Grantee Research Project Results
Final Report: Removal of Cyanotoxins by Multifunctional Biochars
EPA Grant Number: SU839963Title: Removal of Cyanotoxins by Multifunctional Biochars
Investigators: Kan, Eunsung , Venkataraman, Kartik
Institution: Tarleton State University
EPA Project Officer: Callan, Richard
Phase: I
Project Period: October 1, 2019 through September 30, 2020 (Extended to September 30, 2021)
Project Amount: $25,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2019) RFA Text | Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
9 – 9/30/2021 (with one year no-cost extension)
Objective of Research: The goal of this project is to develop a cyclic adsorption and Fenton oxidation-driven regeneration using a novel multifunctional biochar made from agricultural for effective removal of microcystin in drinking water sources.
To achieve the stated goal, our project has the following specific objectives:
Objective 1: Produce, characterize and evaluate a novel multifunctional biochar from agricultural wastes.
Objective 2: Assess adsorption capacity and Fenton oxidation-driven regeneration efficiency of the multifunctional biochar for removal of microcystin in DI water and lake water.
Objective 3: Conduct multiple cycles of adsorption and Fenton oxidation-drive regeneration using the multifunctional biochar.
Summary/Accomplishments (Outputs/Outcomes):
The multifunctional biochars (MFB) derived from the waste hay (discarded Bermudagrass) were produced, characterized and applied for removal of microcystin(MC-LR) in DI water and the real lake water. For effective removal of MC-LR in water, the waste hay was converted to MFB via one step of pyrolysis/activation using FeCl3 activator at 800 oC for 2 h heating under oxygen-limited conditions.
After one step of pyrolysis/activation, MFB possessed highly porous, high surface area biochar with various iron oxides. While high surface area and highly porous structure of MFB resulted in high adsorption of MC-LR, the iron oxides at the surface of MFB played a key role as the catalysts for Fenton and persulfate oxidation as well as magnetic separation after use.
The adsorption characteristics of MFB for MC-LR in water was investigated in detail. MFB showed good adsorption at pH 3-9 indicating its possible application for broad ranges of pH in water. The adsorption kinetics study showed the pseudo-second order and Elvoch models as the best-fitted ones indicating chemisorption would be dominant mechanism. The adsorption of MC-LR onto MFB was also led by the intraparticle diffusion limitation which was highly related to high porosity of MFB. The adsorption isotherm experiment also supported Freundlich isotherm model as the best-fitted one which would indicate chemisorption-driven adsorption of MC-LR. The positive value of ∆H0 (12.33 kJ/mol) indicated the endothermic property of MC-LR adsorption onto MFB. In addition, the negative values of ∆G0 confirmed the spontaneity of this adsorption. Moreover, higher absolute values of ∆G0 with increasing temperature implied that the higher temperature resulted in a more favorable adsorption process. Based on the detailed adsorption studies, the proposed mechanisms associated with adsorption of MC-LR onto MFB included π-π interaction, hydrophobic interaction, hydrogen bonding and electrostatic interaction upon the conditions.
For effective reuse of MFB after being saturated with MC-LR, four regeneration methods were comparatively investigated. Thermal regeneration at 300 oC showed highly efficient regeneration of MC-LR saturated MFB during four cycles although it requires high energy consumption. NaOH-led alkaline desorption also showed possible regeneration of MC-LR saturated MFB which requires neutralization of alkaline effluent. Compared with thermal and alkaline regeneration, Fenton and persulfate oxidation showed promising regeneration of MC-LR saturated MFB. However, persulfate oxidation was found to be more stable and economical regeneration over Fenton oxidation because of longer life-time of sulfate radicals over OH radicals from Fenton reactions.
The persulfate oxidation-driven regeneration (POR) was optimized in terms of pH, persulfate concentration and temperature. The POR was applied to the DI water containing MC-LR and the real lake water containing MC-LR. The POR resulted in high and stable regeneration of MC-LR saturated MFB in DI water and real lake water during four adsorption/regeneration cycles. In this project, the cost-effective production, regeneration, and long-term reuse of MFB indicates high potential of the MFB for practical application of microcystin removal in lake water.
Furthermore, if the MFB is applied for broad ranges of emerging contaminants in surface water, groundwater and wastewater, it will lead to highly efficient and cost-effective removal of toxic contaminants in water while significantly contributing to environmental protection, safe water resource, and ultimately human health.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 5 publications | 2 publications in selected types | All 2 journal articles |
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Zeng S, Kan E. Adsorption and regeneration on iron-activated biochar for removal of microcystin-LR. Chemosphere 2021;273:129649. |
SU839963 (Final) |
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Zeng S, Kan E. Thermally enhanced adsorption and persulfate oxidation-driven regeneration on FeCl3-activated biochar for removal of microcystin-LR in water. Chemosphere 2022;286:131950. |
SU839963 (Final) |
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Supplemental Keywords:
Emerging contaminant, algal bloom, algal toxin, biochar, adsorption, persulfate oxidation, regenerationProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.