(517c) Exploring the Roles of Different Components of Biomass in the Biosorption of Heavy Metals in Wastewater

Lead is a typical heavy metal containment in wastewater and causes serious health problems even under ultralow concentrations. Current technology uses the expensive synthesized ion exchange resin to remove the aqueous lead. For sustainability, it is urgent to search the alternative economic renewable ecological-friendly sorbents, such as hemp. The biosorbents from hemp stalks in this study were raw hemp stalks, deliginified hemp stalks, and cellulose extracted from hemp stalks. The ability of hemp stalks as biosorbents to remove aqueous lead (II) was investigated by the effects of initial pH, particle size, initial ion concentration, the dosage of biosorbents, temperature, and contact time. The biosorbents were characterized by chemical composition, FTIR, SEM, and XRD, and the results indicated that the biosorbents could be a good alternative. Lead (II) biosorption on hemp stalk biosorbents exhibited pseudo second-order kinetics, and intraparticle diffusion is the limiting step. Langmuir isotherm, Freundlich isotherm, Temkin isotherm and Dubinin-Radushkevich (D-R) were used to study the adsorption equilibrium. The adsorption capacities for raw hemp stalks, delignified hemp stalks, and cellulose extracted from hemp stalks were 456.6 mg/g, 512.8 mg/g, and 323.6 mg/g, respectively. In addition, the biosorption capacity based on chemical components for cellulose, hemicellulose, and lignin were 190, 1128, and 325.8 mg/g, respectively. The adsorption of lead (II) on biosorbents from hemp stalks is proven to be a chemical exothermic favorable process by isotherms and thermodynamics. This study shows the possibility of hemp stalks as sustainable biosorbents in wastewater treatment.