| Currently, ibuprofen has been widely used due to the lower toxicity and higher efficacy than aspirin and acetaminophen. Ibuprofen is a new generation of non-steroidal anti-inflammatory drugs. The trace organics of ibuprofen has been detected in drinking water in some countries and regions recently. In the treatment of drinking water, the disinfection by-products、toxicity and its impact on drinking water safety of ibuprofen caused widespread concern. Therefore, it is necessary to study some drinking water treatment processes to improve the removal of ibuprofen and its mineralization, to ensure the sanitation and safety of drinking water.As a new form of advanced oxidation processes(AOPs) and drinking water depth treatment technology, heterogeneous catalytic ozonation technology can get rid of the synthetic refractory organic matter effectively. In this paper, the removal efficiency of ibuprofen will be studied under the conditions of different reactions patterns and factors, combined the effective catalytic activity of silicate-based microfiltration membrane and the strong oxidation of ozone.Whether in the static test research trials, or in a continuous flow of experimental studies, the silicate-based microfiltration membranes have high catalytic activity. In the static test, the initial concentration of ibuprofen 1.0 mg/L and the ozone dosage 2. 5 mg/L, ibuprofen removal was 100% and TOC removal rate of the reaction system was 53.36% at the reaction time 30 min. While in continuous-flow test, the initial concentration of ibuprofen 2.0mg/L, the ozone dosage 2.5 mg/L and hydraulic retention time(HRT)10min, the removal of ibuprofen was 97.0%and TOC removal rate was 53.0%; in HRT 25 min, the removal rate of ibuprofen 100% and TOC removal rate reached 56.18%. With the background of water become more complicated, there is a downward trend of the ability of silicate-based microfiltration catalytic degradation of ibuprofen. But in the static test study of different bodies of water background, ibuprofen initial concentration of 500 ug/L, ozone dosage of 1.0 mg/L, the degradation rate of ibuprofen can guarantee more than 90%. In the both reaction modes, ibuprofen removal has been raised as the p H increased. But with the increase of alkalinity and humic acid concentration in water, the removal of ibuprofen was significantly inhibited. In the static test study, we found that the temperature affects the reaction system at the initial stage. However, with the progress of chemical reactions, the effect of temperature increased weakly. This means that the temperature of the reaction is not significant variation in the static test study.By free radical inhibitors and electron spin resonance(ESR) analysis, it was demonstrated that during the reaction of silicate-based microfiltration membrane catalytic ozonation ibuprofen, the active species of hydroxyl radicals are momentous. Studying silicate-based microfiltration membrane catalytic ozone shows that ozone decomposition is mainly depend on the alkaline substance calcium hydroxide, calcium silicate and polymer ettringite within membrane pores to promote decomposition of ozone to produce more hydroxyl radicals.In the kinetic experiments, the constant of reaction rate of ibuprofen with ozone molecule is 11.18 L/(mol ? s). During the experiment of ozone oxidizing ibuprofen, under conditions of temperature T=18±1℃, p H 6.51, 7.02, 7.43 and 7.85, the apparent rate constant is 19.48, 24.60, 31.38 and 53.94 L/(mol ? s), respectively. At p H 7.10 of the ozonation experiment, the apparent rate constant was kobs=(2.3 ×106)exp(-3124.787/T) L/(mol ? s) under different temperatures. While the analysis of the apparent rate constants versus temperatures leads to the formula kobs=(6.3×105)exp(-2396.0297/T) L/(mol ? s), by which the apparent rate constant can be calculated when p H 7.07 of the catalytic ozonation experiment. Under the terms of temperature T=18±1℃, p H 6.51、7.02、7.43 and 7.85, the apparent rate constant respectively is 87.13, 119.08, 128.27 and 170.36 L/(mol ? s) in the catalytic ozonation experiment. Studies have shown that the silicate-based membrane catalytic ozone can increase the reaction rate constant of ibuprofen. |
PDF Full Text Request