Combustion synthesis of Fe3O4/Ag/C nanocomposite and application for dyes removal from multicomponent systems

The Fe₃O₄/Ag/C nanocomposite was successfully prepared by combustion synthesis using citric acid as fuel. The composition, morphology and structure of the nanocomposite were investigated by Mössbauer spectroscopy, X-ray diffraction (XRD), thermogravimetric (TG)/differential scanning calorimetry (DSC), scanning electron microscopy (SEM)-energy dispersive X-ray (EDX), transmission electron microscopy (TEM) and N₂ adsorption-desorption technique. The magnetic nanocomposite was tested as adsorbent for the removal of Methylene Blue, Acid Orange 7 and Rhodamine 6G in single and multi-component system from aqueous solutions. The effects of solution pH, contact time, adsorbent dose, and initial pollutants concentration on the dyes adsorption were studied. It was demonstrated that working in normal conditions, i.e. solution pH and room temperature (25 °C), removal percentage higher than 90% for single and binary-systems and higher than 75% for ternary-systems was obtained. Adsorption kinetic results showed that pseudo-second-order model describe the experimental data/adsorption process in single and multiple-solute systems. From the Sips isotherm model the maximum adsorption capacities in single systems were determined. The advantage of obtaining low-cost Fe₃O₄/Ag/C nanocomposite with good adsorption capacity and easy magnetic separation, effective in single and multi-component adsorption of both cationic and anionic dyes, represent a strong argument regarding its great potential for practical applications.