Efficient dye removal using cellulose-TiO2 nanocomposites synthesized from millet husk

Abstract

Cellulose was successfully isolated from millet husk via the Alkaline-Hydrogen peroxide method and Cel/TiO₂ NCs were synthesized via the sol-gel process. The extracted cellulose was used to increase the adsorption efficiency of TiO₂. The adsorbents were characterized using FTIR, SEM, and XRD analysis. FTIR spectra of the nanocomposites show that the TiO₂ is bound to the hydroxyl group of the cellulose by hydrogen bonding. A batch adsorption study was carried out to test the effectiveness of the adsorbents on the adsorption of methylene blue (MB) and methyl orange (MO), optimum conditions for the adsorption were found to be 0.5g/100mL at an initial dye concentration of 18mg/L, 25^oC, 20 minutes and pH of 8 for MB while 25 minutes and pH 4 for MO. The crystallite size of Cel/TiO₂ NCs was calculated using the Scherrer equation to be 27.6nm. MB was effectively desorbed using 0.1 mol/L NaOH solution from the adsorbents and the adsorbent exhibited a good reusability. The adsorption data fit the pseudo-second-order model for adsorption kinetics and the Langmuir model for adsorption isotherms. Thermodynamic analysis revealed that the adsorption process was chemisorption, spontaneous, feasible, and endothermic. These findings suggest that the adsorbents could be an economical and efficient solution for removing dyes from wastewater.