Preparation of nanoscale zero-valent iron particles with different coatings for removal of Cr(VI) from water

In this study, we prepared four different nanoscale zero-valent iron particles (NZVI) coated with chitosan, sodium carboxymethyl cellulose, soluble starch and polyvinyl pyrrolidone, respectively. These nanoparticles were characterised by X-ray diffraction (XRD) and scanning electron microscope. The results showed that coated agents can decrease the aggregation of nanoscale zero-valent iron particles, and render them disperse better. The resulting coated iron nanoparticles can be preserved for a long time in the air, suggesting the improved oxidation resistance. In particular, chitosan coated zero-valent iron nanoparticles have a high purity and good dispersibility. The Cr(VI) degradation experiment with the coated nanoscale zero-valent iron showed that the degradation rate was determined by the time, temperature and pH value. The comparison results indicated that the degradation effect of chitosan coated zero-valent iron nanoparticles is optimised.