Degradation Of Typical Beta Blockers In UV/Peracetic Acid Systems

Beta-blockers have been widely used as a specific drug for the treatment of cardiovascular disease since their inception in the 1960s.Such drugs are discharged and accumulate in natural water,causing biological toxicity to aquatic animals and plants.In addition,due to the limited removal effect of conventional water treatment processes on beta blockers,it seriously harms the safety of drinking water.Ultraviolet/peracetic acid（UV/PAA）,as a new advanced oxidation technology,can produce carbon free radicals（·C-R）and hydroxyl radical（·OH）at the same time.Therefore,it is of great significance to systematically study the degradation efficiency and mechanism of various organic micro-pollutants by UV/PAA advanced oxidation system.In view of this,propranolol and atenolol were selected as the target pollutants in this study,and the effect of removing beta blockers by UV/PAA advanced oxidation system was investigated experimentally,and the removal mechanism was revealed.Throughout comparing the degradation effect of propranolol and atenolol in five advanced oxidation systems,such as individual ultraviolet,individual peracetic acid,ultraviolet/hydrogen peroxide（UV/H₂O₂）,UV/PAA,and UV/PAA/TBA,it was found that the degradation effect of UV/PAA system on the substrate was significantly better than that of the individual UV and individual peracetic acid system.The UV/PAA system is able to degrade propranolol and atenolol efficiently under normal temperature（20℃）and neutral conditions,and the degradation efficiency is all over 82%.Also the·OH and·C-R produced in this system play a leading role in the degradation of two kinds of beta blockers,in which·OH contributes more than 40%,and·C-R contributes more than 30%.Through comparative test,it was found that when two kinds of beta blockers were degraded by UV/PAA system,both PAA and hydrogen peroxide（H₂O₂）in the system were degraded by propranolol and atenolol through UV activation reaction;·C-R in the system is derived from UV activation of PAA,whereas·OH is derived from both PAA activation and concomitant H₂O₂ activation in the system.This research also systematically investigate the effects of peracetic acid concentration,substrate concentration,temperature,solution p H,inorganic anion,humic acid and other operating parameters and water quality parameters on the degradation of propranolol and atenolol by UV/PAA system.The experiment results indicate that with the increase of PAA concentration,the decreases of initial concentration of the target pollutant and the reaction temperature increases,the decomposition outcome of the substrate is significantly improved.In addition,both of the two target pollutants can be effectively removed under neutral conditions,the degradation outcome of propranolol is the worst at p H=6,while the degradation of atenolol declines with the increase of p H.Moreover,chloride ion is able to promote the degradation of propranolol,but has no obvious effect on atenolol;and HCO₃^-/CO₃^2-inhibited the degradation of atenolol by competitive free radicals,while it promoted the degradation of propranolol in UV/PAA system.Finally,humic acid will inhibit propranolol and atenolol decomposition since it can compete·C-R and·OH efficiently at the same time.Under the research conditions of this paper,The cost of treating propranolol and atenolol micropolluted water by UV/PAA advanced oxidation technology is 0.46 yuan/m³ and 1.43 yuan/m³ respectively.It has a broad application prospect.