Adsorption of anionic and cationic heavy metals by Zn-Mn-Fe oxide-loaded biochar: Performance and mechanism

Abstract Biochar has a good heavy metal adsorption capacity, but it is difficult to separate the heavy metals from the biochar for reuse after application in wastewater treatment processes. To solve this problem, Zn-Mn-Fe oxide-loaded biochar (ZMFBC) was prepared in this study to fabricate magnetic biochar, and cationic heavy metals (Pb2+, Cd2+) and anionic heavy metals (Cr6+) were selected as target pollutants for removal. The ZMFBC adsorption performance and physicochemical properties were evaluated by combining batch experiments and characterization techniques. The results showed that the Pb2+, Cd2+ and Cr6+ maximum adsorption amounts obtained by ZMFBC were 136.99, 74.63 and 39.06 mg/g, respectively, and the adsorption processes were in accordance with pseudo-second order and the Langmuir model. Functional group could be the main reason for the high adsorption capacity of ZMFBC. With good heavy metal removal performance and easy separation, ZMFBC can be used in a variety of applications where adsorbents are needed to remove contaminants.