绣球花状掺锶碳羟基磷灰石对Pb^(2+)的吸附

Study on Pb^(2+) adsorption by hydrangea-like strontium-doped carbonate hydroxyapatite

以NH_4H_2PO_4、Ca(NO_3)_2·4H_2O、Sr(NO_3)_2和尿素[CO(NH_2)_2]为原材料,通过水热法合成了一种单分散、由纳米片自组装而成的绣球花状三维(3-D)掺锶碳羟基磷灰石(Sr-CHAp),并用于吸附酸性水溶液中的铅离子(Pb^(2+)).研究了溶液p H、吸附时间、初始浓度对Sr-CHAp材料吸附Pb^(2+)的影响及在其在不同p H条件下的吸附机理.采用XRD、SEM、FI-IR和BET等技术对材料及吸附产物进行表征.结果表明,该吸附剂材料表面具有介孔结构,平均孔隙宽度是11.10 nm,具有较大的比表面积(43.54 m^2·g^(-1)),在pH3时对Pb^(2+)具有较高的饱和吸附量(985.1 mg·g^(-1));其等温线吸附数据符合Langmuir模型,动力学吸附数据符合伪二级动力学模型;在酸性溶液中其对Pb^(2+)的吸附主要表现为溶解/沉淀机理,溶液p H值的大小影响吸附后的产物,强酸性条件下有利于PbHPO_4的生成,而p H值为3—6时主要生成Pb_(10)(PO_4)_6(OH)_2.

Using NH4H2PO4,Ca（NO3）2·4H2O,Sr（NO3）2 and urea [CO（NH2）2] as raw materials,monodisperse nanosheets-assembled hydrangea-like three-dimensional（3-D） strontiumdoped carbonate hydroxyapatite（Sr-CHAp） was synthesized by a hydrothermal method,and used as an adsorbent for the removal of lead ions（Pb2＋） from acidic aqueous solutions.The effects of p H value,contact time and initial concentration of Pb2＋ solutions on the adsorption of the Sr-CHAp material and its adsorption mechanism under different p H were studied.The adsorbent and the products were characterized by XRD,SEM,FI-IR and BET etc..The results show that the obtained Sr-CHAp had a mesoporous structure,of which the average width is 11.10 nm.It had a large specific surface area of 43.54 m2·g-1and a high adsorption capacity（985.1 mg·g-1） towards Pb2＋ at p H 3.The isotherm accords with the Langmuir model,and the kinetic data conform to the pseudo-second order kinetic model.The mechanism of Pb2＋adsorption was attributed to dissolution/precipitation process in acid solutions.The products were different at different p H value.Strong acidic solution was favorable for the formation of PbHPO4 while Pb10（PO4）6（OH）2 was the main product when p H wasbetween 3—6.