Research On The Removal Copper-complex From Electroplating Wastewater

Electroplating industry has become one of the world’s three major polluting industries. Due to large amounts of heavy metal complex involved in and discharge standards improving, treatment of heavy metal in electroplating wastewater has become a widespread concern. For treatment of simulating wastewater containing copper combination with single complexing agent (citric acid, tartaric acid and EDTA), the methods of Fenton, UV/H2O2, UV/O3, O3and zero-valent iron were compared to find the optimal treatment methods and the corresponding optimum reactive conditions. The mechanisms of breaking complexation and removing copper were also studied in detail. The results can provide a basis for the realization of industrial applications.The research results showed that for copper-tartaric acid wastewater, all of the above methods can achieve discharge standard. Optimal conditions for Fenton method:initial pH=3.0, Fe2+: H2O2molar ratio is1.0:1, H2O2dosage=0.87g/L, FeSO4-7H2O dosage=7.08g/L, precipitation pH=9.50, reaction time=50min; optimal conditions for UV/H2O2method:initial pH=3.0, H2O2dosage=1.07g/L, precipitation pH=9.50, illumination time=70min; optimal conditions for UV/O3method:Initial pH=3.0, concentration of O3dosage=19.2mg/L, precipitation pH=9.50, reaction time=120min; optimal conditions for zero-valent iron method:initial pH=2.5, iron dosage=0.4g/L, pH precipitation=9.50, the reaction time is16hours.For the copper-citric acid wastewater, only the Fenton and zero-valent iron method can achieve discharge standard of copper, however, UV/H2O2, O3and UV/O3do not contribute excellent effects. Specific reaction conditions are as follows. Optimal conditions for Fenton method:initial pH=6.0, Fe2+:H2O2molar ratio is1.6:1, H2O2dosage=0.93g/L, FeSO4-7H2O dosage=12.08g/L, precipitation pH=9.50, reaction time=50min; optimal conditions for zero-valent iron method:initial pH=2.5, iron dosage=0.8g/L, precipitation pH=9.50, the reaction time is16hours.Compared to the other two kinds of wastewater, copper-EDTA wastewater is the most difficult to deal with. The method of UV/Fenton, zero-valent iron method can achieve the target, however, Fenton, UV/H2O2, O3and UV/O3method do not show fabulous effects. Optimum conditions of UV/Fenton method:initial pH=2.5, Fe2+:H2O2molar ratio is1.6:1, H2O2dosage=1.40g/L, FeSO4-7H2O dosage=18.18g/L, precipitation pH=9.50, reaction time=50min; optimal conditions for zero-valent iron method:initial pH=2.5, iron dosage=0.5g/L, precipitation pH=9.50, the reaction time is18hours.The methods applied in this study are environmental friendly, because they will not produce any poisonous byproducts but also have higher processing efficiency. Through a series of studies, optimal conditions of one or several methods have been found ultimately thereby laying the theoretical foundation for the selection of the actual electroplating wastewater treatment methods.