Synergistic effects of graphene oxide loading and particle size in ice-templated carboxymethyl cellulose-based aerogels on dye removal.

Sustainable carboxymethyl cellulose/graphene oxide (GO) aerogels were fabricated via epichlorohydrin cross-linking and ice-templating for effective methylene blue (MB) removal from aqueous solutions. The synergistic effects of GO loading (1, 3, and 5 wt%) and particle size (500, 10, and 1 nm) on the structural, mechanical, and adsorption properties of aerogels were systematically explored. The optimal dye adsorption capacity (555.6 mg/g) was obtained at 3 wt% GO loading, owing to enhanced π-π stacking, hydrogen bonding, and electrostatic interactions between GO and MB. Conversely, excessive GO loading caused nanosheet aggregation, decreasing adsorption efficiency. Reducing GO particle size to 1 nm notably improved the compressive strength (546 kPa) of aerogels because of uniform dispersion but deteriorated adsorption performance by disrupting interlayer interactions (π-π stacking). The 10 nm-GO composite achieved the optimal balance, demonstrating high adsorption capacity (416.7 mg/g) and adsorbate affinity (KL = 0.387 L/mg). Spectroscopic and morphological analyses confirmed successful cross-linking, improved pore structure, and interfacial compatibility. Adsorption kinetics followed the pseudo-second-order model, whereas the isotherm data fitted well to the Langmuir model, indicating monolayer chemisorption. The aerogel retained > 93% of its initial efficiency after five reuse cycles, demonstrating excellent reusability and potential for sustainable dye-laden wastewater treatment.