Smart superabsorbent alginate/carboxymethyl chitosan composite hydrogel beads as efficient biosorbents for methylene blue dye removal

The presence of toxic dyes in the aqueous medium has threatened environmental safety, and thereby removing them from wastewater in an efficient way is highly desired. Herein, the efficient biosorbents were successfully fabricated via a facile physical gelation process of sodium alginate (SA) and carboxymethyl chitosan (CMCTS) in an acidic aqueous solution. The as-prepared hydrogel beads not only displayed water superabsorbent properties and pH-responsive swelling characters but also exhibited excellent methylene blue (MB) adsorption capacity removal efficiency with experimental maximum MB adsorption capacity of 2518 and 1005 mg g -1 , which are comparable with most reported lignocellulosic and alginate-based hydrogels. The MB adsorption process fitted well in different kinetic and isotherm models and became more heterogeneous in concentrated MB solutions as verified by principal component analysis results. The adsorption mechanism was proposed, and the high dye absorbency was attributed to the strong electrostatic forces between adsorbents and adsorbates. Our current study provides a promising and sustainable composite hydrogels platform targeted to dye decontamination. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The presence of toxic dyes in water threatens environmental safety, making efficient removal of dyes from wastewater highly desired. This study successfully fabricated efficient biosorbents through a simple gelation process of sodium alginate and carboxymethyl chitosan in an acidic aqueous solution. The resulting hydrogel beads showed excellent water absorption properties, pH-responsive swelling characteristics, and high methylene blue (MB) adsorption capacity, comparable to existing lignocellulosic and alginate-based hydrogels. The adsorption mechanism was explained by strong electrostatic forces. This research provides a promising and sustainable approach to dye decontamination.