Employing response surface methodology to optimise the adsorption of malachite green from water using sugarcane bagasse functionalised with polypyrrole

Abstract

Abstract In the present study, adsorption and detoxification of malachite green (MG) dye from water have been executed. Sugarcane bagasse (SCB), rice culm and cattail stem are functionalised by coating with polypyrrole (PPy) by in situ chemical polymerisation in aqueous medium for effective adsorption of MG. The main effects and interaction effects of different factors like pyrrole (Py) concentration, contact time, pH and temperature on adsorption have been investigated by employing the Box–Behnken design and response surface methodology (RSM). The RSM model suggests that 0.78 mol L −1 Py concentration, 50 min treatment time, 18 °C treatment temperature and pH 7 are optimum for achieving 100% removal of MG from water with an adsorption capacity of 16 mg g −1 . The 3D surface plots derived from the RSM model reveal the influence of the factors on MG adsorption. SEM images depict the successful coating of PPy on the cellulosic substrates and the adsorption of MG. Fourier transform IR spectra reveal the adsorption of MG on the surface of PPy‐coated SCB by the formation of intermolecular hydrogen bonds and electrostatic attraction. There is a good possibility of revival of the adsorption capacity of the PPy‐coated adsorbents for repetitive use. It is found that, even after five desorption–adsorption cycles with 5% NaOH solution, the adsorption efficiency of PPy/SCB is retained at about 86%. This study presents a facile design strategy for preparing bio‐based adsorbents with superior adsorption performance through the in situ polymerisation of Py on cellulosic substrates featuring active functional groups. © 2025 Society of Chemical Industry.