Fachgebiet Bodenchemie mit Pedologie, Institut für Bodenkunde und Standortslehre, Universität Hohenheim, 70593, Stuttgart, Germany.
Fachgebiet Bodenchemie mit Pedologie, Institut für Bodenkunde und Standortslehre, Universität Hohenheim, 70593, Stuttgart, Germany.
Environ Pollut. 2020 Oct;265(Pt B):115032. doi: 10.1016/j.envpol.2020.115032. Epub 2020 Jun 19.
Soil contamination with inorganic contaminants such as lead (Pb), copper (Cu) and cadmium (Cd) is a major environmental issue. Silicon (Si) may reduce the mobility of the contaminants in the environment so that we studied the extent and the mechanisms of the interactions between Pb, Cd and Cu and silicic acid during its polymerization. We used tetraethyl orthosilicate as Si source and separately Pb(NO), Cd(NO) or Cu(NO). Selectivity of Si towards the metals was tested in an equimolar solution of all three salts and the polymerizing Si source. Time-dependency of particle growth was examined using dynamic light scattering. Transmission electron microscopy was used for visualizing the particles. We characterized the solid phases by Fourier transform infrared (FTIR) and Si nuclear magnetic resonance (NMR) spectroscopy. Polymerized silica bound relative to the initial concentrations (10 mmol L) up to 2.1‰ Cd, 2‰ Cu and 1.4‰ Pb. The FTIR spectra indicated an incorporation of the metals in the polymeric network. Si-NMR relaxation experiments showed an accelerating effect of Cu on the Si longitudinal relaxation time. It appears that the proportion of the rapidly relaxing components decreases with increasing distance to the surface. This points to a predominant location of Cu centers close to the surface of the Si matrix. Thus, polymerizing silica may contribute to reduced metal mobility in the environment.
土壤受到无机污染物如铅（Pb）、铜（Cu）和镉（Cd）的污染是一个主要的环境问题。硅（Si）可能会降低环境中污染物的迁移性，因此我们研究了在聚合过程中硅酸与 Pb、Cd 和 Cu 相互作用的程度和机制。我们使用正硅酸乙酯作为 Si 源，并分别使用 Pb(NO)、Cd(NO)或 Cu(NO)。在所有三种盐和聚合 Si 源的等摩尔溶液中测试了 Si 对金属的选择性。使用动态光散射研究了颗粒生长的时间依赖性。透射电子显微镜用于可视化颗粒。我们通过傅里叶变换红外（FTIR）和 Si 核磁共振（NMR）光谱对固相进行了表征。聚合二氧化硅结合的量相对于初始浓度（10 mmol L）可达 2.1‰ Cd、2‰ Cu 和 1.4‰ Pb。FTIR 光谱表明金属掺入了聚合网络中。Si-NMR 弛豫实验表明 Cu 对 Si 纵向弛豫时间有加速作用。似乎快速弛豫成分的比例随着与表面距离的增加而减小。这表明 Cu 中心主要位于 Si 基质的表面附近。因此，聚合二氧化硅可能有助于降低环境中金属的迁移性。
