Removal of Cr(VI) from Aqueous Solution by Nanoscale Zero-Valent Iron Grafted on Acid-Activated Attapulgite

The nanoscale zero-valent iron grafted on acid-activated attapulgite (A-nZVI) was prepared by a liquid-phase reduction method and used for Cr(VI) removal from solution with enhanced efficiency. The structure of the composite A-nZVI was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller surface area analysis. nZVI was well-dispersed on the surface of acid-treated attapulgite, and no obvious aggregation was observed due to the support of rod-like structure of attapulgite, which is beneficial to Cr(VI) removal. Batch experiments revealed that the removal of Cr(VI) using A-nZVI was consistent with pseudo-first-order reaction kinetics, and removal efficiency was up to 98.73 % within 60 min for 100 mL 20 mg/L Cr(VI) at the initial pH 7.0 and 4.0 g/L A-nZVI. The pseudo-first-order rate constant kobs was independent of initial Cr(VI) concentration, but there was a good linearity (r2 = 0.95) between kobs and the A-nZVI dosage. This study demonstrates that A-nZVI has the potential to become a promising material for in situ groundwater remediation.