Two　types　of　magnetic　nanoparticles　prepared　with　chemical　agents　(cMNP)　and　iron-containing　sludge　(iMNP),　respectively,　were　synthesized　by　co-precipitation　process　and　used　to　remove　arsenate　[As(V)]　from　water.　The　synthesized　magnetic　adsorbents　were　characterized　by　XRD,　XPS,　TEM,　BET,　VSM　and　FTIR.　The　adsorbents　iMNP　and　cMNP　were　both　mainly　gamma-Fe2O3　in　nanoscale　particles　with　the　saturation　magnetization　of　35.5　and　69.0emu/g　respectively　and　could　be　easily　separated　from　water　with　a　simple　hand-held　magnet　in　2minutes.　At　pH　6.6,　over　90%　of　As(V),　about　400　mu　g/L,　could　be　removed　by　both　adsorbents　(0.2g/L)　within　60min.　The　adsorption　isotherm　of　both　fabricated　materials　could　be　better　described　by　the　Langmuir　adsorption　isotherm　model　than　the　Freundlich＇s,　In　addition,　the　adsorption　kinetics　of　both　adsorbents　described　well　by　the　pseudo-second　order　model　revealed　that　the　intraparticle　diffusion　was　not　just　the　only　rate　controlling　step　in　adsorption　process.　With　the　larger　maximum　As(V)　adsorption　capacity　of　iMNP　(12.74mg/g),　compared　with　that　of　cMNP　(11.76mg/g),　the　iMNP　could　be　regarded　as　an　environmentally　friendly　substitute　for　the　traditional　magnetic　nanoparticles　prepared　with　chemical　agents.