两种形态的活性炭纤维对水中敌草隆吸附性能的对比

Comparison of diuron adsorption onto two forms of activated carbon fiber in aqueous solutions

探讨了粉末和片状两种形态的活性炭纤维对水中敌草隆的吸附行为.结果表明:粉末活性炭纤维的前期吸附速率较快,平衡吸附量大,但达到吸附平衡的时间较长;pH对两者的平衡吸附量的影响趋势一致,且片状活性炭纤维和粉末状活性炭纤维的最佳pH值分别为2.9和3.1;敌草隆在两种活性炭纤维上的吸附皆为多分子层吸附,吸附行为均适宜采用Redlich-Peterson方程进行描述;假二级方程均适用于描述两种形态活性炭纤维对水中敌草隆的吸附动力学过程,但相比较而言,粉末活性炭纤维动力学拟合的相关性差异更加明显;两者的吸附Gibbs自由能(ΔG0)值均小于零,说明两者的吸附过程皆为自发进行的吸附过程.但值得注意的是,片状活性炭纤维的焓变ΔH0>0,说明该吸附反应为吸热反应;粉末活性炭纤维的焓变ΔH0<0,说明该吸附反应为放热反应.

This study explored the adsorption of diuron onto the activated carbon fiber （ACF） in two forms. The results showed that the prophase adsorption rate of powdered active carbon fiber was faster, and equilibrium adsorption capacity was larger. However, the time reaching adsorption equilibrium was longer. The influence of pH on adsorption equilibrium to both forms of the ACF was the similar, with the optimum pH of 2.9 and 3.1, respectively. Adsorption of diuron onto the ACF were multilayer, and could be depicted primarily by Redlich-Peterson function. The pseudo-second-order kinetic model was applicable to describe adsorption kinetics of the ACF in two forms. However, difference of powdered active carbon fiber dynamics fitting correlation was more evident. Gibbs free energy（ AGO） values of both forms were below zero, which indicated both adsorptions were spontaneous. On the other hand, △H0 of square sheet of activated carbon fiber were above zero, indicating that this adsorptive reaction was endothermic, while △H0 of powdered activated carbon fiber were below zero, indicating that this adsorptive reaction was exothermie.