埃洛石纳米管负载锆氧化物吸附水中砷的研究

Adsorption of Arsenate in Water by Zirconia-halloysite Nanotube Material

长期饮用砷污染的水会严重危害人类的健康,因此亟待开发一种高效且便于分离的除砷吸附剂。本研究采用水热法构建了一种新型高效的除砷吸附材料——埃洛石纳米管负载锆氧化物材料(ZrO_(2)/HNT)。使用不同手段对制备的复合材料的组成、结构和形貌进行表征,发现氧化锆纳米颗粒均匀分布在埃洛石纳米管外壁上,晶型为单斜结构。研究表明,ZrO_(2)/HNT可快速、有效地去除溶液中的As(V),吸附反应在30 min内达到平衡。在25℃,As(V)的最高吸附容量为27.46 mg/g,吸附容量随溶液pH升高而降低,共存离子(除PO_(4)^(3–)离子外)对As(V)的吸附性能影响不大。ZrO_(2)/HNT对As(V)的吸附动力学数据符合准二级动力学模型。吉布斯自由能计算结果和Dubinin-Radushkevich(D-R)等温模型拟合结果表明,As(V)去除过程是吸热、化学吸附反应。傅里叶变换红外光谱(FT-IR)和X射线光电子能谱(XPS)研究表明,As(V)的去除机制主要是As(V)与ZrO_(2)/HNT吸附材料中ZrO_(2)表面的羟基发生配体交换,最终形成稳定的内层配合物。本研究表明合成的ZrO_(2)/HNT吸附剂可用于去除水溶液中的As(V)。

Drinking water contaminated with arsenic for a long time will inevitably lead to serious human health problems.Suitable adsorbent for arsenic removal from water is an urgent but a challenging task.In this study,halloysite nanotubes-supported ZrO_(2)(ZrO_(2)/HNT),a novel and efficient arsenate adsorbent,was prepared using a straightforward hydrothermal method.Its morphology and structure were characterized.ZrO_(2) nanoparticles with monoclinic phase were well dispersed on the outer walls of halloysite nanotubes.And the ZrO_(2)/HNT could effectively remove As(V),achieving adsorption equilibrium within 30 min.The saturation As(V)adsorption capacity was 27.46 mg/g at 25℃.Its adsorption capacity decreased with the increase of the solution’s pH.Coexistent ions(except phosphate)showed little effect on adsorption performance of As(V).The As(V)adsorption kinetics fitted well with pseudo-second-order modeland the As(V)removal processes were endothermic which was verified as chemisorption reactions based on calculation of Gibbs free energy and Dubinin-Radushkevich(D-R)isotherm model.Fourier transform infrared(FT-IR)and X-ray photoelectron spectrometer(XPS)study indicated that the As(V)adsorption processes mainly proceeded through ligand exchange between As(V)and hydroxyl groups on the surface of ZrO_(2) in the ZrO_(2)/HNT and formation of inner-sphere surface complexes.This study suggest that the as-synthesized ZrO_(2)/HNT is a potential candidate for practical applications of As(V)removal from water.