UV-LED/NaClO方法降解邻苯基苯酚过程中水质对自由基去除贡献的影响及产物毒性效应分析

Influence of water quality on contribution of free radical removal in the degradation of o-phenylphenol by UV-LED/NaClO method and its product toxicity effect analysis

为去除水中的邻苯基苯酚(OPP),以UV-LED/NaClO方法为降解手段,考察了CO_(3)^(2-)、NO_(3)^(-)、腐殖酸(HA)对OPP去除的影响,探究了HO·、UV-LED、NaClO和含氯自由基(Cl·、ClO·)等对去除贡献的影响,结合降解产物提出可能的OPP降解途径,采用毒性鉴定评估方法,筛选出毒性效应增强产物。结果表明:在pH=7.0±0.2、OPP初始浓度为3μmol·L^(-1)、NaClO=40.3 nmol·L^(-1)条件下,不同组分的去除贡献大小顺序为Cl·>NaClO>UV-LED>其他组分(CO_(3)^(-)·、Cl_(2)^(-)·、O^(-)·等)>HO·>ClO·,Cl·对OPP去除贡献最大为31.13%;当CO_(3)^(2-)和NO_(3)^(-)浓度由0增至1.0 mmol·L^(-1)时,拟一级反应速率常数(k_(obs))逐渐增大,Cl·的相对贡献分别降低30.05%和23.60%,其他组分的相对贡献分别增加72.10%和5.889%;HO·和ClO·的相对贡献随CO_(3)^(2-)投加量的增加,分别降低4.4%和5.4%,随NO_(3)^(-)投加量的增加,相对贡献分别增加16.9%和9.00%;随着HA质量浓度增加,OPP去除的抑制作用增强,不同组分的相对贡献率均不断降低,Cl·抑制效果最为明显,相对贡献率由31.3%降至25.4%;降解产物急性毒性和遗传毒性均呈现先上升后下降的趋势,并于3 min时达到最毒。由此可知:UV-LED/NaClO方法可以有效去除OPP,CO_(3)^(2-)和NO_(3)^(-)可促进OPP去除,而HA会抑制OPP去除;降解产物多数大于母体污染物,但延长反应时间可降解有毒物质;具有毒性效应增强的产物可能为P7(C_(12)H_(8)O_(2))和P12(C_(12)H_(8)O_(3))2种醛类产物。本研究结果可为进一步探究UV-LED/NaClO方法降解水环境中微污染物提供参考。

In order to remove o-phenylphenol(OPP)from water,the UV-LED/NaClO method was used to degrade it.The influences of CO_(3)^(2−),NO_(3)^(−),humic acid(HA)on OPP removal were studied,and the contributions of HO·,UV-LED,NaClO and chlorine radicals(Cl·、ClO·)on OPP decomposition were investigated.Furthermore,the degradation products were identified and the possible degradation pathways of OPP was proposed.In addition,the toxicity identification evaluation method was used to screen the degradation products with increased toxic effects.The result showed that at pH=7.0±0.2,OPP=3μmol·L^(−1),NaClO=40.3 nmol·L^(−1),the contribution order of different species to OPP removal was Cl·>NaClO>UV-LED>other components(CO_(3)^(−)·、Cl_(2)^(−)·、O^(−)·et al.)>HO·>ClO·,and the highest contributed of Cl·to OPP removal was 31.13%.The corresponding kobs increased with the dosages of CO_(3)^(2−)and NO_(3)^(−)increasing from 0 to 1.0 mmol·L^(−1),then the relative contribution of Cl·decreased by 30.05%and 23.60%,respectively,the relative contributions of other components increased by 72.10%and 5.889%,respectively.The relative contribution of HO·and ClO·decreased by 4.4%and 5.4%with the increase of CO_(3)^(2−)concentration,respectively,while increased by 16.9%and 9.00%with the increase of NO_(3)^(−)concentration,respectively.The inhibited effect for OPP removal increased with the increasing of HA concentration,the relative contribution of different species decreased accordingly,and the most inhibitory effects of Cl·occurred,the relative contribution decreased from 31.3%to 25.4%.The acute toxicity and genotoxicity of degradation products showed a increase trend at first,and then a decreased one,and reached the most toxic at 3 min.It can be seen that the UV-LED/NaClO method can effectively remove OPP,CO_(3)^(2−)and NO_(3)^(−)can promote OPP removal,while HA inhibits OPP removal;some intermediate products possessed higher toxicity than their parent pollutants,but prolonging the reaction time can degrade toxic substances;the product with increased toxic effects may be aldehyde products P7(C_(12)H_(8)O_(2))and P12(C_(12)H_(8)O_(3)).The results of this study can provide a reference for further study on the degradation of micro-pollutants in water by UV-LED/NaClO method.