Abstract:
Chromium containing wastewater is seriously hazardous to the natural environment if it is being discharged directly. In order to explore the reaction efficiency of zero-valent iron/biochar (Fe
0-BC) and Cr (Ⅵ), the Fe
0-BC was synthesized by the carbothermal reduction of wood waste and printing and dyeing industry iron mud at different temperatures and applied in the removing of Cr(Ⅵ) in aqueous. The characteristics of Fe
0-BC were detected by specific surface area analyzer and scanning electron microscope (SEM), and the results indicate that the Fe
0-BC-1200 prepared at 1200 °C has the best performance with a specific surface area of the Fe
0-BC is 105.6 m
3/g and a pore diameter of 6.23 nm. The physical phases of Fe
0-BC-1200 are mainly composed of Fe
0, Cu
0, C and a few number of impurities, and the Fe
0 particles are dispersed and attached inside the pore structure of carbon as spherical particles with a uniform size distribution at the nanometer level. Furthermore, the removal process of Cr (Ⅵ) by Fe
0-BC was studied by batch experiments. The Fe
0-BC-1200 shows the best removal performance, which the removal ratio of Cr (Ⅵ) can reach 95.2% under the conditions of initial concentration of 20 mg/L, initial pH value of 3.5 and dosage of 2.5 g/L. The removal process of Cr (Ⅵ) is well predicted by the pseudo-second-order model and Langmuir equation (
R2> 0.99), and the maximum adsorption capacity is 10.71 mg/g. The removal mechanisms mainly include adsorption, reduction and complex precipitation. In addition, the presence of Cu
0 is beneficial to catalyze the oxidation of iron, thus promoting the removal of Cr (Ⅵ). The Fe
0-BC prepared by solid waste has the advantages of low cost and significant detoxification effect on Cr (Ⅵ) wastewater containing, which is a new idea to realize the purpose of ‘dealing pollution with waste’.