Adsorptive removal of reactive azo dye from an aqueous phase onto charfines and activated carbon

This contribution presents results pertaining to the adsorptive removal of reactive azo dye onto a low cost coal-based adsorbent (charfines) and its efficiency in dye colour sorption was compared with activated carbon (F400). Batch sorption studies were performed and the results revealed that charfines demonstrated an ability to adsorb the reactive azo dye. The sorption interaction of reactive dye on to charfines obeys the first order rate equation. The sorption data indicates that the adsorptive removal of the dye from aqueous solution is rather complex involving both boundary layer diffusion and intraparticle diffusion; however, intraparticle diffusion appears to be the rate limiting step. Isothermal data fit well with the rearranged Langmuir adsorption model. Desorption studies further indicated that the charfines facilitated chemisorption in the process of dye sorption while, activated carbon resulted in physisorption interaction. Dye sorption is found to be dependent on the aqueous phase pH and the dye uptake is greater at lower pH.