Flexible aerogel composites for the elimination of crystal violet and methyl orange

The application of porous aerogels for dye adsorption has proven to be an effective approach in wastewater treatment. In this study, bio-cellulose aerogels from coconut fibrils were successfully developed via the formation of physically cross-linking cellulose with non-toxic binders (polyvinyl alcohol (PVA) and xanthan gum (XTG)) resulting from a freeze-drying technique. The flexible aerogel composites demonstrated remarkably low density (27.59–47.76 g/cm³), high porosity (> 96.0%), compressive Young’s modulus (3.82–12.66 kPa), a specific surface area of 518.01 m²/g, and a desorption average pore diameter distribution of 3.77 nm. These aerogels were tested for crystal violet (CV) and methyl orange (MO) adsorption to evaluate their effectiveness in treating dye-polluted water via various conditions such as contact time, pH values, initial concentrations, and temperature. The dye adsorption process reached equilibrium after approx. 30 min and strictly followed pseudo-second-order and the Redlich-Peterson model. FT-IR and SEM-EDX analyses proved that the adsorption mechanism is primarily ascribed to the hydrogen bonding, electrostatic, π-π, and Vander Waals interactions between aerogel and dye molecules. The eco-friendly synthesis of recycled cellulose aerogels from coconut fibrils using green chemicals holds great promise for dye elimination.