Synthesis and characterization of iron oxide-coated silica and its effect on met

2019-09-21 07:06:45

silica coating Iron coated oxide

责任者: Xu, Ying;Axe, Lisa 单位: 来源出处: Journal of Colloid and Interface Science,2005,282(1):11-19 摘要: To accurately model metal mobility and bioavailability in soils and sediments, systematic adsorption studies are needed in considering heterogeneous, well characterized minerals. Two important surfaces are iron oxide and silica, which are ubiquitous and associated with one another in the environment playing important roles in metal distribution. This study focuses on the synthesis and characterization of such a system, iron oxide-coated silica. A three-level fractional factorial study was used to determine the optimum conditions for producing goethite-coated silica. The amount of coating achieved was between 0.59 and 21.36 mg Fe g-1 solid. The most significant factor in coating using either adsorption or precipitation was the particle size of silica, where Fe increased from an average of 0.85 to 9.6 mg Fe g -1 solid as silica size decreased from 1.5 to 0.2 mm. Other factors investigated, including coating temperature, initial iron concentration, and contact time, were of less importance. The iron oxide coatings were observed to be non-uniform, concentrated in rough concave areas. FTIR revealed a band shift as well as a new band indicating changes in the chemical environment of FeO and SiO bonds; these results along with abrasion studies suggest that the interaction between the oxide coating and silica surface potentially involves chemical forces. Because the nano-sized iron oxide coatings increased surface area, introduced small pores, and changed the surface charge distribution of silica, the coated system demonstrates a greater affinity for Ni compared to that of uncoated silica. © 2004 Elsevier Inc. All rights reserved. 关键词: Silica;Adsorption;Iron oxides;Soils;Sediments;Synthesis (chemical);Nanostructured materials;Particle size analysis;Precipitation (chemical);Fourier transform infrared spectroscopy;Metal mobility;Bioavailability;Surface charge distribution