Adsorption of cadmium by magnesium-modified biochar at different pyrolysis temperatures

Abstract

Metal pollution in soil is an increasing concern. Cadmium poses significant risks to ecosystems, and methodologies for its removal, including adsorption, have been researched. There are several environmentally friendly adsorbing materials (such as Biochar) for Cd removal. In this study, to improve the adsorptive capacity of Cd, coconut and peanut shells were used as raw materials to prepare Biochar at 300 °C and 600 °C. The effects of the pyrolysis temperature and material type on the physicochemical properties of the adsorbents were investigated by elemental analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. Magnesium-loaded BC was synthesized to determine its Cd2+ absorptivity. The adsorption characteristics and mechanisms of Cd2+ in an aqueous phase were studied through batch adsorption experiments. The results demonstrated that the pseudo-second-order kinetics model accurately described the adsorption kinetics of adsorbents of Cd2+. The adsorption behavior of the Cd2+ adsorbent conforms to the single layer adsorption described by the Langmuir model. Adsorption of Cd2+ involves a spontaneous endothermic process. The initial pH of the solution greatly influenced the adsorption of Cd2+ and showed a trend of rapid growth and then slow growth. Thus, magnesium-modified biomass carbon has good potential for applications in pollutant remediation.