Fabrication of a low-cost adsorbent supported zero-valent iron by using red mud for removing Pb(ii) and Cr(vi) from aqueous solutions

摘要

In this study, a granular red mud supported zero-valent iron (ZVI@GRM) was successfully prepared and was used to remove Pb( II ) and Cr( VI ) from aqueous solution. Zero-valent iron (ZVI) was synthesized by direct reduction of iron oxide in red mud by maize straw as a reductant at 900 °C in an anoxic atmosphere. The technical characterization (SEM, EDS, XRD, FTIR and BET) revealed that ZVI@GRM was loaded with zero-valent iron and contained different size pores. The factors of adsorption experiments include initial concentration, contact time, pH and temperature. The Pb( II ) and Cr( VI ) removal by ZVI@GRM well fitted the pseudo-second-order kinetics model and the removal of heavy metals was an endothermic process. Essentially, Pb( II ) was transformed to precipitate forms (Pb ~(0) , Pb (OH) _(2) , or 2PbCO _(3) ·Pb (OH) _(2) ) and Cr( VI ) was converted to Cr (OH) _(3) or Cr ~(3+) /Fe ~(3+) hydroxides. The maximum removal capacity for Pb( II ) and Cr( VI ) by ZVI@GRM was 149.42 and 37.14 mg g ~(?1) . ZVI@GRM was a low-cost material and had outstanding performance and great potential in wastewater treatment.