Ag-氨磺酸两步还原去除水中硝酸盐氮

中国环境科学2017,37(2)：543~550ChinaEnvironmentalScienceZn/Ag-氨磺酸两步还原去除水中硝酸盐氮刘燕兰1,汪诗翔1,2,范琴1,何亮1,周安澜1,刘咏1,2*(1.四川师范大学化学与材料科学学院,四川成都610066；2.四川省高校特种废水处理重点实验室,四川成都610066)摘要：为高效地将水中硝酸盐氮(NO3--N)无害化去除,采用液相还原法制备了Zn/Ag双金属,利用XRD和SEM分析材料特征,并将材料用于水中NO3--N的初步还原,使NO3--N选择性地还原为NO2--N;再使用氨磺酸为深度还原剂,将NO2--N进一步还原为N2,探讨还原过程的最佳工艺条件,初步分析该技术的脱氮机理.结果表明,在银负载率为0.028%的Zn/Ag双金属初步还原阶段,用甲酸作pH调节剂控制pH为3.0、EDTA-2Na投加量为1.1g/L、双金属投加量为60g/L、反应时间为30min的条件下还原100mg/LNO3--N,可得到81.9mg/L的NO2--N和4.0mg/L的NH4+-N;在深度还原阶段,在氨磺酸投加量n(NH2SO3H):n(NO2--N)为2:1,pH值为6.0,反应时间为40min的条件下,NO2--N的还原率为100%.整个过程的NO3--N去除率为93.2%,NH4+-N的生成率为3.9%,N2的选择性达到89.3%.分析认为,Zn/Ag双金属的表面性质及体系的pH对NO3--N的还原和NO2--N的积累起关键作用,为NO3--N大量还原为N2提供基础.关键词：Zn/Ag双金属；氨磺酸；还原去除；硝酸盐氮；氮气中图分类号：X703文献标识码：A文章编号：1000-6923(2017)02-0543-08NitrateremovalfromaqueoussolutionsbyZn/Agbimetal-Aminosulfonicacidtwo-stepreductionmethod.LIUYan-lan1,WANGShi-xiang1,2,FANQin1,HELiang1,ZHOUAn-lan1,LIUYong1,2*(1.CollegeofChemistryandMaterialsScience,SichuanNormalUniversity,Chengdu610066,China；2.KeyLaboratoryofTreatmentforSpecialWastewaterofSichuanProvinceHigherEducationSystem,Chengdu610066,China).ChinaEnvironmentalScience,2017,37(2)：543~550Abstract：Toremovenitratefromwastewater,Zn/AgbimetalwaspreparedbychemicalliquidreductionmethodandcharacterizedbyXRDandSEM.TheobtainedZn/AgbimetalwasusedtoconvertofNO3--NintoNO2--Nselectively.Then,theaminosulfonicacidwasemployedtofurtherreduceNO2--NtoN2.Theoptimumreductionconditionsandthedenitrificationmechanismwereproposedbasedonthebatchexperiments.Forthefirststep,with0.028%ofAgloadingratio,pHadjustedto3usingformicacid,1.1g/LofEDTA-2Nadosage,60g/LofZn/Agbimetaland40minofreactiontime,81.9mg/LNO2--Nand4.0mg/LNH4+-Nwasobtainedfrom100mg/LNO3--N.Forthesecondstep,NO2--NwasentirelyreducedtoN2byaminosulfonicacidundertheconditionsoftheratioofn(NH2SO3H)ton(NO2--N)at2to1,pHat6.0andreactiontimeof40min.TheNO3--NremovalandN2productionoftheoverallreactionwere93.2%and89.3%,respectively.Inaddition,theNO3--NreductionbythistwostepreductionprocessproducedNH4+-Nastheby-pro