Selective nanocomposite hydrogels developed from cashew gum/laponite for selective removal

Dyes are significant pollutants in aquatic environments, even at low concentrations. To address this issue, superabsorbent nanocomposite hydrogels were developed using cashew tree gum cross-linked with acrylamide and incorporating laponite as a selective adsorbent for cationic dyes. The hydrogels were characterized through Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TG), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive Spectroscopy (EDS), along with assessments of toxicity, swelling capacity, and adsorption parameters. TG and XRD analysis indicated the incorporation of laponite into the polymer matrix. FTIR showed no significant changes due to the low concentration of laponite. SEM revealed a uniform surface in the laponite-containing hydrogel (HGC-LAP). EDS confirmed the presence and good distribution of Mg and Si elements in HGC-LAP. Although hydrogels without laponite (HGC) showed higher swelling capacity, HGC-LAP demonstrated faster adsorption kinetics, with values approaching those of HGC at equilibrium. The addition of laponite improved the adsorption capacity to 2887.5 mg g⁻¹, and the data fitted the pseudo-second order and Langmuir models. The nanocomposite hydrogels proved to be effective as selective adsorbents in dye mixtures.