Adsorption of Organic Dye on Pillared Clays

- Naturally occurring bentonite clay is pillared with Cr-polycations and Al-polycations to overcome the swelling nature of the clay upon contact with water. Chromium Pillared Clay (CrPC) and Aluminium Pillared Clay (AlPC) were characterized using Scanning Electron Microscope, X ray diffraction, Energy dispersive X ray analysis and point of zero charge. The basal spacing increase in the interlamellar space confirmed the successful pillaring of clays. Acid Violet 19 (AV-19) dye was used as model adsorptive. Batch adsorption kinetic studies at ambient conditions revealed that the Pseudo Second Order (PSO) model could characterize the adsorption. The PSO rate constant for CrPC and AlPC were 0.0082 g/mg min and 0.0831 g/mg min, respectively. Langmuir isotherm fitted the equilibrium results for both the adsorption systems. The maximum adsorption capacity for the AV-19 dye on CrPC was 37.54 mg/g, while it was 24.33 mg/g for AlPC at ambient conditions. Thermodynamic analysis showed that the adsorption in both adsorbents was endothermic. The effect of pH on adsorption capacity suggested that electrostatic interactions were the primary contributing mechanism for dye adsorption on CrPC and AlPC. The results showed that the pillared clay adsorbents effectively treated the AV-19 dye-containing wastewater.