Valorization of Silybum marianum seed shells waste as biosorbent for basic fuchsin dye removal from water: kinetics, isotherms, and thermodynamic studies

Abstract

Over the last decades, the valorization of agro-industrial wastes into adsorbents has received a lot of attention due to the low-cost, high performance and sustainability factors. This work aims to valorize Silybum marianum seed shells (SMSS) as biosorbent for the removal of basic fuchsin dye (BF) from water. The prepared biosorbent from SMSS was characterized to check the morphological and structural proprieties using several techniques including FTIR, XRD, SEM, TGA-DTA, and BET. It was found that SMSS has a fibrous semi-amorphous structure typical of lignocellulosic materials. The study also investigated the impact of numerous operational parameters on basic fuchsin biosorption efficiency, including particle size, biosorbent mass, stirring speed, initial dye concentration, temperature, and pH of solution. Additionally, the research explored the influence of natural water matrices on dye removal. The adsorption performance was found to be higher at basic pH values, reaching 97.50%. The adsorption process was analyzed using different kinetic models, and it was found that the process follows a pseudo-second-order model. The experimental data was thoroughly scrutinized using the Freundlich and Langmuir isotherm models. The results confirm that Langmuir model fits well the BF dye adsorption on SMSS surface. The thermodynamic study revealed that the adsorption process of BF dye onto SMSS was endothermic. Overall, SMSS shows great adsorption ability which might be a good candidate for real wastewater treatment, by considering low-cost and availability of the original waste.