Tetracycline Adsorption Efficiency Using Bagasse Fly Ash Originating from the Sugar Industry in Thailand

Tetracycline (TC) contamination in reservoirs poses environmental and human health risks, particularly antibiotic resistance in ecosystems. Bagasse fly ash (BFA), a by-product from the sugarcane processing industry, has gained attention as an environmentally friendly adsorbent. In this study, we aimed to investigate the mechanism of TC adsorption using batch experiments to evaluate the effects of various factors. For example, pH value ranged from 4 to 10, contact time varied between 0 and 90 min, adsorbent doses were noted as 0.5–2.5 g per 50 mL, the initial concentrations of TC were 10–40 mg/L, and the temperature ranged from 293.15 to 318.15 K. To perform surface characterization of BFA, we employed the scanning electron microscopy (SEM) technique. Based on the results of Fourier transform infrared spectroscopy (FTIR) and surface area analysis (Brunauer–Emmett–Teller; BET), its structure and chemical properties are favorable for TC adsorption. Our results demonstrate that the optimal conditions for adsorption were at pH 7.0 and 60 min contact time. The adsorption capacity tended to increase with the initial concentrations of TC and reached a maximum of 0.58 mg/g when the initial concentration was 40 mg/L. Our kinetic analysis results demonstrate that the pseudo-second-order model exhibited the best fit with the experimental data (R2 = 0.95638); in comparison, the results of the isotherm behavior study using the Temkin model (R2 = 0.97338) indicated the complex adsorption pathway on the BFA surface.