Chitosan Stabilized Sulfide Nano-Zero-Valent Iron Distributed on Phosphorus-Functionalized Biochar for Superior Cd2+ and Cu2+ Removal from Wastewater

A novel chitosan stabilized biochar supported sulfide nano-zero valent iron composite material (CB- S-nZVI ) was prepared to high effectively remove Cd2+ and Cu2+ from wastewater. Batch experiments showed that CB-S-nZVI had higher affinity for Cd2+ and Cu2+ than other nZVI modified materials. The maximum elimination capacities of CB-S-nZVI were 244.15 mg/g for Cd2+ and 163.70 mg/g for Cu2+ at pH 7 and 6, respectively. The decreased temperature could promote the immobilization of Cd2+ and Cu2+ indicating an exothermic process, and the Freundlich model described the removal process of Cd2+ very well. The removal mechanism results showed that Cd2+ and Cu2+ were removed from the aqueous solution by ion exchange, electrostatic attraction, precipitation, and complexation. Overall, this study provided a simple and effective method for sufficiently dispersing S-nZVI on the biochar carrier and coated by chitosan, and the prepared CB-S-nZVI was promising in removing heavy metal ions from wastewater