Repurposing cottonseed meal as dye biosorbent

We successfully repurposed cottonseed meal (CSM) into alginate composite hydrogel beads for dye adsorption via a simple and efficient method. The beads entrapped CSM with up to 80 wt%. Effect of CSM on the physiochemical properties of composite hydrogel beads including swelling behaviors, chemical structures, thermal stability, and methylene blue (MB) adsorption capacity, was investigated. Compared to alginate gel beads, the alginate/CSM composite system exhibited a drastic increase in thermal stability and a synergistic effect in dye adsorption capacity, where the dye adsorption capacity was well maintained, despite the inherently lower capacity when used alone. Such synergistic effect appeared to be linked to the reduced size of CSM particles within the gel network, while dye adsorption mechanism was attributed to the electrostatic attraction and hydrogen bonding between the biosorbents and dye. Our current study offers a feasible and cost-effective approach for upcycling CSM as biosorbent for dye decontamination.