Quantification Of Sulfate Radical Formation And Its Application In Advanced Oxidation Technology

With social progress and economic development, environmental pollution havebecome increasingly prominent. Aquatic pollutants increase rapidly in types andquantities, which is a challenge for water treatment and aquatic protection.Traditional water treatment technologies can not meet with the urban and indus trialdemand of water quality, and advanced oxidation technologies are employed inengineering projects. Advanced oxidation technologies are taking advantages offree radical’s high reactive ability to degradate refractory organics, in which the useof different methods to activate persulfate producing sulfate radical (SO4-) hasreceived widespread attention. In the use of technology characterized by producti onof activated persulfate, it is essential to consider the SO4-yield and degradation oftarget substances in specific water. In this background, we developed competi ti vekinetics method and complete capture method,which are based on the quantificati onof SO4-in UV/PDS system. These two methods were used to assess the yield ofSO4-in different activation systems and the influence of different water matrix onthe degradation of specific target substances by SO4-.In the use the competitive kinetics method, the system is consisted withbenznic acid(BA) and alcohols (methanol, ethanol or t-butanol), in which the BAworked as an indicator, and the alcohol worked as a capture agent. The SO4-yieldwas derived by the kinetics of BA’s degradation and the competition model. Thescavenging rate of alcohols(k(methanol,SO4-)=1.23×107M-1s-1, k(ethanol, SO4-)=5×107M-1s-1, k(tert-butanol,SO4-)=2×106M-1s-1) were derived by thecompetitive system, too. The reaction pathways differ in the reaction of SO4-withdifferent alcohols, and the radical yield calculated under different pH conditionsdiffers too. Excess alcohols were added in the total capture system to capture SO4-,and the SO4-yield was calculated by the products. In different total capture system,the production of product are different. Under different pH conditions, the SO4-yields derived by total capture method are also different.In different waters, the degradation of pollutants by SO4-is influenced by thebackground component in water, which affects the degradation efficiency. Thescavenging rates of different water were evaluated by competitive kinetics modelsand total capture models with the following order: sewage>> surface water> groundwater> drink water. Three anions’ scavenging rates were evaluated by competitivekinetics models with the order: Cl->> NO3-> HCO3-. The competitive kineticsmodels were also applied on the transition metals’ activation of PDS, and the SO4-yields illustrate the efficiency of different transition metals with the following order: Ag(I)> Fe(II)> Fe(III)> Mn(II)>> Ce(III)> Ni(II). Competitive kinetics methodcould quantitatively analyze the production of SO4-and the degradation effect oftarget substances in water by SO4-, which is of great significance to guide practicalproduction and application.