Abstract:
Chromium-containing wastewater was generated in electroplating, metallurgy, printing and dyeing industries, which caused environmental pollution. The sludge-derived biochar (SB) was obtained from the pyrolysis of municipal sludge, and then loaded with nanoscale zero-valent iron (nZVI) to prepare sludge-derived biochar loaded with nanoscale zero-valent iron (nZVI-SB) for the removal of Cr(VI) from water. The effect of the iron to carbon mass ratio, initial pH value, dosage and temperature on the removal of Cr(VI) were explored. SEM-EDS, XRD and XPS were used to characterize the mechanisms of Cr(VI) removal. The results show that nZVI-SB has a desirable removal capacity for Cr(VI). Under the conditions of dosage 0.5 g/L, pH=2 and 40℃, the maximum adsorption capacity of Cr(VI) is 150.60 mg/g by nZVI-SB(1∶1) with a mass ratio of 1∶1 between Fe and SB. The Cr(VI) removal process can be fitted by Langmuir adsorption isotherm and pseudo-second-order kinetic equations. The removal mechanisms of Cr(VI) mainly include adsorption, reduction and co-precipitation. The present study confirms SB and nZVI can synergically remove Cr(VI).