Study On The Fenton-like Oxidation Of Dye Wastewater With Copper Based Catalysts

The printing and dyeing wastewater are difficult to degrade,and has been widely regarded as one of the problems of water pollution control at home and abroad.It is known that its large amount of industry emissions,complex composition of water quality,wastewater with deep chromaticity,high content of organic harmful compounds,and other characteristics.In the study of dyeing wastewater treatment,Fenton oxidation method is an effective advanced oxidation technology that can produce strong oxidative hydroxyl radicals,and effectively degrade the organic pollutants in wastewater.But the Fenton reagent(Fe²⁺/H₂O₂)in the oxidation system has the disadvantages of narrow operating pH range and difficult recovery of iron ions,while copper catalysts are favored by more and more researchers in recent years because of their wide operating pH range,high catalytic activity,and low cost and availability.In the second chapter of this thesis,based on the synthesis of copper hydroxy nitrate?Cu₂?OH?₃NO₃?,the different morphologies of copper hydroxy fluoride?CuOHF?were prepared by solvothermal method with different amounts of HF.The synthesized samples were characterized by XRD,XPS,FT-IR and SEM,and they were first applied as heterogeneous Fenton-like catalyst for dye wastewater treatment.According to the experimental results,pure Cu₂?OH?₃NO₃ was synthesized without adding HF.When the addition amount of HF was more than 0.1 mL,the synthesized sample was pure CuOHF and had different morphology.Through the research on the catalytic degradation of rhodamine B by CuOHF with different morphology,it was found that the spherical CuOHF synthesized with 0.15 mL of HF has the best catalytic degradation effect on rhodamine B at 30?,and the degradation of rhodamine B by different morphologies of CuOHF showed good catalytic performance at 40?.In the third chapter of this thesis,the spherical CuOHF was selected as the research object.Under the heterogeneous Fenton-like conditions,the stability,catalytic mechanism and main factors affecting the catalytic performance of the spherical CuOHF was explored by repeated experiments,radical trapping experiments and catalytic degradation experiments.The experimental results show that under the optimal conditions of pH=4.5?the initial pH of the solution?,CuOHF addition of 0.15 g/L and H₂O₂ addition of 20 mmol/L,the decolorization rate of 50mg/L of Rhodamine B was 98.05%,and the TOC removal rate reached 46.55%at 120min.In addition,it not only has high catalytic performance in the range of pH=3.5⁹.5,but also can degrade high concentration of Rhodamine B.Before and after the catalytic reaction,its phase,structure and morphology almost keep the same,and the CuOHF catalytic activity does not decrease significantly after five cycles.The radical scavenging experiments show that the oxidation process was based on producing·OH to degradation of Rhodamine B.In the fourth chapter of this thesis,the introduction of F^-to the Cu²⁺/H₂O₂homogeneous system for the first time,and explores the catalytic degradation of Rhodamine B by Cu²⁺/F^-/H₂O₂ homogeneous system.By changing the initial conditions of the reaction system,the optimal reaction conditions for the catalytic degradation of Rhodamine B solution were obtained as follows:there is no need to adjust the pH of the solution with a initial concentration of 50 mg/L of Rhodamine B,the concentration of Cu²⁺and F^-was 1.5 mmol/L and 7.5 mmol/L respectively,H₂O₂concentration was 20 mmol/L,the reaction temperature was 50?,the decolorization rate was 99.1%after 60 min of reaction,and the TOC removal rate was 23.71%.The system has high catalytic oxidation performance in the range of pH=3.8¹1,but shows poor treatment effect under the condition of peracid?pH=3?.The free radical trapping experiment and EPR test show that the system is·OH oxidation process.In the fifth chapter of this thesis,the spherical of copper hydroxy phosphate?Cu₂?OH?PO₄?was synthesized by solvothermal method at pH=8,n?Cu?/n?P?=1.6,and 130?for 48 h.Then it was first applied to degrade Rhodamine B in the bicarbonate activated hydrogen peroxide system?BAP?.Under the optimal conditions of 20 mmol/L H₂O₂,20 mmol/L NaHCO₃,70 mg of catalyst,reaction temperature of50?,and after 120 min,eventually making Rhodamine B degradation rate and TOC removal rate up to 91.12%and 37.67%,respectively.The leaching rate of catalyst metal ions in the weak alkali environment provided by bicarbonate is only 0.995mg/L.The radical scavenging experiments show that the reaction process was based on the radical degradation mechanism,and the key role may be·OH and·O₂^-.