在模拟含Zn^2+废水中加入Mg^2+和Al^3+,以NaOH为沉淀剂,研究金属盐水解即时合成层状双氢氧化物(LDH)去除Zn^2+的可行性。详细探讨了体系终点pH值、配料中Mg^2+/Zn^2+摩尔比值及反应温度和时间对Zn^2+去除率的影响,结合X射线衍射分析(XRD)探讨了Zn^2+去除机理,并与化学沉淀法进行了比较。结果表明,实验条件下只有pH值显著影响Zn^2+去除率(P〈0.05),在9.0~11.0范围内去除效果最佳,达99%以上。通过XRD分析结合即时合成法特点,废水中Zn^2+主要是在晶体生成阶段以Zn-Mg-Al三元LDH化合物形式被去除的。与化学沉淀法相比,即时合成法效果更好,适用pH值范围更广,用来处理含Zn^2+废水更具优势。
The possibility of Zn (Ⅱ) removal from synthetic wastewater by layered double hydroxide (LDH) prepared in-situ was investigated experimentally. The LDH prepared in-situ by Zn (Ⅱ), Mg (Ⅱ), Al (Ⅲ) coprecipitating with NaOH. The effects of pH, Mg ( Ⅱ)/Zn (Ⅱ) molar ratio, reaction temperature and time on removal effciencies of Zn (Ⅱ) were studied when [Mg (Ⅱ) + Zn (Ⅱ) ]/Al (Ⅲ) molar ratio was 2.0. The efficiencies are found to be different significantly at the 0.05 level under different pH, the most effective effciency occurs in the pH range of 9.0 to 11.0, removal effciencies of Zn (Ⅱ) from wastewater are more than 99%. Other factors exert no significant effects on removal effciencies of Zn (Ⅱ). The products were characterized by X-ray diffraction (XRD), which indicates that removal of Zn (Ⅱ) from wastewater mainly occurs in the crystal formation stage as Zn-Mg-Al-LDH, with consideration of the characteristics of the in-situ method itself. Compared with conventional sedimentation treatment with NaOH, the in-situ method is more effective and suitable for a wider pH range.