Adsorption of methyl orange from equeous solution using thermally activated montmorillonite clay

Abstract

In this study, Montmorillonite clay was thermally activated and used as an adsorbent for the removal of methylene blue dye in aqueous solution. The thermally activated clay was characterized using SEM, TGA, XRF, XRD, and FT-IR techniques. FTIR spectra showed the presence of different peaks at 1015.55cm-1 indicative of stretching vibrations for Si-O groups. The band at 492.05 and 479.91cm-1 are due to the Al-O-Si and Si-O-Si bending vibrations; also, the band at 551.90cm-1 was assigned to the couple Al-O and Si-O out of plane vibrations. SEM showed a significant particle size reduction, irregular spherical shape, partially broken and flake-like surface morphology. XRF showed the percentage concentration of silicon dioxide in montmorillonite (58.032%), while Al2O3 is 15.888%. XRD also showed the average particle size of 40.42nm. TGA showed high mass loss at a temperature 100 -250◦C, and smaller mass loss at the range of 580-650◦C. The thermally activated montmorillonite clay demonstrated good dye removal properties with optimum efficacy of 93.8%, for the montmorillonite.Thermodynamic parameters, such as ΔGo, ΔHo and ΔSo were also calculated. Kinetics data were tested by applying isotherm models: Langmuir and Freundlich.The methyl orange dye adsorption of montmorillonite was best fitted with Langmuir model (R²= 0.999). The thermodynamic data computed show that the process of the dye adsorption was spontaneous and endothermic. This shows that the thermally activated montmorillonite clay could serve as a suitable wastewater treatment material for methyl orange dye in textile industry.