The sol-gel synthesis and characterization of mullite precursor derived from rice husk silica and aluminum nitrate hydrate [(Al(NO 3 ) 3 .9H 2 O] has been investigated. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) coupled with Rietveld analysis, and scanning electron microscopy (SEM). FTIR results showed the presence of Si-O-Si, Al-O-Al, and Si-O-Al functional groups, which were associated with mullite, corundum, quartz, and cristobalite, as verified by XRD analysis. It is concluded that mullite formation started at 1150 o C, and its abundance increased rapidly with an increase in temperature from 1150-1350 o C, resulting in increased phase content from 30.9 to 67.7 wt%. Although mullite was formed at a low temperature, the complete reaction between corundum and silica to form mullite was not achieved.This finding demonstrated that rice husk silica is a potential alternative raw material for the production of mullite ceramic.
A series of titania thin films was prepared by chemical bath deposition (CBD) of TiCl 3 on indium tin oxside (ITO) glass at room temperature, followed by calcinations at 500°C for 4 hours. The effect of cyclic deposition on phase composition, microstructure and electrical resistivity of TiO 2 thin films was characterised using X-ray diffraction, scanning electron microscopy and four-point probe respectively. Results showed that TiO 2 films produced by single deposition cycle were amorphous. In contrast, those produced by 5 and 6 deposition cycles were partly amorphous and partly crystalline with the formation of rutile. Both the film thickness and electrical resistivity increased with an increase in the number of deposition cycles.
This study investigated the use of electrochemical method to prepare aluminosilicates from rice husk silica and aluminum metal. The aluminosilicate precursors were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy. The precursors were subsequently sintered at 700-1400 °C and their microstructures and phase compositions were characterized. Results showed that the proposed method could be used to prepare aluminosilicates with high uniformity in terms of surface morphology and the particle size with mullite and quartz as the major phases formed.
Cellulose Crystalline Cladophora sp. (CCC) was successfully isolated from the freshwater algae Cladophora sp. by used the hydrolysis method. The alkaline treatment can affect the structure of CCC that is showed by the spectrum of Fourier Transform Infrared (FTIR). The typical range for lignin does not appear here, which indicates the delignification process using NaOH plus hydrolysis of HCl has succeeded in removing lignin. The spectrum associated with functional group impurity (1800-1050 cm−1) with lipid, protein, and nucleid acid content are still seen after alkaline treatment and acid hydrolysis. Analysis of crystallinity with X-ray Diffraction (XRD) data showed that CCC had the highest crystallinity index on CD-K (93.4%), Cd-P (66.6%), and Cd-S (63.04%). The smallest particle size for each cellulose is Cd-K (9.5 nm), Cd-S (25.23 nm), and Cd-P (49.57 nm). Based on these results, the CCC production from Cladophora sp. using alkaline and acid hydrolysis treatment is enough to get samples with high crystallinity. The CCC product has the potential to be an excellent reinforcing material for biomaterial-based polymer materials.
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