TY - JOUR
T1 - Synthesis and characterization of iron oxide-coated silica and its effect on metal adsorption
AU - Xu, Ying
AU - Axe, Lisa
N1 - Funding Information: This material is based upon work supported by the National Science Foundation under Grant BES 0089903 and the DuPont Young Professor's Grant. The authors thank James A. Dyer and Noel C. Scrivner of DuPont Engineering Technology for their input and support. We are also grateful to two anonymous reviewers for their helpful comments.
PY - 2005/2/1
Y1 - 2005/2/1
N2 - 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.
AB - 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.
KW - Adsorption
KW - Coating synthesis and characterization
KW - Iron oxide-coated sand
KW - Nickel
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U2 - 10.1016/j.jcis.2004.08.057
DO - 10.1016/j.jcis.2004.08.057
M3 - Article
C2 - 15576075
SN - 0021-9797
VL - 282
SP - 11
EP - 19
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 1
ER -