As magnetic fillers, e.g., nanomagnetite, reduce the mechanical strength of produced magnetic papers, additives should be used. In this study, nanomagnetic papers were produced through an in-situ method by synthesizing magnetic cellulose fibers with kraft fibers and iron salts in a nitrogen atmosphere. Then, gluconic acid was added to improve the mechanical strength. The properties of nanomagnetic papers were investigated via different methods. The nanomagnetite particle size ranged from 1 to 84 nm. Scanning electron microscopy demonstrated the deposited nanomagnetite particles on the surface of the fibers. The saturation magnetization of the nanomagnetic papers treated with 0%, 1%, 2%, or 3% gluconic acid (per dry weight of the pulp) was 7.54, 5.64, 4.81, and 0.55 emu/g, respectively. The nanomagnetite particles loaded on the fibers decreased as the gluconic acid content was increased. The nanomagnetic papers exhibited superparamagnetic behavior. Elevation of the gluconic acid content caused an increased tensile and burst index, as well as a reduced tear index. It also led to augmented brightness and diminished opacity.

Effects of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidation were evaluated for magnetic bio-nanocomposites of nanocrystalline cellulose (NCC). The magnetic bio-nanocomposites were prepared using NCC and nanomagnetite (NM) to produce organic compounds. The NCC was oxidized by sodium bromide (NaBr), sodium hypochlorite (NaOCl), and TEMPO. The oxidized NCC (ONCC) was characterized by Fourier-transform infrared spectroscopy (FTIR) and conductometry. The bio-nanocomposite particles from the NCC and the ONCC were prepared via in situ precipitation of iron salts from alkaline solution. The resultant bio-nanocomposites were coated on the surface of kraft paper. The magnetic bio-nanocomposite and coated papers were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results revealed that the carboxyl groups were introduced successfully on the NCC surface. The bio-nanocomposite particles showed good dispersion in the surface of the papers. The saturation magnetizations of the coated papers with magnetic bio-nanocomposites of NCC and ONCC were 10.9 and 14.57 emu/g, respectively. The magnetic coated papers exhibited a superparamagnetic behavior. The strengths, apparent density, and air resistance of the coated paper with the ONCC bio-nanocomposites increased in comparison to the NCC coated sample, while the water absorption diminished due to the TEMPO-oxidation.