Methylene Blue and Malachite Green Removal From Aqueous Solution Using Waste Activated Carbon

Abstract

In the present investigation, Waste Activated Carbon (WAC) collected from domestic water filter has been used for the removal of two cationic dyes methylene blue (MB) and malachite green (MG) from synthetic solution. The surface of WAC is characterized to know the mechanism of adsorption reaction and the effect of different adsorption parameters like pH, temperature, contact period, adsorbate and adsorbent doses are also studied for the said adsorption study. The optimum contact times for MB and MG adsorption on WAC are 60 and 120 minutes respectively, whereas pH is having no significant effect on adsorption. However, % adsorption increases slowly with the increase of pH from 2.5 to 7. Adsorption of both the dyes on WAC is exothermic, spontaneous, and favorable in nature. Langmuir isotherm and pseudo-second-order kinetics are obeyed well. Langmuir’s maximum monolayer adsorption capacities are found to be 15.38 and 18.87mg/g for MB and MG, respectively. Temkin isotherm, and Morris-Weber equations are also obeyed well. Temkin’s isotherm concludes the physicochemical nature of adsorption, and Morris Weber equation indicates possibilities of intraparticle diffusion. The interaction between these two cationic dyes and WAC can be explained through electrostatic force of attraction or by hydrogen bonding.