Adsorption of Aryl Azothieno[2,3-b]pyridine Dyes on Corncobs

Abstract

Nowadays, water pollution is considered one of the most global unwanted environmental problems, so its treatment is of great importance. In this study, Corncobs, which are considered agro-cellulosic wastes, were used as highly efficient and low-cost sorbents for the adsorptive removal of some 4,6-dimethyl-2-(aryldiazenyl)thieno[2,3-b]pyridine-3(2H)-one dyes from aqueous solutions. The influences of the different operating parameters such as solution pH, sorbent dose, dye concentration, particle size, and contact time are extensively examined. From the experimental results, we found that the adsorption capacity attained its highest value at pH 12 and particle size 0.125 mm, also the adsorption reached equilibrium after 90 minutes. Results revealed that the adsorption data is well described by Langmuir and Freundlich isotherms with higher values of maximum adsorption capacities. It was found that the kinetic model for Ia, Ic and Id are consistent with a pseudo-second-order (R2 >0.99) and Ib is consistent with a pseudo–first-order (R2 >0.99). Therefore, kinetic studies demonstrated that the adsorption process is well fitted by pseudo-second-order model and ruled by pore diffusion and film diffusion mechanism.