摘要
采集辽宁省某锌厂周边农田耕作层(0~20 cm)土壤样品,以FeCl_3-柠檬酸为淋洗剂,研究在不同pH、温度和离子强度的实验条件下,其对土壤中Pb和Cd的淋洗动力学特征及淋洗机理。结果表明,在实验条件下,随淋洗时间延长,土壤中Cd、Pb的淋洗量不断增加,Pb、Cd的淋洗过程可分为快速反应阶段、慢速反应阶段和解吸平衡阶段;当pH=3、4、5和6,温度为25、35和45℃,离子强度为0.01、0.05、0.2和0.5 mol·L^(-1)时,描述土壤中Pb、Cd淋洗动力学过程时Elovich方程(R^2=0.787 0~0.994 8,SE=0.000 2~0.024 2)均优于双常数方程(R2=0.819 2~0.995 5,SE=0.007 6~0.294 5)优于一级动力学方程(R2=0.219 8~0.632 1,SE=0.052 9~0.815 5),说明在不同环境条件下,该淋洗动力学过程为非均相扩散过程;随pH(6~3,pH=5除外)降低、温度(25~45℃)升高和CaCl_2浓度(0.01~0.5 mol·L-1)升高,Pb、Cd淋洗量均增大。
Heavy metal contaminated-soil was sampled from a 0 ~ 20 cm layer of cultivated land close to a zinc plant in Liaoning province,China,and the kinetic characteristics and mechanism of the washing process were examined. A washing solution containing FeCl_3 and citric acid was used to remove Pb and Cd from the soil sample. The effects of pH,environment temperature（ T）,and ionic strength（ IS） on the washing kinetics were also investigated. Under the experimental conditions examined（ pH = 3,4,5,and 6; T = 25 ℃,35 ℃,and 45℃,IS = 0. 01 mol·L^（-1）,0. 05 mol·L^（-1）,0. 2 mol·L^（-1）,and 0. 5 mol·L^（-1））,the leaching amounts of Cd and Pb increased with washing time. The washing process can be divided into three main stages： 1） the rapid reaction stage,2） the slow reaction stage,and 3） the desorption equilibrium stage. In addition,the kinetics of washing heavy metals from the soil sample could be better described using the Elovich equation（ R2= 0. 787 0—0. 9948,SE = 0. 000 2—0. 024 2） than using the double constant equation（ R2= 0. 819 2—0. 995 5,SE =0. 007 6—0. 2945）,or the first order kinetic equation（ R2= 0. 219 8—0. 632 1,SE = 0. 052 9—0. 815 5）. It was therefore suggested that the mechanism involved the heterogeneous diffusion of Pb and Cd from within the soil to the solution. With an increase in pH（ 6—3,with the exception of pH 5）,the amount of Cd and Pb removed by washing was lower,while with an increase in T（ 25—45 ℃） or IS（ CaCl_2）（ 0. 01 ~ 0. 5 mol·L^（-1））,the amount of Cd and Pb removed was higher.
作者
许端平
李晓波
王宇
孙璐
车轶夫
李翰良
XU Duanping ＊ LI Xiaobo WANG Yu SUN Lu CHE Yifu LI Hanliang(College of Environmental Science and Engineering, Liaoning Engineering Technology University, Fuxin 123000, China College of Urban Construction, Changchun School Of Architecture, Chang ehun 130600, China)
出处
《环境工程学报》
CAS
CSCD
北大核心
2016年第11期6753-6760,共8页
Chinese Journal of Environmental Engineering
基金
格平绿色助学行动辽宁环境科研"123工程"资助项目(CEPF2013-123-2-5)
国家自然科学基金资助项目(41373125)
