坡缕石/氧化铝复合材料对磷的吸附动力学和热力学

Kinetics and thermodynamics of the adsorbing phosphate from water on palygorskite/alumina compound material

以坡缕石粘土为原料,通过溶胶-凝胶法制备坡缕石/氧化铝复合材料,通过静态吸附实验研究了复合材料吸附水中磷的动力学特征、吸附平衡和热力学参数,探讨了吸附机理。结果表明,复合材料对磷有较好的吸附作用,吸附过程能较好地符合准二级动力学方程,吸附速率常数随初始浓度的增大而减小,随温度的升高有所增大;吸附平衡能较好地符合Langmuir方程和D-R方程,吸附过程吸热,ΔG为-25^-21 kJ/mol,是物理吸附和化学吸附并存的过程。

In this paper,palygorskite/alumina composite materials were prepared as the adsorbent by using sol-gel technique,and the adsorption properties and mechanisms of complex adsorbing phosphate were investigated,with a discussion on the adsorption kinetics and thermodynamic characteristics.The results demonstrate that the adsorption processes of phosphate on complex surface follow the pseudo-second-order equation most effectively and the rate constant increases with decreasing initial concentration and the rise of temperature.The adsorption isotherms fit Langmuir equation and D-R equation fairly well.The adsorption enthalpy is positive and the adsorption Gibbs free energy changes are in the range of-25^-21 kJ/mol.The adsorption process is endothermic and spontaneous,with the coexistence of physical adsorption and chemical adsorption.