Recovery of spent electroless nickel plating (EN) bath decreases the drainage of waste water and saves resources. During the treatment of spent EN bath by electrodialysis, the removals of harmful components, such as phosphite, sulfate and sodium ions, were significant, meanwhile the reduction rates of useful components, for example, hypophosphite and nickel ions, were slow, which was beneficial to the regeneration of spent EN bath. The process was characterized in terms of limiting current density, membrane fouling, removal of main components, and current eficiency. The correlation between working current, concentration changes and run time was discussed. Using actual spent EN bath the fouling behavior of the membranes was investigated in long-term experiments.

The NiCr plasma-sprayed deposition, as an intermediate layer, is normally used to improve the adhesion between the metal substrate and the ceramic coating. Defects, such as pores and micro-cracks, generally exist in the ceramic layer, and lead to corrosion beneath the coating. The present work used plasma-sprayed specimens, such as the Cr2O3 ceramic coatings with and without a NiCr intermediate layer and the single NiCr coatings, etc. which were deposited on a SUS316L stainless steel substrate. The results of corrosion tests and electrochemical experiments indicated that the corrosion resistance of the 80NiCr (80Ni-20Cr) coating was weaker than that of the SUS316 substrate, while that of 50NiCr (50Ni-50Cr) was better than that of the substrate. The existence of 80NiCr plasma-sprayed intermediate layer decreased the corrosion resistance of the Cr2O3 ceramic coated specimen, while the 50NiCr increased it. The microstructure analysis demonstrated that both the 80NiCr and 50NiCr plasmasprayed coatings consisted of the matrix and a second-phase structure. Energy dispersive spectroscopy (EDS), wave dispersive spectroscopy (WDS) and X-ray diffractometry (XRD) analysis showed that the components of the matrix and the second-phase in 50NiCr were different from those in 80NiCr. In addition, this paper preliminarily discusses the corrosion mechanism of 80NiCr and 50NiCr intermediate layers. The different chromium content in the matrix of the 80NiCr and 50NiCr coatings might have caused the difference in the corrosion resistance between them. It can be predicted that the decrease of porosity by means of plasma spraying or sealing treatment of the ceramic coating, as well as by regulating the components of the NiCr intermediate layer, would improve the corrosion resistance of Cr2O3 ceramic coated materials.

As a result of their great chemical inertness, ceramics and functionally gradient materials (FGM) are being used increasingly as coatings on machine parts. However, studies have shown that ceramic-coated materials still exhibit corrosion behavior. The objective of this work was to study the corrosion and erosion-corrosion behavior of ceramics and FGM-coated materials in erosion environments. Test results showed that plasma-sprayed ceramic coatings, with or without NiCr (80% Ni-20% Cr) undercoating, did not inhibit corrosion completely but did reduce the corrosion rate. It was found that NiCr undercoating does not improve corrosion resistance; however, it can improve the mechanical cohesion between ceramics and substrate. Although ceramics and FGM coatings were found to decrease the additive and synergistic effects of erosion and corrosion, they did not show erosion-corrosion resistance as expected, particularly FGM coatings. The erosion-corrosion wastage of these coatings was generally greater than that calculated by combining pure erosion and corrosion. To improve the corrosion and erosion-corrosion resistance, it was necessary to modify the composition of the NiCr compound by varying the ratio of nickel and chromium or by decreasing the porosity in the ceramic-coated layers and combining these with a sealing treatment.

在试验研究的基础上，确定溶解氧、pH值、金属离子等对酱油废水色度降解的影响，明确了酱油废水色度构成物质的转化条件及适宜于COD和色度同步去除的运行控制条件. 研究表明，在厌氧条件下，有机物质和色度构成物质同步去除，不发生明显的相互转化；在好氧条件下相当长的氧化时段中，色度构成物质及其它成分降解的中间产物重新转化造成色度增加，即存在着COD和色度的不同去除问题. 控制水解酸化的pH在7.0～7.2的范围，向水中投加适量的Ca2+，有效避免了色度在处理过程中的反复转化，实现了色度与COD的同步去除。