Wang Xing-Xing, Lin Jian-Wei, Zhan Yan-Hui, Zhang Zhi-Bin, Xing Yun-Qing, Jiang Bo-Hui, Chu Ming
College of Marine Science, Shanghai Ocean University, Shanghai 201306, China.
College of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China.
Huan Jing Ke Xue. 2017 May 8;38(5):1936-1946. doi: 10.13227/j.hjkx.201611072.
In this study, hydrous zirconium oxide (HZO) samples precipitated at different pH values were prepared, characterized and used as adsorbents to remove phosphate from aqueous solution. The adsorption characteristics and mechanisms of phosphate on these HZO samples were investigated. The results showed that the presence of Na slightly enhanced the adsorption of phosphate on HZO samples prepared at precipitation pH of 4.8 and 8.0, but it greatly enhanced the adsorption of phosphate on HZO prepared at precipitation pH of 10.6. The presence of Ca slightly enhanced the adsorption of phosphate on HZO prepared at precipitation pH of 4.8, but it significantly enhanced the adsorption of phosphate on HZO samples prepared at precipitation pH of 8.0 and 10.6. The presence of HCO or SO inhibited phosphate adsorption onto HZO, and the inhibitory effect of these anions on phosphate adsorption onto HZO precipitated at pH 4.8 was much higher than that on phosphate adsorption onto HZO samples precipitated at pH 8.0 and 10.6. The phosphate adsorption was dependent upon solution pH, and it decreased with increasing solution pH. The Langmuir, Freundlich and Dubinin-Redushckevich (D-R) isotherm models fitted well to the adsorption equilibrium data of phosphate on HZO samples precipitated at pH 4.8, 8.0 and 10.6. In the presence of Na but in the absence of Ca, there was no significant difference of the maximum phosphate monolayer adsorption capacity derived from the Langmuir isotherm model among HZO samples prepared at precipitation pH of 4.8, 8.0 and 10.6. In the presence of Ca, the maximum phosphate monolayer adsorption capacity derived from the Langmuir isotherm model for HZO precipitated at pH 8.0 or 10.6 was much higher than that for HZO precipitated at pH 4.8. The mechanism for phosphate adsorption onto HZO mainly obeyed the inner-sphere complexing mechanism. The surface chloride and hydroxyl groups played the key role in the adsorption of phosphate on HZO precipitated at pH 4.8 or 8.0, while only the surface hydroxyl groups played the key role in the adsorption of phosphate on HZO precipitated at pH 10.6. Results of this work demonstrated that the HZO precipitated at pH 8.0 or 10.6 was a more promising adsorbent for removing phosphate from wastewater than the HZO precipitated at pH 4.8.
在本研究中，制备了在不同pH值下沉淀的水合氧化锆（HZO）样品，对其进行了表征，并用作吸附剂以去除水溶液中的磷酸盐。研究了磷酸盐在这些HZO样品上的吸附特性和机理。结果表明，Na的存在略微增强了磷酸盐在沉淀pH为4.8和8.0时制备的HZO样品上的吸附，但大大增强了磷酸盐在沉淀pH为10.6时制备的HZO上的吸附。Ca的存在略微增强了磷酸盐在沉淀pH为4.8时制备的HZO上的吸附，但显著增强了磷酸盐在沉淀pH为8.0和10.6时制备的HZO样品上的吸附。HCO或SO的存在抑制了磷酸盐在HZO上的吸附，并且这些阴离子对磷酸盐在pH 4.8时沉淀的HZO上吸附的抑制作用远高于对磷酸盐在pH 8.0和10.6时沉淀的HZO样品上吸附的抑制作用。磷酸盐的吸附取决于溶液pH值，并且随着溶液pH值的升高而降低。Langmuir、Freundlich和Dubinin-Redushckevich（D-R）等温线模型很好地拟合了磷酸盐在pH 4.8、8.0和10.6时沉淀的HZO样品上的吸附平衡数据。在存在Na但不存在Ca的情况下，由Langmuir等温线模型得出的最大磷酸盐单层吸附容量在沉淀pH为4.8、8.0和10.6时制备的HZO样品之间没有显著差异。在存在Ca的情况下，由Langmuir等温线模型得出的pH 8.0或10.6时沉淀的HZO的最大磷酸盐单层吸附容量远高于pH 4.8时沉淀的HZO。磷酸盐在HZO上的吸附机理主要遵循内球络合机理。表面氯和羟基在磷酸盐在pH 4.8或8.0时沉淀的HZO上的吸附中起关键作用，而只有表面羟基在磷酸盐在pH 10.6时沉淀的HZO上的吸附中起关键作用。这项工作的结果表明，与在pH 4.8时沉淀的HZO相比，在pH 8.0或10.6时沉淀的HZO是一种更有前景的用于去除废水中磷酸盐的吸附剂。
