(464f) Effect of Thermochemical Process Parameters on Adsorption of Microcystin-LR and Nutrients on Biomass-Derived Pyrolyzed Hydrochar

Frequent and unpredictable harmful algal blooms (HAB) have plagued Great Lakes and Coastal waters in the U.S. Eutrophication has been identified as one of the major sources of Microcystin toxin outbreak in the Lake Erie and Lake Okeechobee. To protect our water, both the prevention of eutrophication and the control of HAB outbreaks are necessary. This study focuses on synthesizing pyrolyzed hydrochar from corn stover to adsorb both nutrients and Microcystin-LR (MCLR) from water. The underneath hypothesis of this study was that both hydrochar porosity and functionality play a role in nutrient and MCLR adsorption. To test the hypothesis, wet waste corn stover was first hydrothermally carbonized (HTC) at 180-260℃ for 30 min to enhance the functionality and hydrophobicity. Hydrochars, solid products of HTC, were then pyrolyzed at 400-800 ℃ for 60 min to enhance porosity. The resulting pyrolyzed hydrochars underwent physical characterizations by thermogravimetric analysis, ultimate analysis, and Brunauer-Emmett-Teller (BET) surface area to evaluate porosity and chemical composition, whereas chemical characterizations including Fourier Transform Infrared Spectroscopy and Boehm titration were performed to identity and quantify functional groups of the pyrolyzed hydrochars. Finally, batch adsorption of phosphate, and MCLR were performed at room temperature. While phosphate adsorption was evaluated by ion chromatography method, Enzyme-linked Immunosorbent Assay (ELISA) and high-performance liquid chromatography techniques were deployed for the MCLR adsorption. Results indicate that increase in porosity results in effective nutrient and MCLR adsorption. However, adsorption isotherms indicated that MCLR adsorption follows Freundlich-type adsorption, whereas nutrient follows Langmuir-type. Molecular simulations reveal the difference in adsorption phenomena.