Microcrystalline cellulose modified chitosan aerogels to enhance Congo Red dye adsorption

Abstract

Carbohydrate based aerogels were synthesized via a straightforward procedure including freeze-drying of chitosan (Ch) hydrogels of different concentrations cross-linked with glutaraldehyde and incorporating microcrystalline cellulose (MCC) powder to enhance mechanical strength and modify adsorption properties. The increase in Ch content and the incorporation of MCC resulted in samples that exhibited higher densities, lower swelling degrees and accessible porosities while demonstrated improved stabilities. These aerogels were evaluated as adsorbents of the textile dye Congo Red (CR) by isothermal and kinetic studies. Even when relatively simple theoretical models were used to predict these results, in order to eliminate modeling bias, a validation method based on error functions in addition to the more commonly used R², was applied. Equilibrium adsorption capacities obtained in kinetic studies increased 150 % changing Ch concentration from 4 % to 5 %, and 196 % adding 50 % by weight of MCC. The adsorption tests for initial concentrations of CR below 100 mg/L demonstrated that the aerogels exhibited increased adsorption capacity for higher Ch content or incorporation of MCC. Thermodynamic studies indicated enhanced adsorption at higher temperatures. These environmentally friendly aerogels demonstrated comparable or superior adsorption capacities to other bio-based materials, offering a simple, economical, and effective solution for pollutant removal.