The synthesis of PEG/MoS₂-modified biochar for the efficient removal of Cr(vi) in solution: performance and mechanism

A highly efficient new type of biological adsorbent (PEG/MoS₂@BC) was prepared via hydrothermal synthesis using rice straw biochar, polyethylene glycol, and molybdenum disulfide as raw materials. The effects of different factors on the adsorption performance of PEG/MoS₂@BC for removing Cr(vi) ions from aqueous solutions were analyzed through various experiments. The experimental results indicate that a PEG-MoS₂ composite material was successfully loaded onto the surface of biochar. There was a large number of functional groups on the surface of PEG/MoS₂@BC. Polyethylene glycol and biochar effectively reduced the aggregation of MoS₂. The process for the adsorption of Cr(vi) by PEG/MoS₂@BC can be better described using the pseudo-second-order model and the Langmuir model. The adsorption of Cr(vi) ions was an endothermic chemical process. The reaction mechanism for PEG/MoS₂@BC removing Cr(vi) ions mainly includes complexation reactions, reduction reactions, electronic attraction, and physical adsorption. After five reuse cycles, the adsorption rate still reached 80.23%. The adsorption material PEG/MoS₂@BC exhibited high reusability and stability.