Recovery of chromium (VI) from hazardous APV wastewater using a novel synergistic extraction system

As a well-known hazardous material, chromium (VI) in industrial wastewater has always attracted extensive attention. Many studies have focused on the recovery of Cr (VI) which is still challenging and received considerable interest. In this study, a novel synergistic extraction system using amide as extractant and Cyanex 272 as synergistic extractant was built to recover chromium (VI) from the APV wastewater. After optimizing the process parameters of extractant concentration, initial pH, extraction temperature, extraction time, extraction phase ratio, ammonia concentration and stripping phase ratio, the final extraction and stripping efficiency reached more than 99% and 98%, respectively. The Cr₂O₃ product with a purity of 99.52 was prepared and the organic phase could be effectively regenerated for recycling. The extraction mechanism of chromium (VI) in the synergistic extraction system was investigated in-depth with slope method, ESI-MS analysis and FT-IR analysis. In addition, molecular electrostatic potentials analysis was used to display visually the formation process of the extract complex. This paper offered a unique approach to guide sustainable chromium (VI) recovery from hazardous wastewater with great industrial and theoretical significance.