Remediation of cadmium and chromium using modified Vitex doniana waste plant Seed's biochar in quarry site surface water

Abstract

Industrial effluents contain hazardous combinations of suspended particulates and dissolved solids in various ratios; the wastewater from cementitious material production activities is no exception. Since heavy metals seriously threaten environmental and human health, developing effective and economical removal techniques is imperative. Due to its efficiency and effectiveness in absorbing heavy metals, biochar has attracted research attention. Therefore, this study used modified biochar from Vitex doniana seeds to remove cadmium (Cd) and chromium (Cr) in cement-producing activities area surface water. The enhancement and functionalization of the modified Vitex doniana seed biochar (MVDS) over the Vitex doniana seed biochar (VDS) were characterized using SEM-EDX, proximate analysis, FTIR, and BET. In the first 60 ​min of adsorption experiments, the MVDS biochar performed best, with an 85.0% removal efficiency and a 338.6 ​mg ​g⁻¹ total cadmium adsorption capacity, whereas the first 45 ​min revealed an 84.1% removal efficiency and a 328.0 ​mg ​g⁻¹ total chromium adsorption capacity. The adsorption process was more multilayer heterogeneous from the isotherm studies, which is evident in the best fitting of the Freundlich model compared to the Temkin and Langmuir models. Additionally, the Pseudo Second order (PSO) kinetic model provided the best explanation for the adsorption process, and the thermodynamics investigation confirmed the viability and spontaneity of the process. The modified biochar from Vitex doniana waste plant seeds successfully removed cadmium and chromium from surface water and can be used for water treatment.