Synergistic effect in simultaneous adsorption of cationic and anionic emerging contaminants by chitosan aerogels containing nanocellulose-modified tannic acid

Abstract

Emerging contaminants (ECs) are present in the environment and can affect aquatic fauna and flora. Due to the difficulty in removing ECs from water, new technologies must be developed. Most studies report the adsorption of ECs in single systems and few works have investigated the uptake in multicomponent systems, which limits the applicability of adsorbents for real samples which usually contain different ECs. In this work, chitosan aerogel beads containing crystalline nanocellulose and modified tannic acid were synthesized and employed in the adsorption, in multicomponent systems, of the emerging contaminants VBB dye, CPC surfactant, and SC drug. The maximum removal potential in single systems was 1407, 698, and 934 mg·g−1 for VBB, CPC, and SC, respectively. The aerogels demonstrated high efficiency in the elimination of contaminants in real samples (>99 %). The CS@NC–mTA beads were able to remove the RR250 and RO122 anionic dyes in multicomponent systems, which were not adsorbed in single system, and achieved elevated removal capacities of 298 and 311 mg·g−1, respectively. In multicomponent assays with cationic contaminants, a synergistic effect was also observed, and the uptake of SC and CPC increased in 209.6 % and 40.9 % in the presence of the VBB dye. For the first time, a synergistic effect on the adsorption of cationic contaminants is reported. XPS analyses and adsorption data suggest that electrostatic, π-π, cation-exchange and H-bonds play important role in the process. These results indicate the great potential of the CS@NC–mTA beads in the water treatment for real samples.