Water-Dispersible Magnetic Particle-Graphene Oxide Composites: Synthesis, Characterization and Application in the Removal of Selenium Oxyanions

Selenium is toxic in excess with a high mobility in water. Existing adsorbents only show some removal capacity for selenite but perform poorly (typical removal percentage < 50 %) for selenate, the more bioavailable and soluble species. In this thesis, two Magnetic particle-Graphene Oxide composites (MGOs) were synthesized, characterized and applied to selenium removal from simulated water, with an significant removal percentage of > 99.9 % for selenite and 80 -- 95 % for selenate at pH ~ 6 within 10 seconds. Acidic pH and low temperature could enhance the selenium adsorption on MGOs. It is proposed that the selenium adsorption on MGOs involves the formation of inner-sphere and outer-sphere complexes. MGOs can be separated effectively under an external magnetic field and recycle. Our results show that MGOs composites have excellent removal capability of selenite and selenate from simulated water and can be applied for the removal of selenium from wastewater.