Tailored glutamine modified nanozeolite-Y/xanthan gum composite based on rice straw for enhanced adsorption of cadmium ions from aqueous media

Abstract

This research utilized eco-friendly biocomposites nanoparticles to remove Cd^2 + from aqueous solutions. Herein, solid adsorbents were fabricated; nanozeolite-Y (Z), nanozeolite-Y/xanthan gum (ZX), and glutamine modified nanozeolite-Y/xanthan gum (GZX) based on rice straw. Various characterization techniques were used, including surface area, SEM, TEM, XRD, ATR-FTIR, and zeta potential to investigate the fabricated solid adsorbents. The effectiveness of the adsorption capacities of the prepared solid adsorbents towards cadmium ions were studied under different adsorption conditions. The results were analyzed using various nonlinear kinetic models (pseudo-first order, pseudo-second order, and Elovich), as well as nonlinear isotherm models (Langmuir, Freundlich, and Temkin). Characterization tools proved that GZX verified surface area of 735.20 m²/g, pore radius of 1.02 nm, pH_PZC= 6.70, acceptable thermal stability, and various surface chemical functional groups. The maximum adsorption capacity of GZX as calculated by nonlinear Langmuir model was found to be 339.1 mg/g at pH 6, 20 °C, and after 50 min of shaking time. Kinetic and thermodynamic studies verified that the adsorption of Cd²⁺ onto all the fabricated solid adsorbents are fitted well with pseudo-second order model, spontaneous, and endothermic. Sustainability of the fabricated GZX was confirmed by its well reusability after ten cycles of adsorption and desorption with only 4 % loss in its adsorption capacity. The formed GZX composite is a promising material in the removal of heavy metal ions from aqueous media.