Jang Suk Hyun, Min Byung Gil, Jeong Young Gyu, Lyoo Won Seok, Lee Sang Cheol
School of Advanced Materials and Systems Engineering, Kumoh National Institute of Technology, Gumi 730-701, Republic of Korea.
J Hazard Mater. 2008 Apr 15;152(3):1285-92. doi: 10.1016/j.jhazmat.2007.08.003. Epub 2007 Aug 6.
We have prepared hydroxyapatite/polyurehthane (HAp/PU) composite foams with two different HAp contents of 20 and 50 wt.% and investigated their removal capability of Pb2+ ions from aqueous solutions with various initial Pb2+ ion concentrations and pH values of 2-6. HAp/PU composite foams synthesized exhibited well-developed open pore structures which provide paths for the aqueous solution and adsorption sites for Pb2+ ions. With increasing the HAp content in the composites, the removal capability of Pb2+ ions by the composite foams increases owing to the higher adsorption capacity, whereas the removal rate is slower due to the less uniform dispersity of HAp in composite foams. The removal rate of Pb2+ ions is also slower with increasing the initial Pb2+ ion concentration in aqueous solutions. The removal mechanism of Pb2+ ion by the composites is varied, depending on the pH value of aqueous solution: the dissolution of HAp and precipitation of hydroypyromorphite is dominant at lower pH 2-3, the adsorption of Pb2+ ions on the HAp/PU composite surface and ion exchange reaction between Ca2+ of HAp and Pb2+ in aqueous solution is dominant at higher pH 5-6, and two removal mechanisms compete at pH 4. The equilibrium removal process of Pb2+ ions by the HAp/PU composite foam at pH 5 was described well with the Langmuir isotherm model, resulting in the maximum adsorption capacity of 150 mg/g for the composite foam with 50 wt.% HAp content.
我们制备了羟基磷灰石/聚氨酯（HAp/PU）复合泡沫材料，其中HAp的含量分别为20 wt.%和50 wt.%，并研究了它们在不同初始Pb2+离子浓度和pH值为2 - 6的水溶液中对Pb2+离子的去除能力。合成的HAp/PU复合泡沫材料呈现出发达的开孔结构，为水溶液提供了通道，并为Pb2+离子提供了吸附位点。随着复合材料中HAp含量的增加，复合泡沫材料对Pb2+离子的去除能力因吸附容量较高而增加，而去除速率较慢是由于HAp在复合泡沫材料中的分散性不够均匀。随着水溶液中初始Pb2+离子浓度的增加，Pb2+离子的去除速率也较慢。复合材料对Pb2+离子的去除机制因水溶液的pH值而异：在较低pH值2 - 3时，HAp的溶解和羟磷灰石的沉淀占主导；在较高pH值5 - 6时，Pb2+离子在HAp/PU复合表面的吸附以及HAp中的Ca2+与水溶液中的Pb2+之间的离子交换反应占主导；在pH值4时，两种去除机制相互竞争。在pH值为5时，HAp/PU复合泡沫对Pb2+离子平衡去除过程用Langmuir等温线模型描述良好，对于HAp含量为50 wt.%的复合泡沫，其最大吸附容量为150 mg/g。
