Preparation And Performance Of Iron Oxides For Arsenic Removal

In recent decades,arsenic pollution in water has attracted growing attention around the world.Arsenic pollution has been reported in many countries and areas,such as China,Mexico,the Southeast Asia,Argentina.To date,many methods are used to remove arsenic pollutants from water,including the membrane separation,the chemical precipitation,the ion-exchange,the adsorption and so on.Among all these methods,the adsorption is a cost-effective,environmentally-friendly and convenient treatment method for arsenic removal.Iron oxides adsorbent have been widely studied due to the advantages of wide distribution,low cost and the high adsorption capacity to arsenic.In this thesis,we devote ourself to develop the novel iron oxides adsorbent for arsenic removal.Zwitterionic dopamine sulfonate(ZDS)modified Fe3O4(ZDS-Fe3O4)adsorbent and ?-Fe2O3 nanosheets adsorbent were prepared successfully and used to remove arsenic pollutants in water.(1)Zwitterionic dopamine sulfonate(ZDS)modified Fe3O4(ZDS-Fe3O4)nanoparticles were prepared successfully.Fe3O4 can adsorb arsenic species based on the surface complex interaction.Nevertheless,the aggregation of Fe3O4 nanoparticles would lead to the decrease of adsorption sites.ZDS modification strategy was helpful to improve the dispersibility and stability of Fe3O4 adsorbent.Because ZDS can prevent the aggregation of nanoparticles through the strong ionic interactions of quaternary ammonium group and sulfonate group with water molecules.The result of arsenic removal performance demonstrated that ZDS-Fe3O4 adsorbent showed improved adsorption capacity to arsenic compared with Fe3O4 adsorbent without modification.The removal efficiency showed an increase of 15.25%and 24.48%for As(?)and As(?)respectively.(2)?-Fe2O3 nanosheets were prepared successfully by the method of silicate assisted hydrothermal synthesis.The surface hydroxy group configuration of each plane for ?-Fe2O3are different.The surface hydroxy group of(001)plane is doubly coordinated.Whereas other planes,such as(100),(110)and(012)planes,are single coordinated surface hydroxy group.The adsorption capacity and affinity of silicate on(001)plane of ?-Fe2O3 was much higher than that on other planes.The growth behaviour of(001)plane was blocked by the large amount of adsorbed silicate.Therefore,?-Fe2O3 nanosheets were obtained.The result of arsenic removal performance showed that the maximum adsorption capacity to As(?)of ?-Fe2O3 nanosheets was 0.33 mg g-1,which was three times than that of commercial activated carbon adsorbent.