Investigation of isotherm and kinetic of methylene blue adsorption by Tobacco residues activated carbon/ZnO nanocomposites with non-linear method

Industrial wastewater is one of the major environmental pollutants. Discharge of the colorful industrial effluent into the receptive waters leads to eutrophication and has mutagenic and carcinogenic properties. Therefore, the aim of this study was to investigate the removal of methylene blue (MB) from aqueous solutions by tobacco residues activated carbon and ZnO nanocomposite (TRAC/ZnO). This is an experimental-lab study. The effect of various parameters on adsorbent performance was investigated. The non-linear isotherms and kinetics of adsorption were determined. The dye concentration was measured in wavelength of 664 nm by spectrophotometer. The results indicated that the removal rate of dye increased with increasing the contact time and dose of adsorbent pH but the removal rate decreased with increasing the initial concentration of dye.  The maximum adsorption was achieved at initial concentration of 50 mg.L-1, pH=10, Ultrasonicated time of 8 min and adsorbent dosage of 0.05 g/L-1. In addition, the dye removal with TRAC/ZnO nanocomposite was best fitted to Ferundlich isotherm (R2=0.96) and pseudo second order kinetic (R2=0.92). This study showed that the TRAC/ZnO nanocomposite is highly capable of removing MB dye from aqueous solutions in low contact time. Therefore, the TRAC/ZnO nanocomposite can be considered as an effective adsorbent in dye removal.