Thermal characterization of ferronickel slag waste has been studied using TG / DTA, XRD, and SEM-EDX. The characterization of the initial samples of ferronickel slag was carried out TG / DTA to 1200°C. The result obtained is at a temperature of 800°C, there is an increasing mass and up to 4.68% at a temperature of 1200°C. At temperature of 807.4°C to 845.8°C, an exothermic reaction occurs. The increasing mass is due to the ferronickel slag which is originally in the form of metal, and then it was roasted to undergo an oxidation reaction so that the metal that has been formed, it returned into oxides. So that the weight of the sample mass increase. Samples of ferronickel slag added with sodium carbonate were also analyzed using TG / DTA. The results obtained are 2 endothermic peaks at temperatures of 90.6°C and 858.9°C with a total mass reduction of 49.3%. At a temperature of 90.6°C, there is a heavy loss caused by 2.38% loss of surface water. The XRD result of ferronickel slag is composed of enstatite (MgSiO3), forsterite (Mg2SiO4), fayalite (Fe2SiO4), and quartz (SiO2) structures. From the XRD analysis, the composition of silica oxide associates with magnesium and iron in the form of enstatite, forsterite, and fayalites is a very dominant composition. The roasting process of a mixture of ferronickel slag with sodium carbonate was carried out by heating at a temperature of 800-1000°C for 1 hour, and the sample result of roasting were analyzed using XRD. The result of roasting shows that the roasting process takes place more perfectly at higher temperature; it is indicated by the increasing phase intensity of SiO2 and the formation of sodium silicate (Na2SiO3). The result of SEM shows that the higher the temperature, the distribution of Na, Si, and O elements tend to cluster in the same place or spot, while the elements of Mg, Si, and O are less bonded.

AbstrakTelah dilakukan penelitian terhadap kemampuan karbon aktif sebagai adsorben untuk menyerap ion Al dan Fe dalam larutan sodium silikat. Penelitian ini dilakukan dalam skala laboratorium menggunakan metode batch. Penentuan kondisi optimum meliputi massa adsorben, pH, waktu kontak dan temperatur larutan. Hasil analisis dengan Spektrofotometer Serapan Atom (SSA) menunjukkan efisiensi adsorpsi tertinggi oleh karbon aktif aktivasi HCl pada larutan sodium silikat mencapai 88,43% untuk ion Al dan 41,6% untuk ion Fe, sedangkan pada karbon aktif aktivasi H 2 SO 4 57,09 % untuk ion Al dan 35 % untuk ion Fe dan karbon aktif komersil menyerap ion Al sebesar 87,74% dan 11,35% untuk ion Fe.Kata kunci : Adsorpsi, Karbon aktif, Metode batch, SSA. AbstractThe research done on the ability of activated carbon as adsorbent to adsorb the ions Al and Fe in solution of sodium silicate. This research was conducted in laboratory scale using batch method. Determination of optimum conditions include the mass of adsorbent, pH, contact time and temperature of solution. Results of analysis by Atomic Absorption Spectrofotometer (AAS) showed that highest adsorption efficiency on carbon activated by HCl in sodium silicate solution reached 88.43% for the ions Al and 41.6% for Fe ions, where as the carbon activated by H 2 SO 4 57.09 % for the ions Al and 35% for the ions Fe and commercial activated carbon to absorb the ions Al of 87.74% and 11.35% for Fe ions.

Transparent conductive oxide (TCO) glass is one of most important components in dyesensitized solar cell (DSSC) device. In addition to its high electrical conductivity, transparency is another important requirement that must be achieved in fabricating TCO. One TCO film is fluorine-doped tin oxide (FTO), which can be considered as the most promising substitution for indium-doped tin oxide (ITO), since the latter is very expensive. However, the fabrication techniques for TCO film need to be carefully selected; the synthesis parameters must be properly optimized to provide the desired properties. In this work, FTO glass has been fabricated by the ultrasonic spray pyrolisis technique with different precursors, i.e. tin (II) chloride dihydrate (SnCl 2 .2H 2 O) and anhydrous tin (IV) chloride (SnCl 4 ), as well as different solvents, i.e. ethanol and methanol. For both conditions, ammonium fluoride (NH 4 F) was used as the doping compound. The resulting thin films were characterized by use of a scanning electron microscope (SEM), x-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy and a four-point probe test. The results of the investigation show that the highest transmittance of 88.3% and the lowest electrical resistivity of 8.44×10 -5 Ω.cm were obtained with the FTO glass processed with 20 minutes of spray pyrolysis deposition and 300 o C substrate heating, using SnCl 4 as the precursor and methanol as the solvent. It can be concluded that TCO fabrication with tin chloride precursors and ammonium fluoride doping using ultrasonic spray pyrolisis can be considered as a simple and low cost method, as well as a breakthrough in manufacturing conductive and transparent glass.

lmenite (FeO.TiO2) ore from Bangka island-Indonesia is a potential raw material for synthesizing titanium dioxide (TiO2), which can be used further as pigmen and photocatalyst. The fabrication of TiO2 particles from ilmenite can be carried out through the solvent extraction using sulfuric acid route. Therefore, the solubility of the ilmenite ore in sulfuric acid environment is one of the key factors to obtain the desired TiO2 particles. The current research is aimed at comparing the solubility of pristine Bangka ilmenite ore with that of precedingly decomposed by sodium hidroxide (NaOH) in pressurized and atmospheric reflux reactors. The dissolution of both precursors was carried out in those reactors under various temperatures of 75, 100, 125, 150 and 175°C. The results showed that the optimum dilution was achieved at 150°C. The obtained recovery of ilmenite was 88.8 % for the pressurized reactor and 75.5% for the atmospheric reflux reactor. The solubility of titanium (Ti) element increased steadily to reach a recovery of 68% at 150°C and decreased significantly afterwards. It was also found that the increase of iron (Fe) element solubility was proportional to the increase of processing temperatures.

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