Adsorptive Removal of Malachite Green From Aqueous Solution Using Magnetized <i>Casuarina equisetifolia</i> Pine‐Derived Biosorbent

ABSTRACT A magnetically modified biosorbent derived from Casuarina equisetifolia pines (m‐CEP) was developed for the removal of malachite green (MG), a cationic dye, from aqueous media. The prepared adsorbent material was characterized for its structural, morphological, and elemental features to understand its suitability in augmenting dye wastewater remediation. The results infer that 0.010 g biosorbent was proficient in removing 5 mg L −1 of MG (pH 5.0) when agitated at 250 rpm for 60 min. Isothermal behavior was evaluated using nonlinear isotherm models like, Langmuir, Freundlich, and Sips models while the rate‐limiting steps were found using kinetic models. The adsorption equilibrium and kinetic data were best fitted by the Sips isotherm and pseudo‐first‐order kinetic models, respectively. The maximum adsorption capacity was found to be 4.50 mg g −1 . The thermodynamic behavior of MG removal by m‐CEP powder described the feasibility of adsorption and the type of heat involved. Equilibrium sorption capacities, rate constants, and correlation coefficients explain that MG dye removal by m‐CEP is presumably monolayer adsorption, spontaneous, and endothermic nature.