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Sub-phosphate as a reducing agent in electroless nickel plating technology because of its excellent performance in various industrial fields has been widely used. However, nickel plating solution After 67 cycles, the byproduct HPO32-accumulate to high concentrations, and will produce nickel phosphite precipitation hinder the deposition of Ni-P alloy layer, making the deposition rate significantly slower, rough coating and the emergence of a pinhole and other quality problems, and even the bath will be the spontaneous decomposition scrapped, which resulted in the electroless nickel plating costs rise, the impact of the application and development of the technology of electroless nickel plating. With electroless plating nickel technology application scope and scale of production continues to expand, if not addressed direct emissions, will not only destroy the ecological balance, environmental pollution, serious harm to human health, but also cause a great waste of resources. Therefore, the study of chemical nickel plating wastewater treatment technology is increasingly attracted extensive attention at home and abroad. Currently, chemical nickel plating wastewater treatment mainly two ways: (1) the liquid waste discharged after treatment or recycling a part of nickel, phosphorus before discharge; (2) chemical nickel plating effluent purification regeneration. The subject from the point of view of protecting the environment, conserving resources, according to the chemical characteristics of nickel plating wastewater, bath harmful HPO32-electrodialysis technology not only can be removed, but also remove excess Na and SO42-in theory can reach unlimited extension of the life of the bath. - To allow them to reduce environmental pollution and ecological damage, on the other hand, chemical plating nickel liquid waste rich in nickel, phosphorus resources, it resource utilization, which is the chemical nickel plating effluent purification and resources Utilization explore a practical way. According to domestic research point of view, the electroless nickel plating liquid electrodialysis regeneration exist some problems, as HPO32-removal rate is too low; aging loss of useful component in the liquid, causing secondary pollution waste; the electrodialysis treatment after the bath can only reach the fourth cycle of fresh plating bath plating; According to reports electrodialysis treatment after plating extended only about 17 cycles far the gap with foreign countries;, etc.. The subject in the laboratory within homemade electrodialysis device for purifying chemical nickel plating wastewater, the bath regeneration. Three kinds of ion-exchange membrane electrodialysis regeneration treatment, Guangdong electroless nickel plating plant waste HPO32-removal rate, and Ni2 and H2PO2-loss rate was measured to determine which one ion exchange membrane desalination rate and HPO32-and H2PO2-selective better. The experimental results show that the ion selective heterogeneous film on the chemical nickel plating wastewater to be better than the homogeneous membrane. And such a better performance of the ion exchange membrane to the test, and inspected in several process conditions on the removal rates of the various ion, obtain a suitable operating conditions in the present experiment. Give optimum conditions: J = 65mA/cm2, pH = 4.5, v = 1L/45s results show: the anionic HPO32-and the H2PO2-selectivity is not obvious, and useful substances causing a huge loss of H2PO2-. Under these conditions bath regeneration cost will be relatively high, increasing the difficulty of a concentrated liquid treatment. Also the regeneration of the bath performance test, the result is: plating rate 10.56μm / h, hardness of 480HV, phosphorus content 12%, the surface morphology of the coating obtained with the new coating of the third cycle of the cylinder bath morphology basic Similar resistance to the mere mention of the salt spray test to meet its production needs.
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