Wu Hanjun, Zhang Huali, Yang Qingxue, Wang Dongsheng, Zhang Weijun, Yang Xiaofang
Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China.
School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430074, China.
Materials (Basel). 2017 Nov 17;10(11):1320. doi: 10.3390/ma10111320.
In this work, calcined chitosan-supported layered double hydroxides (CSLDO) were synthesized through a co-precipitation method that restrained the particles' aggregation of LDHs and exhibited huge specific surface areas, which can enhance the fluoride adsorption capacity. CSLDOs were characterized by physical and chemical methods and used for fluoride adsorption in an aqueous solution. The results indicated that the nanoparticles were constructed first and then assembled to form a porous and layered structure, and chitosan-supported layered double hydroxides (CSLDHs) calcined at 400 °C (CSLDO400) showed the highest specific surface area of 116.98 m²·g and the largest pore volume of 0.411 cm³·g. CSLDO400 exhibited excellent adsorption performance at a wide pH range from 5 to 9 for fluoride. The adsorption kinetics indicated that the adsorption reached equilibrium after 120 min, and followed a pseudo-first-order model. It agreed well with the Langmuir isotherm with maximum adsorption amounts of 27.56 mg·g. The adsorption of fluoride ions was spontaneous and endothermic. Furthermore, CSLDO400 showed a high stability for fluoride removal; it could still achieve 68% removal for fluoride after repeating five times of adsorption-desorption cycles. This study demonstrated that CSLDO400 is a promising functional material to remove fluoride from surface/ground water.
在本研究中，通过共沉淀法合成了煅烧壳聚糖负载层状双氢氧化物（CSLDO），该方法抑制了层状双氢氧化物颗粒的聚集，并展现出巨大的比表面积，从而提高了氟吸附容量。采用物理和化学方法对CSLDO进行了表征，并将其用于水溶液中的氟吸附。结果表明，纳米颗粒首先形成，然后组装成多孔层状结构，在400℃煅烧的壳聚糖负载层状双氢氧化物（CSLDO400）表现出最高的比表面积，为116.98 m²·g，最大孔体积为0.411 cm³·g。CSLDO400在pH值为5至9的宽范围内对氟表现出优异的吸附性能。吸附动力学表明，吸附在120分钟后达到平衡，并遵循准一级模型。它与Langmuir等温线吻合良好，最大吸附量为27.56 mg·g。氟离子的吸附是自发且吸热的。此外，CSLDO400对氟去除表现出高稳定性；在重复五次吸附-解吸循环后，其对氟的去除率仍可达到68%。本研究表明，CSLDO400是一种从地表水/地下水中去除氟的有前景的功能材料。
