Revealing the roles of biomass components in the biosorption of heavy metals in wastewater by various chemically treated hemp stalks

Abstract

BackgroundLead is a typical heavy metal contaminant that can result in severe health problems even at ultralow concentrations. Current state-of-the-art technology relies on expensive synthetic ion-exchange resins, but hemp can be an economical and ecological sustainable alternative to synthetic sorbents. In addition, the roles of various components in biomass are not clear in the biosorption process. MethodsThe various roles of biomass components in the biosorption of heavy metals were determined by investigating removing aqueous lead(II) ions by biosorbents derived from raw and chemically treated hemp stalks, such as delignification and mercerization. Various biosorbents were characterized by FTIR, SEM, and XRD to rationalize the biosorption process. Significant findingsLead(II) biosorption exhibited pseudo-second-order kinetics with intraparticle diffusion as the rate-limiting step, and the biosorption process was exothermic and favorable. Based on the biosorption capacities of various chemical-treated biosorbents, the capacities for cellulose, hemicellulose, and lignin were 277.39, 878.46, and 17.96 mg/g. Due to its hydrophilic nature and multi-functional groups, hemicellulose exhibited superior performance to commercial ion-exchange resins. Lignin is not suitable as biosorbents for removing aqueous heavy metals because of its hydrophobic property. The obtained results demonstrate the feasibility of using biosorbents derived from hemp stalks as sustainable and economical materials for wastewater treatment.