Síntese e caracterização de um nanocompósito de grafite magnético para adsorção dos corantes Reactive Black 5 (RB5) e Azul de Metileno (AM)

Abstract

Magnetic graphite nanocomposite (NGM) based on magnetic nanoparticles (NPs) and graphite nanoplatelets has been synthesized by a novel hydrothermal synthesis route. NGM and its precursors were characterized by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). The nanomaterial discoloration efficiency (%Ads) using reactive black 5 (RB5) and methylene blue (AM) textile dyes in aqueous solution as target pollutant were evaluated. The influence of adsorptive parameters on effluent discoloration efficiency responses was evaluated from a 23 factorial design and the response surface analysis of central rotational composite design. Adsorption parameters evaluated include: adsorbent mass, adsorbate concentration and agitation speed. It was observed that the parameters agitation speed (rpm) and concentration of adsorbate (mg L-1) are the factors more significant than any other combination and it is highly indicated that they should be parameterized in combination. NGM statistical results showed %Ads ~98% in the RB5 removal, extremely high adsorption velocity, since it reached the adsorption equilibrium within 10 minutes of contact with the adsorbate and it presented 99% adjustment for pseudo first and second order kinetics, besides it presented a maximum adsorptive capacity of ~93 mg g-1 for the adjustment of Langmuir model, predominant in this system. The %Ads of AM onto NPs and graphite was ~59% and 100%, respectively. The study shows that NGM can be magnetically separated from the aqueous solution without introduce any byproduct during adsorption and presented favorable adsorptive properties, which makes evident its applicability of use as environmental remediator. The application of this synthetic rout becomes of technological interest when, besides being unprecedented and low cost, NGM adsorptive properties are attractive to effectively discolor wastewater.