu. Degradation of per- and Polyfluoroalkyl Substances (PFAS) in a Continuous Flow Liquid-phase Plasma Discharge System. University of Idaho Institute for Health in the Human Ecosystem Annual Research Symposium, April 7, 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Rivera, C., A. Nasir, R. Ndeddy Aka, RJ., S. Deng, S. Wu. 2023. Destroying perfluorooctanoic acid in water by continuous liquid-phase plasma discharge. ASABE 116th Annual International Meeting. Paper#: 2301504. Omaha, NE. July 9-12, 2023.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2024
Citation:
Celiannie Rivera, Alia Nasir, Robinson Junior Ndeddy Aka, *Sarah Wu. Rapid destruction of perfluorooctanoic acid in water by a continuous flow liquid-phase plasma discharge process. Submitted to Water Research.
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Progress 02/01/22 to 01/31/23
Outputs
Target Audience: Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project in this period has provided training and professional development for 1 Master's student, 1 PhD student, 1 visiting scholar, and 1 undergraduate researcher. How have the results been disseminated to communities of interest? What do you plan to do during the next reporting period to accomplish the goals?In the next year, further verification of feasibility and optimization for PFOS removal and defluorinationwill be conducted.
Impacts
What was accomplished under these goals?
For Objective 2,Experiments were carried out in two phases. In phase I, two carrier gases (argon and air) were studied and compared for their performance in removing PFOA by CFLPPD, and argon gas was found to be more effective than air (91.75% for argon vs. 79.55% for air). Then argon was used as the carrier gas in Phase II to evaluate other operating parameters including gas flow rate, water flow rate, water conductivity, and power applied using a two-level partial factorial design. The two levels for the tested parameters were 300 and 900 μs/cm for conductivity, 70 and 150 mL/min for water flow rate, 0.5 and 1.5 sL/min for gas flow rate, and 100 and 200 W for power applied. The results showed that gas flow rate was the most significant factor among the four factors affecting the removal efficiency of PFOA by CFLPPD (p = 0.0029). The best combination of the four operating parameters was obtained (conductivity = 300 µs/cm, water flow rate = 150 mL/min, gas flow rate = 1.5 sL/min, and power = 100 W), under which the CLPD could achieve a PFOA removal rate of 93.4%. The breakdown pathway was estimated to be from PFOA to PFHPA, to PFHXA, to PFHeA, to PFBA, and then to H2O, CO2, F-, and organics, and simultaneous direct defluorinationto F-and long/ short-chain organics. For Objective 1, PFOS degradation was tested with CLPD treatment and was found to be feasible and the removal and defluorination is in a lower rate than those for PFOA.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
McDowell, E., S. Wu. Survey of Local PFAS Contamination and Development of a Plasma-Based Treatment Technology. 2023 Partners in Science National Conference. San Diego, CA. January 13-14, 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Wu, S. 2022. Invited Jack Talk: Engineering plasma technology for tackling emerging contaminants in water. 2022 Partners in Science National Conference. San Diego, CA. January 14-15, 2022.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2022
Citation:
Degradation of Perfluorooctanoic Acid in Water by A Continuous Flow Liquid-Phase Plasma Discharge Process
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Progress 02/01/21 to 01/31/22
Outputs
Target Audience: 1. Research institutions and companies engaged in drinking water/wastewater treatment research 2. Ordinary citizens who are interested in impact of emerging contaminants and remediation technologies Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project in this period has provided training and professional development for 1 Master student, 1 PhD student, and two undergraduate researchers. How have the results been disseminated to communities of interest?The results have been disseminated to the communities of interest through conference presentations at the University of Idaho,Partners in Science National Conference, andColorado Water Quality Forum. What do you plan to do during the next reporting period to accomplish the goals?1. For objective 1, the feasibility of remediation and breakdown of PFOS in drinking water by CFLPPD will be evaluated and the mechanism for C-F bond breaking will be investigated with OES. 2. For objective 2, the significant CFLPPD processfactors influencing PFOS removal and defluorination will be determined.
Impacts
What was accomplished under these goals?
For objective 1, the CFLPPD reactor was configured and successfully operated in a series of 16 subsequent experiments designed to evaluate the removal of PFOA from drinking water.The mass balance calculations suggest that PFOA undergoes initial C-F bond breakage. Once the C-F bonds are broken, fluoride (F-) is released and PFOA is transformed into shorter-chain PFAS, some of which were identified. About 25% of the F-was not accounted for in the fluorine mass balance. Based on the literature, it may be present as fluorine gas (and so cannot be easily quantified) or in various of PFAS intermediates that we were not able to detect/identify. Some PFAS may have also absorbed to tubing or other reactor parts. Fluorine mass balance has revealed a high defluorination rate of 93.6% out of all removed organic fluorine. For Objective 2, five operational parameters were identified as potentially influencing PFOA degradation in water: conductivity (300 vs. 1000 us/cm), water flow rate (70 vs. 150 ml/min), gas type (argon vs. air), gas flow rate (0.2 vs 1 L/min), and power (100 vs. 200 Watt). The CFLPPD reactor was tested to determine the appropriate ranges for each of the five operating parameters using a two level, partial factorial design, evaluatedthe CFLPPD operational parameters for their significance in affecting PFOA degradation in water and assessed PFOA removal rates.?ANOVA analysis indicated that only gas type (argon or air) was significant in affecting the extent of PFOA degradation in water. The removal of PFOA was greater when argon was the carrier gas (up to 93% in 60 min for argon and up to 82% for air in 60 min). The overall amount of PFOA removal was also greater with argon.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
McDowell, E., S. Wu, C. Rivera, A. Nasir, R. Ndeddy Aka. Survey of Local PFAS Contamination and Development of a Plasma-Based Treatment Technology. 2022 Partners in Science National Conference. San Diego, CA. January 14-15, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Wu, S. 2021. Destruction of PFAS in water with liquid phase plasma discharge technology. Colorado Water Quality Forum. Online. November 15, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Krosuri, A., S. Wu, C. Rivera. Degradation of PFAS in water using an electrohydraulic plasma discharge process. University of Idaho Center for Health in the Human Ecosystem Annual Research Symposium, April 20, 2021.
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