Synthesis of magnetic nanocomposite (Fe3O4/acerola seed) for cationic dye removal

ABSTRACT The removal of methylene blue (MB) from aqueous solution by NaOH-treated acerola seeds (AS) impregnated with Fe3O4 nanoparticles (MAS) was investigated. Magnetic nanoparticles were obtained through chemical precipitation of a Fe2+/Fe3+ mixture by ammonia, in the presence of treated AS powder. The nanocomposite obtained was characterized by FTIR, XRD, and nitrogen physisorption. MAS characterization results indicated the successful incorporation of Fe3O4 nanoparticles on the AS. The influence of adsorbent mass (0.2–0.8 g), pH (4.0–10.0), and agitation (80–120 rpm) on the adsorption of MB on MAS were investigated through a 23 full factorial design. The adsorption equilibrium and kinetics studies suggested that the Sips isotherm model (R2 = 0.989), with a qmax of 73.07 mg·g−1, adequately explains the adsorption process and the pseudo-first-order model (R2 = 0.997) could be regressed well with experimental data. The Weber–Morris model indicates that diffusion in the boundary layer is the limiting step of the process. The statistical analysis of the factorial design suggests that from the first-order regression model (R2 = 0.9972), the optimum effective remotion was: pH at 10.0, adsorbent mass at 0.8 g, and an agitation speed at 120 rpm, resulting in a removal of 99.32%. Results revealed that the MAS is a promising potential adsorbent for dye removal.