Comparative adsorption of tetracycline onto unmodified and NaOH-modified silicomanganese fumes: Kinetic and process modeling

Silicomanganese fumes (SMF) are industrial waste and a potential low-cost adsorbent for the removal of contaminants from water. In this study, the adsorption performance of SMF and NaOH-modified SMF (SMF-Na) for the removal of tetracycline (TC) from an aqueous solution was investigated. The characterization results showed the presence of functional groups (SiO2,-OH and C-O-C), a considerably higher surface area of the SMF-Na (142.59 m2 g-1) compared to the SMF (7.73 m2 g-1). The TC adsorption was favored under acidic conditions (pH 2-3) and increased with an increasing amount of adsorbent. The adsorption equilibrium was achieved in 360 min, and the presence of Na+ ions insignificantly influenced the TC adsorption. The Avrami model fitted better to the kinetic data with R2 = 0.995. The isothermal data was well represented by the Redlich-Peterson and Langmuir model. The maximum monolayer ad-sorption capacity of SMF and SMF-Na was 117 and 129 mg g-1, respectively. The thermo-dynamic results confirmed that the TC adsorption was endothermic and predominantly governed by physical forces. The removal of TC onto SMF and SMF-Na was maintained above 90 % even after five regeneration cycles The results suggested that SMF-Na is a promising al-ternative adsorbent for the removal of tetracycline antibiotics from wastewater streams. (c) 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.