“…In addition, magnetite (Fe 3 O 4 ) and maghemite (γ-Fe 2 O 3 ) nanoparticles provide the opportunity for their recovery and handling in water systems due to their magnetic response. 147 Functionalized Fe 3 O 4 nanoparticles by amines, 148,149,150 cyclodextrin, 151 polymers 152 and polyacrylic acid 153 were used for the adsorption of Cu 2+ , Cd 2+ , Pb 2+ , Ni 2+ , Cr(VI) whereas combination with polypyrrole, 154 silica 155,156 or humic acid 157 were investigated for the uptake of Cr(VI), U(VI), Hg 2+ , Pb 2+ , Cd 2+ , Cu 2+ . The efficiency of oleic acid-coated Fe 3 O 4 nanoparticles for the uptake of As(III) and As(V) was examined for various sizes in the range 12-300 nm.…”