Synthesis of zero-valent iron/biochar by carbothermal reduction from wood waste and iron mud for removing rhodamine B.

This study proposes a new process to synthesize zero-valent iron/biochar (Fe-BC) by carbothermal reduction using wood waste and iron mud as raw materials under different temperature. The characterization results showed that the Fe-BC synthesized at 1200 °C (Fe-BC-1200) possessed favorable adsorption capacity with the specific surface area of 103.18 m/g and that the zero-valent iron (Fe) particles were uniformly dispersed on the biochar surface. The removal efficiency of rhodamine B (RB) was determined to evaluate the performance of the prepared Fe-BC. Fe-BC-1200 presented the best performance on RB removal, which mainly ascribes to that more Fe particles generated at higher temperature. The equilibrium adsorption capacity reached 49.93 mg/g when the initial RB concentration and the Fe-BC-1200 dosage were 100 mg/L and 2 g/L, respectively, and the pseudo-second-order model was suitable to fit the removal experimental data. LCMC and XRD analyses revealed that the removal mechanism included the physical adsorption of biochar and the redox reaction of Fe. Moreover, copper existing in the iron mud was also reduced to Cu, which was beneficial to catalyze the oxidation of iron; the degradation of RB was promoted at the same time.