Chromium (VI) removal from water using starch coated nanoscale zerovalent iron particles supported on activated carbon

Abstract

Starch coated nanoscale zerovalent iron (S-nZVI) was immobilized in activated carbon (AC) and its Cr (VI) removal characteristics were studied. Macroscopic evidence and mechanism analysis proved that S-nZVI and AC were closely linked and mutual complementary. Different factors including pH of the original solution, reaction time, and mass ratio (S-nZVI@AC/Cr =10:1, 20:1, 30:1, 50:1, 60:1, 70:1) were studied to analyze the removal rate. Results showed that the removal rate of Cr (Ⅵ) could reach 99.96% under the condition of pH of 5, and temperature =25 °C, when the mass ratio of S-nZVI@AC/Cr was 60:1. The removal of Cr(Ⅵ) by S-nZVI@AC followed pseudo-second-order kinetics. X-ray diffraction (XRD) resulted demonstrate that S-nZVI@AC existed in a Fe₃C state before reaction and in a Fe(III) state after reaction. XPS (X-ray photoelectrons spectroscopy) analysis suggested that the mechanism of Cr (VI) removal by S-nZVI@AC is adsorption and reduction. S-nZVI@AC might be a potential composite material for the purification and detoxification of Cr (VI) in water because of its efficiency and stability.

Keywords:

• Activated carbon
• adsorption
• chromium
• kinetics
• nanoscale zerovalent iron
• starch

Additional information

Funding

This research was financially supported by the Project (2017zy011) of Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources, the Project (2017C003) of Hubei Key Laboratory of Regional Development and Environmental Response (Hubei University), and the Natural Science Foundation of Hubei Province of China (2017CFB350).