Magnetic paper sheets were prepared from bleached sugarcane bagasse fibers and cobalt ferrite nanoparticles by lumen loading method. Sugarcane bagasse is an important fibrous raw material widely used worldwide for papermaking, whereas cobalt ferrite nanoparticles is an appropriate material for fibers modification given their magnetic properties. Cobalt ferrite nanoparticles were synthetized by coprecipitation method and coated with silica by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) molecules. Then, silica coated magnetic nanoparticles were functionalized with polyethylenimine (PEI), as retention aid, by electrostatic bonding. It was observed that the loading degree of magnetic fibers depends on nanoparticles concentration and PEI dosage, which was determined by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) shows the deposition of coated nanoparticles on the surface and into macropores of fibers. All samples exhibited ferromagnetic behavior. The coercivity values of magnetic fibers are higher than 0.2 kOe. This indicates that these fibers could be used to produce paper for magnetic recording purposes. Magnetic papers with 10 and 20% of modified fibers were manufactured. Brightness and tensile index of papers were decreased with the rise of loading degree. CIEL*a*b analysis shows the color differences between unmodified and modified papers.
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