Removal of Anionic Dye Congo Red from Aqueous Solutions Using Sawdust Modified by Polyaniline: Adsorption Isotherm and Kinetics Study

This research deals with the application of polyaniline coated on wood sawdust (PANi/SD) for the removal of anionic dye congo red (CR) from aqueous solutions. The influence of process variables such as adsorbent dose, initial dye concentration, pH of test solution, contact time and breakthrough curves were studied. In order to find out the possibility of reuse, desorption study was also carried out in this investigation. Surface characteristics of PANi/SD were investigated using Fourier transform infrared (FTIR) technique. Among the different parameters affecting the removal of dye, it was found that pH of the solution has the most pronounced effect. Sorption/desorption of dyes can be simply controlled via pH adjustment. The experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir. It was found that the adsorption of CR on PANi/SD followed the pseudo-second order equation which indicates that the adsorption process is chemisorption controlled.