Competitive and synergistic effects of phosphate and cadmium coadsorbed on goethite
Competitive and synergistic effects of phosphate and cadmium coadsorbed on goethite
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针铁矿共吸附磷酸盐和镉的竞争协同效应
DOI：
10.1016/j.chemosphere.2023.138171
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发表时间：
--
期刊：
影响因子：
8.8
通讯作者：
Hui Li
中科院分区：
文献类型：
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作者：
Liang Tao;Wenjie Chen;Yuxin Liu;Feng Yang;Dong Liu;Junfen Liang;Saihong Liu;Hui Li
中国南方土壤酸化加剧了重金属尤其是镉（Cd）的环境风险，人类活动加速了土壤酸化。长期施用化肥会增加土壤中磷的含量，从而影响土壤环境中重金属的生态地球化学。采用不同的分析方法，研究了不同P（V）/Cd（II）摩尔比条件下P（V）-Cd（II）与针铁矿（α-FeOOH，一种广泛分布于红壤地区的典型氧化铁）相互作用的关键机制。用有机缓冲液排除pH干扰后，发现P（V）的存在增强了Cd（II）在α-FeOOH上的吸附过程，Cd（II）的吸附类型由单一的内球络合转变为内外球络合. zeta电位分析、X射线衍射（XRD）、高分辨透射电子显微镜（HRTEM）和X射线光电子能谱（XPS）的结果表明，在不同P（V）/Cd（II）摩尔比下，P（V）促进Cd（II）吸附的主要机制不同。静电吸附和三元复合物的形成被证明是控制Cd（II）的反应性的关键机制，其中共沉淀发生在高P（V）/Cd（II）的摩尔比，大大提高了Cd（II）和P（V）的固定。在稳定pH条件下，Cd（II）和P（V）在α-FeOOH上的共吸附机制包括竞争和协同作用，研究结果表明，人类活动对土壤环境中重金属活性的影响值得关注。
Soil acidification in southern China increases the environmental risk posed by heavy metals, especially cadmium (Cd), and has been accelerated by anthropic activities. Long-term fertilizer use increases the quantity of phosphate (P) in soils, which affects the biogeochemistry of heavy metals in soil environments. In this study, various analytical methods were used to investigate the critical mechanisms controlling P(V)–Cd(II) interactions with goethite (α-FeOOH, a typical iron oxide widely distributed in red soil areas) with added P(V)/Cd(II) in different molar ratios (to simulate the annual P fertilizer surplus). After excluding pH interference by using organic buffers, Cd(II) adsorption processes on α-FeOOH were found to be enhanced by the presence of P(V), whereas the Cd(II) adsorption type changed from single inner-sphere complexation to both inner- and outer-sphere complexation. The results of a zeta potential analysis, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) showed different dominant mechanisms underlying the promotion of Cd(II) adsorption by P(V) at different P(V)/Cd(II) molar ratios. Electrostatic adsorption and the formation of ternary complexes were proven to be the critical mechanisms controlling the reactivity of Cd(II), where coprecipitation occurs at high P(V)/Cd(II) molar ratios and considerably enhances the fixation of Cd(II) and P(V). The mechanism for Cd(II) and P(V) coadsorption onto α-FeOOH under stable pH conditions was found to include both competitive and synergistic effects, and the results in this study show that more attention should be given to the impact of anthropic activities on the reactivity of heavy metals in the soil environment, especially farmland.