One-step and acid free synthesis of γ-Fe2O3/SBA-15 for enhanced arsenic removal

A novel, one-step synthesis strategy is proposed to fabricate γ-Fe2O3/SBA-15 nanocomposite using triblock copolymer pluronic P123 as a structure directing agent without adding acids. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses suggested that iron was mainly present as γ-Fe2O3 in the composite. Transmission electron microscopy (TEM) measurement showed that this material had highly ordered hexagonal array of uniformed channels and N2 adsorption-desorption isotherms revealed that the surface area of this material was 983–1049 m2/g. Vibrating sample magnetometer (VSM) measurements explained that these materials possess magnetic properties (6.23 emu/g). Batch adsorption experiments showed that low pH was beneficial for arsenic removal by γ-Fe2O3/SBA-15. The presence of NO3− and SO42- had no influence on the uptake of arsenic, however the existence of H2PO4− and SiO32- showed negative effects on arsenic removal. After five adsorption–desorption cycles, the removal rate of arsenic maintained at larger than 70.5%. The arsenic adsorption was well fitted by a pseudo second-order kinetic model. The isotherm data agrees well with the Langmuir model better than the Freundlich model. This study suggests that γ-Fe2O3/SBA-15 is promising adsorbent for efficient removal of arsenic from groundwater.