Removal of pyridine from aqueous solution using low cost activated carbons derived from agricultural waste materials

Abstract

The purpose of this study is to suggest an efficient process, which does not require a big investment for the removal of pyridine from wastewater. Activated carbons developed from agricultural waste materials were characterized and utilized for the removal of pyridine from wastewater. Systematic studies on pyridine adsorption equilibrium and kinetics by low cost activated carbons were carried out. Adsorption studies were carried out at different temperatures, particle size, pH and adsorbent doses. Both Langmuir and Freundlich models fitted the adsorption data quite reasonably. The results indicate that the Langmuir adsorption isotherm model fits the data better as compared to the Freundlich adsorption isotherm model. Various mechanisms were established for pyridine adsorption on developed adsorbents. Further, the data are better correlated with non-linear form as compared to the linear one. The kinetic studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent and solid to liquid ratio. The adsorption of pyridine follows the first order rate kinetics. On the basis of these studies, various parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated to establish the mechanisms. It is concluded that the adsorption occurs through a particle diffusion mechanism at temperatures 10 and 25 °C while at 40 °C it occurs through film diffusion mechanism. Similarly at concentrations 25 and 50 mg/l the adsorption is particle diffusion controlled while at⩽50 mg/l it is film diffusion controlled.