Papers by Keyword: Hydrothermal Conversion

Abstract: Fluoro/hydroxyapatite (FHAp) were prepared by hydrothermal at 150 °C for 24 hours with different of starting materials. The conversion of hydroxyapatite (HAp) and tricalcium phosphate to FHAp showed the rod-like shape with 200 nm. While, the morphology of FHAp from crocodile eggshell as CaCO₃ form with different in phosphorus and fluoride source showed the unique structure evolution from rod-like hexagonal crystals, dumbbell to ball shape. Two distinctive morphology, first when using NaF as fluoride source with (NH₄)₂HPO₄ precursor show the large cubic structure in high magnification it is tufted hexagonal crystal and it bundle like structure. As the pH value decreases in NH₄F, it increases crystal size. For H₃PO₄ as phosphate precursor found that unique structure evolution from rod-like hexagonal crystals to dumbbell structure and then form the sphere assembly with a size of several micrometers.

Abstract: Calcium phosphate materials can be produced using a number of wet methods that are based on hydrothermal or co-precipitation methods that might use acidic or basic chemical environments. In our previously published works, we have investigated calcium phosphates such as monetite, hydroxyapatite, and whitlockite which were successfully produced by mechano-chemical methods and/or hydrothermal treatments from a range of marine shells and corals which were obtained from the Great Barrier Reef. The aim of the current work was to analyze and compare the mechanisms of conversion of one hard coral species and one calcified algae species from the Great Barrier Reef.

Abstract: Possible catalytic activity of different metals in hydrothermal reduction of CO₂ into formic acid with Zn was investigated under low temperatures. Among the several catalysts (Cu, Fe and Sn) were used, Cu shows the best catalytic activity for the formic acid production. The formic acid yield is as high as 61% under hydrothermal condition. XRD analysis was also carried out to investigate the possible role of reactants.

Abstract: A new and green technology for converting microalgae to high value-added chemicals with solid metal oxides catalysts under hydrothermal conditions was proposed. The results indicated that ZrO₂, among other test catalysts, can prominently boost the production of acetic acid and a highest yield of 24% was achieved at 300 °C for 2 h with a filling rate of 50%. The metal oxides catalyst provided a promising solution to obtain acetic acid from microalgae conversion.