Ultrahigh selective and efficient removal of anionic dyes by recyclable polyethylenimine-modified cellulose aerogels in batch and fixed-bed systems

A new type of polyethylenimine modified cellulose (PMC) aerogels were synthesized through a chemical cross-linking process, by which plenty of amine groups were introduced to the surface of cellulose aerogels. FT-IR, SEM, EDS, BET and XPS were used to characterize the physicochemical properties of this novel composite. The prepared aerogels were used to remove anionic dyes from effluents and it exhibited excellent adsorption performance in batch and fixed-bed experiments. Adsorption results indicated that PMC could efficiently, selectively separate anionic dyes from dye mixtures and maintain the maximum absorption capacity even after ten regeneration cycles, exhibiting superior selectivity and desirable recyclability. The maximum adsorption capacities of PMC for rose bengal and methyl blue were 1310.21 and 1333.04 mg/g, respectively, which were much higher than those of previously reported results. The Kinetics and isothermal adsorption data were well described by pseudo-second-order kinetic model and Langmuir model. The breakthrough curves obtained from fixed-bed systems were well fitted by Thomas model. Most importantly, anionic dyes could be efficiently removed even with high concentrations of coexisting anions. All these results manifested that PMC could be a promising candidate for sewage treatment, profiting from the fascinating merits of easy separation, low-cost, high adsorption capacity, strong anti-environment disturbance, superior reusability and selectivity.