摘要
通过模拟降雨进行土柱淋溶实验来研究降雨条件下纳米零价铁镍(nZVI/Ni)对污染土壤六价铬迁移的影响,并测定淋溶液的Cr(Ⅵ)浓度、pH、电导率和累积释放量.使用改进BCR连续提取法测定淋溶后各层土壤的铬形态分布,分析施加nZVI/Ni对土壤中铬形态的影响.结果表明,降雨条件下六价铬的释放过程主要分为快速和慢速释放两个阶段.随着淋溶体积的增加,土壤淋溶液的pH逐渐升高后最后趋于平稳,电导率和Cr(Ⅵ)浓度迅速下降后趋于平稳.模拟降雨条件下,土壤中投加nZVI/Ni显著降低了淋溶液中Cr(Ⅵ)的累积释放量.投加0.10%nZVI/Ni土壤淋溶液的Cr(VI)累积释放量低于空白对照57.53%.在nZVI/Ni投加量相同时,模拟降雨的pH值越低nZVI/Ni的修复效果越好;降雨的淋溶次数对修复效果基本无影响;采用均匀混合的方式投加nZVI/Ni有着更好的修复效果.在土壤中nZVI/Ni对Cr(Ⅵ)修复过程中,纳米铁材料起主要作用,Fe(Ⅱ)的贡献很小.土壤经nZVI/Ni修复后,可还原态铬含量减少,可氧化态铬含量增加,表明纳米零价铁镍可以降低土壤中铬的迁移性,降雨条件下对六价铬污染土壤具有一定的修复效果.
Rain can accelerate acidification of chromium-contaminated soils,resulting in chromium release and environmental risk. The current study aims to investigate the release of chromium in the remedied soils by nano zero-valent iron/nickle（nZVI/Ni） under the simulated rain and to determine the pH,electrical conductivity and Cr（Ⅵ） concentration. The effects of simulated rain with different pH values also were studied. The chromium speciation in different soil layer was measured by the modified BCR sequential extraction method. The results showed that soil leaching process can be divided into a rapid release phase and a slow release phase. With the increase of leaching volume,the pH value of soil leaching solution gradually increased then decreased,and finally stabilized;electrical conductivity and Cr（Ⅵ） concentration decreased then became steady. 0. 10% nZVI/Ni（W/W） significantly reduced the accumulative Cr（Ⅵ） concentration in soil leachate,decreased by57.53% compared with the CK; Under the same conditions,the lower pH value of simulated rain,the better remediation effect the nZVI/Ni has. The leaching times of simulated rain had no influence on the remediation effect. Uniform mixing of the nanormaterial with soil had the greater remediation effect. After nZVI/Ni was applied,reducible fraction of chromium was translated to the oxidisable fraction. The results indicate that nZVI/Ni can effectively reduce the mobility of chromium in soils.
出处
《环境化学》
CAS
CSCD
北大核心
2017年第4期812-820,共9页
Environmental Chemistry
基金
山西省基础研究计划项目(2013011040-1
2008011020)资助~~
关键词
模拟降雨
六价铬
纳米零价铁镍
土柱实验
simulated rain
Cr（Ⅵ）
nano zero-valent iron/nickel
column experiment
