| Most of the research on persulfate advanced oxidation technology is based on the oxidation technology of highly active sulfate radical(SO4·ˉ).The activity of SO4·ˉ is very strong,and it can oxidize many kinds of refractory organic pollutants.However,its ability of selective oxidation is poor.SO4·ˉ oxidize the target at the same time also will react with the background components in the water,which is harmful for real water/waste water treatment.On the one hand,the waste of oxidant can be caused,on the other hand,this process may produce toxic substances.Recent studies have reported that copper oxide(Cu O)can effectively activate persulfates(PDS)under mild reaction conditions,and this activation process does not produce SO4·ˉ.Cu O is one of the main corrosion of copper pipe fittings and copper alloy pipe fittings in the water distribution network.As a new advanced nonradical oxidation system,the oxidation capacity of organic micro-pollutants by PDS/Cu O remains to be further investigated.In addition,the potential risk of producing disinfection by-products in PDS/Cu O system should be studied.This paper examines the oxidation ability of PDS/Cu O system for iodide,substituted phenol(methyl phenol,nitrophenol,chlorophenol and bromophenol)and several kinds of organic micro-pollutants(carbamazepine,furfuryl alcohol,paracetamol and sulfamethoxazole).The transformation of iodine(Iˉ)in PDS/Cu O system was investigated.Iˉ was quickly oxidized to hypoiodous acid(HOI)and further transformed to iodate(IO3ˉ)in the PDS/Cu O system.The oxidation rate of PDS/Cu O system increases with the increase of PDS dosage or Cu O dosage.PDS/Cu O oxidation I ˉ overall reaction rate =0.052[PDS]0.74[Cu O]1.11[Iˉ],the overall reaction rate is in third order.The initial p H value of the solution is adjusted,and the rate of the reduction of Iˉ follows the following order: p H7 > p H8 > p H6 > p H9.The existence of NOM can significantly inhibit the oxidation efficiency of Iˉ in the PDS/Cu O system,and the inhibition effect is enhanced with the increase of the initial NOM concentration.When NOM concentration is 1,2 and 5mg C/L,the conversion rate of Iˉ by PDS/Cu O system reduces from 100% to 72.48%,41.29% and 21.9%,respectively.In the presence of NOM,I-DBPs are generated in the system,and the production rate of I-DBPs decreases with the increase of NOM concentration.In view of the different substituent of substituted phenol,the reaction time required to remove 100% of target substances(initially 10μM)is: bromophenol(20 min)< methyl phenol(30 min)< chlorophenol(40 min)< nitrophenol(50 min).In view of the different position of substituent,PDS/Cu O oxidation of methyl phenol,chlorophenol and bromophenol,there is no obvious difference of o-and p-substituted phenol in oxidation rate,the removal of m-substituted phenol is slowest.But in view of the different nitrophenol,the oxidation rate of PDS/Cu O system is: 3-nitrophenol > 2-nitrophenol > 4-nitrophenol.The reciprocal of the concentration of substituted phenol in the PDS/Cu O system is basically linear with the reaction time,indicating that the reaction between PDS/Cu O and substituted phenol is a pseudo secondary reaction to substituted phenol.The oxidation capacity of PDS/Cu O system to organic compounds with different functional groups is as following: the sulfonated organic compounds SMZ > aromatic phenol organic compounds APAP > double bond organic compounds FFA > double bond organic compounds CBZ,when the initial p H of solution is 6,the corresponding removal rate after 60 minutes of reaction cycle is 64.4%,59.6%,36% and 16.7% respectively.When the initial p H of the solution changes,the oxidation capacity of the PDS/Cu O system to SMZ is: p H7 > p H6 > p H9.After 60 minutes of reaction cycle,the removal rate of SMZ is 68.8%(p H7),64.4%(p H6),and 40.7%(p H9). |
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