Mg/Al水滑石对水中痕量邻苯二甲酸酯的吸附动力学和热力学

Adsorption kinetics and thermodynamics of trace phthalate esters on Mg/Al hydrotalcite

研究了Mg/Al水滑石对水中痕量邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二辛酯(DnOP)的吸附动力学和热力学特性。结果表明,在所研究的浓度范围内,3种邻苯二甲酸酯的吸附动力学曲线均符合准二级速率方程,DMP、DEHP和DnOP分别在600、200和200 min基本达到吸附平衡;3种邻苯二甲酸酯的吸附等温线基本符合Langmuir和Freundlich吸附等温方程;在283～308 K范围,pH=6.36,3种邻苯二甲酸酯初始浓度均为50μg/L时,吸附过程ΔH为负值且绝对值为5～12 kJ/mol,表明吸附为放热过程,以表面物理吸附为主,邻苯二甲酸酯在Mg/Al水滑石上的吸附是色散力、诱导力、取向力和氢键力等多种作用力协同作用的结果。

The adsorption kinetics and thermodynamics of trace dimethyl phthalate ester, di-（2-ethylhexyl） phthalate and di-n-octyl phthalate on Mg/A1 hydrotalcite were studied. The results showed that the adsorption kinetics of phthalate esters all fitted the pseudo-second order kinetics, and the equilibrium of the three phthalate esters was reached in 600, 200 and 200 min, respectively. The adsorption isotherms could be described by both Langmuir and Freundlich models. The adsorption enthalpy value was estimated to be - 5 - - 12 kJ/mol at pH 6.36 in the temperature range of 283 - 308 K, indicating that the adsorption is exothermic in nature mainly dominated by the physical interaction including dispersion force, induction force, orientation force and hydrogen bond force.