电增强活性炭纤维吸附有机污染物的动力学研究

研究了在电极化条件下,几种具有代表性污染物质在活性炭纤维上的电吸附动力学特性.结果表明,各种污染物的电吸附动力学比较好地符合Lagergren一级吸附动力学,其平衡吸附量在电极化下的增加量各不相同.在400mV的极化电位下,苯酚钠的吸附量从开路时的0.008 3mmol·g^-1增加到0.18 mmol·g^-1,增加了17倍;而对硝基苯酚的吸附量从开路时的2.93mmol·g^-1降到2.65 mmol·g^-1.在-400mV的极化电位下,苯胺的吸附量从开路时的3.60 mmol·g^-1增加到3.88 mmol·g^-1;而十二烷基苯磺酸钠的吸附量从开路时的2.20 mmol·g^-1降到1.59 mmol·g^-1.说明不同取代基的苯衍生物,电吸附改变量不相同,供电子基团的单取代苯,正极化都能明显增强其吸附量;但是吸电子基团的单取代,正负极化对吸附量的影响都很小;供体-共轭桥键-受体型结构的苯衍生物,正负极化都使其吸附减弱但吸附速率加快.静电作用在离子型污染物的电吸附中表现明显.

Kinetics of Enhanced Adsorption by Polarization for Organic Pollutants on Activated Carbon Fiber

The adsorption kinetics for model pollutants on the activated carbon fiber(ACF) by polarization was investigated.Kinetics data obtained for the adsorption of these model pollutants at open-circuit and 400mV,-400mV polarization was applied to the Lagergren equation,and adsorption rate constants(K_a) were determined.With the anodic polarization of 400mV,the capacity of sodium phenoxide increases from(0.008 3mmol·g^-1) at open-circuit to 0.18mmol·g^-1,and a seventeen-fold enhancement is achievable;however,the capacity of pnitrophenol decreases from 2.93 mmol·g^-1 at open-circuit to 2.65 mmol·g^-1.With the cathodal polarization of-400mV,the capacity of aniline improves from 3.60 mmol·g^-1 at open-circuit to 3.88 mmol·g^-1;however,the capacity of sodium dodecylbenzene sulfonate reduces from 2.20 mmol·g^-1 at open-circuit to 1.59 mmol·g^-1. The enhancement for electrosorption changes with different groups substituting. Anodic polarization enhances the adsorption of benzene with electron-donating group.But whether anodic or not cathodal polarization has less effect on the adsorption of electron-accepting aromatic compounds,and decreases the adsorption of benzene bearing donor-conjugate bridge-acceptor but increases the adsorption rate.Electrostatic interaction plays a very important role in electrosorption of ion-pollutants.