Removal of arsenic from copper smelting wastewater using zinc slag to synthesize scorodite

Acidic arsenic-containing wastewater from copper smelting poses a potential threat to human and environmental safety due to its high toxicity, acidity, high volumes, and difficulty to be processed and utilized. This study proposed a technique to leach environmentally stable scorodite from wastewater using natural zinc slag as a solid iron source. The leaching behavior of scorodite was investigated through a combination of room-temperature adsorption and high-temperature reactions, after which the underlying mechanisms of this reaction were explored through adsorption kinetics and thermodynamics. Our findings indicated that the optimal reaction conditions of zinc slag with wastewater were the following: Fe/As ratio=2.5, 80 degrees C, 10 h. The initial arsenic concentration in the wastewater was reduced from 13,040 mg/L to 140.5 mg/L, with 98.9% of the arsenic being removed. The toxicity characteristic leaching procedure (TCLP) results for the precipitates showed that the leaching concentration of arsenic was only 2 mg/L. For Fe2SiO4 in zinc slag, FeS dissolves to release iron ions, generating FeAsO4 center dot 2H(2)O, FeAsO4, and secondary minerals. Ca2Al2SiO7 generates gypsum to provide surface active sites for the growth of scorodite. This study proposes the industrial application of zinc slag for arsenic removal from copper smelting wastewater, providing a strong methodological basis to promote the development of non-ferrous metallurgical enterprises in a green and efficient manner.