The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite pa...The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite particles (KP) produced from coconut shells and kyanite mineral respectively were characterized. X-ray Florence (XRF), X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze the oxide compositions, crystalline phases and microstructures of CSA and KP. The XRF analysis revealed major oxides in CSA and KP as SiO2 and Fe2O3;and Al2O3 and SiO2 respectively. The XRD analysis revealed the presence of Quartz, Hematite, Andradite and Gaultite phases at major peaks in diffractogram of CSA;and Quartz and Beryl phases at major peaks in the diffractogram of KP. The crystallite sizes of the quartz phases in CSA and KP at diffraction angle of 26.72°C and 20.91°C were determined as 638.28 Åand 789.38 Årespectively. From the SEM image of CSA, it was observed that particles of different sizes are present in the microstructure of CSA. The average size of the particles in the microstructure of CSA is 26.24 μm. A similar result was observed in the SEM image of KP and average size of the particles is 3.074 μm. Also, the energy dispersive X-ray (EDX) spectrums of CSA and KP revealed the presence of many elements with calcium as the major element in CSA and Aluminium as major element in KP. The presence of the crystalline phases in CSA (SiO2, Al2O3, andradite, gaultite and hematite) and KP (SiO2 and Al2O3) will make them good strengthening materials for the production of Aluminium based composites that can be used in applications where a good combination of strength and wear characteristics is a basic requirement like brake disc.展开更多
The pyrolysis of coconut shell, coconut shell residue and de-ashed coconut shell residue was studied with the thermogravimetric technique, and the pyrolysis kinetics models were established.It was found that for cocon...The pyrolysis of coconut shell, coconut shell residue and de-ashed coconut shell residue was studied with the thermogravimetric technique, and the pyrolysis kinetics models were established.It was found that for coconut shell residue and de-ashed coconut shell residue, pyrolysis mainly occurred between 280—370℃, and there was only a single peak in their DTG curves.But in the case of raw coconut shell, two stages of 230—300℃ and 300—350℃, were involved in the pyrolysis process, which resulted in two peaks in the DTG curve.Apparent activation energies for the pyrolysis of these three materials were estimated, and the difference of apparent activation energies in the low temperature range was more evident than in the high temperature range and the highest reaction rate appeared in the high temperature stage.When used for making activated carbon, coconut shell residue and de-ashed coconut shell residue have more advantages than coconut shell.The pyrolysis temperature is in a narrow range.The pyrolysis process is easy to control and is noted for energy saving.展开更多
文摘The use of waste materials to produce engineering components is currently attracting so much interest due to their low cost, availability and environmental impact. In this study, coconut shell ash (CSA) and kyanite particles (KP) produced from coconut shells and kyanite mineral respectively were characterized. X-ray Florence (XRF), X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze the oxide compositions, crystalline phases and microstructures of CSA and KP. The XRF analysis revealed major oxides in CSA and KP as SiO2 and Fe2O3;and Al2O3 and SiO2 respectively. The XRD analysis revealed the presence of Quartz, Hematite, Andradite and Gaultite phases at major peaks in diffractogram of CSA;and Quartz and Beryl phases at major peaks in the diffractogram of KP. The crystallite sizes of the quartz phases in CSA and KP at diffraction angle of 26.72°C and 20.91°C were determined as 638.28 Åand 789.38 Årespectively. From the SEM image of CSA, it was observed that particles of different sizes are present in the microstructure of CSA. The average size of the particles in the microstructure of CSA is 26.24 μm. A similar result was observed in the SEM image of KP and average size of the particles is 3.074 μm. Also, the energy dispersive X-ray (EDX) spectrums of CSA and KP revealed the presence of many elements with calcium as the major element in CSA and Aluminium as major element in KP. The presence of the crystalline phases in CSA (SiO2, Al2O3, andradite, gaultite and hematite) and KP (SiO2 and Al2O3) will make them good strengthening materials for the production of Aluminium based composites that can be used in applications where a good combination of strength and wear characteristics is a basic requirement like brake disc.
文摘The pyrolysis of coconut shell, coconut shell residue and de-ashed coconut shell residue was studied with the thermogravimetric technique, and the pyrolysis kinetics models were established.It was found that for coconut shell residue and de-ashed coconut shell residue, pyrolysis mainly occurred between 280—370℃, and there was only a single peak in their DTG curves.But in the case of raw coconut shell, two stages of 230—300℃ and 300—350℃, were involved in the pyrolysis process, which resulted in two peaks in the DTG curve.Apparent activation energies for the pyrolysis of these three materials were estimated, and the difference of apparent activation energies in the low temperature range was more evident than in the high temperature range and the highest reaction rate appeared in the high temperature stage.When used for making activated carbon, coconut shell residue and de-ashed coconut shell residue have more advantages than coconut shell.The pyrolysis temperature is in a narrow range.The pyrolysis process is easy to control and is noted for energy saving.
