Degradation Of Propranolol And Imipramine In Aqueous Solution By Vacuum-Ultraviolet

With the development of human society,the environmental problems caused by Pharmaceutical and Personal Care Products?PPCPs?are becoming more and more prominent.They have had an influence on the growth of animals,plants and even human beings.As a commonly used beta-blocker and anti-depressant,propranolol?Pro?and Imipramine?IMI?have very limited removal in the conventional treatment process.Existing advanced oxidation processes?AOPs?often need to add additional oxidants to improve the degradation efficiency of pollutants,and there are certain drug residues and effect problems.Compared to other AOPs,the vacuum ultraviolet?VUV?is a very promissing advanced oxidation technology with advantages of mild operating condition,wide adaptation,and requires no additional adding chemical agents.Therefore,a VUV system was built in this paper,and the degradation efficiency of the VUV system on Pro and IMI was studied.Compared with the common ultraviolet(UV₂₅₄)system,the VUV system degraded Pro and IMI effectively.The removal rate of Pro and IMI reached 97.21%and 87.68%within 15 min,while only 32.58%and 30.69%in UV₂₅₄ system.We found that both direct photolysis of ultraviolet light and active free radicals contributed to the degradation of pollutants in VUV system,while·OH plays a important role.The removal of TOC showed that most of Pro and IMI were degraded into intermediate products in 30min.The effects of substrate concentration,reaction temperature,light intensity,pH,inorganic anion and humic acid on the degradation of Pro and IMI were also investigated in VUV system.The results showed that the removal of Pro and IMI decreased with the increase of their initial concentration,while the increase of pH,illumination intensity and tempreture enhanced the degradation rate of Pro and IMI.We also found that the dissolved oxygen in water had little effect on the degradation of Pro and IMI in VUV system,while inorganic anions?Cl^-,HCO₃^-?and humic acid in water inhibit the degradation of Pro and IMI to a certain extent.Among them,the inhibitory effect of Cl^-was most obviously.In addition,we found ten intermediate products in the degradation process of Pro and eight intermediate products in the degradation process of IMI by HPLC-MS.Meanwhile,three possible degradation pathways of Pro and IMI in the VUV system were proposed.Furthmore,the degradation of Pro and IMI in the real water was investigated,we used the water and tap water to replace the ultra-pure water of the laboratory.Results showd that the degradation of VUV system declared but the degradation rate of target pollutant is still high,the removal rate reached more than 58%in 15 min.