摘要
为掌握不同酸碱条件下赤泥中毒性元素浸出特性,研究了pH值对赤泥中重金属元素(Pb、As、Cr)及氟元素(F-)浸出行为的影响,采用定pH值序批式方法分别对不同区域5种代表性赤泥样品进行浸出试验。结果表明,在偏酸性条件(pH=6左右)时,随硝酸持续添加,pH值下降趋势变缓,形成酸中和缓冲区域。4种毒性元素浸出特性随pH值增加均呈现V字型浸出模式,Pb、Cr、F-的最高浸出质量浓度出现在pH=2左右,分别达到4.39 mg/L、87.2 mg/L、109mg/L;最低浸出质量浓度分别出现在pH值为5.5~8;As元素最小浸出质量浓度在pH=5.5处,不同样品最大浸出质量浓度在pH=2和pH=13左右均有出现,酸性条件最高达4.2 mg/L,碱性条件为1.9 mg/L。
In order to pursue the impact of the pH value on the leaching features of the toxic elements from the red mud(RM),the present paper has made an investigation of such heavy metals as Pb,As,Cr and F-in HNO3-HCl O4-HF-HCl and conducted digestion tests to investigate their content rate of such heavy metals in the RM.And,in so doing,we have first of all done a pre-test to get the predicted acid/base addition amount in accordance with the target pH value at 13,12,10.5,9,8,7,5.5,4,2,respectively.What's more,the pH-dependent leaching test has also been done to guarantee the toxic elements leaching at the target pH values as has been mentioned above.And,finally,different concentration rates of heavy metals have been analyzed by using the inductively coupled plasma mass spectrometry(ICP-MS)and ion chromatography(IC)to determine F-concentration rate at the various pH values.The results of our investigation indicate that:Pb,As and Cr turn to be the maximum heavy metal contents in the RM.At the same time,the acid neutralization capacity(ANC)curve has been found to be a sharp decrease of pH value when acid is added,while a buffering plateau has also been noticed from pH=6 to pH=2.All the elements concerned above tend to reveal a V-shaped leaching behavior as a function of the pH value.Among them,the highest leaching concentration rates of Pb,Cr and F-taking place in a range between the pH value range from 2 to 13,and the leaching concentration rates of Pb,Cr and F are respectively turning to be 4.39 mg/L,87.2 mg/L and 109 mg/L.But,in the acid condition,with 1.9 mg/L,the maximum leaching efficiencies of Pb,Cr and As can be made as high as up to 54.5%,50.9%and 33.7%,respectively.And,in contrast,the lowest leaching concentration rates of Pb,Cr and F-that take place at the pH values ranges between 5.5-8.In addition,the minimalist level of the leaching concentration of As comes about when the pH value is equal to 5.5.Nevertheless,the higher leaching concentrations in the acid and alkali prove to reach4.2 mg/L in the acid condition.
作者
崔宇龙
陈剑楠
彭道平
张毅博
黄涛
CUI Yu-long;CHEN Jian-nan;PENG Dao-ping;ZHANG Yi-bo;HUANG Tao(Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 611756,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2019年第4期1323-1328,共6页
Journal of Safety and Environment
基金
国家自然科学基金青年基金项目(41701347)
关键词
环境工程学
赤泥
PH
毒性元素
浸出特性
environmental engineering
red mud
pH
toxic elements
leaching characteristics
