Experimental Study On Regeneration Of Acidic Copper Chloride Etching Waste Liquor

It is inevitable that large amounts of acidic copper chloride etching waste liquor with high copper contentof80^-130g L^-1are discharged in the PCB manufacturing process. Waste etching solution is usually recycledwith simple chemical oxidation and electrochemical methods at present. These methods can remove Cu⁺fromthe etching liquid waste and recover the etching performance fast and efficiently. However problems also existthat the chemical oxidation method will inlarge the volume of the etching solution, electro-chemical method isvery strict with the electrochemical reactor, and the phenomenon of anode chlorine and cathodic hydrogenevolution in the process of electrochemistry have never been able to avoid. Accordingly, how to oxidize orextract the Cu⁺in the etching waste liquid has important significance to renew the waste etching solution.The paper studied regeneration of acidic copper chloride etching waste liquor prepared in laboratory withsolvent extraction method and hollow fiber supported liquid membrane-stripping distributed （HFSLM）technology. And simulation etching experiments adout regenerative etching liquor were also made.In solvent extraction experiment, TBP was used as extractant, sulfonated kerosene was used as thinner,and H₂O₂was used as back-extractant to selectively extracted Cu⁺from acidic copper chloride etching wasteliquor. The effects of TBP contentration, O/A, extraction time, concentration of HCl and Cl-on extractionefficience were investigated,and so were the effects of O/A, back-extraction time, concentration of H₂O₂onback extraction efficience. The composition of extraction and back-extraction compound were analysed withIR， UV spectroscopy, chemical concentration analysis, the slope method, and XRD analysis. The Experimentresult indicates:Firstly, the best extraction phase composition was70%TBP⁺30%sulfonated kerosene, O/A is1:1, the HCl concentration was no less than2mol L^-1, extraction equilibrium time needs2min and extractionefficiency had no relevant to do with concentration of Cl-in the process when TBP extract Cu⁺from etchingwaste liquid.Second, the best O/A was5:4, back-extraction equilibrium time needs4min and the H₂O₂concentration was4%.And then Cu⁺was extracted by TBP in the shape of HCuCl₂·2TBP, and he aqueousphase obtained in the back-extraction experiments was CuCl₂solution.In HFSLM system, polyethersulfone hollow fiber tube was used as support. TBP/sulfonated kerosene,adhered in shell of pipe, formed liquid film. Feed phase and stripping phase circularly flow across the tube andshell. It was investigated how concentration of the organic phase, the flow rate of aqueous phase and theconcentration of stripping agent impact on mass flux of HFSLM. Experimental results show that Mass fluxincrease as concentration of H₂O₂is increasing, and increase at first and then decrease as concentration of TBPand the flow rate of aqueous phase increase. And it is determined as the optimal operating conditions that TBPcontent is5%, flow rate of aqueous fluid is40.16/40.05mL min^-1and concentration of H₂O₂is6%. Finally,mass transfer model was established as InC_c/C_p=nA/V_f.P_e.t, and the total mass transfer parameters wascalculated as3.14×10-5m·s^-1.In etching experiments, acidic copper chloride etching liquor compounded in the laboratory, renewableliquid obtained through solvent extraction method and HFSLM technology were used as etchants.Experimental datas show that three etching rates were extremely close. It explains that solvent extraction method and HFSLM technology can recover etching performance of acidic copper chloride etching wasteliquor efficiently.The results showed that the solvent extraction with TBP/sulfonated kerosene as extractant, Cu⁺could beextracted in acidic copper chloride etching waste liquor all at once.When H₂O₂was used as the reextractionagent, on one hand extractant can be regenerated efficiently, on the other hand the reextraction product CuCl₂may be recycled to regulate the renewable liquid of etching waste liquor, and the “zero” emissions and recyclewere truly achieved. HFSLM greatly improved the stability of supported liquid membrane, extraction and backextraction process were done at the same time, the operation were simple and convenient, and it had highlyselective to extract Cu⁺in the acidic copper chloride etching waste liquor.