磷酸二氢钾、膨润土、氢氧化钙联合固定土壤中Pb、Cd的研究

发布时间：2018-01-08 20:44

本文关键词：磷酸二氢钾、膨润土、氢氧化钙联合固定土壤中Pb、Cd的研究　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：重金属污染土壤治理工作是一项迫切而艰巨的任务,尤其以Pb、Cd最为严重。本研究针对土壤Pb、Cd复合污染,采用磷酸二氢钾、膨润土、氢氧化钙三种修复材料进行原位固定修复实验。在前人研究的基础上,对固定材料的投加方式进行了改变,将混料实验设计用于土壤重金属的修复研究中,通过配方形式使各种材料的效能最大化。首先,为了准确表征固定剂的修复效果,对常用的五种重金属生物有效态浸提方法(0.1M CaCl2、1M NH4OAc、0.005M DTPA、0.05M EDTA-2Na和TCLP)进行了优选实验,对五种提取方法提取土壤中Pb、Cd量和小麦草吸收土壤中Pb、Cd量进行了相关性分析和回归分析,结果表明,DTPA提取土壤Pb、Cd量作为生物有效态重金属含量表征较为合适。所以,选取DTPA提取Pb、Cd量作为后续实验中Pb、Cd固定率的表征手段。其次,对配方固定剂投加量进行了研究,根据土壤重金属固定过程贡献度的大小,选取磷酸二氢钾、膨润土、氢氧化钙为3:1:1的比例进行实验。在固定剂投加量占土壤质量的0,0.83%,1.66%,5.00%,8.33%时,对土壤理化性质、XRD表征、DTPA提取土壤Pb、Cd量、小麦草吸收Pb、Cd量、土壤中Pb、Cd形态分布变化、土壤过氧化氢酶和脲酶活性进行了分析。结果表明,配方固定剂(3:1:1)用量在2%时既对重金属有明显的固定效果,同时又不影响小麦草的生长。最后,在2%的固定剂投加量下进行了Design-Expert软件的混料设计,探究了磷酸二氢钾、膨润土、氢氧化钙不同配比对Pb、Cd固定率和土壤pH的影响,并根据软件得出了最优配比。结果表明,以Pb、Cd固定率同时达到最大为限制条件,软件给出的最优配方为:磷酸二氢钾(75.6%)+膨润土(24.4%),Pb、Cd固定率分别为72.98%和61.31%。验证试验结果表明,Pb、Cd固定率可分别达到65.34%和54.73%。
[Abstract]:The soil heavy metal pollution is an urgent and arduous task, especially in Pb, Cd is the most serious. In this study, soil Pb, Cd compound pollution, using potassium dihydrogen phosphate, bentonite and calcium hydroxide were fixed in situ repair experiment three repair materials. On the basis of previous research on fixed material dosage the way of change, the mixture design for remediation of heavy metals in the soil, through the formulation of various materials to maximize the effectiveness. First of all, in order to accurately characterize the repairing effect of fixing agent, five kinds of heavy metal bioavailability of commonly used extraction methods (0.1M CaCl2,1M NH4OAc, 0.005M DTPA, 0.05M and EDTA-2Na TCLP) were selected for experiment, five kinds of extraction methods of soil Pb, Cd and Pb in soil and wheat grass absorption, Cd makes the correlation analysis and regression analysis, the results show that DTPA soil Pb extraction, Cd As the characterization of content of heavy metals bioavailability is relatively appropriate. Therefore, choosing DTPA Pb Cd extraction, as in the subsequent experiment Pb, characterized by means of Cd fixed rate. Secondly, the formulation of the fixed dosage were studied according to the process of heavy metals in soil fixed contribution, selection of potassium dihydrogen phosphate, bentonite, calcium hydroxide as the ratio of 3:1:1 for the experiment. In the fixed dosage for soil quality 0,0.83%, 1.66%, 5%, 8.33%, on the physical and chemical properties, soil XRD characterization, DTPA soil Pb extraction, Cd, wheat grass absorb Pb, Cd, Pb in soil, change of Cd distribution, soil catalase and urease activity was analyzed. The results show that the formula of fixing agent (3:1:1) at a dosage of 2% is fixed on the heavy metal effect is obvious, while not affecting wheat grass growth. Finally, the mixture of Design-Expert software in 2% fixed agent dosage Design, explore the potassium dihydrogen phosphate, bentonite, calcium hydroxide with different ratio of Pb, Cd and pH of the fixed rate of soil, and according to the software to obtain the optimal ratio. The results showed that in Pb, Cd fixed rate also reached the maximum limit conditions, the optimum formula of software given is: (75.6%) KH2PO4 + bentonite (24.4%), Pb, Cd fixed rates were 72.98% and 61.31%. test results showed that Pb, Cd fixed rate can reach 65.34% and 54.73%. respectively.

【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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