Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin, 300191, China.
Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin, 300191, China; Department of Soil Quality, Wageningen University, P.O. Box 47, 6700, AA, Wageningen, the Netherlands.
Water Res. 2019 Jun 15;157:372-380. doi: 10.1016/j.watres.2019.03.077. Epub 2019 Mar 29.
Among natural organic matter (NOM), oxyanions and metal (hydr)oxides, a complicated interaction exists in natural aquatic and terrestrial systems and in waste waters. Effects of seven types of NOM (four humic acids (HA), three fulvic acids (FA)) that vary in properties on the adsorption of oxyanions, including phosphate, arsenate and arsenite, at goethite-water interface were quantitatively studied. Results show that the adsorption of oxyanions to goethite is decreased by the presence of NOM, especially for phosphate and arsenate at low pH. In general, the effects of the three FA are similar, which are more effective than HA in reducing oxyanion adsorption at low pH (<6). Differences were observed between the four HA in their competition with oxyanions. The adsorption of phosphate, arsenate and arsenite in the presence of NOM are well described with both the NOM-CD (CD: Charge Distribution) and LCD (Ligand and Charge Distribution) model. The NOM-CD model is relatively simple to use, whereas the LCD model can better reveal different factors in the interaction, including the spatial distribution of adsorbed NOM on oxide surface. According to these two models: site density of carboxylic groups, protonation constant of carboxylic groups, and particle size of NOM are major properties of NOM determining its effect on oxyanion adsorption to oxides. At relatively low loadings, morphological change of adsorbed NOM takes place, and the degree of morphological change of adsorbed NOM depends on the particle size, site density of carboxylic groups and aromaticity of NOM. The influence of particle size on the interaction becomes more important at higher NOM loadings. The results suggested that the fixation or removal efficiency of phosphate, arsenate and arsenite with iron oxides (e.g. goethite) can be significantly decreased by the presence of NOM, especially when NOM rich in acidic and aromatic groups.
在天然有机物 (NOM)、含氧阴离子和金属 (氢)氧化物中，天然水和陆地系统以及废水中存在着复杂的相互作用。定量研究了七种性质不同的 NOM（四种腐殖酸 (HA)、三种富里酸 (FA)）对针铁矿-水界面上含氧阴离子（包括磷酸盐、砷酸盐和亚砷酸盐）吸附的影响。结果表明，NOM 的存在会降低含氧阴离子在针铁矿上的吸附，尤其是在低 pH 值下对磷酸盐和砷酸盐的吸附。一般来说，三种 FA 的作用相似，在低 pH(<6) 下，它们比 HA 更能有效地减少含氧阴离子的吸附。在与含氧阴离子的竞争中，四种 HA 之间存在差异。在 NOM 存在的情况下，磷酸盐、砷酸盐和亚砷酸盐的吸附都可以用 NOM-CD（CD：电荷分布）和 LCD（配体和电荷分布）模型很好地描述。NOM-CD 模型使用相对简单，而 LCD 模型可以更好地揭示相互作用中的不同因素，包括吸附在氧化物表面上的 NOM 的空间分布。根据这两个模型：羧酸基团的位密度、羧酸基团的质子化常数和 NOM 的粒径是决定 NOM 对氧化物上含氧阴离子吸附影响的主要性质。在相对较低的负载下，吸附 NOM 的形态发生变化，而吸附 NOM 的形态变化程度取决于 NOM 的粒径、羧酸基团的位密度和芳香度。在较高的 NOM 负载下，粒径对相互作用的影响变得更加重要。结果表明，在 NOM 存在的情况下，铁氧化物（如针铁矿）对磷酸盐、砷酸盐和亚砷酸盐的固定或去除效率会显著降低，特别是当 NOM 富含酸性和芳香基团时。
