The Adsorption Rules Of Aniline And Phenol On The Activated Carbon Fibers Under Electric Polarization

For adsorptive separation processes, the adsorption rate and capacity are two important factors affecting the costs. This paper investigates the application of an electrochemical technique for the removal of aniline and phenol, from water streams using a carbon-based electrode. Activated carbon fibers(ACFs) with high surface area and narrow micropores were used as electrode. For a better understanding of the process, adsorption is investigated under both open circuit(OC) and controlled polarization conditions, the latter in anodic directions. It is found that anodic polarization enhance the kinetics of adsorption of the aniline and phenol on ACFs, and the extent of which are strongly related to the applied polarized potential. The adsorption kinetics at different polarization potentials follows the Lagergren adsorption rate law. The prediction results are in good agreement with experimental data for the electrosorption of organic substances The adsorption kinetics of aniline shows the dependence on polarized potential, and the adsorption rate constant increases by 79%, from 4.99×10^-3 min^-1 at OC to 8.91×10^-3min^-1 at polarization of 500mV; while the adsorption rate constant of phenol increases by 84%, from 5.26×10^-3min^-1 at OC to 9.68×10^-3min^-1 at polarization of 500mV.Competitive adsorption of aniline and phenol from aqueous solutions on ACFs by the anodic polarization is investigated. The electrosorption kinetics for the adsorption rate and adsorption capacity of two-component aniline and phenol on ACFs are studied. The adsorption/electrosorption on ACFs follows pseudo-first-order adsorption kinetics. Compared with open potential, the adsorption rates of both aniline and phenol are improved to 1.97 times and 0.66 times with bias potential increasing, respectively. The adsorption capacity of aniline under 0.5 V is 1.42 times higher than that of open potential, but the adsorption capacity of phenol is almost unchanged.The ACFs and their surface characteristics are investigated before and after electrochemical polarization.The scanning electron micrograph(SEM) and Fourier transform infrared spectroscopy(FT-IR) are analyzed. The enhancement of adsorption was not due to direct electrochemical degradation, but might mainly be due to the increase of adsorption interaction forces under electric field.