| Highly toxic Chromium(Cr)is one of the heavy metal pollution monitoring indicators in water.With the rapid development of electroplating,printing and dyeing,leather and other industries,plenty of industrial waste water containing Cr(VI)ions were discharged into the water and caused serious water pollution.Hence,how to effectively remove the Cr(VI)ions in waste water has become a hot research topic.Polyaniline(PANI)is a conductive polymer with unique doping properties and reversible redox properties,which not only can adsorb Cr(VI),but also can reduce Cr(VI)to Cr(III).However,in the process of Cr(VI)removal,powered polyaniline is difficult to be recycled and cause secondary pollution.Therefore,this work aim to solve the secondary pollution problem caused by polyaniline with nanostructure during the progress of Cr(VI)removal and choose modified fiber ball(m-FB)as a carrier to load polyaniline.The main research contents in our work include:(1)PANI/m-FB composite with macrostructure was prepared by chemical oxidation polymerization and the optimum reaction conditions were determined.The experimental results show that the best concentration of H2O2 to modify the fiber balls is 10 g/L.When the molar concentration ratio of aniline to tartaric acid is 4:1 and the reaction is carried out in ice bath for 24 h,the prepared PANI/m-FB composite has the best performance.(2)The effect of reaction time,pH value and solution concentration on Cr(VI)adsorption capacity of the composites as well as the regeneration performance of composite were studied.The results show that the optimum pH value for composite to remove Cr(VI)is 5.0 and the maximum removal capacity is 293.13 mg/g.After 5 times of regeneration experiments,the removal percentage of Cr(VI)still remained more than 80%,which indicates that the composite exhibits a good recycling and regeneration performance.(3)The adsorption progress and removal mechanism of Cr(VI)by PANI/m-FB composite were analyzed.The adsorption kinetics experiment shows that pseudo second-order kinetics is more accurate to fit the process of Cr(VI)removing,indicating that the adsorption process is mainly controlled by the chemical reaction process.And Freundlich model fits the isothermal adsorption model better,indicating that Cr(VI)is easy to be adsorbed by PANI/m-FB composite. |
