|
Haloacetic acids (HAAs) is a common organic pollutants in drinking water or other water system disinfection process, disinfectants and water natural organic matter (NOM) reaction produced a class of disinfection by-products (of DBPs). The DBPs mainly include monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), a bromoacetate (MBAA), dibromoacetic acid (DBAA), bromo-chloroacetic acid (BCAA), dichloroacetic acid, a bromine (BDCAA), dibromo chloroacetic acid (CDBAA), the three bromine acid (TBAA), nine kinds. Chlorination process DCAA and TCAA largest proportion. HAAs has a strong cause of \Disinfection method disinfection byproducts (D / DBPs Rule), the U.S. Environmental Protection Agency (US EPA) regulations since 1998 the total amount of HAAs in drinking water should not exceed 60μ / L shall not exceed 30μ / L after 2000. In 2006, China's Ministry of Health issued a GB / T 5749-2006 \the provisions of DCAA and TCAA limits, 50μg / L and 100 μg / L, respectively. This shows that the control and reduction technology on HAAs has a very significant meaning. This thesis to DCAA and TCAA target contaminants, HAAs formation routes and degradation were discussed, the specific content and conclusions are as follows: (1) the establishment of HAAs analytical method, using gas chromatography and ion chromatography The two analytical method detection limit and recovery rates are in line with the requirements set by the U.S. EPA. Optimum chromatographic conditions, Gas Chromatography the HAAs recoveries between 86.92% -108.00% detection limit in between 0.48-0.62μg / L; the ion chromatography recoveries between 71.70% -100.19%, the prosecution the limit in between 12.58-14.16μ / L. (2) humic simulated organic precursor, sodium hypochlorite as the disinfectant, the process of drinking water disinfection by laboratory simulation to investigate the concentration of humic acid, the amount of chlorine, pH value, reaction temperature, reaction time and other conditions of the halogen Acetate Production. The results showed that the humic acid is proportional to the amount of available chlorine concentration of haloacetic acids generated. In addition, the formation of haloacetic acids within a certain range with the prolongation of reaction time, reaction temperature, the increases and decreases with the increase of the pH value (3) Photo-Fenton oxidation degradation HAAs simulated water samples, reaction time, Fenton reagent dosage, initial pH, light intensity of haloacetic acids degradation effect, and to investigate the degradation kinetics of HAAs. The results show that the Photo-Fenton oxidation degradation of HAAs conditions: light intensity of 500W/m2 Fe2 dosage to 1.0 mmol / L H2O2 dosage of 5.0 mmol / L, reaction time of 60 min, the reaction at room temperature, the initial pH of 4.0, under this condition, the concentration of 100μg / L DCAA and TCAA degradation rate of 90.32% and 87.77%, respectively, in the actual water quality pH of 7.0, the same concentration of DCAA and TCAA The degradation rate of 75.34% and 68.80%, respectively. Light and Fenton oxidation degradation of HAAs have a synergistic effect. Photo-Fenton oxidation degradation of HAAs order kinetics equation, the apparent activation energy of DCAA and TCAA were 52.42 kJ · mol-1, 56.46 kJ · mol-1. (4) using the the ultrasonic assisted zero-valent iron reductive degradation of HAAs analog water samples. The effects of initial pH, iron dosage, reaction temperature, reaction time, initial halogen acetic acid concentration on the rate of degradation. The results show that the iron dosage 4.0g / L, room temperature reaction 4h, the pH value of 4.0, the initial concentration of 50μ / L DCAA and TCAA degradation rate of 82.01% and 87.33%, respectively. a pH of 7.0 under neutral conditions, the same concentration of DCAA and TCAA degradation rate of 63.22% and 67.56%, respectively. Ultrasound-assisted zero-valent iron reduction degradation of HAAs order kinetics equation of DCAA and TCAA apparent rate constant of 0.1550 min-1, 0.3418 min-1.
|