A novel MnOx-impregnated on peanut shells derived biochar for high adsorption performance of Pb(II) and Cd(II): Behavior and mechanism

Abstract

Heavy metal ion pollution (e.g., Hg, Pb, Cr, Cd) that has a great threat to human health is a global concern, because of their great toxicity (e.g., carcinogenicity and mutagenicity). Therefore, it is necessary to find an economical and efficient technology to remove metal. In recent years, modified biochar plays an important role in the removal of heavy metal. However, most of the biochar modification methods rely on high temperature and long time, which limits their application in practical engineering. In this study, we firstly synthesized HMBC (MnOX-OBC, peanut shells as raw materials) using H2O2-NaOH method, where the materials only need to be modified for 10 min at ambient temperature to obtain high adsorption performance. The maximum Pb(Ⅱ) and Cd(Ⅱ) adsorption capacities of HMBC were 164.59 mg g−1 and 36.77 mg g−1, respectively, which were 7.2 times and 5.6 times that of the unmodified PBC (peanut shells derived biochar), and the main adsorption mechanisms were complexation, ion exchange, cation-π interaction and precipitation. The adsorption process of lead and cadmium by HMBC was more consistent with the Freundlich model and Pseudo-second-order adsorption kinetics. HMBC had high selectivity for lead and cadmium, and the adsorption performance of HMBC was basically not reduced after five cycles. The above experimental results show that the newly prepared HMBC has the potential to treat lead and cadmium industrial wastewater.