(716g) Adsorption of Microcystins By Sargassum-Derived Biochars: Evaluation of the Characteristics, Mechanisms and Factors Influencing Adsorption.

Sargassum, brown seaweed, accumulates in large quantities on ocean shores, causing visual and olfactory nuisances that affect tourism and fishery industries, with decomposing Sargassum producing hydrogen sulfide, prompting warning for individuals with respiratory illnesses to avoid affected areas. Thus, the valorization of this biomass to biochar presents as a sustainable option, as this material provides valuable surface qualities suitable for water purification. Due to climatic and anthropogenic events, increasing cyanobacterial blooms which release hepatotoxic Microcystins (MC) to the US freshwaters remain a concern livelihood of humans and aquatic life. Thus, the employment of Sargassum derived biochar for the remediation of these toxins, would be beneficiary for utilizing ocean’s litter for the river’s aid. Synthesis involved hydrothermal carbonization (HTC) at temperatures 180, 220, and 260 ℃ for 30 min followed by chemical activation with KOH at activation temperature 800℃ with KOH to hydrochar ratio 2:1. Physical (Thermogravimetric Analysis, Ultimate Analysis), morphological (Brunauer-Emmet-Teller surface area, Scanning Electron Microscopy), and chemical characterization (Fourier Transform Infrared Spectroscopy, surface charge, Boehm Titration) were performed to study the resulting Seaweed Char based on the varying synthesis conditions. Batch adsorption experiments were conducted against Microcystins (Microcystin-LR and Microcystin-YR) for varying conditions (dosage amount, contact time, pH, and initial concentration). These investigations showed both physisorption and chemisorption mechanisms involving the uptake of Microcystins along with higher selectivity to Microcystin-LR. Consequently, use of Sargassum biochar has been shown to be highly efficient and cost effective for the purification of MC affected waters.