Removal of Pb(II) and Cr(VI) from aqueous solutions using the fly ash-based adsorbent material-supported zero-valent iron

Abstract In this study, a granular adsorbent material containing zero valent iron (ZVI-GAM) was made with fly ash as skeletal material, bentonite as binder and Enteromorpha prolifera as pore former. Zero-valent iron was synthesized by direct reduction of iron ore tailings with the coke as reductant at 900 °C in the anoxic atmosphere. SEM/EDX, XRD, FTIR and BET analysis were used to characterize ZVI-GAM. SEM image showed that there were many different size pores in ZVI-GAM. XRD analysis indicated the presence of iron in zero-valent state. FTIR analysis revealed that the surface of ZVI-GAM owned the groups responsible for the heavy metals adsorption. The specific surface area of ZVI-GAM was 8.19 m 2 /g. ZVI-GAM was used as reaction and adsorbent material for the removal of Pb(II) and Cr(VI) from aqueous solutions. The factors affecting Pb(II) and Cr(VI) ions removal by ZVI-GAM in a batch model were studied including initial heavy metal concentrations, contact time, adsorbent dosage, pH values and temperature. Maximum removal capacity for Pb(II) and Cr(VI) by ZVI-GAM was found to be 78.13 mg/g and 15.70 mg/g. ZVI-GAM had the best adsorption and reduction capacity for Cr(VI) and Pb(II) and could reduce Cr(VI) to Cr(III) and Pb(II) to Pb 0 . Therefore, ZVI-GAM was an effective, low-cost and recyclable material and had great potential to be a promising technique for heavy metal remediation.