Fe3O4/Polystyrene-Alginate Nanocomposite as a Novel Adsorbent for Highly Efficient Removal of Dyes

In this study, Fe3O4/polystyrene-alginate nanocomposite with high adsorption capacity was successfully prepared. Characterization of Fe3O4/polystyrene-alginate nanocomposite was carried out by various instruments, including SEM, EDX, FT-IR, XRD, and TGA. Then, the prepared nanocomposite was applied to remove malachite green as a cationic dye from aqueous solutions. The kinetic study was performed and the results showed the suitability of the pseudo second-order kinetic model (R² = 0.994). The influence of different parameters, such as initial dye concentration, solution pH, adsorbent dosage, and contact time on the procedure was extensively investigated. The maximum adsorption of malachite green onto Fe3O4/polystyrene-alginate nanocomposite was found at an initial concentration of 20 mg/L, pH 7, adsorbent’s dosage 500 mg/L, contact time equal to 20 min. To understand the nature of the adsorption procedure, the equilibrium adsorption isotherms were investigated. The linear correlation coefficients of Langmuir and Freundlich isotherms were obtained. The adsorption of malachite green was better fitted to Langmuir isotherm (R² = 0.996). According to the Langmuir isotherm model, the maximum adsorption capacity of Fe3O4/polystyrene-alginate nanocomposite for sequestering malachite green was about 90.81 mg/g. In addition, negative ΔG^0 and ΔH^0 values obtained through thermodynamic investigation implied that the adsorption of malachite green onto Fe3O4/polystyrene-alginate nanocomposite was simultaneous and exothermic in nature, respectively.