摘要
为高效地将水中硝酸盐氮(NO_3^--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NO_3^--N的初步还原,使NO_3^--N选择性地还原为NO_2^--N;再使用氨磺酸为深度还原剂,将NO_2^--N进一步还原为N_2,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l.lg/L、双金属投加量为60g/L、反应时间为30min的条件下还原100mg/LNO_3^--N,可得到81.9mg/L的NO_2^--N和4.0mg/L的NH_4^+-N;在深度还原阶段,在氨磺酸投加量n(NH_2SO_3H):n(NO_2^--N)为2:1,pH值为6.0,反应时间为40min的条件下,NO_2^--N的还原率为100%.整个过程的NO_3^--N去除率为93.2%,NH_4^+-N的生成率为3.9%,N_2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NO_3^--N的还原和NO_2^--N的积累起关键作用,为NO_3^--N大量还原为N_2提供基础.
To remove nitrate from wastewater,Zn/Ag bimetal was prepared by chemical liquid reduction method andcharacterized by XRD and SEM.The obtained Zn/Ag bimetal was used to convert of NO3--N into NO2--N selectively.Then,the aminosulfonic acid was employed to further reduce NO2--N to N2.The optimum reduction conditions and thedenitrification mechanism were proposed based on the batch experiments.For the first step,with0.028%of Ag loadingratio,pH adjusted to3using formic acid,1.1g/L of EDTA-2Na dosage,60g/L of Zn/Ag bimetal and40min of reaction time,81.9mg/L NO2--N and4.0mg/L NH4+-N was obtained from100mg/L NO3--N.For the second step,NO2--N was entirelyreduced to N2by aminosulfonic acid under the conditions of the ratio of n(NH2SO3H)to n(NO2--N)at2to1,pH at6.0andreaction time of40min.The NO3--N removal and N2production of the overall reaction were93.2%and89.3%,respectively.In addition,the NO3--N reduction by this two step reduction process produced NH4+-N as the by-product ata yield of3.9%.The surface properties of Zn/Ag bimetallic and the solution pH played key roles for the accumulation ofNO2--N,which promoted the conversion of NO3--N into N2.
作者
刘燕兰
汪诗翔
范琴
何亮
周安澜
刘咏
LIU Yan-lan;WANG Shi-xiang;FAN Qin;HE Liang;ZHOU An-lan;LIU Yong(College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610066, China;Key Laboratory of Treatment for Special Wastewater of Sichuan Province Higher Education System, Chengdu 610066, China)
出处
《中国环境科学》
EI
CAS
CSSCI
CSCD
北大核心
2017年第2期543-550,共8页
China Environmental Science
基金
四川省教育厅重点项目(15ZA008)
成都市科技局项目(2014-HM01-00211-SF)
四川师范大学横向课题(02476905)
