One pot synthesis of nano EMD for effective adsorption of toxic dyes

Abstract

A simple electrochemical technique was employed to synthesize nanocorn electrolytic manganese dioxide (EMD) in presence of a structure directing agent poly vinyl pyrollidone (PVP) at optimum concentration in the aqueous acidic manganese sulphate bath. XRD and SEM analyses confirm the formation of MnO2 with nano corn shaped crystals at optimum concentration i.e 20 mg.L−1 of PVP. The finely ground material successfully employed for the removal of toxic dyes chicago sky blue (CSB) and malachite green (MG) from aqueous solution. Various process parameters such as different adsorbents, adsorbent dose, contact time, initial dye concentration and pH were varied and optimised for both the dyes. It was found that EMD20PVP showed 99.61% of adsorption efficiency at an optimum dose of 0.04 g / 20 mL of the 100 mg.L−1 chicago sky blue dye solution at room temperature within 20 minutes. However same EMD20PVP sample showed 99.5% adsorption efficiency at an optimum dose 0.07 g / 20 mL of the 100 mg.L−1 Malachite green dye solution at room temperature within 120 minutes. From the adsorption kinetics study it was concluded that, adsorption process follows pseudo-second order kinetics and adsorption isotherm confirms the reaction follows Langmuir adsorption for both the dyes.