High-performance activated rice straw biochar: a sustainable triple-bottom-line adsorbent for removal of water pharmaceutical pollution

at pH 5 for SMX and CLN, respectively. Additionally, a prototype fixed-bed column system demonstrated high efficiency, removing 97.92% of SMX from continuous-flow wastewater effluent within 40 minutes. Beyond targeting specific contaminants, the activated RSR biochar also improved overall wastewater quality by significantly reducing total suspended solids (TSS), chemical oxygen demand (COD), biological oxygen demand (BOD), and total organic carbon (TOC). The main adsorption mechanisms identified include pore-filling, electrostatic attraction, hydrogen bonding, and π-π electron donor-acceptor (EDA) interactions, with chemisorption acting as the rate-limiting step. Moreover, activated RSR-BC material can be reused up to four times with 69.7% removal, highlighting its effectiveness in removing pharmaceuticals from water. Overall, this study demonstrates how agricultural waste, such as rice straw, can be valorized into a high-performance adsorbent for advanced water purification, supporting sustainable development goals (SDGs) and circular economy principles.