Fabrication of chitosan/alginate porous sponges as adsorbents for the removal of acid dyes from aqueous solution

Effective wastewater remediation requires the development of suitable adsorbents. In this study, a strategy based on electrostatic interactions between the amino groups of chitosan and the anionic groups of acid dyes was developed for the removal of acid dyes from aqueous solution. By adjusting the fabrication parameters, chitosan/alginate porous sponges with controlled specific areas and pore structures were obtained. To enlarge the adsorption area, the adsorbents were processed via a freezing and lyophilization method to form three-dimensional porous sponges. Acid dyes in aqueous solution were adsorbed by the porous sponges, mainly through an electrostatic interaction mechanism. When the molar ratio of chitosan to alginate was fixed at 1.5:1, the porous sponges showed a maximum adsorption removal capacity of 1468.9 +/- 16.3mgg(-1) for acid red B14 at a dye concentration of 150mgL(-1) and pH of 2. The adsorption capacity of this system was significantly enhanced compared with those of control groups such as chitosan powder. Thus, chitosan porous scaffolds provide a novel method for improving the removal capacities of chitosan-based materials for cleanup of acid-dye-contaminated water.