Fabrication of Acid-modified Corn Plant By-product-based Biochar for Efficient Adsorption of Sulfamethoxazole from Aqueous Solutions

Antibiotic pollution is of great interest owing to growing concerns about antibiotic resistance worldwide. This study aims to fabricate acid-modified biochar (CBM-A) from corn plant byproducts (CRs) for sulfamethoxazole (SMX) adsorption in aqueous solutions. CBM-A was synthesized via pyrolysis at 700 °C and modified with 14% H3PO4. Kinetics, isotherms, and thermodynamics were investigated in combination with material characterization to elucidate the adsorption behaviors and mechanisms. The results showed that pyrolysis and acid modification effectively enhanced SMX adsorption by CR because of the increased number of binding groups, specific surface area, and porosity. SMX adsorption on CBM-A was optimized at a natural pH of 6.3, initial SMX concentration of 30 mg L-1, CBM-A dose of 1.5 g L-1, contact time of 2 h, and temperature of 298 K. Under the optimal conditions and initial SMX concen-tration range of 10–200 mg L-1, the maximum SMX adsorption capacity (qmax) of CBM-A was 63.29 mg g-1. The Langmuir isotherm (R2 = 0.9945) and Pseudo-second-order kinetic (R2 = 0.9928) models were appropriate for describing SMX adsorption on CBM-A. The adsorption process was favorable and endothermic. Owing to its facile preparation, high qmax value, and short equilibrium time, CBM-A is considered a promising biosorbent for eliminating SMX from aqueous solutions.