Regenerated cellulose/polyethyleneimine composite aerogel for efficient and selective adsorption of anionic dyes

With the requirement of sustainable development in modern society, it is urgent to develop the environmentally friendly adsorbents for selective filtration and separation of toxic dyes from hazardous wastewater. Herein, a stable, reusable, and highly compressible three-dimensional regenerated cellulose/polyethyleneimine composite aerogel (RC/PCA) was successfully prepared directly using cheap cotton pulp as raw material and N-methyl morpholine-N-oxide (NMMO) as the "green" solvent, in which the regenerated cellulose (RC) with hydroxyl groups converted from cotton can interact with polyethyleneimine (PEI) with amine groups. After further crosslinking of RC, PEI and glutaraldehyde (GA), the RC/PCA can be used to selectively absorb anionic dyes from the ternary mixed dye system, which maximal adsorption capacity for methyl orange (MO) can be up to 980.39 mg/g. Moreover, the obtained stable RC/PCA can be repeatedly used at least 50 times for the removal of MO (20 mg/L) with a high filtration efficiency of 99.8 %. The kinetics and isothermal adsorption data were described via the pseudo-second-order kinetic model and Langmuir model. Therefore, this research proposes a novel strategy for developing low-cost, highly efficient, regenerated cellulose-based adsorbents to extract organic dyes from wastewater for potential practical applications.