纳米羟基磷灰石稳定悬浮体系的制备及其钴吸附性能

Nano hydroxyapatite stable suspension system:Preparation and cobalt adsorption performance

为改善纳米羟基磷灰石(HAP)作为重金属离子吸附剂的吸附性能,模拟了人体中聚合物诱导的类液体前驱体矿化过程,利用聚丙烯酸(PAA)作调控剂通过水热法制备出了稳定悬浮的纳米HAP体系,探究了PAA的COOH与Ca的物质的量之比(R)、反应pH、水热温度对制备的纳米HAP的影响。在优化出的合成条件(R=1、pH=9.00、180℃)下制备的纳米HAP是由细小颗粒组成的梭形结构,能够在保持几十纳米粒径尺寸的同时稳定悬浮。继而探究了吸附时间、初始金属离子浓度、吸附环境的pH、悬浮性对纳米HAP的Co^(2+)吸附性能的影响。吸附结果表明吸附动力学符合准二级动力学模型,吸附过程包括表面吸附与粒子内扩散。Freundlich、Langmuir模型线性方程拟合结果与实验结果均具有较高契合度,对应的Langmuir模型线性拟合最大吸附量为229.358 mg·g^(-1)。对Co^(2+)去除率随吸附环境pH(6.48~9.00)的升高而增大,主要吸附机制为表面配位反应。制备的纳米HAP悬浮液吸附量明显优于非悬浮的对照纳米HAP。

To improve the adsorption performance of nano-hydroxyapatite(HAP)as a heavy metal ion adsorbent,the polymer-induced liquid-like precursor mineralization process in the human body was simulated.A stable suspended nano HAP system was prepared by hydrothermal method using polyacrylic acid(PAA)as a regulator.The effects of R(the ratio of the amount of substance of COOH in PAA to Ca),reaction pH,and hydrothermal temperature on the prepared nano HAP were investigated.The optimized synthesis conditions for nano HAP were R=1,pH=9.00,180℃,which is a spindle-shaped structure composed of small particles and stably suspended while maintaining several tens of nanoparticle sizes.Subsequently,the effects of adsorption time,initial metal ion concentration,pH of adsorption environment,and suspension on the Co^(2+)adsorption performance of nano HAP were investigated.The adsorption results indicate that the adsorption kinetics follow a pseudo-second-order kinetic model,and the adsorp-tion process includes surface adsorption and intra-particle diffusion.The linear equation fitting results of the Freun-dlich and Langmuir models had a high degree of agreement with the experimental results.The adsorption belongs to the chemical adsorption of non-uniform adsorbents,and the linear fitting result of the Langmuir model correspond-ing to the maximum adsorption amount was 229.358 mg·g^(-1).The removal rate of Co^(2+)increased with the increase of adsorption environment pH(6.48-9.00),and the main adsorption mechanism was surface coordination reaction.The adsorption capacity of the prepared nano HAP suspension was significantly better than that of the non-suspended control nano HAP.The addition of PAA enhances the adsorption capacity of nano HAP.