Iwan Hastiawan

LSO apatite-YSZ composite as a solid electrolyte for solid oxide fuel cells

LSO (Lanthanun Silicate Oxide) Apatite-YSZ (Yttria-stabilized zirconia) composite has been synthesized by combining the LSO apatite with commercial YSZ with different composition ratio (LSO Apatite:YSZ = 60:40wt.% and 50:50 wt. %). Structure, morphology, and conductivity of sintered pellets composite (sintered at 1330oC for 3 hours) were characterized by XRD, SEM, and impedance spectroscopy, respectively. The sintered density of the composite materials with 50:50 wt. % and 60:40 wt. % (apatite: YSZ) ratios were 3.785 g.cm−3 and 3.770 g.cm−3, respectively. The typical peak of LSO and YSZ were observed in the X-ray pattern of the composite materials. The conductivity of the LSO apatite : YSZ composite 50:50wt. % and 60:40 wt. % ratios showed high level of ionic conductivities with values of 1.26 × 10−3 S/cm and 1.60 × 10−4 S/cm, respectively,with very low level of activation energy (0.95–1.02 eV) at 700 °C. These results indicate that the LSO-YSZ composite materials are good conductors that can be used as s...

Synthesis of gadolinium doped titanium(IV) oxide and their photocatalytic activity to decrease chemical oxygen demand (COD) value of water pollutants

Pesticides are widely used for the control of plant disease. Unfortunately they are highly toxic to terraneous and aquatic life; this is a particular problem in agricultural areas. TiO2 is widely used for pesticide control because of its photocatalytic activity, but it still has inadequacy in its wide band gap. Alternatively, the wide band gap of TiO2 could be narrowed by modification with rare earth element such as gadolinium, so the photocatalytic activity of TiO2could be significantly enhanced. The purpose of this experiment is to synthesize Gd/TiO2 and its application to reduce COD of water pollutants such as carbosulfan pesticide. This experiment is done by doping gadolinium oxide into titanium tetra isopropoxide by sol-gel method. The crystal structure is characterized by using XRD, shown anatase successfully obtained with the smallest crystallite size is 37.655 nm, indicated optimum calcination time is 4 hours. SEM-EDX result shown morphology of crystal is big aggregates. Photocatalytic activity is tested to carbosulfan pesticide, obtained the COD percent decreases up to 87.88%.Pesticides are widely used for the control of plant disease. Unfortunately they are highly toxic to terraneous and aquatic life; this is a particular problem in agricultural areas. TiO2 is widely used for pesticide control because of its photocatalytic activity, but it still has inadequacy in its wide band gap. Alternatively, the wide band gap of TiO2 could be narrowed by modification with rare earth element such as gadolinium, so the photocatalytic activity of TiO2could be significantly enhanced. The purpose of this experiment is to synthesize Gd/TiO2 and its application to reduce COD of water pollutants such as carbosulfan pesticide. This experiment is done by doping gadolinium oxide into titanium tetra isopropoxide by sol-gel method. The crystal structure is characterized by using XRD, shown anatase successfully obtained with the smallest crystallite size is 37.655 nm, indicated optimum calcination time is 4 hours. SEM-EDX result shown morphology of crystal is big aggregates. Photocatalytic activity is...

Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, (1H, and 13C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

Preparation and conductivity of composite apatite La9.33Si6O26 (LSO) - Zr0.85Y0.15O1.925 (YSZ)

A great challenge to reduce high operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature SOFC (IT-SOFC, 500-750 °C), is the development of solid electrolyte materials with high ionic conductivity at intermediate temperature range. In response to this challenge, here we report a novel composite material La9.33Si6O26 (LSO)-Zr0.85Y0.15O1.925 (YSZ). LSO-YSZ composite synthesis was carried out by combining LSO with commercial YSZ (9:1, 8:2, 7:3) using hydrothermal method. In order to get dense pellet, all of the product were sintered at 1450 °C for 3 hours. X-ray diffraction pattern of the entire pellets show typical both of LSO and YSZ pattern which indicate that the composite was succesfully formed. The highest conductivity was detected in YSZ-7LSO (YSZ:LSO = 7: 3), i.e 1.72 × 10−4 Scm−1 at 700 °C and also has low activation energy (0.88 eV). This result suggests that the LSO-YSZ composite materials are good oxide ion conductor and potential to be used as an alternative solid electr...