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

Abstract A novel, one-step synthesis strategy is proposed to fabricate γ-Fe 2 O 3 /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-Fe 2 O 3 in the composite. Transmission electron microscopy (TEM) measurement showed that this material had highly ordered hexagonal array of uniformed channels and N 2 adsorption-desorption isotherms revealed that the surface area of this material was 983–1049 m 2 /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-Fe 2 O 3 /SBA-15. The presence of NO 3 − and SO 4 2- had no influence on the uptake of arsenic, however the existence of H 2 PO 4 − and SiO 3 2- 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-Fe 2 O 3 /SBA-15 is promising adsorbent for efficient removal of arsenic from groundwater.