Ag+改性羟基磷灰石制备及其除氟抑菌特性研究

利用原位共沉淀法制备Ag⁺改性羟基磷灰石(Ag-HAP)吸附剂,考察Ag⁺/Ca²⁺摩尔比对Ag-HAP吸附剂除氟抑菌效果的影响。红外光谱和X-射线粉末衍射实验表明Ag⁺置换Ca²⁺进入HAP晶格中,形成了Ag⁺-Ca²⁺新晶格。利用Langmuir和Freundlich吸附等温方程对实验数据进行拟合,对比相关系数R²值,Langmuir模型能更好地描述该吸附过程,且Ag-HAP吸附剂对氟离子的吸附更趋于单分子层吸附。计算了吸附热力学和动力学参数值,探讨了Ag-HAP吸附剂对氟离子的吸附机理。ΔG⁰＜0、H⁰＞0和ΔS⁰＞0,说明Ag-HAP吸附剂对氟离子的吸附是自发的、吸热的熵增过程,温度升高有利于吸附。吸附活化能E_a=12.645 kJ/mol,迁移能E=7.331 kJ/mol说明该吸附过程以物理吸附为主。Ag-HAP吸附剂对氟离子的吸附符合拟二级反应动力学方程。利用龙头式净水器模拟Ag-HAP吸附剂除氟抑菌的动态吸附过程,抑菌实验表明Ag-HAP吸附剂的加入大大提高了饮用水的抑菌性能。

Fabrication of Hydroxyapatite-Modified Ag+ and Its Property for Defluorination and Bacteriostasis Activity

Hydroxyapatite-modified Ag⁺ (Ag-HAP) adsorbent was prepared by in-situ co-precipitation method. The effect of Ag⁺/Ca²⁺ molar ratio on defluorination and bacteriostasis was investigated. The infrared spectroscopy and XRD results show that Ag⁺ displaces Ca²⁺ into HAP lattice, forming a new Ag⁺-Ca²⁺ lattice.Both models including Langmuir and Freundlich can predict experimental data conducted. However, Langmuir model has better correlation coefficient than Freundlich model. The adsorptions of fluoride on Ag-HAP adsorbent are more agreeable with monolayer adsorption mode. The thermodynamic and kinetics parameters of adsorptions were obtained. The ΔG⁰＜0, ΔH⁰＞0 and ΔS⁰＞0 indicate that adsorption of fluoricle is a spontaneous and endothermic process with increased entropy, and an increase in temperature benefits adsorption. Activation energy of adsorption E_a=12.645 kJ/mol and migration energy E=7.331 kJ/mol indicate that adsorption is mainly physical adsorption. Kinetic adsorption data show that adsorption process follows the pseudo-second-order kinetic. The dynamic adsorption process of Ag-HAP adsorbent for defluorination and bacteriostatic inhibition was simulated by using a bibcock type water purifier. The bacteriostatic experiments show that the addition of Ag-HAP adsorbent greatly improves the bacteriostatic performance of drinking water.