The direct photolysis of N-nitrosodiethylamine(NDEA) in water with ultraviolet(UV) irradiation was investigated.Results showed that NDEA could be completely degraded under the direct UV irradiation.The effects of the experimental conditions,including the initial concentration of NDEA,humic acid and solution pH,were studied.The degradation products of NDEA were identified and quantified with gas chromatography-mass spectrometry(GC-MS) and high performance liquid chromatography(HPLC).It was confirmed that methylamine(MA),dimethylamine(DMA),ethylamine(EA),diethylamine(DEA),NO2-and NO3-were the main degradation products.The photolysis degradation mechanism of NDEA was also discussed.As a result of N-N bond fission,NDEA was degraded by direct UV irradiation.
This paper investigated the feasibility of sonication as an advanced treatment method for drinking water production and used comprehensive indexes of water quality to examine its efficiency. Results show that sonication significantly reduces the toxicity of water. Sonication with 5 W/L at 90 kHz lasting for 30 rain decreases the water SUVA and the disinfection byproduct formation potential （DBPFP） by 38.7% and 27. 2% respectively. Sonication also decreases the UV254 by more than 50% through destroying unsaturated chemical bonds. Higher sound intensity and higher frequency benefit the reduction of TOC and UV254. Besides, sonication significantly increases the affinity of organics with granular activated carbon （ GAC ） , and thus the hybrid sonication-GAC method reduces the water TOC, COD, UV254, and DBPFP by 78.3%, 69.4%, 75.7%, and 70.0% respectively. Therefore, sonication and the hybrid sonication-GAC metbod are proposed as advanced treatment methods for drinking water.
In order to realize hydrogen generation under visible light, novel CdS/TiO_2 nanotubes arrays are de- veloped by electrochemical anodization of Ti in 0.15 mol/L NH_4F + 0.08mol/L H_2C_2O_4 electrolyte. The diameter of the nanotube is 80―100nm and the length is approximately 550 nm. The CdS nano-particles are deposited on the TiO_2 nanotubes arrays by chemical bath deposition (CBD) in the ammonia-thiourea system. A 300W Xe lamp is used as the light source, CdS/TiO_2 nanotube arrays are used as the photoanode with the application of 1.0V bath voltage, and 0.1 mol/L Na_2S + 0.04 mol/L Na_2SO_3 solution is used as the electrolyte, then the rate of photoelectrocatalytic hydrogen generation is 245.4 μL/(h·cm^2). This opens new perspectives for photoelectrocatalytic hydrogen generation by using CdS/TiO_2 nanotubes arrays.
