A novel scheme for the utilization of Cu slag flotation tailings in preparing internal electrolysis materials to degrade printing and dyeing wastewater

About 60 million tons of Fe-rich Cu slag (IRCS) are generated annually worldwide during Cu slag flotation and cause irreversible water and soil pollution. Current research provides an environmentally friendly technology, the preparation of internal electrolysis materials (IEMs) through the carbothermal reduction of IRCS, for the degradation of printing and dyeing wastewater. XRD and SEM-EDS indicated that carbothermal reduction could promote the conversion of fayalite to zero-valent iron (ZVI), and ZVI could effectively form IEM with residual carbon. The degradation capacity of IEM for methylene blue (MB) was remarkably improved compared with raw IRCS after roasting for 60 min at 1100 degrees C with 35% anthracite dosage. MB degradation efficiency improved by increasing the IEM dosage and reaction temperature and decreasing the MB concentration and solution pH. FTIR, XRD, SEM-EDS, and XPS all detected the formation of Fe oxide or Fe hydroxide. UV-vis and TOC demonstrated that the characteristic groups of MB were destroyed and resulted in the mineralization of MB. MB degradation could be attributed to the Fe2+, [H], and center dot OH produced by the galvanic reaction induced by IEM. Overall, this study offers theoretical guidance in the treatment of printing and dyeing wastewater and the reuse of IRCS.

Automated summary

This study introduces an environmentally friendly technology to treat printing and dyeing wastewater using internal electrolysis materials (IEMs) prepared through the carbothermal reduction of Fe-rich Cu slag (IRCS). The improved degradation efficiency of methylene blue (MB) was achieved by promoting the conversion of fayalite to zero-valent iron (ZVI) and the formation of IEM with residual carbon. By adjusting the IEM dosage, reaction temperature, MB concentration, and solution pH, the degradation capacity of MB can be further enhanced.