| Naproxen (NPX) is a synthetic non-steroidal anti-inflammatory drug (NSAID). Because of its good antipyretic, anti-inflammatory and analgesic effect, it is mostly used in its sodium salt form in medical care as an analgesic, antiarthritic and antirheumatic. As it enters the aquatic environment by direct or indirect emission, NPX was detected in a variety of environmental water, even in drinking water. Its presence at low or high concentrations could bring about harmful toxicological consequences. For instance, people who ingest trace amounts of NPX for a long time may have a higher risk of having a heart attack or a stroke than people who are not exposed to this medication. Therefore, it is clear that much attention should be paid on NPX in the aquatic environment.This paper studied the oxidation degradation of NPX and the effects of impact factors on the oxidation of NPX by NaClO, and investigated the oxidation pathways and products. Besides, the oxidation degradation of NPX and the effect of pH value were investigated by NaClO in the presence of Br. All of these are supposed to find a viable technology for NPX treatment.First, the oxidation degradation of NPX and the effects of impact factors on the oxidation of NPX were investigated by NaClO, the results showed that NPX could be degraded quickly and effectively by NaClO. Under the conditions of pH 4.8, NaClO/NPX molar ratio 20.0 and response time 46s, NPX was completely degraded and the removal rate of NPX reached 100%. The toxicity evaluation illustrated that some of the intermediate products formed were more toxic than NPX. The TOC evaluation indicated that removal ratio of TOC increased with the increasing mole ratio of NaClO to NPX before it stabilized at about 22.5%, and the removal ratio of TOC lagged behind the NPX’s, which mean that NPX could not fully mineralized by NaClO.The effects of impact factors on the oxidation of NPX by NaClO were evaluated. The results demonstrated that the degradation rates of NPX reduced gradually with the increase of NPX dosages.The degradation rate of NPX in the aquatic environment with the different pH values were investigated by NaClO. The results show that the solution with low pH value accelerated the degradation of NPX, and removal efficiency of NPX had a strong dependence on the pH of solution. Under the conditions of pH 3, NPX was completely degraded and the removal rate of NPX reached 100%. The effects of supplementary material in medical NPX capsules on the degradation of NPX were investigated by NaClO, the results illustrated that supplementary material had opposite effects on it.Finally, degradation experiment on NPX was performed by NaClO in the presence of Br-.The results indicated that the removal rate of NPX reached 100% under the conditions of Br-/NaClO/NPX mole ratio 1/5/1, while the removal rate of NPX only reached 45.65% under the conditions of Br/-NaClO/NPX mole ratio 0/5/1. The removal rate of NPX differ by more than 50% under two conditions, which indicated that Br- play a stimulative role in degradation of NPX by NaClO. And the impact of pH values on degradation of NPX were evaluated by NaClO in the presence of Br-. The results indicated that initial pH values had obvious effect on the degradation of NPX in the range of 3 to 5, while had no effect on it in the range of 5 to 9. And the removal rate of NPX reached 100% under the conditions of Br-/NaClO mole ratio 0.5/5 and pH 3.The oxidation products were detected by HPLS/MS, the oxidation products of NPX were analyzed through the spectra, which were 1-(6-hydroxy-2-naphthyl)ethanone; 1-(6-hydroxy-2-naphthyl)ethylene;1-(8-chloride-6-hydroxy-2-naphthyl)ethylene; 2-(5,8-dichloro-6-methoxy-4-hydroxy-2-naphthyl)propionic acid; 2-(5,8-dichloro-6-methoxy-2-naphthyl)propionic acid; 1-(5,8-dichloro-6-hydroxy-2-naphthyl)ethanone; 2-(5,8-dichl-oro-6-hydroxy-2-naphthyl)propionic acid. Moreover, we speculated oxidation degrada-tion pathway for NPX by NaClO. |
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