Fe3O4@HA@Ag magnetic nanocomposites (MNCs) were successfully synthesized by the simple reflux method for the removal of azo dyes from the industrial aqueous media. Fe3O4@HA@AgMNCs exhibited high catalytic activity to reduce MB within 20 min from the waste water. The obtained materials were characterized by the means of different techniques. Powder X-ray diffraction(XRD) analysis confirmed the single-phase of Fe3O4 spinel structure. SEM and TEM analysis indicated that Fe3O4@HA@AgMNCs were nanoparticles like structure with small agglomeration. TG result showed that the products contained 9% of HA. The characteristic peaks of HA at 1601 cm(1) and 1703 cm(1) was observed by the means of FT-IR spectra of Fe3O4@HA@AgMNCs. The hysteresis(sigma-H) curves revealed Fe3O4@HA@AgMNCs exhibit a typical superparamagnetic characteristic with a saturation magnetization of 59.11 emu/g and measured magnetic moment is 2.45 mu(B). The average magnetic particle dimension(D-mag) is 13.25 nm. In accordance, the average crystallite and particle dimensions were obtained as 11.50 nm and 13.10 nm from XRD and TEM measurements, respectively. Magnetocrystalline anisotropy was offered as uniaxial and calculated effective anisotropy constant(K-eff) is 2.96 x 10(5) Erg/g. The blocking temperature was estimated as 522K. The size-dependent saturation magnetization suggests the existence of a magnetically dead layer as 0.793 nm for Fe3O4@HA@AgMNCs. The UV-vis diffuse reflectance spectroscopy (DRS) and Kubelka-Munk theory were applied to determine the optical properties of powder samples. The direct optical energy band gap(E-g) values were estimated from Tauc plots between 1.62 eV and 2.12 eV. (c) 2016 Elsevier B.V. All rights reserved.