Removal of Hexavalent Chromium from Simulated Wastewater by Polyethylene Glycol-Modified D201 Resin-Supported Nanoscale Zero-Valent Iron

摘要

In view of the increasingly prominent heavy metal pollution problem in water, D201 resin-supported polyethylene glycol-modified nanoscale zero-valent iron (PEG-nZVI/D201) was fabricated to remove Cr(Ⅵ) in wastewater. PEG-nZVI/D201 can overcome the agglomeration and oxidation drawbacks of nZVI effectively, and improve the removal efficiency of Cr(Ⅵ). Its Cr(Ⅵ) removal rate was 33.6 higher than that of bare nZVI when the dosage of PEG-nZVI/D201 was 1.0 g·L~(-1), the Cr(Ⅵ) concentration was 50 mg·L~(-1), and the initial pH was 5.0. The maximum adsorption capacity of Cr(Ⅵ) on PEG-nZVI/D201 reached 134.56 mg·g~(-1) at 318 K. The Langmuir model better describes the adsorption of Cr(Ⅵ) on PEG-nZVI/D201. Thermodynamic parameters show that the adsorption process is spontaneous and endothermic. The mechanism of Cr(Ⅵ) removal by PEG-nZVI/D201 is as follows: firstly, protonated PEG-nZVI/D201 adsorbs Cr(Ⅵ) by electrostatic attraction, then nZVI reduces most of Cr(Ⅵ) to Cr(Ⅲ) through its strong reducibility, and finally,Cr(Ⅲ) can form Cr_xFe_(1-X)(OH)_3 co-precipitation with Fe(Ⅲ) produced by oxidation of nZVI.