Degradation of chlortetracycline with simultaneous removal of copper (II) from aqueous solution using wheat straw-supported nanoscale zero-valent iron

Nanoscale zero-valent iron (NZVI) materials as environmental remediation agents have attracted intense research interests due to its high reactivity and reducing ability. Herein, NZVI supported on wheat straw (WS-NZVI) composites were synthesized by liquid phase reduction method for application in simultaneous removal of chlortetracycline (CTC) and copper (Cu2+). The synthesized composites (WS-NZVI) showed favorable removal ability for both CTC and Cu2+ in aqueous solution through redox and adsorption processes. In single pollutant removal system, the maximum removal capacity of 1280.802 and 376.4 mg/g for CTC and Cu2+ were achieved by WS-NZVI, respectively, demonstrating the excellent removal ability for CTC and Cu2+. In addition, in the CTC-Cu2+ binary pollutant removal system, the removal capacity of CTC was promoted under low initial Cu2+ concentration ([Cu] < 10 mg/L) and was inhibited under high initial Cu2+ concentration ([Cu] > 10 mg/L); while the removal capacity of Cu2+ was reduced with the increase of initial CTC concentration. The removal mechanisms were investigated by XPS and HPLC-MS. The simultaneous removal of CTC and Cu2+ in the binary pollutant removal system was shown to be a complicated process, including the following aspects: CTC and Cu2+ were adsorbed to the surface of WS-NZVI, the Fe-0 in WS-NZVI reduced Cu2+ to Cu-0 and degraded CTC to smaller molecules. This study develops a potentially effective wheat straw-supported nanoscale zero-valent iron material for simultaneous removal CTC and Cu2+ and provides a new sight for complex wastewater treatment.