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In order to control the particle size and morphology, zinc carbonate hydroxide Zn 5 (CO 3 ) 2 (OH) 6 nanoparticles have been synthesized using a reverse microemulsion technique. The pseudo-ternary phase diagrams of the two microemulsion systems, prepared using CTAB/1-butanol/n-octane/aqueous phase system with the aqueous phase comprised of either zinc nitrate (Zn(NO 3 ) 2 ) or sodium carbonate (Na 2 CO 3 ), were experimentally constructed. The nanoparticles synthesized by mixing of the two emulsion systems were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The nanoparticles were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Several important experimental parameters have been investigated for the ability to control particle size and morphology as the function of water/surfactant molar ratio (ω), water/oil molar ratio ( S ) and the initial concentration of reactants in the aqueous phase. Results indicate that ω values have the ability to affect the particle size and levels of aggregation, while S values had no apparent effect. In addition, the initial concentration of reactants in the aqueous phase was considered to be an important parameter as raising its values from 0.1 M to 0.5 M produced an unknown phase of zinc carbonate, exhibiting larger particle size with a unique flake like morphology. [ABSTRACT FROM AUTHOR]

Zinc carbonate hydroxide Zn 5 (CO 3 ) 2 (OH) 6 nanoparticles have been successfully synthesised by the hydrothermal treatment of an aqueous solution of zinc acetate dihydrate (Zn(CH 3 COO) 2 ·2H 2 O) and urea (NH 2 CONH 2 ) at 120 °C. The as-synthesized nanoparticles were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). XRD and SEM revealed Zn 5 (CO 3 ) 2 (OH) 6 nanoparticles produced in 20-40 nm size range with spherical morphology. TGA showed the expected one-step decomposition of zinc carbonate hydroxide to zinc oxide (ZnO) between temperatures of 180 °C and 350 °C. The hydrothermal reaction time (2, 3 and 4 hours) studied did not show any significant effect on the particle size and morphology. However, the crystallinity of the synthesised nanoparticles seems to be enhanced at longer hydrothermal reaction time by showing larger XRD diffraction peaks. [ABSTRACT FROM AUTHOR]

A novel magnetic SO 4 /Fe-Al-TiO 2 solid acid catalyst was synthesized for biodiesel production via the (trans)esterification of waste cooking oil (WCO). The nanocomposite catalyst was prepared by the sequential functionalisation of commercial rutile/anatase mixed phase TiO 2 nanoparticles (NPs) with alumina as a buffer layer, and subsequently hematite to impart magnetic character, prior to sulfation with chlorosulfonic acid to introduce Brønsted acidity. XRD showed that the SO 4 /Fe-Al-TiO 2 catalyst comprised titania (rutile and anatase phases), aluminium sulphate, and hematite nanoparticles, while electron microscopy revealed the layer-by-layer assembly of these components within the SO 4 /Fe-Al-TiO 2 catalyst. FTIR confirmed the presence of surface sulphate groups SO 4 2− and S 2 O 7 2− /S 3 O 10 2− , creating a predominantly Brønsted acid catalyst with high acid loading. The catalyst achieved 96% fatty acid methyl ester (FAME) yield from WCO after 2.5 h of reaction at 90 °C, using 3 wt% of the magnetic catalyst, and a methanol:oil molar ratio of 10:1. SO 4 /Fe-Al-TiO 2 was also effective for feedstocks containing up to 20 wt% of free fatty acid (FFA), and showed excellent stability for WCO (trans)esterification over 10 recycles. [ABSTRACT FROM AUTHOR]