Kinetic Study and Effect of Coexisting Ions on the Adsorption of Polyvinyl Alcohol (PVA) by Activated Carbon Fibres

摘要

A synthetic polymer pollutant, polyvinyl alcohol (PVA), is widely detected in wastewaters and natural waters. In this study, commercial activated carbon fibres (ACF) were tentatively used for adsorptive removal of PVA. Adsorption kinetics and the effect of coexisting ions on the adsorption of PVA were investigated. Kinetic models including pseudo-first-order, pseudo-second-order and Elovich models were used to simulate the kinetic data. The correlation coefficients of nonlinear pseudo-second-order and Elovich models are all above 0.969. The correlation coefficient of linear pseudo-second-order kinetic model is above 0.999, which is especially higher than those of linear pseudo-first-order model. The kinetic study indicates that both pseudo-second-order and Elovich kinetic models could describe the adsorption kinetics better. It can be inferred that chemisorption occurred between the PVA molecules and ACF while rate-determining step might be diffusive in nature. It is worthy to mention that most of the uptake occurred within the initial 120 min. Nitrate anions have no significant influence on PVA adsorption. For the common inorganic anions such as bicarbonate, phosphite and sulphate, the inhibition was observed with increasing concentrations. The presence of humic acid inhibited the PVA uptake as well.