[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 (Ka) were determined. With the anodic polarization of 400mV, the capacity of sodium phenoxide increases from 0.0083mmol x g(-1) at open-circuit to 0.18mmol x g(-1), and a seventeen-fold enhancement is achievable; however, the capacity of p-nitrophenol decreases from 2.93 mmol x g(-1) at open-circuit to 2.65 mmol x g(-1). With the cathodal polarization of -400mV, the capacity of aniline improves from 3.60 mmol x g(-1) at open-circuit to 3.88 mmol x g(-1); however, the capacity of sodium dodecylbenzene sulfonate reduces from 2.20 mmol x g(-1) at open-circuit to 1.59 mmol x 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.