Facile synthesis and modification of layered double hydroxides (LDH) for adsorption of Orange I and Acid Red 114 dyes from aqueous solution: Performance and mechanism study

Adsorption with Layer Double Hydroxides (LDHs) and their thermal decomposition products is one potential technique for treating textile dye-contaminated effluents. The produced adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Thermal Gravite Analysis (TGA). This method provides high efficiency for dye removal at a low cost. The primary goal of this study was to investigate the adsorption of the textile azo dyes ORI/AR114 on both calcined and non-calcined Mg-Al-CO₃ LDHs. It looked at how the pH of the medium, contact time, and dye concentration affected the adsorption process. The highest elimination capacities of ORI and AR114 were 487 mg g⁻¹ (at pH 5 and contact time of 120 min) and 559 mg g⁻¹ (at pH 11 and contact time of 60 min), respectively, with an initial concentration of 100 mg/L and temperature of 25 °C. AR114 and ORI performed similarly to Freundlich and Langmuir models in terms of removal. According to the thermodynamic study, the process was exothermic and spontaneous. Mg-Al-LDH adsorbs azo dyes via electrostatic interaction. In addition to its high adsorption capacity, Mg-Al-500 maintained an adsorption capacity greater than 78 % (AR114) and 72 % (ORI) after three adsorption–desorption cycles. LDHs have been shown to be an effective way to clean dye-contaminated water.