Biocomposite of sodium-alginate with acidified clay for wastewater treatment: Kinetic, equilibrium and thermodynamic studies

Clay-based composites were prepared, characterized, and applied for the elimination of Blue FBN (BFBN) and Rose FRN (RFRN) dyes. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Thermogravimetric (TGA) and X-ray diffraction analyses were performed to check the interaction of dye molecule with adsorbents. The analysis showed a successful interaction between adsorbent and dyes ions. The experimental data was best fitted with Freundlich isotherm for both dyes (BFBN and RFRN). The findings revealed that at 80 min the adsorption grasped equilibrium in the case of both dyes and succeeded the pseudo-second-order kinetics model. Furthermore, the enthalpy (ΔH°), Gibbs free energy (ΔG°) and entropy (ΔS°) changes suggested that adsorption was exothermic, physical and spontaneous in nature. The maximum adsorption capacities were determined as 76.39% for BFBN and 59.85% for RFRN dye at pH 2.0 and 30 °C. Composites found to be stable at higher temperature and regenerated using MgSO₄ eluting agent. The textile effluent colour was removed up to 50.35 and 54.95% using raw and modified clay, respectively. The modified clay showed promising efficiency for adsorption of synthetic BFBN and RFRN dyes from aqueous solution, which could be a viable option for the treatment of industrial wastewater and textile effluents.