Study On Treating Dye Wastewater By In Situ Copper Ferrite Process And The Recycling Of R-CuFe₂O₄

This research is based on the ferrite process which is applied to heavy metal waste water in recent years.Hazardous heavy metals could commonly coexist with dyes in some effluents.Hence,the copper ferrite process was adopted to treat such binary waste water.Oxidation method and neutralization titration are two common ways of ferrite process.The synchronous removal of dyes and Cu²⁺by these two methods were compared.The main mechanism of dye removal was put forward through reaction thermodynamics and solid products characterization for methylene blue removal.The prospect of this process which was used to actual dye wastewater was valued by column reactor.Finally,the recycle of excess sludge was studied.The research contents and results are listed as follows:?1?Four types of simulated dye wastewater containing methylene blue,tartrazine,Congo red and crystal violet were treated by copper ferrite process of oxidation,and the influencing factors of operational parameters in this process were studied.The main mechanism of dye removal was put forward through reaction thermodynamics and solid products characterization for methylene blue removal.Results showed that copper ferrite process of oxidation could effectively remove four kinds of simulated dye wastewater through adjusting reaction conditions appropriately.The maximum capacities of copper ferrite process for methylene blue,crystal violet,tartrazine and Congo red were 349.2,382.2,402.5 and 831.8 mg·g^-1,respectively,under reaction condition of n(Cu²⁺)of 0.01 mol·L^-1,n(Fe²⁺)of 0.025 mol·L^-1,OH/M=1.7?hydroxyl and metal molar ratio?,reaction temperature of 40°C and reaction time of 60 min.Comprehensive physical interactions,including sweeping effect,encapsulation and high active surface adsorption of in situ Fe-Cu precipitates were the dominant mechanisms in dye removal by copper ferrite process of oxidation.?2?Ferrite process of neutralization was applied to treat methylene blue–Cu²⁺binary wastewater,and the operational parameters were optimized.Results showed that the optimum operating conditions were OH/M of 1.7,Fe/Cu of 2?iron and copper molar ratio?,reaction time of 5 min.The precipitates,separated by magnetism,were roasted at 650°C.XRD analysis found that the products were copper ferrite.Copper ferrite,as an effective environmental catalyst was applied to the advanced treatment.The residual concentration of methylene blue was 0.6259 mg·L^-1,and the concentration of Cu²⁺was below detectable limit of ICP-OES.Compared with oxidation,the dyes and heavy metals'removal of neutralization were more efficient.?3?Treating dye wastewater from an industrial park in Dong Guan by column reactor,the optimum operating conditions were OH/M of 1.7,Fe/Cu of 2,reaction time of 5 min.Keeping a continuous operation of 5 hours,the removal of COD,Cu²⁺and dyes were 77.86%,99.73%and 91.97%,respectively.The result proves that ferrite process could be applied to treat actual dye wastewater.?4?The residual sludge was recovered by aerobic roasting.According to the thermogravimetric analysis,the roasting temperature of the precipitates was determined to be 750°C.The products which were considered as CuFe₂O₄ with small mount of Fe₂O₃ by XRD were named r-CuFe₂O₄.The saturation magnetization,coercivity and isoelectric point were 32.7 emu·g^-1,200.6 G and 7.12,respectively.The maximum capacities of r-CuFe₂O₄ for Congo red and Sb???were 49.04 mg?g^-11 and79.24 mg?g^-1,respectively.r-CuFe₂O₄ showed excellent ability to active persulfate,and the removal rate of 2,4-DCP was 78.1%.The r-CuFe₂O₄ has great potential in the field of environmental engineering.