Adsorption of Methylene Blue dye using Polymethacrylic acid modified with dihydroxy benzene-Redox polymer

In the present work, Poly Methacrylic Acid was synthesized by radical polymerization and functionalized with catechol and hydroquinone by an oxidative decarboxylation using potassium dichromate as an oxidant. The percentage of substitution was found to be 91% and 94.5% for PMAA/CAT and PMAA/HQ respectively. The modified polymers were used as an adsorbent to remove Methylene Blue dye from aqueous solution. The effect of various parameters, such as contact time, pH, dye concentration, and adsorbent dosage, were systematically examined and fixed the optimum time, pH, dye concentration and the adsorbent dosage for the effective removal of methylene blue from the aqueous solution. The adsorption capacity of PMAA/CAT and PMAA/HQ were found to be24.3mg/g and24.5mg/g with the adsorption efficiencies of 97% and 98% at pH 7 studied for 50 minutes with the initial dye concentration of 25mg/L for 0.1g/L of the adsorbents. The changes on the surface of the polymers before and after the adsorption was analysed using FTIR specra and SEM images and found to have considerable changes after the adsoption of the methylene blue. Equilibrium isotherms like Langmuir and Freundlich models were carried out for modified PMAA and were found to follow Langmuir adsorption isotherm model better than the Freundlich model. The adsorption kinetic study were carried out for pseudo first-order and pseudo-second order and results showed that the adsorption of MB on modified PMAA were controlled by pseudosecondorder kinetics.