This has led to a great deal of study and work to create practical methods for reducing the amount of HABs in impacted ecosystems. Flocculation has emerged as one of the best alternative treatment technologies as polyaluminum chloride (PAC)-modified biochar demonstrates that at a dosage of 0.05-0.30 g/L powdered biochar removes about 90% of toxins and 67% of cellular suspension from water, in under 2 hours. While exhibiting high effectiveness for the remediation of HAB, PAC has raised several environmental concerns which has led to the search for materials with natural coagulation properties. Therefore, in this study, chitosan and tannin were used to modify biochar for the remediation of Karenia Brevis and brevetoxin, a common HAB and its associated toxin.
These modified biochars were chemically characterized using N2 adsorption-desorption, scanning electron microscopy, and energy-dispersive X-ray. The crystallinity was determined by X-ray powder diffraction and proximate and ultimate analysis. Zeta potential was used to determine the surface ionization properties. In addition, kinetic, equilibrium, and dosage studies were performed to understand the adsorption and elimination capacity of the modified biochars. To experimentally determine the applicability of the modified biochars, flocculation studies were performed, and the toxin removal was quantified using liquid chromatography.