Adsorption of tripolyphosphate from aqueous solution by Mg-Al-CO3-layered double hydroxides

作者：Xing Kun^*; Wang Haizeng; Guo Lugang; Song Weide; Zhao Zhengpeng

来源：Colloids and Surfaces A: Physicochemical and Engineering Aspects , 2008, 328(1-3): 15-20.

DOI：10.1016/j.colsurfa.2008.06.015

• Adsorption
• Tripolyphosphate
• Mg-Al-CO3-LDH
• Mg-Al-CO3-CLDH

The adsorption of tripolyphosphate anions (P3O105-) from aqueous solution on Mg-Al-CO3-layered double hydroxides (Mg-Al-CO3-LDHs) and its calcined product (Mg-Al-CO3-CLDH) were investigated. Experiments were carried out as a function of contact time, temperature, initial concentration of solution, adsorbent dosage, initial pH of solution and different phosphate species. The results show that the Mg-Al-CO3-LDH and Mg-Al-CO3-CLDH can be used as effective adsorbents for the removal of P3O105- from aqueous solution. The adsorption of P3O105- on Mg-Al-CO3-LDH and Mg-Al-CO3-CLDH are by ion exchange and 'memory effect', respectively. The adsorption processes are followed the pseudo-second-order kinetic model. The rate constants are increased with temperature. The activation energy values on Mg-Al-CO3-LDH and Mg-Al-CO3-CLDH are 11.70 kJ mol(-1) and 98.40 kJ mol(-1). The adsorption data are fitted well with the Langmuir adsorption isotherm equations. The maximum adsorption capacities on Mg-Al-CO3-LDH and Mg-Al-CO3-CLDH from 298 K to 313 K are 34.52-38.00 mg P3O105- g(-1), 118.67-132.92 mg P3O105- g(-1), respectively. The adsorption capacities are increased with temperature shows that the adsorption processes are endothermic. The removal rate is changed insignificantly for a wide initial pH of 4.0-10.0. The affinity sequences of different phosphate species on Mg-Al-CO3-LDH and Mg-Al-CO3-CLDH are both HPO42- > H2PO4- > P3O105-.

• 出版日期2008-10-1
• 单位中国海洋大学