Removal of Cr(VI) from aqueous solutions by magnetite nanoparticles with different sizes and crystal structure

In this work a few nanopowders of magnetite (Fe3O4) produced by different methods were used as a sorbents. Three techniques were applied to make the nanopowders: (1) gas-phase synthesis, (2) chemical precipitation from water solution, and (3) laser atomization. Using these methods, the particles with different sizes and crystal structure have been produced. The effects of the particles size and structure of nanopowders on the removal of toxic Cr(VI) from an aqueous solution imitating ground waters and wastewaters with pH = 7.4–7.8 were studied at different solution temperatures. It is shown that magnetite is effective sorbent for the removal of Cr(VI) from polluted natural waters and sewage. It is found that sorption of Cr(VI) by magnetite is irreversible and has chemisorption character, and even small rise in temperature of the solution during the sorption process sharply increases efficiency of the sorption.