Preparation of novel magnetic porous biochar and its adsorption mechanism on cerium in rare earth wastewater

A novel and efficient process for the removal of Ce(IV) from aqueous solutions was sought, and a new magnetic porous biochar (PBC/ZF) was synthesized by loading ZnFe2O4 (ZF) onto porous biochar (PBC) using a one-step hydrothermal method. The SEM observation of the external features showed that the cubic spinel structured ZnFe2O4 (ZF) particles were loaded onto the porous biochar (PBC) surface. This resulted in a composite with superb paramagnetic properties as well as higher adsorption properties. In addition, the microstructure was characterized by FTIR, which demonstrated that the target material was supplied with a large amount of carboxyl groups (-COOH) by citric acid during the synthesis process. The BET showed that the target material had a higher specific surface area than ZnFe2O4 with PBC, confirming the successful preparation of the target material after activation of the biomass using ZnCl2 immersion as well. The effect of different factors on the adsorption effect was investigated experimentally. The results showed that PBC/ZF had a good adsorption effect on Ce(IV) with a short adsorption equilibrium time and a maximum adsorption capacity of 228.9 mg/g at room temperature with lower acidity (pH = 2.5). The adsorption kinetics and isotherm analysis showed that the Ce(IV) adsorption process fitted well with the quasi-secondary kinetic model and Langmuir model. It indicates that the process is a single molecular layer adsorption process. It was demonstrated that PBC/ZF also has high removal rate for high concentration Ce(IV) solution, and it is easy for solid-liquid separation under the action of applied magnetic field after adsorption. It provides a new treatment method and theoretical support for the adsorption treatment technology of Ce (IV) wastewater.