电增强活性炭纤维吸附有机污染物的动力学研究

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

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.

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 （Ka） 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 p-nitrophenol decreases from 2.93 mmol·g^-1 at open-circuit to 2.65 mmol·g^-1With 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.