掺硅碳羟基磷灰石的制备及其对Pb2+的吸附性能

以废弃蛋壳、硅酸钠为原料,采用水热法制备掺硅碳羟基磷灰石(Ca10(PO4)6-x-y(SiO4)x(CO3)y(OH)2-x-y,Si-CHAP),研究其对溶液中Pb2+子的吸附性能.采用BET比表面积、红外光谱、X光衍射、扫描电镜等分析手段对样品进行表征,实验考察了pH值、反应时间以及温度等对Si-CHAP吸附Pb2+的影响.结果表明,Si-CHAP是一种具有较大比表面积的介孔材料,其比表面积为323.25m2/g.Pb2+初始浓度为300mg/L并加入2g/L的吸附剂,室温下反应时间90min后,Si-CHAP对溶液中铅离子去除率和吸附容量分别为99.39%和149.09mg/g. Langmuir等温吸附方程能较好描述铅离子在Si-CHAP上的吸附平衡,准二级动力学方程式描述铅离子在Si-CHAP上吸附的最佳吸附动力学模型,热力学参数表明Si-CHAP吸附铅离子是自发、吸热和熵值增加过程.

Adsorption characteristics of Pb2+ from aqueous solution and synthetic silicon-substituted carbonate hydroxyapatite particles

To investigate the use of egg shells and sodium silicate to regulate the hydrothermal crystallization of silicon-substituted carbonate hydroxyapatite (Si-CHAP, (Ca10(PO4)6-x-y(SiO4)x(CO3)y(OH)2-x-y). The obtained Si-CHAP was characterized by BET surface area, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and investigated as metal adsorption for Pb2+ from aqueous solutions. The effect of various parameters on the adsorption process such as contact time, solution pH, and temperature was studied to optimize the conditions for maximum adsorption. The results showed that the Si-CHAP was mesoporous material with high surface area, and its BET surface area was 323.25m2/g. The removal efficiency and adsorption capacity of Pb2+ by Si-CHAP could reach 99.39% and 149.09mg/g, respectively, when the initial Pb2+ concentration was 300 mg/L and the solid/liquid ratio was 2 g/L at 90 min and room temperature. The adsorption of Pb2+ onto Si-CHAP was well described by the Langmuir equation. The kinetics of adsorption was well fitted by the pseudo-second order kinetic model. Thermodynamic parameters indicated that the adsorption is spontaneous, endothermic accompanied by increase in entropy. This research is expected to provide novel functional materials for treating the heavy metal waste water.