2020 Fiscal Year Research-status Report
Novel activated carbon for effective perfluoroalkyl substance (PFASs) removal by minimizing problematic desorption.
| Project/Area Number |
20K22425
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| Research Institution | Hokkaido University |
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Principal Investigator |
PAN LONG 北海道大学, 工学研究院, 博士研究員 (90884007)
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| Project Period (FY) |
2020-09-11 – 2022-03-31
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| Keywords | desorption / pore diffusion model / adsorp-reversibility / micopollutant |
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| Outline of Annual Research Achievements |
One related paper was submitted and in the progress of evaluation for publication.
In the first stage of this research, the achievement was to clarify the adsorption and desorption mechanism of the target micopollutants on activated carbon (AC). Previous studies rarely mentioned the desorption of adsorbates and gave no information about desorption kinetics in a dynamic flowing system. But the desorption should not be neglected if we want to solve the problem of short-chain perfluoroalkyl substances (PFAS) removal. By using 2-methylisoborneol (MIB) as a secondary micropollutant, the adsorption-desorption process in activated carbon is successfully described by a branched-pore diffusion model combined with IAST-Freundlich isotherm.
The more MIB breakthrough detected in the effluent during its contamination period, the higher ratio of desorbed/adsorbed MIB amount would be in the no-contamination period. Therefore, AC in the membrane tank should be replaced while the breakthrough concentration is low in terms of not only the removal rate but also the desorption risk. The diffusivity of MIB molecules in the pore of AC particles was decreased with time. The decrease in the intraparticle diffusivity, which would be caused by the fouling of AC while receiving the coagulant-injected natural water, reduced the removal rate of MIB during the MIB contamination period, but it also hindered the desorption of MIB in the no-contamination period and then prevented the effluent MIB concentration from becoming high.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
It is more cost-effective and healthy for a laboratory technician to use a substitute target micropollutant rather than directly start with the cancerogenic perfluoroalkyl substances (PFAS) to study the adsorption-desorption phenomena and get used to the operation of experiments.
Considering the trace pollutants existing in the aqueous environments, the accurate concentration detection is necessary. However, the current laboratory is hard to fully provide the conditions. The target compounds will be changed back to PFAS after the detection methods or facilities have been improved.
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| Strategy for Future Research Activity |
After the study of adsorption-desorption characters and the effective model for describing the microcosmic progress, the next step is to find out the impact of adsorbents' properties on the adsorption-desorption of target adsorbates.
The different adsorption-desorption performance on different activated carbon with varied properties will be detected. Then the modification of activated carbon will be made to improve the absorption and reduce the desorption.
There is still a problem of PFAS measurement for the research. But the substitute could work and exhibit the mechanism which is as important as the application.
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| Causes of Carryover |
Due to the difficulty of target compounds' measurement, the cheaper substitute was chosen and conducted with the basic study. In order to prepare for the measurement charge in the next year, the article cost was lower than the plan.
Due to the impact of COVID-19, the conference was canceled or delayed. In order to save the cost for the future experiments, there is no cost for attending the conferences.
The cost of others will happen in this month for the paper publication.
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