NEW CORRELATION METHOD OF LIQUlD-PHASE ADSORPTION EQUILIBRIUM BY FRONTIER ORBITAL THEORY

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1.Data-Base for Liquid Phase AdsorptionThe experimental results showed that the amounts of the aromatic hydrocarbons adsorbed were large, whose substituting groups were electron-donating. On the other hand, it was found that the amounts of the aromatic hydrocarbons with electron-attracting groups adsorbed were small. Aromatic compounds with electron donation groups showed the hysteresis of adsorption and desorption in the liquid phase on activated carbon. On the other hand, aromatic compound with electron attracting groups showed no hysteresis. No hysteresis was detected for all adsorbates on the synthetic adsorbents.2.Correlation of Affinity Coefficient in Liquid-Phase AdsorptionThe adsorptive interaction of hydrocarbons in aqueous solution on the activated carbon and the synthetic adsorbents was regarded as a mixing of HOMO and LUMO.The method to estimate the adsorption energy was proposed according to the frontier orbital theory and the semi-empirical molecular orbital calculation. It was found that the charge transfer interaction plays an important role in liquid-phase adsorption and the affinity coefficient determined by D-R equation can be correlated by the ratio of adsorption energy of some adsorbate to that of the reference adsorbent. The prediction method of adsorption equilibrium was proposed.3.Effect of Surface Modification on Adsorption and Desorption Characteristics in Liquid-PhaseWhen activated carbon and graphite were oxidized, the amount adsorbed of aromatic compounds were decreased. The desorption characteristic, however, was improved by wet oxidation. The influence of surface functional groups of the carbon on adsorption and desorption characteristics was explained taking into account the change of adsorption energy by oxidation. It was deducted that the surface modification with electron-attracting groups is useful to increase the amount adsorbed on synthetic adsorbents.