On cobalt ferrite production by sol-gel from orange fruit residue by three related procedures and its application in oil removal

Magnetic separation of oil from water by cobalt ferrite (CoFe2O4) was studied. Ferrite was produced using orange albedo and pectin extraction (PI) and commercial residue bagasse (PII – with pectin extraction and PIII - raw), as an organic ligand. X-ray diffraction and 57Fe Mossbauer data suggest that the three procedures resulted in samples with approximately 90% of CoFe2O4. PII samples show the smallest particle (and grain) sizes, as estimated from Scanning Electron Microscopy (and X-ray diffraction) experiments, and the higher concentration of defective or distorted structures, as deduced from FTIR, 57Fe Mossbauer and magnetic measurements. UV–Vis data indicate that the PII samples are more efficient in adsorbing lubricating oil in water emulsion. Adsorption of oil in emulsion that was not reported before in the literature for non-functionalized ferrites. The PII samples also adsorbed approximately 8 g.g−1 of pure lubricating oil. It was proven that residue from commercial orange juice production (used in PII and PIII) can successfully be used to prepare cobalt ferrite capable of removing oil from a synthetic effluent.