Experimental Study On Degradation Of Atrazine In Water By Peroxysulphate Advanced Oxidation Process

With the rapid development of national economy and industry,environmental pollution and energy crisis are frequent and increasingly serious.Environmental pollution has become a global problem affecting human survival and sustainable development.Among them,the water resources on which human beings rely on to survive are especially serious,and the consequences are particularly serious.Therefore,water pollution is one of the most urgent problems facing all countries in the world.Atrazine(ATZ),as a widely used herbicide widely used in agriculture,has stable chemical properties and slow degradation under natural conditions.With many years of use,there are more serious residues in the soil,and it enters the water through surface runoff and leaching.Because its structure is highly stable,it is difficult to be biodegraded,and it is difficult to be oxidized by drugs.The process of microbial mineralization is very slow,which has led to the pollution of surface water and groundwater in some areas.In this study,atrazine was used as the target pollutant.Based on the advanced oxidation technology of peroxysulphate(PS),UV and Fe2+ were applied to activate PS to oxidize ATZ.The oxidation degradation efficiency of ATZ is improved by changing the experimental parameters such as pH,activation strength,dosage and temperature of oxidant.In this paper,the degradation kinetics of two kinds of activation methods were discussed.Finally,the radical groups in UV activation process were captured,and the possible degradation pathways of ATZ were speculated.The reaction of UV/PS degradation of ATZ conforms to the quasi first order kinetic reaction,and the UV activation of PS can effectively degrade ATZ in water.The degradation efficiency of UV/PS system to ATZ was mainly affected by UV intensity,PS dosage and temperature.With the increase of these three variables,the treatment efficiency of ATZ increased,while the change of pH had no obvious effect on the degradation efficiency of the whole system.The efficiency of using Fe2+ to activate PS in the degradation of ATZ in water is influenced by pH,Fe2+ concentration,PS dosage and temperature.In different pH reaction fluids,the existence of Fe2+ is different,which leads to the different activation ability of PS,which makes the degradation efficiency of ATZ significantly different.Secondly,under alkaline conditions,·OH also has an effect on the degradation effect of ATZ.The addition ratio of Fe2+ and PS is another key factor in the system.They interact with each other,and the degradation efficiency of ATZ is not significantly improved by single factor plus addition.The degradation of ATZ was found to be consistent with the first order kinetic reaction when the degradation kinetics of ATZ degradation by Fe2+ activated PS degradation was found.It is divided into two stages,the former lmin is a fast reaction,and the reaction speed is gradually steady.In the experiment of free radical capture in UV/PS system,it was found that the composition of free radicals was different under different pH conditions.Under acidic conditions,only SO4-·existed.In pH7,SO4-·in the experimental system had chain reaction to produce ·OH.While under pH9 conditions,excessive ·OH would undergo quenching reaction.Moreover,in the reaction system of UV/PS,the PS system alone has no degradation effect on ATZ,and the degradation efficiency of UV/PS is obviously greater than that of ATZ degradation alone.Through the detection and analysis of LC-MS,it is considered that the main way of ATZ degradation is to replace the chlorine atoms with hydroxyl groups and remove the ethyl or isopropyl groups on the branched chains.The two ways are not isolated,but the three azine ring is not oxidized.