Study On Analytical And Degradation Methods For Some Organic Contaminants In Water Environment

In this study, we investigated the analytical method for dimethyl sulfide and dimethyl disulfide, nanomaterial-based degradation methods for removal of methylene blue dye and SDBS surfactant. The main contents are as followings:1,A headspace solid phase microextraction (HS-SPME) combined with gas chromatography/flame photometric detection (FPD) has been developed for the determination of dimethyl sulfide and dimethyl disulfide in wastewater from constructed wetlands. The various parameters including type of fibers, extraction temperature, pH value, ionic strength, sample volume were investigated for optimization of HS-SPME performance for dimethylsulfide and dimethyldisulfide. The DB-VRX capillary column (1.4μm,60 m×0.25 mm) was used for separation of dimethylsulfide and dimethyldisulfide with 1 mL/min of high purity nitrogen as carrier gas by GC. The initial oven temperature was 50℃, then was programmed at a rate of 8℃/min until 120℃, holding 2 min, and then a rate of 6℃/min until 180℃, holding the final temperature for 3 min. The enriched targets were detected by FPD. Under the optimized conditions, the linear dynamic ranges were 1060-13780 and 159-4240 ng/L for dimethylsulfide and dimethyldisulfide, respectively. The detection limits (3σ) for dimethylsulfide and dimethyldisulfide were 1020 and 140 ng/L, respectively. The relative standard deviations for the determination of studied compounds were less than 7%. By using dimethyl sulphide as internal standard, the proposed method has been successfully applied to the analysis of dimethyl sulfide and dimethyl disulfide in wastewater and recoveries are in the range of 85-114% and 105-113% for dimethylsulfide and dimethyldisulfide, respectively.2,Ultrasound-assisted nano-Fe3O4 nanoparticles for catalyzed degradation of methylene blue dye wastewater in the presence of hydrogen peroxide. Based on the fact that nano-Fe3O4 has similar property of hydrogen peroxidase, nano-Fe3O4 is able to enhance the catalytic ability of hydrogen peroxide. The optimal experimental conditions were obtained as follows:600 mg/L of nano-Fe3O4, 0.32 mol/L of hydrogen peroxide, pH at 5,3 min of ultrasonic time,30℃of ultrasonic temperature, 2 h of reaction time. The 92% removal rate was obtained with good reproducibility. 3,Ultrasound-assisted nano-Fe3O4 nanoparticles for catalyzed degradation of SDBS surfactant wastewater in the presence of hydrogen peroxide. Various factors affecting the SDBS removal were investigated and the optimal degradation conditions were obtained as follows:480 mg/L of nano-Fe3O4,0.05 mol/L of hydrogen peroxide, pH at 3,3 h of reaction time. The 84% removal rate was obtained with good reproducibility.