Preparation And Performance Of Iron Oxide Spheres/Polyethersulfone Ultrafiltration-Adsorption Dual-functional Membranes

Arsenic-containing wastewater has serious damage to human health.It is of great significance to study the efficient treatment technology of arsenic-containing wastewater.In this paper,we immobilized Fe3O4 microspheres in polyethersulfone(PES)ultrafiltration membrane by the traditional blending method and a new reverse-filtration membrane method to construct a dual-functional membrane with both ultrafiltration and adsorption properties.The main contents are as follows:1.Fe3O4 microspheres were synthesized by hydrothermal method,and characterized by field emission scanning electron microscopy,nitrogen adsorption specific surface area analyzer,atomic fluorescence spectroscopy,and so on.The results show that the Fe3O4 microspheres have a high BET specific surface area(31.9 m2/g),a size of about 250 nm and a tiny nanocrystal with 20 nm inside.Fe3O4 microspheres own excellent adsorption capacity(525.6mg/g),quick adsorption speed and almost no coexistence of ions.2.Through the traditional blending method,different amount of Fe3O4 microspheres were dosed during the preparation of UF membrane casting solution,and UF membrane was prepared by non-solvent phase inversion method.The thermogravimetric analysis,field emission scanning electron microscopy,ultrafiltration performance evaluation apparatus and atomic fluorescence spectrometry were used to analyze the ultrafiltration and adsorption properties of the blend membranes.Through the test of ultrafiltration performance,it was found that the addition of Fe3O4 microspheres will improve the hydrophilicity of casting solution,so the ultrafiltration membrane prepared by the blending method with the increase of blended Fe3O4 microspheres,pure water flux.The flux of M4 pure water with 0.3%Fe3O4 microspheres was the highest,reaching 302.52 L/m2/h.However,the rejection of bovine serum albumin(BSA)firstly increased and then decreased.When the 0.1%Fe3O4 microspheres were blended,the BSA retention reached 96.97%,and the pure water flux was 267.32 L/m2/h.Through the test of adsorption properties,it was found that with the increase of blended Fe3O4 microspheres,the adsorption of arsenic on the blend membrane gradually increased,and M4 had the strongest adsorption capacity for arsenic,reaching 2.51 mg/g.3.We developed a new adsorptive membrane by modifying the porous support layer of a phase inversion formed membrane for arsenic removal.Fe3O4 microspheres were immobilized in the support layer of the membrane by reverse filtration,followed by dopamine polymerization.The prepared adsorptive membrane was compared with a virgin membrane without Fe3O4 microspheres and a Fe3O4 blended membrane in terms of membrane structures and separation performance.The adsorptive membrane prepared by our new method had comparable water permeability and rejection performance with the virgin membrane without Fe3O4 microspheres,but higher rejection performance and dynamic adsorption capacity than the membrane prepared by the conventional blending method.Both static and dynamic adsorption modes were used to evaluate the adsorption performance of the membranes.Our new adsorptive membrane also had excellent regeneration performance.After three regeneration cycles,the membrane was still capable of treating more than 2 tons of As-contaminated water/m2.The adsorptive membrane of 1 m2 could treat over 7 tons of water to the drinking water standard in terms of arsenic concentration during three regeneration cycles.Therefore,our adsorptive membrane may pave a new way for arsenic removal from water and ensuring drinking water security.