羟基磷灰石对水溶液中Fe^(3+)的吸附动力学及热力学研究

The adsorption of Fe^(3+) ions from aqueous solution by hydroxyapatite:Kinetic and thermodynamic study

研究了羟基磷灰石(HAP)对水溶液中Fe3+的吸附动力学及热力学。研究表明,HAP对水溶液中Fe3+的吸附符合Langmiur等温吸附,ct/q=0.006 4 ct+0.018 3;该吸附反应符合一级反应动力学方程,ln CR=-0.043 5 t+4.324 4;吸附反应活化能为Ea=36.26 k J/mol;标准摩尔反应焓为正值表明反应过程吸热;当温度大于285.7 K时,吉布斯自由能小于0,反应可自发进行。

The kinetics and thermodynamics of the adsorption of aqueous iron （Ⅲ ） on hydroxyapatite were in- vestigated. The result indicates that the adsorption equilibrium follows Langrnuir adsorption isotherm： ct/q = 0. 006 4 ct ＋ 0. 018 3. The reaction of adsorption is in accord with the first reaction kinetics equation： lnCR = - 0. 043 5 t ＋ 4. 324 4, and the reaction of adsorption energy Ea is 36.26 kJ/mol. Thermodynamic parameters were calculated. The positive values of standard enthalpy of adsorption has revealed the enothermic nature of the adsorption process. The negative values of Gibbs free energy are indicative of the spontaneity of the adsorption process when the temperature is higher than 285.7 K.