Advanced carbo-catalytic degradation of antibiotics using conductive polymer-seaweed biochar composite: Exploring N/S functionalization and non-radical dynamics

Polyaniline (PANI) and Saccharina Japanica seaweed (kelp) biochar (KBC) composites were synthesized in-situ through polymerization. This study presents a novel approach to the degradation of sulfamethoxazole (SMX), a prevalent antibiotic, using a PANI-KBC composite to activate peroxymonosulfate (PMS). Extensive characterizations of the PANI-KBC composite were conducted, resulting in successful synthesis, uniform distribution of PANI on the biochar surface, and the multifunctional role of PANI-KBC in SMX degradation. A removal efficiency of 97.24% for SMX (10 mg L−1) was attained in 60 min with PANI-KBC (0.1 g L−1) and PMS (1.0 mM) at pH 5.2, with PANI-KBC showing effectiveness (>92%) across a pH range of 3.0–9.0. In the degradation of SMX, both radical (SO4•− and •OH) and non-radical (1O2 and electron transfer) pathways are involved. The reaction processes are critically influenced by the roles of SO4•−, 1O2 and electron transfer mechanisms. It was suggested that pyrrolic N, oxidized sulfur (−C−SO2−C−), structural defects, and O−CO were implicated in the production of 1O2 and electron transfer processes, respectively, and a portion of 1O2 originated from the conversion of O2•−. The study evaluated by-product toxicity, composite reusability, and stability, confirming its practical potential for sustainable groundwater remediation.