Potassium hydroxide-modified algae-based biochar for the removal of sulfamethoxazole: Sorption performance and mechanisms

Biochar has been deemed one of the most promising sorbents for the removal of organic pollutants from aqueous solution. In this study, potassium hydroxide-modified Enteromorpha prolifera biochars (PEBCs) were prepared for the first time and applied for efficient sorption of a typical antibiotic, sulfamethoxazole (SMX). The characteristics of PEBCs, including morphology, pore structure, graphitization degree, surface functional groups, and surface element composition, were investigated. Moreover, sorption kinetic and isotherm experiments were carried out to explore the sorption process, performance, and mechanisms. The maximum sorption capacity for SMX can reach 744 mg g−1, which is much higher than that reported for sorbents. The sorption of SMX onto PEBCs was controlled by both physical and chemical processes. Moreover, pore filling, hydrogen bonding, partitioning, π-π stacking, and electrostatic interactions were possible sorption mechanisms. This study indicated that the structure and properties of algal biochar can be further improved by potassium hydroxide modification at high temperature and applied as an excellent sorbent for the removal of antibiotics from aqueous solution.