AFM and SEM characterization of iron oxide coated ceramic membranes |
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Authors: | B S Karnik M J Baumann S J Masten S H Davies |
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Affiliation: | (1) Department of Civil & Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA;(2) Department of Chemical Engineering & Materials Science, Michigan State University, East Lansing, MI 48824, USA |
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Abstract: | Alumina–zirconia–titania (AZT) ceramic membranes coated with iron oxide nanoparticles have been shown to improve water quality
by significantly reducing the concentration of disinfection by-product precursors, and in the case of membrane filtration
combined with ozonation, to reduce ozonation by-products such as aldehydes, ketones and ketoacids. Commercially available
ceramic membranes with a nominal molecular weight cut-off of 5 kilodaltons (kD) were coated 20, 30, 40 or 45 times with sol
suspension processed Fe2O3 nanoparticles having an average diameter of 4–6 nm. These coated membranes were sintered in air at 900 °C for 30 min. The
effects of sintering and coating layer thickness on the microstructure of the ceramic membranes were characterized using atomic
force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). AFM images show
a decreasing roughness after iron oxide coating with an average surface roughness of ∼161 nm for the uncoated and ∼130 nm
for the coated membranes. SEM showed that as the coating thickness increased, the microstructure of the coating changed from
a fine grained (average grain size of ∼27 nm) morphology at 20 coating layers to a coarse grained (average grain size of ∼66 nm)
morphology at 40 coating layers with a corresponding increase in the average pore size from ∼57 nm to ∼120 nm. Optimum water
quality was achieved at 40 layers, which corresponds to a surface coating morphology consisting of a uniform, coarse-grained
structure with open, nano-sized interconnected pores. |
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