Palygorskite-supported sulfide-modified nanoscale zero-valent iron for Congo red removal

In this work, the optimum conditions for the synthesis of nano zero valent iron sulfide were studied in detail using orthogonal experiment. The palygorskite-supported sulfide-modified nanoscale zero-valent iron (S-nZVI/P) was prepared, characterized, and further applied to remove Congo red (CR) in aqueous solutions. The results of structural characterization showed that the Fe0 was coated with FeS layers. The influence of sulfidation conditions on the removal rat e of CR was investigated in detail, and the results revealed that S-nZVI/P prepared at 30°C with a Fe/S ratio of 1 was found to effectively remove CR. Moreover, S-nZVI/P showed a significantly enhanced removal rate towards CR as compared with nZVI/P and nZVI, suggesting that sulfidation treatment is a promising method to improve the reactivity of nZVI.