Although reverse osmosis (RO) has been widely used in the recycling of metal plating wastewater, organic compounds and heavy metals in the RO concentrate are difficult to remove by conventional treatment. A combination process including Fenton oxidation and a biological aerated filter was used to treat RO concentrate containing complex Cu and Ni from metal plating. During the Fenton treatment, Cu and Ni ions were released due to degradation of organic compounds and then removed by pH adjustment and coagulation. The concentrate was further treated using by a biological aerated filter. Optimum conditions were as follows: initial pH of influent of 4.0; dosage of H2O2 of 5.0 mmol l(-1); ratio of n(Fe2+)/n(H2O2) of 0.8; precipitation pH of Cu and Ni ions of 8.0; and a hydraulic retention time of the biological aerated filter of 2.5 h. The results showed that concentrations of effluent COD, Cu and Ni ions were less than 40 mg l(-1), 0.5 mg l(-1) and 0.3 mg l(-1), respectively; this means the treated effluent meets the emission standards for pollutants from electroplating set by China's Environmental Protection Agency.
A solid-phase preparation method is applied to the synthesis of a novel supported rubber antioxidant, silica-supported 2,2 0 -methylenebis(6-tert-butyl-4-methyl-phenol) (SiO 2 -2246), by directly reacting 2,2 0 -methylenebis (6-tert-butyl-4-methyl-phenol)(antioxidant 2246) with silica. FTIR, Raman spectroscopy and TGA confirm that the antioxidant 2246 is chemically bonded on the surface of the silica particles. The SEM observation shows that the SiO 2 -2246 is homogeneously dispersed in the styrene-butadiene rubber (SBR) matrix. The results of the apparent activation energy and the attenuated total reflectance infrared spectrometry indicate that the antioxidative efficiency of the SiO 2 -2246 in SBR is superior to the corresponding low-molecular-weight 2246. The thermal oxidative stability of the SBR/SiO 2 -2246 composites is much higher than that of the SBR/SiO 2 /2246 composites by comparing their mechanical properties retentions and crosslinking densities. Additionally, the advantages of SiO 2 -2246 also include low migration, low volatility, and low pollution.
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