碳纳米管/羟基磷灰石复合材料对水体F^-的去除研究

Effective Removal of Fluoride by carbon nanotubes/hydroxyapatite composites

以碳纳米管(CNT)和羟基磷灰石(HAP)为原料,通过原位合成法制备碳纳米管/羟基磷灰石(CdH)复合材料.利用XRD、FTIR、SEM与氮气吸附^-脱附等表征其结构形貌,并通过静态吸附实验考察CdH对氟离子(F^-)的吸附性能.结果表明,室温下,CdH对F^-的吸附容量为11.05mg/g,明显高于HAP(5.02mg/g).吸附动力学模型、Weber^-Morris方程、Langmuir和Freundlich方程拟合结果表明, F^-在CdH表面进行Langmuir单分子层吸附,其吸附过程符合准二级动力学方程,并且颗粒内部扩散起主要作用.pH值为6时有利于CdH对F^-的去除.此外,结合反应前后固样XPS分析可知Cd H对F^-的吸附机制主要为离子交换作用.

To improve the removal efficiency of fluoride ion(F-)in aqueous solution,Carbon nanotubes(CNT)-doped hydroxyapatite(HAP)composites(CdH)were synthesized via in-situ synthesis and characterized by XRD,FTIR,SEM and N 2 adsorption-desorption isotherms.The adsorption performance was investigated by static adsorption experiments and analyzed with adsorption kinetic models,Langmuir and Freundlich isotherm adsorption models,and Weber-Morris equation.The optimal pH value for fluoride removal was 6.The adsorption capacity of CdH reached 11.05mg/g at room temperature,which was much higher than that of HAP(5.02mg/g).The results implied the occurrence of Langmuir monolayer adsorption once F-contacted the surface of CdH.The adsorption kinetics fitted the pseudo-second order model,and the internal diffusion of particles played the major role in the adsorption process.Moreover,the XPS results of CdHs before and after fluoride adsorption demonstrated that the mechanism of fluoride removal by CdH is mainly ion exchange.