Biodegradable aminated alginate-chitosan porous polymer for efficient indoor formaldehyde capture

Formaldehyde, even at low concentrations, poses a significant indoor pollutant risk, underscoring the need for efficient and sustainable sorbents. This study introduces a novel, multifunctional, and fully biodegradable adsorbent derived from waste shrimp shells. The shells were converted into soluble chitosan, which was then physically crosslinked with branched amine-modified alginate, resulting in a porous biuret-modified alginate/chitosan (BCC) polymer. BCC, with a 6 wt% biuret content, demonstrated exceptional adsorption performance for low-concentration formaldehyde, achieving a capacity of 1.97 mg·g^-1-159% higher than alginate and 149 % greater than activated carbon. The adsorption kinetics followed the pseudo-second-order model, and the Sips isotherm model suggested a chemical adsorption-dominated mechanism, with physical adsorption acting as a supplementary process. Additionally, BCC exhibited excellent reusability, maintaining high adsorption efficiency after four regeneration cycles, and incorporated a colorimetric signaling function, with a detection threshold of 0.07 mg·m^-3 and a sensitivity of 0.02 mg·m^-3. These findings provide valuable insights and a theoretical basis for developing effective, safe, and environmentally friendly formaldehyde adsorbents.