Polymethacrylic acid functionalised with dihydroxy benzene as an adsorbent for the removal of Malachite Green dye

Abstract

Abstract The present work reports the investigation performed by comparing the adsorption abilities of modified/grafted polymethacrylic acid (PMAA) functionalized with dihydroxy benzene like catechol (CAT) and catechol-hydroquinone (CAT-HQ) by an oxidative decarboxylation method using potassium dichromate as an oxidant to absorb Malachite green (MG) dye from aqueous solution through batch experiments. The percentage of substitution of monomers with PMAA was found to be 94.5% and 95.7% for PMAA/CAT and PMAA/CAT-HQ respectively. The FTIR and SEM studies were determined to reveal the modification of PMAA. In order to efficiently extract malachite green from the aqueous solution, the effects of different parameters like contact time, pH, dye concentration and adsorbent dosage were systematically studied. The change on the surface morphology of the polymers after the adsorption of dye was analysed using FT-IR spectra and SEM images and found to have considerable changes after the adsorption of the chosen dye. The test of adsorption studies has shown that the Langmuir isotherm model is better than the Freundlich model. The monolayer adsorption capacity of PMAA/CAT and PMAA/CAT-HQ were found to be 97mg/g and 102 mg/g at 31°C.