School of Environmental and Chemical Engineering, Shanghai University, No.99 Shangda Road, Shanghai, 200444, PR China; Center of Green Urban Mining & Industry Ecology, Shanghai University, No.99 Shangda Road, Shanghai, 200444, PR China.
School of Environmental and Chemical Engineering, Shanghai University, No.99 Shangda Road, Shanghai, 200444, PR China; Center of Green Urban Mining & Industry Ecology, Shanghai University, No.99 Shangda Road, Shanghai, 200444, PR China.
Chemosphere. 2023 Oct;338:139425. doi: 10.1016/j.chemosphere.2023.139425. Epub 2023 Jul 5.
The electroplating wastewater containing various metal ions was treated by adding sodium dodecyl benzene sulfonate (SDBS) and regulating pH value, and the resulting precipitates were characterized by X-ray diffraction (XRD). The results showed that organic anions intercalated layered double hydroxides (OLDHs) and inorganic anions intercalated layered double hydroxides (ILDHs) were in-situ formed to remove heavy metals during the treatment process. In order to reveal the formation mechanism of the precipitates, SDB intercalated Ni-Fe OLDHs, NO intercalated Ni-Fe ILDHs and Fe-DBS complexes were synthsized by co-precipitation at various pH values for comparison. These samples were characterized by XRD, Fourier Transform infrared (FTIR), element analysis as well as the aqueous residual concentrations of Ni and Fe were detected. The results showed that OLDHs with good crystal structures can be formed as pH≤7, while ILDHs began to form at pH = 8. When pH < 7, complexes of Fe and organic anions with the ordered layered structure were formed firstly, and then with increase in pH value, Ni inserted into the solid complex and the OLDHs began to form. However, Ni-Fe ILDHs were not formed when pH ≤ 7. The K (Solubility Product Constant) of OLDHs was calculated to be 3.24 × 10 and that of ILDHs was 2.98 × 10 at pH = 8, which suggested that OLDHs might be easier to form than ILDHs. The formation process of ILDHs and OLDHs were also simulated through MINTEQ software, and the simulation output verified that OLDHs could be easier to form than ILDHs at pH ≤ 7. Information from this study provides a theoretical basis for effective in-situ formation of OLDHs in wastewater treatment.
含各种金属离子的电镀废水通过添加十二烷基苯磺酸钠（SDBS）并调节 pH 值进行处理，所得沉淀物通过 X 射线衍射（XRD）进行表征。结果表明，在处理过程中形成了有机阴离子插层层状双氢氧化物（OLDHs）和无机阴离子插层层状双氢氧化物（ILDHs），以原位去除重金属。为了揭示沉淀物的形成机制，通过共沉淀在不同 pH 值下合成了 SDB 插层 Ni-Fe OLDHs、NO 插层 Ni-Fe ILDHs 和 Fe-DBS 配合物进行比较。这些样品通过 XRD、傅里叶变换红外（FTIR）、元素分析进行了表征，并检测了 Ni 和 Fe 的水残留浓度。结果表明，在 pH≤7 时可以形成具有良好晶体结构的 OLDHs，而在 pH=8 时开始形成 ILDHs。当 pH<7 时，首先形成具有有序层状结构的铁和有机阴离子配合物，然后随着 pH 值的增加，Ni 插入固体配合物中并开始形成 OLDHs。然而，当 pH≤7 时，未形成 Ni-Fe ILDHs。在 pH=8 时，OLDHs 的 K（溶度积常数）计算值为 3.24×10，ILDHs 的 K 计算值为 2.98×10，表明 OLDHs 可能比 ILDHs 更容易形成。还通过 MINTEQ 软件模拟了 ILDHs 和 OLDHs 的形成过程，模拟输出验证了在 pH≤7 时 OLDHs 比 ILDHs 更容易形成。这项研究的信息为在废水处理中有效原位形成 OLDHs 提供了理论依据。
