蔬菜地土壤对Cr(Ⅵ)的吸附-解吸特征研究  

Characteristics of Adsorption and Desorption of Cr(Ⅵ)in Vegetable Soil

作　　者：童鑫 黄宇 蓝志鹏 杨杰文 TONG Xin;HUANG Yu;LAN Zhi-peng;YANG Jie-wen(College of Resources and Environment,Zhongkai University of Agriculture and Engineering,Guangzhou 510225,China)

机构地区：[1]仲恺农业工程学院资源与环境学院,广东广州510225

出　　处：《江西农业学报》2022年第12期79-84,共6页Acta Agriculturae Jiangxi

基　　金：国家自然科学基金项目(41671235)。

摘　　要：以韶关某蔬菜地土壤为研究对象,研究了反应时间、反应物浓度、pH值、共存离子等因素对Cr(Ⅵ)吸附反应的影响,并在此基础上研究了Cr(Ⅵ)的解吸特征,区分了有机质和氧化铁等组分对Cr(Ⅵ)吸附的贡献。结果表明:在pH值为4.0~6.0的范围内,Cr(Ⅵ)吸附反应48 h可达到平衡。Cr(Ⅵ)吸附百分比随着pH值的上升而下降,且pH值越低,静电吸附方式所占比例越高,这是因为pH值越高,土壤表面负电荷量越多,对Cr(Ⅵ)的静电斥力越强。Cu^(2+)的存在可降低土壤表面负电荷量,由此促进Cr(Ⅵ)吸附和提高静电吸附方式所占比例;加入H_(2)PO_(4)^(-)后,土壤表面负电荷量增加,Cr(Ⅵ)吸附受到抑制,但专性吸附方式所占比例有所提高。在所研究的初始浓度范围内,去除有机质、非晶质氧化铁和游离氧化铁后,Cr(Ⅵ)的最大吸附量分别下降24.63、6.40和9.89个百分点。本结论将有助于了解Cr(Ⅵ)在该土壤固、液两相的分配平衡、生物有效性和迁移性,对其污染风险控制可提供一定的理论支撑。A vegetable soil in Shaoguan was taken as the research object,and the effect of reaction time,reactant concentration,pH and co-existing ions on Cr(Ⅵ)adsorption was investigated.On this basis,the desorption characteristics of Cr(Ⅵ)were studied,and the contribution of organic matter and ferric oxide to Cr(Ⅵ)adsorption was distinguished.The results showed that equilibrium of Cr(Ⅵ)adsorption could be obtained within 48 h in the examined pH range of 4.0~6.0.The increase in pH could make the soil surfaces more negatively charged and then enhance the electrostatic repulsion towards Cr(Ⅵ),resulting in the decrease of Cr(Ⅵ)adsorption.This finding was further evidenced by that the contribution of electrostatic attraction to Cr(Ⅵ)adsorption was more pronounced at low pH.The existence of Cu(Ⅱ)could make the soil surfaces less negatively charged,which could promote Cr(Ⅵ)adsorption and increase the proportion of electrostatic adsorption.By contrast,the introduction of H_(2)PO_(4)^(-) could lead to the soil surfaces more negatively charged,resulting in the decrease in Cr(Ⅵ)adsorption and the increase in the proportion of specific adsorption.In the examined initial concentration range,the maximum percentage of Cr(Ⅵ)adsorption decreased by 24.63,6.40 and 9.89 percentage points,respectively after the removal of organic matter and iron oxides.Overall,the results above were helpful to understand the distribution of Cr(Ⅵ)between soil solid and aqueous pH ases as well as its bioavailability and mitigation in soils and could also provide fundamental knowledge for controlling the environmental risk of Cr(Ⅵ).

关 键 词：Cr(Ⅵ) 蔬菜土 吸附 解吸 

分 类 号：S154.1[农业科学—土壤学]