The present research consists of two parts. In the first part, a new magnetic material of nickel ferrit coated with acrylonitrile butadiene styrene (ABS) polymer and silver nanoparticles or titanium dioxid-silver (Ag/TiO2) nanoparticles, antibacterial magnetic nanocomposite has been made and in particular these nanocomposites have been aimed at studing the antibacterial properties of them against four of different bacteria and the comparison of antibacterial properties between Ag and Ag/TiO2. The most antibacterial property of nanocomposite is NiFe2O4@ABS@Ag-TiO2, due to the presence TiO2 in the nanocomposite. TiO2 increases the antibacterial properties of silver nanoparticles. In the second part of this study, the development of new magnetic nanocomposite magnetite with non-magnetic coatings 3-mercoptopropyltrimethoxysilan (MPTMS) and gold nanoparticles was studied and the effect of removing water pollutants in the textile industry was investigated. This new magnetic nanocomposite Fe3O4@ MPTMS @Au with structure core-shell-shell was synthesized by sol-gel method. The new nanocomposite was studied for its efficiency in adsorption of methylene blue (MB) as a model of paints which has been widely used in aquatic solutions of textile industry. The adsorption test was carried out at various laboratory condition such as temperature, starring speed and contact time of adsorbent and dye, The results indicates that the adsorption capacity of MB dye rises by the increase in the temperature, stirring speed and the contact time between MB and adsorbent. The Fe3O4@ MPTMS @Au nanocomposite removes about 80% of paint from the solution in 20 minute contact time and removes about 100% of dye from the solution at temperature of 60 °C which dye has been removed completely. This nanocomposite easily separated from the solution with help of week magnetic field. Therefore this new adsorbent could be regarded as a very good adsorbent for methylene blue removal. The structure and properties of the nanocomposites were studied by using X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) techniques, antibacterial test and UV-Vis spectroscopy.