Harnessing corncob-derived materials for the elimination of sulfamethoxazole from water

Abstract

In this study, corncob biomass was pyrolyzed at 400 °C (BC400) and 600 °C (BC600) to investigate the sorption properties of sulfamethoxazole (SMX). Sorption experiments were conducted at different pH levels (3, 7, and 10) and solution temperatures (20, 26, and 32 °C). The results showed that the biochar yield of BC400 (31.68 ± 0.85 %) was higher than that of BC600 (26.10 ± 0.42 %). However, BC600 significantly improved the surface area (279 m² g⁻¹) compared to BC400 (4.8 m² g⁻¹), resulting in a threefold increase in SMX⁰ sorption at pH 3 (5.849 mmol kg⁻¹ vs. 1.803 mmol kg⁻¹). At pH 7, the sorption for SMX⁻ reached 2.859 mmol kg⁻¹ for BC600, while no sorption was observed for BC400. Computational simulations indicated that sorption is spontaneous, endothermic, and primarily entropy-driven, governed by intraparticle diffusion. This work highlights the importance of pyrolysis temperature for enhancing SMX⁻ sorption at neutral pH using pristine corncob biochar.