水热改性棉铃壳对水中氟的吸附

采用水热法制备了改性棉铃壳吸附剂,通过比表面积分析仪、扫描电镜和红外光谱仪表征了棉铃壳改性前后表面结构和官能团变化,并通过批实验分析了改性棉铃壳对水中F-吸附动力学及热力学特征,考察了温度、pH对吸附性能的影响。结果表明,磷酸水热改性后棉铃壳比表面积为121.7 m2/g,是改性前的18.5倍;通过水热改性可以减少酸性基团数量,有利于吸附阴离子。氟离子吸附实验结果显示,吸附反应符合准二级动力学模型,Langmuir模型能更好地描述反应的单分子层吸附特征,分离因子R L在0~0.5之间。改性棉铃壳对F-的吸附属于自发进行的吸热反应。

Adsorption of fluoride in water on modified cotton shell by hydrothermal method

The adsorbent was obtained from cotton shell modified by hydrothermal method.Characteristics of the adsorbent derived from cotton shell were analyzed using BET,SEM and FTIR analyzer.The kinetics and thermodynamics of their adsorption were measured by batch experiments.Meanwhile,the influences of temperature and initial pH on adsorption capacity were also considered.The results show that the BET surface of modified cotton shell is 121.7 m2/ g,about 18.5 times of the original one.The adsorption of anion is promoted by acidic groups decreased for modified cotton shell.The kinetics of adsorption follows well the pseudo-second order equation.Equilibrium isotherm data are well fitted by the Langmuir equation of monolayer adsorption,indicating that the adsorption mainly occurs on surface active sites of modified cotton shell.The R L value in the range 0 ~ 0.5 confirms the favorable adsorption.Adsorption of fluoride on modified cotton shell is an endothermic,spontaneous process and more favorable at higher temperatures.