Wang Shixiang, Liu Yong, Fan Qin, Zhou Anlan, Fan Lu, Mu Yulan
College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610066, China E-mail:
Water Sci Technol. 2016 Dec;74(12):2946-2957. doi: 10.2166/wst.2016.466.
An environmental friendly and economic natural biopolymer-sodium humate (HA-Na) was used to capture Hg(II) from aqueous solutions, and the trapped Hg(II) (HA-Na-Hg) was then removed by aluminium coagulation. The best Hg(II) capturing performance (90.60%) was observed under the following conditions: initial pH of 7.0, coagulation pH of 6.0, HA-Na dosage of 5.0 g L, Al(SO).18HO dosage of 4.0 g L, initial Hg(II) concentration of 50 mg L and capturing time of 30 min. The HA-Na compositions with the molecular weight beyond 70 kDa showed the most intense affinity toward Hg(II). The results showed that the reaction equilibrium was achieved within 10 min (pH 7.0), and could be well fitted by the pseudo-second-order kinetics model. The capturing process could be well described by the Langmuir isotherm model and the maximum capturing capacity of Hg(II) was high up to 9.80 mg g at 298 K (pH 7.0). The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis showed that the redox reaction between Hg(II) and HA-Na and the coordination reaction of carboxyl and hydroxy groups of HA-Na with Hg(II) were responsible for Hg(II) removal. The successive regeneration experiment showed that the capturing efficiency of humates for Hg(II) was maintained at about 51% after five capture-regeneration recycles.
一种环境友好且经济的天然生物聚合物——腐殖酸钠（HA-Na）被用于从水溶液中捕获Hg(II)，然后通过铝混凝去除捕获的Hg(II)（HA-Na-Hg）。在以下条件下观察到最佳的Hg(II)捕获性能（90.60%）：初始pH为7.0，混凝pH为6.0，HA-Na用量为5.0 g/L，Al₂(SO₄)₃·18H₂O用量为4.0 g/L，初始Hg(II)浓度为50 mg/L，捕获时间为30分钟。分子量超过70 kDa的HA-Na组合物对Hg(II)表现出最强的亲和力。结果表明，在10分钟内（pH 7.0）达到反应平衡，并且可以很好地用准二级动力学模型拟合。捕获过程可以用Langmuir等温线模型很好地描述，在298 K（pH 7.0）时Hg(II)的最大捕获容量高达9.80 mg/g。傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）分析表明，Hg(II)与HA-Na之间的氧化还原反应以及HA-Na的羧基和羟基与Hg(II)的配位反应是去除Hg(II)的原因。连续再生实验表明，经过五次捕获-再生循环后，腐殖酸盐对Hg(II)的捕获效率保持在约51%。
