Sodium alginate/polyethyleneimine/polydopamine@cellulose nanofiber composite aerogel as a novel adsorbent for Cr

In this work, a novel SA/PEI/PDA([alpha])CNF (SPCP) aerogel adsorbent was prepared for efficient hexavalent chromium (Cr(VI)) and dyes removal. Sodium alginate was used as the skeleton ingredient, nanocellulose fiber as the reinforcing agent, while polyethyleneimine provides functional groups, and polydopamine was added to improve the adsorption capacity of the aerogel toward cationic dyes. Several methods were used to characterize the SPCP aerogel, and thorough research showed that the aerogel's adsorption capacities for CR, Cr(VI), and MB were 1078.06, 2827.38, and 596.96 mg/g, respectively. In addition, it was established that the pseudo-second-order kinetics provides the most accurate way to the adsorption kinetic process while the Langmuir model provides the most accurate representation of the adsorption isotherm. Additionally, SPCP aerogel still retained exceptional adsorption capability after five adsorption-desorption cycles. Thereupon, SPCP, this biomass composite aerogel exhibits notable benefits, such as high adsorption capacity, marvelous sustainability, cost-effectiveness, and easy operation, which was considered to be a promising adsorbent for the wastewater treatment.