Enhanced adsorption of sulfamethoxazole antibiotic on amine grafted activated carbon using (3-Aminopropyl) triethoxysilane (APTES)

Abstract

This study focused on developing a specialized adsorbent for efficiently removing Sulfamethoxazole (SMX) from complex matrices. We utilized activated carbon (AC) grafted with amine groups using (3-Aminopropyl)triethoxysilane (APTES) as the adsorbent. Thanks to the modification of the carbon surface with amine groups, which altered the material's surface charge and promoted interactions between the amine groups and the sulfonate groups in the SMX molecule, the AC/APTES material showed a significant enhancement in adsorption capacity. Under optimum conditions (pH 6, 3 mg mL⁻¹ adsorbent dosage, 60 min), the adsorption capacity reached 53.47 mg g⁻¹. The Langmuir isotherm model well fit the experimental data. Kinetics follows a pseudo-second-order model and intra-particle diffusion model, suggesting the predominant role of chemisorption over physisorption. Thermodynamic results indicated that SMX adsorption onto AC/APTES was spontaneous and exothermic. AC/APTES has high re-usability after five recycling cycles while maintaining removal efficiency above 78 %. High removal efficiency around 92 % was achieved with water samples from various lakes in Hanoi.