Kinetics of enhanced adsorption by polarization for organic pollutants on activated carbon fiber

The adsorption kinetics for model pollutants on activated carbon fiber(ACF)by polarization was investigated in this work.Kinetics data obtained for the adsorption of these model pollutants at open-circuit,400 mV,and−400 mV polarization were applied to the Lagergren equation,and adsorption rate constants(Ka)were determined.With the anodic polarization of 400 mV,the capacity of sodium phenoxide was increased from 0.0083 mmol/g at open-circuit to 0.18 mmol/g,and a 17-fold enhancement was achieved;however,the capacity of p-nitrophenol was decreased from 2.93 mmol/g at open-circuit to 2.65 mmol/g.With the cathodal polarization of−400 mV,the capacity of aniline was improved from 3.60 mmol/g at open-circuit to 3.88 mmol/g;however,the capacity of sodium dodecylben-zene sulfonate was reduced from 2.20 mmol/g at open-circuit to 1.59 mmol/g.The enhancement for electrosorption changed with dif ferent groups substituting.Anodic polarization enhances the adsorption of benzene with the electron-donating group.But whether anodic or not,cathodal polariza-tion had less effect on the adsorption of electron-accepting aromatic compounds,and decreased the adsorption capacity of benzene-bearing donor-conjugate bridge-acceptor,while increasing its adsorption rate.Electrostatic interaction played a very important role in the electrosorption of ion-pollutants.

Dynamic fate modeling of γ-hexachlorocyclohexane in the lower reaches of the Liao River

A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants(POPs)in the Liao River.The model parameters,namely fugacity capacity,degradation rate,and transfer coefficient,are profoundly affected by tem-perature.This model is used to simulate the fate of γ-hexachlorocyclohexane(c-HCH)in the lower reaches of the Liao River from 1998 to 2008.Modeling results show that c-HCH fugacity capacities in air,water,and sediment increase as temperature decreases,and the transfer and transformation rate coefficients increase as temperature increases.The varia-tions of transfer and transformation parameter D values depend on fugacity capacities,and transfer and transformation coefficients simultaneously.The performance of the model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River.The predicted values agree well with the observed value in the order of magnitude,in most cases within the factor of 3.It is believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.