Synthesis Of Magnetic Sulfur-doped Fe₃O₄ Nanoparticles And The Mechanisms For Efficient Removal Of Arsenic

As a common metalloid element,Arsenic（As）is widely found in nature and human activities.Arsenic pollution is mainly caused by natural effects such as weathering,dissolution,erosion and human activities such as mining,chemical production,agriculture,etc.Arsenic contamination in water not only seriously threatens human health,but also influences the development of ecosystem.Drinking or long-term exposure to arsenic-contaminated water can cause a range of serious diseases such as liver cancer,lung cancer and skin cancer.Even low level of arsenic can also cause pathological changes in people.Therefore,the treatment of arsenic-contaminated water has become a global issue attracting great concern.Removal of arsenic from water is significant for protecting human health and the environment.In this paper,a novel magnetic sulfur-doped Fe₃O₄ nanoparticles（Fe₃O₄:S）was used to remove As（Ⅴ）and As（Ⅲ）from water and compared with undoped adsorbent（Fe₃O₄）.The results showed that the magnetic sulfur-doped Fe₃O₄ nanoparticles（Fe₃O₄:S）exhibited different adsorption capacities for As（Ⅴ）and As（Ⅲ）in water.For As（Ⅴ）,Fe₃O₄:S nanoparticles could efficiently remove As（Ⅴ）in water,and the adsorption performance was improved to a large extent than undoped Fe₃O₄.For As（Ⅲ）,the adsorption performance of Fe₃O₄:S nanoparticles was slightly lower than that of Fe₃O₄.In addition,Fe₃O₄:S could be separated efficiently from aqueous solution after adsorption with an external magnetic field,which would be favorable for its application.In order to study the adsorption mechanisms of adsorbents,X-ray diffraction（XRD）,energy dispersive X-ray fluorescence（ED-XRF）,transmission electron microscope（TEM）,Fourier transform infrared（FTIR）,X-ray photoelectron spectroscopy（XPS）,and vibrating sample magnetometer（ⅤSM）were used to detect and investigate the structures,morphologies and surface chemical states of the prepared adsorbents before and after adsorption.The analysis showed that the Fe-OH groups played a significant role in the adsorption of As（Ⅴ）and As（Ⅲ）.The removal of As（Ⅲ）by Fe₃O₄:S nanoparticles involved the adsorption process and the oxidation of As（Ⅲ）to As（Ⅴ）.Finally,the nanoparticles prepared in this paper were applied to the actual smelting wastewater,and the adsorption performance of magnetic sulfur-doped Fe₃O₄ nanoparticles（Fe₃O₄:S）on the actual arsenic-containing industrial wastewater was investigated.This provided a certain theoretical and technical basis to the development and application of Fe₃O₄:S.