Study On The Degradation Of Sodium Saccharin By Ozone Oxidation Technology

In recent years,artificial sweeteners have been detected in the environment of various countries and have become a new type of pollutant and have received widespread attention.As the"first generation"artificial synthetic sweetener,sodium saccharinate has a complicated synthesis process and serious pollution of production wastewater.It is difficult for biochemical treatment to discharge it up to the standard,and it needs advanced treatment.In addition,people also have considerable controversy about the safety of SAC.Based on its accumulation in the environment and the potential harm to humans and organisms,it is necessary to consider finding suitable methods to effectively remove it.Taking SAC as the target pollutant,this paper studies the degradation effects of three advanced oxidation technologies:ozone(O₃),ozone/hydrogen peroxide(O₃/H₂O₂)and ozone/persulfate(O₃/PMS)on SAC,focusing on the initial SAC The influence of reaction conditions such as concentration,oxidant dosage,pH and temperature on the degradation effect of SAC,the kinetic analysis of the reaction process,and the reaction mechanism through free radical quenching experiments.Now draw the following conclusions:(1)The optimal conditions for degradation of SAC by O₃ alone are the initial SAC concentration of 10 mg/L,pH=9,the O₃ concentration of 2.5 mg/L and 35°C;when the initial concentration of SAC is 50 mg/L,the maximum degradation of SAC by O₃/H₂O₂ The optimal conditions are that the dosage of H₂O₂ is 15?mol/L,pH=9,the O₃ concentration is2.5 mg/L and 35°C;the optimal conditions for O₃/PMS to degrade SAC are PMS dosage 10mg/L,pH=8,and O₃ concentration 2.5 mg/L and 35°C.(2)Experimental analysis has studied the reaction kinetics of the degradation of SAC in the three systems of O₃,O₃/H₂O₂ and O₃/PMS,indicating that the reaction processes under different reaction conditions are in line with the first-order reaction kinetics,which can be derived from the first-order reaction rate The factors that affect the degradation of SAC in the O₃ system are the initial concentration of the SAC reaction>ozone concentration>pH>temperature;the factors that affect the degradation of the SAC in the O₃/H₂O₂ system are pH>H₂O₂ dosage>temperature;the influence in the O₃/PMS system The factor of SAC degradation effect is temperature>pH>PMS dosage.(3)The research on the reaction mechanism of the degradation of SAC by three advanced oxidation technologies based on ozone has found that most of the degradation of SAC is dominated by the indirect oxidation of hydroxyl radicals,and the contribution of hydroxyl radicals accounts for more than 90%of the total degradation reaction,so it is speculated that SAC The degradation mechanism is the hydroxylation of the benzene ring.Under acidic conditions,in addition to O₃ oxidation in the O₃/PMS oxidation system,PMS is activated by acid to produce SO4^-·,which synergistically acts on the degradation and mineralization of SAC.As the pH increases,the indirect oxidation of hydroxyl radicals gradually increases..From the perspective of SAC removal rate and salinity,the O₃/PMS oxidation system is better than the O₃/H₂O₂ oxidation system than the single ozone oxidation system.The single ozone technology is under optimal conditions at 10 mg/L of SAC within20 minutes.It is completely degraded,so it is more suitable for the advanced treatment of SAC in domestic sewage,surface water and groundwater.O₃/H₂O₂ and O₃/PMS technology treats 50 mg/L SAC under optimal conditions to be completely degraded and mineralized within 60 minutes The degrees are 44.11%and 58.52%,respectively,so it is suitable for the pretreatment of higher concentration of SAC production wastewater.