You Wen-Dan,Ye Pu,Yang Bin,Luo Xin,Fang Jie,Mai Zi-Tian,Sun Jian-Liang
Benzodiazepines are one group of psychoactive drugs widely detected in water environments, and their persistence during conventional wastewater treatment has raised great concerns. Here we investigated the degradation of 17 benzodiazepines in water by UV/H2O2 treatment. The results showed that the UV/H2O2 treatment significantly increased the degradation of 17 benzodiazepines in phosphate buffer solutions at pH 7.0. This can be attributed to the high reactivity of hydroxyl radicals (·OH) towards benzodiazepines with second-order rate constants of 3.48 × 109 M−1 s−1–2.44 × 1010 M−1 s−1. The degradation of alprazolam, a typical benzodiazepine, during the UV/H2O2 treatment was increased with the increasing H2O2 dosage. The solution pH influenced the alprazolam degradation significantly, with the highest degradation at pH 7.0. Water matrix, such as anions (Cl−, HCO3−, NO3−) and humic acid, decreased the degradation of alprazolam by UV/H2O2 treatment. Based on the degradation products identified using quadrupole time-of-flight mass spectrometer, the degradation mechanisms of alprazolam by UV/H2O2 treatment were proposed, and hydroxylation induced by ·OH was the main reaction pathway. The degradation of 17 benzodiazepines by UV/H2O2 treatment in wastewater treatment plant effluent and river water was lower than that in phosphate buffer solutions. The results showed that the benzodiazepine psychoactive drugs in natural water can be effectively removed by the UV/H2O2 treatment.
Biyang Zhu,Liuting Li,Kseniya Hileuskaya,Baojun Xu,Lijun You
Although ultraviolet (UV)/H 2 O 2 treatment could effectively improve the bioactivities of polysaccharides, the relationship between free radical-induced structural changes and the bioactivities of products remains unknown. Therefore, this work investigated the changes in the chemical characteristics and chain conformations of degraded dextrans by the UV/H 2 O 2 system as well as their antioxidant and anti-inflammatory activities. The apparent degradation efficiencies of dextrans under different UV/H 2 O 2 parameters were first investigated. UV/H 2 O 2 treatment effectively destroyed the pyranose rings and glycosidic bonds of dextrans and significantly improved their uronic acid and carboxy contents. Furthermore, conformational studies revealed that besides the rapid decrease in the molecular weight, the compact spherical conformation of dextrans was gradually depolymerized into the flexible random coil conformation. Moreover, the significant antioxidant and anti-inflammatory activities of the degraded dextrans were mainly attributed to their more extended random coil chains, increased quantity of reducing groups, and lower molecular sizes. This study contributes to investigating the structure–activity relationship of polysaccharides prepared by free radicals-mediated degradation.
危险品化学品经营许可证（带存储）