Magnetic nanocomposites have been well recognized as promising candidates for enzyme immobilization, DNA extraction, targeted drug delivery, and removal of various metal ions. In this paper, dedoped Fe3O4/PPy nanocomposite has been obtained by simple ammonia-washing of the newly-formed Fe3O4 nanoferrofluid/PPy derived from in situ polymerization approach. The magnetic nanocomposite is characterized with XRD, FT-IR, TEM, BET, zeta potential, and magnetomety techniques, and further tested in the role of separating Ag(I) from mixed metal-ion solutions containing Ag(I), Mg(II), Cu(II), Zn(II), As(III), and Pb(II). The adsorption of Ag(I) upon dedoped Fe3O4/PPy is an endothermic and spontaneous chemisorption process, ensuring rapid separation of Ag(I) from aqueous solution. The maximum adsorption capacity of Ag(I) upon dedoped Fe3O4/PPy is 143.3 mg g(-1). The total adsorption process preferably follows the Langmuir model and the pseudo-second order kinetics. Mg(II), Cu(II), Zn(II), and As(III) have minor effects whereas Pb(II) has a relatively remarkable effect on selective separation of Ag(I) from solutions. The magnetic nanocomposite is featured with superparamagnetism, a multicore-shell structure, a soft-base surface, excellent reusability, and a high anti-interfering ability for selective separation of Ag(I) from multiionic solutions, presenting a promising candidate for practical application in selective separation of Ag(I) from silver-containing emissions. (C) 2015 Elsevier B.V. All rights reserved.