Solid oxide fuel cell is one of the alternative energy sources with high efficiency and low emiss... more Solid oxide fuel cell is one of the alternative energy sources with high efficiency and low emissions. Solid oxide electrolyte is an important component of this fuel cell. A new electrolyte that suitable at medium temperature is needed to be developed. Apatite type lanthanum silicate is one of the electrolytes, which can operate at medium temperature. Increasing performance of apatite lanthanum silicate such as ionic conductivity can be achieved by doping. The purpose of the present study was to synthesize the electrolyte of Lanthanum silicates oxide with hydrothermal method and to investigate the effect of Ti 4+ dopant on apatite electrolyte characteristics such as crystal lattice parameter and conductivity. The results showed that samples of La 9.33 Si 6-x Ti x O 26 with x = 0.1, 0.2, 0.3 were successfully synthesized. The value of c on the crystal lattice parameter increases with increasing the doping content of Ti 4+. Increasing c value on the crystal lattice parameter is directly proportional to the conductivity. Apatite La 9.33 Si 5.7 Ti 0.3 O 26 showed the highest conductivity of 2.4 × 10-4 S/cm at 700°C.
Nowadays, many studies on separation of rare earth elements have been conducted due to its divers... more Nowadays, many studies on separation of rare earth elements have been conducted due to its diverse utilization. One of its applications in medical area is the utilization of gadolinium in the form of Gd-DTPA complex for contrast agent in magnetic resonance imaging (MRI). In the preparation of Gd-DTPA, there is a possibility of residual Gd 3+ which is toxic in nature and therefore requires separation process before it can be applied. The separation of Gd 3+ from Gd-DTPA complex can be performed by nanofiltration-complexation method. In the present study, Gd-DTPA complex was prepared by reacting Gd2O3 with DTPA ligand with reflux followed by separation of Gd 3+ from Gd-DTPA with nanofiltration membrane with varying pressure (5.8, 6.0, 6.2 and 6.4 bars) at 40°C followed by determination of flux and rejection coefficient of the membrane. The results of the present study indicate that flux of the permeate increased with increasing pressure up to 339.94 L.m-2. hour-1 while rejection decreased down to 9.02% at 6.4 bars. The concentration of Gd 3+ presence in the Gd-DTPA after the filtration process was 0.201 ppm.
Conductivities of Sn(IV) doped lanthanum silicates apatite as an electrolyte for intermediate tem... more Conductivities of Sn(IV) doped lanthanum silicates apatite as an electrolyte for intermediate temperature solid oxide fuel cells (ITSOFCs) have been examined. Dense ceramic pellet of La9.33Si6-xSnxO26 (x: 0.1; 0.3; 0.5) have been prepared by sintering at 1773K for 3 hours. The sample La9.33Si5.7Sn0.3O26 shows higher conductivities than comparable La9.33Si5.9Sn0.1O26 and La9.33Si5.5Sn0.5O26 samples indicating the importance of dopant concentration. Low activation energy of all samples (Ea < 1.1 eV) indicate that the Sn(IV) doped electrolytes are good conductors that can be used for ITSOFCs.
The crystalline structure of La9.33Si6O26 apatite-type lanthanum silicates was investigated by X-... more The crystalline structure of La9.33Si6O26 apatite-type lanthanum silicates was investigated by X-ray powder diffraction at room temperature. The hydrothermal synthesis condition was optimized to yield ultrafine and highly homogeneous La9.33Si6O26 powders. The results after rietica refinement indicate that optima crystal apatite structure was formed after being synthesized for six days at 503 K and was in agreement with the P63/m space group. The lattice parameter of the sample was in agreement with ICSD No 158963.
Reducing a high-operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature... more Reducing a high-operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature SOFC (IT-SOFC, 500-750 o C) poses a great challenge in the sense of developing solid electrolyte at intermediate temperature range. In response to this, we report a novel composite La 9.33 Si 6 O 26 (LSO)-Ce 0.85 Gd 0.15 O 1.925 (CGO) in this study. The synthesis of LSO-CGO composite was carried out by combining LSO with CGO (9:1, 8:2, and 7:3 in weight ratio) using solid state reaction method. In order to get a dense pellet, all of the products were sintered at 1500°C for 3 hours. The X-ray diffraction pattern of sintered pellets show typical patterns for both of LSO and CGO which indicate that the composite was successfully formed. The highest conductivity was detected in 7LSO-3CGO, i.e. 2.10× 10-3 S cm-1 at 700 o C and also has low activation energy (0.60 eV). This result suggests that the LSO-YSZ composites are good oxide ion conductors and may potentially be used as an alternative solid electrolyte in IT-SOFC technology.
2011 2nd International Conference on Instrumentation, Communications, Information Technology, and Biomedical Engineering, 2011
Apatite-type lanthanum silicates are of great interest because of their high ionic conductivity i... more Apatite-type lanthanum silicates are of great interest because of their high ionic conductivity in which it is potential to be used as electrolyte for the solid oxide fuel cell (SOFC) application. In the present work, we report 29Si solid state NMR studies of several doped lanthanum apatite silicates prepared by hydrothermal method. For the undoped apatite La9.33Si6O26 three peaks are
As a semiconductor, zinc oxide (ZnO) has better UV absorbing properties compared to other semicon... more As a semiconductor, zinc oxide (ZnO) has better UV absorbing properties compared to other semiconductor materials, and therefore, it has better dye degrading abilities. However, ZnO tends to agglomerate, which lead to poor degradation compared to the other semiconductors. In this study, to overcome the agglomeration of ZnO, silica (SiO 2) was combined with ZnO. The composite was tested for its photocatalytic activity. The ZnO/SiO 2 photocatalyst was fabricated on a glass plate. In order to investigate the addition of SiO 2 on ZnO, X-ray diffraction (XRD) and scanning electron microscope-energy disper-sive X-ray spectroscopy (SEM-EDS) was used. The result of the XRD analysis demonstrates similar peak results with ZnO XRD data from ICSD 157132 with a hexagonal structure. The results indicate that the ZnO structure did not change after the addition of SiO 2 , while SEM-EDS results showed that SiO 2 was supported on ZnO with 8% composition. The optimal composition was found to be ZnO/SiO 2 95/5, as indicated by high degradation activity, which can degrade up to 89% methylene blue.
Solid oxide fuel cell is one of the alternative energy sources with high efficiency and low emiss... more Solid oxide fuel cell is one of the alternative energy sources with high efficiency and low emissions. Solid oxide electrolyte is an important component of this fuel cell. A new electrolyte that suitable at medium temperature is needed to be developed. Apatite type lanthanum silicate is one of the electrolytes, which can operate at medium temperature. Increasing performance of apatite lanthanum silicate such as ionic conductivity can be achieved by doping. The purpose of the present study was to synthesize the electrolyte of Lanthanum silicates oxide with hydrothermal method and to investigate the effect of Ti 4+ dopant on apatite electrolyte characteristics such as crystal lattice parameter and conductivity. The results showed that samples of La 9.33 Si 6-x Ti x O 26 with x = 0.1, 0.2, 0.3 were successfully synthesized. The value of c on the crystal lattice parameter increases with increasing the doping content of Ti 4+. Increasing c value on the crystal lattice parameter is directly proportional to the conductivity. Apatite La 9.33 Si 5.7 Ti 0.3 O 26 showed the highest conductivity of 2.4 × 10-4 S/cm at 700°C.
Nowadays, many studies on separation of rare earth elements have been conducted due to its divers... more Nowadays, many studies on separation of rare earth elements have been conducted due to its diverse utilization. One of its applications in medical area is the utilization of gadolinium in the form of Gd-DTPA complex for contrast agent in magnetic resonance imaging (MRI). In the preparation of Gd-DTPA, there is a possibility of residual Gd 3+ which is toxic in nature and therefore requires separation process before it can be applied. The separation of Gd 3+ from Gd-DTPA complex can be performed by nanofiltration-complexation method. In the present study, Gd-DTPA complex was prepared by reacting Gd2O3 with DTPA ligand with reflux followed by separation of Gd 3+ from Gd-DTPA with nanofiltration membrane with varying pressure (5.8, 6.0, 6.2 and 6.4 bars) at 40°C followed by determination of flux and rejection coefficient of the membrane. The results of the present study indicate that flux of the permeate increased with increasing pressure up to 339.94 L.m-2. hour-1 while rejection decreased down to 9.02% at 6.4 bars. The concentration of Gd 3+ presence in the Gd-DTPA after the filtration process was 0.201 ppm.
Conductivities of Sn(IV) doped lanthanum silicates apatite as an electrolyte for intermediate tem... more Conductivities of Sn(IV) doped lanthanum silicates apatite as an electrolyte for intermediate temperature solid oxide fuel cells (ITSOFCs) have been examined. Dense ceramic pellet of La9.33Si6-xSnxO26 (x: 0.1; 0.3; 0.5) have been prepared by sintering at 1773K for 3 hours. The sample La9.33Si5.7Sn0.3O26 shows higher conductivities than comparable La9.33Si5.9Sn0.1O26 and La9.33Si5.5Sn0.5O26 samples indicating the importance of dopant concentration. Low activation energy of all samples (Ea < 1.1 eV) indicate that the Sn(IV) doped electrolytes are good conductors that can be used for ITSOFCs.
The crystalline structure of La9.33Si6O26 apatite-type lanthanum silicates was investigated by X-... more The crystalline structure of La9.33Si6O26 apatite-type lanthanum silicates was investigated by X-ray powder diffraction at room temperature. The hydrothermal synthesis condition was optimized to yield ultrafine and highly homogeneous La9.33Si6O26 powders. The results after rietica refinement indicate that optima crystal apatite structure was formed after being synthesized for six days at 503 K and was in agreement with the P63/m space group. The lattice parameter of the sample was in agreement with ICSD No 158963.
Reducing a high-operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature... more Reducing a high-operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature SOFC (IT-SOFC, 500-750 o C) poses a great challenge in the sense of developing solid electrolyte at intermediate temperature range. In response to this, we report a novel composite La 9.33 Si 6 O 26 (LSO)-Ce 0.85 Gd 0.15 O 1.925 (CGO) in this study. The synthesis of LSO-CGO composite was carried out by combining LSO with CGO (9:1, 8:2, and 7:3 in weight ratio) using solid state reaction method. In order to get a dense pellet, all of the products were sintered at 1500°C for 3 hours. The X-ray diffraction pattern of sintered pellets show typical patterns for both of LSO and CGO which indicate that the composite was successfully formed. The highest conductivity was detected in 7LSO-3CGO, i.e. 2.10× 10-3 S cm-1 at 700 o C and also has low activation energy (0.60 eV). This result suggests that the LSO-YSZ composites are good oxide ion conductors and may potentially be used as an alternative solid electrolyte in IT-SOFC technology.
2011 2nd International Conference on Instrumentation, Communications, Information Technology, and Biomedical Engineering, 2011
Apatite-type lanthanum silicates are of great interest because of their high ionic conductivity i... more Apatite-type lanthanum silicates are of great interest because of their high ionic conductivity in which it is potential to be used as electrolyte for the solid oxide fuel cell (SOFC) application. In the present work, we report 29Si solid state NMR studies of several doped lanthanum apatite silicates prepared by hydrothermal method. For the undoped apatite La9.33Si6O26 three peaks are
As a semiconductor, zinc oxide (ZnO) has better UV absorbing properties compared to other semicon... more As a semiconductor, zinc oxide (ZnO) has better UV absorbing properties compared to other semiconductor materials, and therefore, it has better dye degrading abilities. However, ZnO tends to agglomerate, which lead to poor degradation compared to the other semiconductors. In this study, to overcome the agglomeration of ZnO, silica (SiO 2) was combined with ZnO. The composite was tested for its photocatalytic activity. The ZnO/SiO 2 photocatalyst was fabricated on a glass plate. In order to investigate the addition of SiO 2 on ZnO, X-ray diffraction (XRD) and scanning electron microscope-energy disper-sive X-ray spectroscopy (SEM-EDS) was used. The result of the XRD analysis demonstrates similar peak results with ZnO XRD data from ICSD 157132 with a hexagonal structure. The results indicate that the ZnO structure did not change after the addition of SiO 2 , while SEM-EDS results showed that SiO 2 was supported on ZnO with 8% composition. The optimal composition was found to be ZnO/SiO 2 95/5, as indicated by high degradation activity, which can degrade up to 89% methylene blue.
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Keywords: Doped lanthanum silicates apatite, ITSOFCs, electrolyte.
Keywords: Doped lanthanum silicates apatite, ITSOFCs, electrolyte.