方解石基羟基磷灰石的制备及其对水中氟化物的去除效能研究

Synthesis of the calcite-based hydroxyapatite and its performance of fluoride removal from water

采用方解石基羟基磷灰石材料去除水溶液中的氟化物。研究吸附剂用量、反应时间、F-初始浓度、共存阴离子分别对吸附量的影响,以及吸附过程中材料渗透率的变化。结果表明:反应在100min达到平衡,饱和吸附量为10.98mg/g;吸附量随着吸附剂用量、F-初始浓度的提高以及反应时间的延长而增大,当反应达到平衡时不再发生变化;除HCO-3外,其他共存阴离子(NO-3、SO2-4和Cl-)对吸附量影响不大;材料渗透率随反应时间的延长而下降,但大大高于传统羟基磷灰石材料的渗透率;方解石基羟基磷灰石材料对水溶液中氟化物的吸附符合Langmuir等温吸附方程以及Psuedo-二级动力学吸附模型,符合单层吸附反应。同时,采用扫描电子显微镜(SEM)、X射线衍射(XRD)对方解石基羟基磷灰石材料及其反应产物进行表征,探讨方解石基羟基磷灰石材料的除氟机制。

Calcite-based hydroxyapatite was applied to remove fluoride from aqueous solution. Effects of adsor- bent amount, reaction time,initial F- concentration,coexisting ions on F adsorption capacity, as well as the permea- bility change of adsorbent during adsorption process was fully investigated. Results showed that the adsorption reac- tion reached equilibrium at 100 rain,during which the saturation binding capacity reached 10.98 mg/g. The binding ca- pacity increased with the increase of adsorbent amount, initial F-concentration and the extension of reaction time, while it kept in stable after reached equilibrium. The coexisting anions had little impacts on binding capacity except HCO3-. The permeability of calcite-based hydroxyapatite was decreased with extending the reaction time, but it still much larger than that of traditional hydroxyapatite. The adsorption kinetics and isotherm for F- could be well fitted by a pseudo-second-order kinetic and Langmuir isotherm models respectively,indicated that F- adsorption belonged to monolayer adsorption reaction. The X-ray diffraction （XRD） and scanning electron microscopy （SEM） were used to characterize the structure of calcite-based hydroxyapatite and its production with F- , base on which, the mechanism of F- removal from aqueous solutions was investigated.