土壤中典型矿物对锑的吸附-沉积行为研究

Adsorption-Deposition Behavior of Typical Minerals on Antimony in Soil

矿物开采、煤炭燃烧等人类活动使大量的锑进入土壤,造成严重的锑污染,危害人类健康。厘清环境中锑的吸附-沉积行为对锑的环境归趋预测及污染防治具有重要意义,但土壤中典型矿物对锑的吸附沉积行为缺乏系统比较,界面吸附形态也难以表征。为了系统地比较土壤中典型矿物对锑的吸附能力差异,本文选用土壤中常见的5种金属氧化物(赤铁矿、针铁矿、水铁矿、氧化铝、斜方锰矿)和1种黏土矿物(高岭石),探究Sb(Ⅲ)和Sb(Ⅴ)在其表面的吸附热、动力学行为,并基于原位拉曼光谱表征分析了锑的吸附形态,推测其吸附机理。结果表明:铁锰氧化物对锑的吸附容量较大,而氧化铝、高岭石对锑吸附容量较小,6种典型矿物对Sb(Ⅲ)和Sb(Ⅴ)吸附容量(mg/g)分别为水铁矿(101.4、55.9)>斜方锰矿(16.52、7.58)>针铁矿(13.30、5.67)>赤铁矿(5.13、3.70)>氧化铝(1.66、1.69)>高岭石(0.27、0.51);受锑存在形态及矿物表面电位的影响,酸性条件下有利于Sb(Ⅴ)的吸附,吸附量较之碱性环境有24%~78%增加,而Sb(Ⅲ)的吸附受pH值影响较小(变化范围0.3%~14%);土壤中典型矿物对不同浓度的Sb(Ⅴ)主要为吸附作用,而Sb(Ⅲ)在较高浓度时,可能在矿物表面发生沉积,形成Sb_(2)O_(3)。本文通过采用拉曼光谱,基于锑的特征谱峰,可方便地对矿物表面吸附态和沉积态的锑进行原位表征。

Human activities such as mineral mining and coal combustion cause a large amount of antimony to enter into environmental soil.Exploring the adsorption deposition behavior of antimony on typical soil minerals is important for predicting the environmental fate of antimony and preventing its pollution.Thus,six kinds of commonly found metal hydroxides and clay minerals in soil(namely hematite,goethite,ferrihydrite,aluminum oxide,ramsdellite,and kaolinite)were selected to investigate the adsorption thermodynamic and kinetic behavior of Sb(Ⅲ)and Sb(Ⅴ)on their surfaces,and speculate the adsorption mechanism.The order of adsorption capacities(mg/g)of six soil minerals for Sb(Ⅲ)/Sb(Ⅴ)were as follows:ferrihydrite(101.4,55.9)>ramsdellite(16.52,7.58)>goethite(13.30,5.67)>hematite(5.13,3.70)>aluminum oxide(1.66,1.69)>kaolinite(0.27,0.51).Affected by the speciation of antimony and the surface potential of minerals,acidic conditions were favorable for the adsorption of Sb(Ⅴ),while the adsorption of Sb(Ⅲ)was less affected by pH.The Sb_(2)O_(3) formed after deposition was characterizedin situ by Raman spectroscopy.Sb(Ⅴ)adsorbed on the mineral by adsorption at different concentrations,while Sb(Ⅲ)deposits on the mineral surface at higher concentrations.The BRIEF REPORT is available for this paper athttp://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202404210093.