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Lithium-ion thermal battery management systems are continuously being developed to ensure better battery performance, safety, and capacity. Li-ion battery performance is strongly influenced by its operating temperature. Thus, to maintain its safety and performance, a thermal management system in the form of cooling fluid is necessary to maintain battery temperature. The purposes of this study are to predict the thermal characteristics of LFP battery numerically and determine the temperature distribution among cells in the variations of discharge rate from 0.5C to 1C. A constant 0.1 m/s air flow rate at 25°C are used for evaluating the thermal performance of the twenty-five 26650 LFP battery cells arranged in a 5 × 5 battery pack configurations. In this work, we do both numerical computation and direct experiment. Computational investigation was done using ANSYS Fluent 2020. The battery heat generation model used was Equivalent Circuit Model (ECM) which provided by ANSYS Fluent 2020. Then, the numerical results are validated by an experiment. The data obtained from the experiment are temperatures profile and contours of temperature. The temperature profile is drawn from the data recorded by a 4-channel thermocouple thermometer, while the contours of temperature are captured by using thermal camera. The investigation results reveal that a higher C-Rate gives a higher battery pack temperature; the temperatures achieve in the simulation and experiment show no big difference; and overall battery pack temperatures are below 34°C for 3600 s running. The maximum temperature difference among cells is lower than 5°C. An evenly distributed air flow provides uniform temperature distribution inside the battery pack. [ABSTRACT FROM AUTHOR]

Silica aerogels having very high surface area and pore volume have been succesfully synthesized from bagasse ash by ambient pressure drying (APD) method. Silica in bagasse ash was extracted by alkali extraction to produce sodium silicate solution. This is done by boiling bagasse ash in 2 N NaOH solution under continuous stirring for 1 h. To avoid the collapse of gel structure during drying at ambient pressure condition, the silica surface was modified with alkyl functional groups by a single step sol-gel process. Silicic acid produced by exchanging Na+ ions in dilute sodium silicate solution with H+ ions from cation resin was added with trimethylchlorosilane (TMCS) and let the reaction of TMCS with water pore proceeds for several minutes to produce hexamethyldisilazane (HMDS) and HCl. Then, HMDS was added to allow the modification of silica surface in which the silanol groups were exchanged with alkyl groups originating from HMDS. The solution pH was then adjusted to 8-9 by adding NH4OH solution to induce gel formation. The hydrogel was aged at 40 °C for 18 h and at 60 °C for 1 h. Then, it was dried at 80 °C at ambient pressure condition. The silica aerogels obtained have specific surface, as measured by BET method, ranging from 450.2 to 1360.4 m2/g depending on the synthesis condition. The pore volume was ranging from 0.7 to 1.9 cm3/g. It seems that silica aerogels with very high surface area and pore volume can be obtained if the silanols group in the silica surface was exchanged succesfully with alkyl groups from HMDS. [ABSTRACT FROM AUTHOR]

Anaerobic digestion in biogas industry is associated to the production of several greenhouse gases, namely carbon dioxide, methane and nitrous oxide. As a consequence, dedicated measures should be taken in order to reduce these emissions. Efforts to limit the increase in atmospheric CO2 concentrations while meeting increasing global energy demand can only be achieved by implementing a comprehensive technology portfolio, such as carbon capture and storage (CCS) measures. In this work, CCS technology was applied to remove CO2 in biogas with Ca(OH)2 aqueous solution using a continuous bubble column reactor. The bubble column with diameter D = 13.95 cm and the ratio of liquid height to diameter H⁄D = 4. The raw biogas was introduced into the bottom of the column to flow upward, while the Ca(OH)2 aqueous solution introduced into the top to flow downward. It was found that CO2 removal increases with decreasing the ratio of the superficial velocity of biogas to the superficial velocity of the Ca(OH)2 aqueous solution. About 70% CO2 removal is achieved at the ratio of the superficial velocity of biogas to the superficial velocity of the Ca(OH)2 aqueous solution of 0.4. The obtained PCC showed dominant morphology identical with calcite which is rhombohedral or cube form calcite with a size range of 600 - 1000 nm. [ABSTRACT FROM AUTHOR]

Studies on several factors influencing the stability of ZnO colloids were discussed in this paper. Parameters such as colloidal and LiOH concentrations were explored to see the effect on the ZnO colloid's stability and characteristics. The ZnO colloids were prepared using the sol-gel method, and zinc acetate dihydrate was used as a zinc source. Distillation equipment was used to avoid moisture exposure so the reaction could be carried out under the ambient temperature. Lithium hydroxide was added to the mixture to experience crystal formation and form stable colloidal ZnO. Particle Size Analyzer (PSA) was used to investigate size distribution and solution zeta potential. The results reveal that the most optimum conditions to produce ZnO particles were at 0.14 M LiOH with a particle size of 27.7 nm. When colloid concentration increases, the particle size increases up to 2.57 µm at a colloid concentration of 0.3 M. The best results also showed that ZnO colloids tend to emit blue luminescence under ultraviolet light and go to yellow-greenish luminescence color after aging, which is stable for an extended period. [ABSTRACT FROM AUTHOR]

The steel industries account for 6% of the world's CO2 emissions. The number of emissions will continue to increase as the steel industry in Indonesia grows. Generally, steel production uses blast furnaces which can produce large CO2 emissions. The blast furnace process emissions called blast furnace gas (BFG) contain 20.7% mol of CO2. The high CO2 content also causes the calorific value of the gas to be low, so the gas must be purified to increase its calorific value to be used for power generation. In addition, the steel industry also produces steel slag as waste with a high CaO content (45.2%) but with low economic value. To increase its economic value, CaO content can be used to absorb CO2 from BFG to produce Precipitated Calcium Carbonate (PCC). The use of PCC is very broad for various industrial needs, such as a filler in the paper industry which can increase paper brightness. Therefore, the "Precipitated Calcium Carbonate from Blast Furnace Gas and Steel Slag" plant is expected to be a solution to reduce CO2 emissions from the steel industry. BFG and steel slag as raw materials were obtained from PT. Krakatau Posco. The PCC production process consists of three main stages, namely: (1) Pre-Treatment Steel Slag; (2) Carbonation; and (3) Purification. In the pre-treatment stage, the pH-swing method was used to extract CaO with NH4Cl solvent using pH control. The use of NH4Cl solution is advantageous because it can be recycled. This process obtained a solution of CaCl2 and NH4OH, which was then reacted with CO2 from BFG in a bubble column reactor, resulting in a carbonation process. In the reactor, PCC (CaCO3) and several impurities are formed. The PCC solids formed will then be filtered, dried, and reduced in size so that the moisture content and size are under PCC specifications for the paper industry. Besides producing PCC, purified BFG will be recycled and used as fuel for power generation. The plant location is integrated with PT. Krakatau Posco in the industrial area, Cilegon, Banten, West Java, with a production capacity of 12,750 tons/year. From the results of the economic analysis, with the capital expenditure (capex) of about IDR 337 million and operational expenditure (OPEX) of about IDR 89 million: the payback period is about 6.35 years, and the break-even point (BEP) is 32.38%. [ABSTRACT FROM AUTHOR]

An electrospray drying method has been proposed to produce silica (SiO2) nanoparticles with precise qualities. However, the phenomena of jet-formation in the electrospray process are difficult to capture in field observation, so it requires further investigation using two-dimensional multiphase CFD simulation. It studied the cone-jet formation of the electrospray process which involves multiphase flow and electric potential. The outcomes are volume fraction contour, velocity vectors, electric potential contour, electric current magnitude, and predict the final particle size. The CFD shows 1 ml/h precursor solution results in a thin jet diameter. The entire electric potential contours provide an inversed parabola profile with the biggest electric current magnitude at 14 kV (at the center of the jet). The smallest predicted particle size (0.3 µm) is produced at 1 ml/h. [ABSTRACT FROM AUTHOR]

This study aims to show changes in the performance of combustion using pulse combustion at specified intervals using simulation. Simulations is performed using Computational Fluid Dynamics analysis (CFD) software Ansys Fluent 15.0. Analysis used 2D illustration axisymmetric with k-ε turbulence models. Propane was selected as fuel at a flow rate of 15 L/min. Air with flow rate of 375 L/min is used as oxidizer. To investigate the advantages of using pulse combustion, the simulated pulse combustion is compared to normal combustion without a pulse. This is done by displaying descriptions of the phenomenon, mechanisms and results output gas combustor. From the analysis of simulation results showed that in 1 minute burning time, burning fuel without requiring pulse as much as 15 L while the pulse combustion requires half of the fuel which is 12.5 L. However, the higher average of temperature was generated by pulse combustion and the amounts of unburned fuel that comes out of the combustor less than without the use of pulse combustion. So, it can be concluded that the pulse combustion is more efficient than combustion without a pulse. [ABSTRACT FROM AUTHOR]

Flame assisted spray dryer are widely uses for large-scale production of nanoparticles because of it ability. Numerical approach is needed to predict combustion and particles production in scale up and optimization process due to difficulty in experimental observation and relatively high cost. Computational Fluid Dynamics (CFD) can provide the momentum, energy and mass transfer, so that CFD more efficient than experiment due to time and cost. Here, two turbulence models, k-ε and Large Eddy Simulation were compared and applied in flame assisted spray dryer system. The energy sources for particle drying was obtained from combustion between LPG as fuel and air as oxidizer and carrier gas that modelled by non-premixed combustion in simulation. Silica particles was used to particle modelling from sol silica solution precursor. From the several comparison result, i.e. flame contour, temperature distribution and particle size distribution, Large Eddy Simulation turbulence model can provide the closest data to the experimental result. [ABSTRACT FROM AUTHOR]

In our previous study, the effect of temperature for fabrication ZnO-SiO2 nanocomposite had been investigated. It was found that the optimum condition for the photocatalytic activity was obtained when the nanocomposite was synthesized at temperature of 400 °C. In the present study, the effect of SiO2 loading on the ZnO-SiO2 nanocomposite were investigated as well as the photocatalytic performance. ZnO-SiO2 nanocomposites have been synthesized by a combination liquid and gas-phase processes. Colloidal silica was prepared by sol-gel method, where water glass was used as a precursor. The water glass was diluted into demineralized water and passed it into activated cation resin using HCl 2 M to allow the exchange of H+ and Na+ ions. While, ZnO was obtained by decomposition of Zn(CH3COO)2.2H2O inside tubular spray reactor. The effect of SiO2 concentration ranging from 0 to 2 %wt was used. Characterization of ZnO-SiO2 nanocomposites was carried out by morphological analysis with scanning electron microscope (SEM), crystallinity analysis with X-ray diffraction (XRD), functional group analysis with Fourier transform infrared (FTIR) and photocatalytic test by evaluating the degradation rate of methylene blue (MB) under UV and sunlight irradiation. It was found that the best photocatalytic performance was attained when the concentration of SiO2 was equal to 1 % wt at temperature of 400°C. The degradation efficiency reached 95 % using this parameter. [ABSTRACT FROM AUTHOR]

We have been succesfully synthesized monodispersed magnetite nanoparticles by electro-oxidation of iron in plain water without using any surfactant. The characteristics of particles produced, i.e., crystallinity, size, and magnetic behavior, are influenced by the synthesis conditions including the current density and the inter-electrodes distance. The crystallinity and size of particles increase by increasing the current density and by decreasing the inter-electrodes distance. The mean size of magnetite nanoparticles produced by this method ranging from 10 to 30 nm depending on the synthesis conditions. Although there are some impurities in the form of FeOOH, which is a non-magnetic material, the nanoparticles still exhibit ferromagnetic behavior with a relatively high saturation magnetization ranging from 60 to 70 emu.g- and a coercivity ranging from 140 to 295 Oe depending on the synthesis condition. This simple method appears to be a promising synthetic route to producing magnetite nanoparticles for many applications. [ABSTRACT FROM AUTHOR]

In this study, ZnO-Ag nanocomposites with different Ag loadings have been successfully synthesized by spray pyrolysis using nitrogen as a carrier gas. The Ag loading with various concentrations from 0 to 10 %wt was doped to the ZnO particles. The performance of products, ZnO-Ag nanocomposites, was subsequently tested by measuring the photocatalytic degradation of organic waste from the textile dye. Morphology, crystallite size and crystalline phase, surface area and functional group of hydroxyl of the produced nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. SEM images indicated that the average particle size of the nanocomposite measured by ImageJ software increased with increasing Ag loading. The average size of nanocomposite with Ag loading at 0, 1, 5, and 10 %wt were 784, 850, 856 and 954 nm, respectively. The XRD results detected the existence of Ag in ZnO-Ag nanocomposite. However, the addition of Ag in the nanocomposite did not alter the crystallite size significantly, where the crystallite size was found approximately around 18 to 57 nm. Moreover, BET analysis showed the increase of specific surface area with increasing Ag content in exception for Ag content at 5 %wt. Finally, ultraviolet (UV) light was used as an irradiation source to evaluate the performance of photocatalytic degradation of textile-dye-waste from the textile industry in Gresik-Indonesia. The results showed that Ag loading at 5 %wt produced the highest degradation efficiency among the other concentrations including the pristine ZnO. This research resulted in a simple and effective route for fabricating ZnO-Ag nanocomposite; therefore, it can be considered as a potential candidate for the direct application in degradation of textile-dye-waste. [ABSTRACT FROM AUTHOR]

Precipitated calcium carbonate (PCC) is one of the versatile materials that can be used in many fields such as in papermaking, glass, rubber, plastic, paint, pharmacy, food, cosmetics, detergent and biomaterials. PCC with different chemical and physical properties such as particle size, specific surface area, morphology, and chemical purity is important for its application. In this work, PCC was synthesized by carbon mineralization of biogas with Ca(OH)2 solution using a bubble column contactor. Sucrose was added as an additive to increase the conversion to PCC. The bubble column contactor comprises a cylindrical column 7.3 cm in diameter and 100 cm high and is equipped with a perforated plate gas distributor. The effect of concentration of Ca(OH)2 solution and sucrose concentration to PCC characteristic was investigated in continuous operation. When the pH of the solution has decreased to about 7.0, flow of biogas was terminated. In continuous operation, raw biogas was injected into bottom column through gas distributor, while Ca(OH)2 solution was sprayed into liquid surface at top column with constant flow rate and liquid height of 50 cm. The outflow solution from the bottom of the column was collected and the pH is measured. PCC in the solution was filtered and dried, and then examined to determine particle size distribution, morphology of particle, and crystallinity using particle size analyzer (PSA), scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The results showed that the effect of additive on the particle size of PCC formed was found to be insignificant. The particle size of PCC formed was around 4 – 5 μm depend on the amount of additive added. [ABSTRACT FROM AUTHOR]

Organic waste derived from the textile dye of textile industry in Gresik is toxic and dangerous to humans and the ecosystem. The waste from textile dye must be handled properly before its disposal to the river. Photodegradation of the organic pollutant by catalyst derived from semiconductor materials is one of the promising methods. ZnO is widely used as photocatalyst because of its wide bandgap energy (3.4 eV) and large free excitation binding energy. Furthermore, the addition of ZnO with noble metals can enhance the photocatalytic performance. In this study, ZnO-Ag nanocomposites have been successfully synthesized via a one-step process using spray pyrolysis method. Pure oxygen was used as the carrier gas. The effect of Ag content ranging from 0 to 10 %wt on the photocatalytic performance was studied. Zinc acetate dihydrate 0.1 M and silver nitrate were used as precursors to produce ZnO-Ag nanocomposite inside the tubular reactor. The produced nanocomposites were analyzed by Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD). SEM observation showed that the morphology of the produced nanocomposite was sphere-like structures with interwoven nanoplate particles with some aggregation. The different crystallite size was also observed by XRD analyses. Based on the XRD patterns, the existence of Ag in the nanocomposite was detected when the Ag concentration was greater or equal to 5 %wt. Brunauer–Emmett–Teller (BET) was also performed to estimate the specific surface area of the nanocomposites, where the increase of Ag content is proportional to the specific surface area. Fourier Transform Infrared Spectroscopy (FTIR) was conducted to better understand the functional groups in the nanocomposites and dye pollutants. Finally, the photocatalytic activity of ZnO-Ag was evaluated by the degradation of the dye pollutants from textile home industry at Kabupaten Gresik under UV light irradiation. The photocatalytic activity of the ZnO-Ag was higher than that of pristine ZnO, where the maximum photodegradation was obtained at Ag content as much as 5 %wt with the degradation efficiency that reached 23%. [ABSTRACT FROM AUTHOR]

Biogas is produced when certain kinds of bacteria digest organic substances in an anaerobic environment. Typical raw biogas consists of about two thirds of methane (CH4) and one third of carbon dioxide (CO2). Even though raw biogas can be used directly to generate power, but the large volume of CO2 reduces the heating value of the gas, increasing compression and transportation costs and limiting economic feasibility. In this work, the raw biogas from small scale digester was upgraded by counter-current contacting it with a saturated Ca(OH)2 solution in a bubble column contactor to capture CO2. The bubble column comprises of a cylindrical column 7.3 cm in diameter and 100 cm high and is equipped with a perforated plate gas distributor. The CO2 content in upgraded biogas exit from top bubble column was sampled and measured using Gas Chromatography. The effect of ratio raw biogas to Ca(OH)2 solution flow rate with different liquid height and concentration of Ca(OH)2 solution on CO2 removal were investigated. The results showed that CO2 removal depends on the superficial velocity of the biogas, the flow rate of the Ca(OH)2 solution, the liquid height. The absorption of CO2 increases as the absorbent flow rate increases and decreases as the gas flow rate increases. The use of Ca(OH)2 above the solubility shown in the continuous process showed higher absorption of CO2. However, the increasing CO2 absorption is not significant with increasing Ca(OH)2 concentration. The highest absorption of CO2 obtained in the continuous process is 79.34 %. [ABSTRACT FROM AUTHOR]

Sugarcane bagasse is generated in large quantities during the processing of sugarcane in the sugarcane industry. For a country like Indonesia with its vast agricultural residues such as sugarcane bagasse, it is imperative to have an efficient power generation system utilizing the residues. Gasification of sugarcane bagasse is a carbon dioxide emission neutral source of energy and also has the advantage of syngas production. Syngas composition varies based on gasification technology used and can be adapted to specific applications. Among the gasification technologies that are widely used are downdraft and fludized beds. The objective of this work, therefore, is to provide a comparison between downdraft and fluidized bed gasification based on the production capacity of syngas using Aspen Plus simulation. The sugarcane bagasse used in the simulation was obtained from sugar factory PG Gempolkrep Mojokerto, East Java. The results show that at the ratio of steam to biomass equal 1.0, H2 decreases with increasing temperature both with downdraft and fluidized bed gasification. CO increases with increasing temperature in the downdraft gasification, but decreases with increasing temperature in fluidized bed gasification. At temperature 750°C, H2 increases with increasing the ratio of steam to biomass, but decreases with increasing the ratio of steam to biomass. Meanwhile, CO decreases with increasing the ratio of steam to biomass for both downdraft and fluidized bed gasification. From the aspect of CO2 produced, it can be concluded that fluidized bed gasification is more environmentally friendly than downdraft gasification. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles had been successfully synthesized by premixed combustion spray pyrolysis. Zinc acetate was dissolved in distilled water was selected as a liquid precursor. Zinc nitrate was also used for comparison the effect of precursor type on the generated particles morphology and the crystallinity. The premixed combustion reaction used liquefied petroleum gas (LPG) mainly consisting of butane and propane as a fuel and compressed air used as an oxidizer. The liquid precursor was atomized using a custom two fluid nozzle to generate droplets. Then, the droplets were sprayed by the flow of air as a carrier gas into the premixed combustion reactor. The zinc precursor was decomposed to zinc oxide due to the high temperature as a result of combustion reaction inside the reactor resulting in nanoparticles formation. The particle size decreased with the increase of the fuel flow rate. In addition, it can be found that at the same flow rate of fuel, the particle size of zinc oxide synthesized using zinc nitrate is larger than that of the use of zinc acetate as a precursor. [ABSTRACT FROM AUTHOR]

Zinc oxide-silicon dioxide (ZnO-SiO2) nanocomposite particle have been synthesized using spray decomposition method. This method is expected to produce nanoparticle in a continuous process, producing spherical particle, and high purity product. The influence of ratio precursor concentration was investigated in this experiment to know the characteristic of ZnO-SiO2 nanocomposite. The precursors were prepared by mixing zinc acetate and silicon dioxide solution using distilled water as a solvent. Compressor nebulizer was used to atomize a precursor solution into discrete droplets. ZnO-SiO2 particle was evaluated by X-ray diffraction (XRD) and scanning electron microscope with energy dispersive X-ray (SEM-EDX) to investigate their crystal structure, morphology, and composition. Particle ZnO-SiO2 obtained from this method have hexagonal crystals, the particle shape was spherical, and have a good dispersion of ZnO and SiO2. [ABSTRACT FROM AUTHOR]

ZnO-SiO2 nanocomposite particles were prepared by sonochemical method under continuous ultrasound irradiation for an hour. Zinc nitrate and sodium silicate were used as zinc oxide and silica sources, respectively. Silica concentration was varied to investigate the effect of silica on the characteristics of the generated composite particles and they were also compared to ZnO particles. Morphology, crystallinity, chemical bonding analysis, photoluminescence spectra, and photocatalytic activity were characterized by scanning electron microscopy (SEM), X-Ray diffraction, Fourier Transform Infrared (FTIR), luminescence spectrophotometer, and UV-Vis spectrophotometer, respectively. Nanorod structures were observed for pure ZnO, ZnO-SiO2 particles with 250 ppm and 750 ppm silica addition during synthesis. Spherical agglomerated particles were found for particle with 0.1 M silica addition. The crystalline size and photocalytic activity decreased with the silica addition. A strongest chemical bonding for ZnO and SiO2 was also observed for particle with 0.1 M silica addition based on FTIR spectra. However, the highest photoluminescence emission by excitation wavelength at 250 nm, was observed for ZnO-SiO2 particles with 750 ppm silica addition with emission peak at 515 nm wavelength. [ABSTRACT FROM AUTHOR]

Diffusion flame spray drying has become promising method in nanoparticles synthesis giving several advantages and low operation cost. In order to scale up the process which needs high experimentation time and cost, Computational Fluid Dynamics (CFD) by Ansys Fluent 15.0 software has been used. Combustion characteristic in diffusion flame reactor may affects particle size distribution. This study aims to observe influence of fuel type to combustion characteristic in the reactor. Large Eddy Simulation (LES) and non-premixed combustion model are selected for the turbulence and combustion model respectively. Methane, propane, and LPG in 0.5 L/min were used as type of fuel. While the oxidizer is air with 200% excess of O2. Simulation result shown that the maximum temperature was obtained from propane-air combustion in 2268 K. However, the stable temperature contour was achieved by methane-air combustion. [ABSTRACT FROM AUTHOR]

The advantages of Pulse Combustion process than the normal combustion was presented in this research. Reviews of phenomena and mechanisms of pulse combustion was compared with normal combustion which air or fuel was streamed continuously. Multi-dimensional simulation of turbulent flow in the combustion chamber was performed by computational fluid dynamics (CFD) with ANSYS FLUENT 15.0 software. 2D illustration axis symmetry with turbulence models k-turbulence combustion reaction using Eddy Dissipation models was used to analyze this process that has a high turbulence. Propane was used as the type of fuel with flow rate of 15 L/min. the flowrate 375 L/min of air was used as oxidizer, to meet the needs of propane and oxygen ratio of 1: 5. Based on the result, pulse combustion has higher combustion efficiency than normal combustion. This result was judged from fewer fuel that was not burned. Another advantage of using pulse combustion was the back flow of tailpipe that decrease the number of unburned reactants. The efficiency increased because of the unburned fuel would be contacted back and undergo combustion. Pulse Combustion gas output also has higher temperature and higher speed than normal combustion. [ABSTRACT FROM AUTHOR]

Antioxidant compounds from mangosteen pericarps have been extracted with low-transition-temperature mixture (LTTM) assisted hydrothermal method. Extracted antioxidant compounds were determined as xanthone and total phenolic compounds. The effects of temperature, concentration of LTTM, and sonication pretreatment on the recovery of xanthone and total phenolic compounds were investigated. Extraction were carried out in a batch extractor at various temperatures (120 - 160°C), concentrations of LTTM (0.1 - 0.3 mg/mL), and sonication pretreatments (0 - 10 min). LTTM used for extraction was consisted of citric acid as hydrogen bond donor and alanine as hydrogen bond acceptor. Xanthone and total phenolic compounds were analyzed by spectrophotometer. In order to determine the effect of extraction condition on the antioxidant efficiency of the extract, the antioxidant efficiency of extract were analyzed by DPPH assay method. Based on the result, the recovery of xanthone increased as increasing temperature and concentration of LTTM. Inversely, the recovery of total phenolic compounds decreased as increasing temperature. The sonication pretreatment had significantly effect on the recovery of both xanthone and total phenolic compounds, however the optimum condition of sonication pretreatment was at 5 min. The antioxidant efficiency of the extract was affected by the extraction condition, and the highest antioxidant efficiency was 1.395 obtained at temperature of 120°C, LTTM concentration of 0.3 mg/mL, and sonication time of 5 min. [ABSTRACT FROM AUTHOR]

The purpose of this research is to study the simulation of the combustion characteristics and performances in pulse combustor using different excess air composition and different pulse combustor geometry using CFD (Computational Fluid Dynamics) software Ansys FLUENT 15.0. The distribution of temperature, pressure, and fluid velocity using 2D axisymmetric with k-e turbulence models. Two kind geometries of pulse combustors were selected and compared their performance. The first combustor, called geometry A has expanded tail-pipe with diameter 10 mm expanded to 20 mm with length 86 mm. The second combustor, called geometry B has cylinder tailpipe which 10 mm in diameter and 200 mm in length. Air and propane were selected as oxidizer and fuel, respectively, at temperature 27oC and pressure 1 atm with varied excess air of 0%, 23%, 200%, and 500%. The simulation result shows that the average temperature of outflow gas combustion decreased with increasing the excess air. On the other hand, the pressure amplitude increased with increasing the excess air. Amplitude of presure for excess air of 0%, 23%, 200% and 500% were 14,976.03 Pa; 26,100.19 Pa; 41,529.02 Pa; and 85,019.01 Pa, respectively. The geometry of pulse combustor affected the performance of gas combustion produced. Geometry A showed that the energy produced in the combustion cycle amounts to 538,639 to 958,639 J/kg. On the other hand, geometry B showed that the generated energy was in the range 864,502 to 1,280,814 J/kg. Combustor with geometry B provided more effective combustion performance rather than B caused by its larger heat transfer area sectional area. [ABSTRACT FROM AUTHOR]

The size distribution of silica particles as a model material from colloidal silica solution precursor in the flame assisted spray dryer method were studied numerically using Computational Fluid Dynamics (CFD). CFD has ability to solve the momentum, energy and mass transfer equation well. k-e model was used to describe the turbulence model and non-premixed combustion model was used to combustion model. Collision and break-up model were also considered to predict the final particles size distribution. For validation, LPG with flow rate of 0.5 L/minute LPG and 200% excess air were used as energy sources. At this condition, numerical solution agreed well to the experimental work resulting in polydisperse size distribution. Therefore, others excess air, 100% and 150% were also observed using CFD and evaluated their contribution to their particles size distribution. Monodisperse particles size distribution were obtained when the combustion used 150% excess air. [ABSTRACT FROM AUTHOR]

The multiphase polymerization reaction of the silica sol formation produced from silicic acid and potassium hydroxide solutions in laboratory scale agitated tank was studied. The reactor is equipped with four segmental baffle and top entering impeller. The inside diameter of reactor is 9 cm, the baffle width is 0.9 cm, and the impeller position is 3 cm from tank bottom. The diameter of standard six blades Rushton and three blades marine propeller impellers are 5 cm. The silicic acid solution was made from 0.2 volume fraction of water glass (sodium silicate) solution in which the sodium ion was exchanged by hydrogen ion from cation resin. The reactor initially filled with 286 ml silicic acid solution was operated in semi batch mode and the temperature was kept constant in 60 °C. The 3 ml/minute of 1 M potassium hydroxide solution was added into stirred tank and the solution was stirred. The impeller rotational speed was varied from 100 until 700 rpm. This titration was stopped if the solution in stirred tank had reached the pH of 10-11. The morphology of the silica particles in the silica sol product was analyzed by Scanning Electron Microscope (SEM). The size of silica particles in silica sol was measured based on the SEM image. The silica particle obtained in this research was amorphous particle and the shape was roughly cylinder. The flow field generated by different impeller gave significant effect on particle size and shape. The smallest geometric mean of length and diameter of particle (4.92 µm and 2.42 µm, respectively) was generated in reactor with marine propeller at 600 rpm. The reactor with Rushton impeller produced particle which the geometric mean of length and diameter of particle was 4.85 µm and 2.36 µm, respectively, at 150 rpm. [ABSTRACT FROM AUTHOR]

Valuable compounds, such as xanthone and phenolic compounds, from mangosteen pericarps was extracted by hydrothermal treatment at temperatures of 120-160 oC and pressures of 5 MPa using batch and semi-batch extractor. This method is a simple and environmentally friendly extraction method requiring no chemicals other than water. Under these conditions, there is possibility for the formation of phenolic compounds from mangosteen pericarps from decomposition of bounds between lignin, cellulose, and hemicellulose via autohydrolysis. In order to increase the amount of extracted valuable compounds, sonication pre-treament was performed prior to the hydrothermal extraction process. 30 min of sonication pre-treatment could increase significantly the amount of xanthone and phenolic compounds mangosteen pericarps extraction. In batch-system, the xanthone recovery approach to 100% at 160 °C with 30 min sonication pretreatment for 150 min extraction time. Under semi-batch process, the total phenolic compounds in the extract was 217 mg/g sample at 160 °C with 30 min sonication pre-treatment for 150 min total extraction time. The results revealed that hydrothermal extraction assisted sonication pre-treatment is applicable method for the isolation of polyphenolic compounds from other types of biomass and may lead to an advanced plant biomass components extraction technology. [ABSTRACT FROM AUTHOR]

Nanostructured ZnO was synthesized by a sonochemical reaction. Ultrasonic irradiation were set up in continuous, pulse in 3 seconds on and a second off (on:off = 3:1), and pulse in 2 seconds on and a second off (on:off = 2:1) wave modes for 1.5 hours. The characteristics of particles generated by these modes such as morphology, crystallinity, FTIR, photoluminescence, and photocatalytic activity to degrade methylene blue were compared. Zinc nitrate and ammonia water-based solutions were selected as chemicals without the addition of other surfactants. The morphology of the generated ZnO particles could be tuned from flower-like, needle- or hairy-like, and spherical structures by changing the mode of ultrasonic irradiation from continuous, on:off=3:1, and on:off=2:1 modes, respectively. The generated particles indicated that a wurtzite structure of ZnO in a hexagonal phase was formed. The crystalline sizes of particles generated in continuous, on:off=3:1, and on:off=2:1 modes were 28, 27, 24 nm. A similar position of reduction peak of FTIR in all samples indicated that no differences in particles chemical bonding characteristics. Photoluminescence intensity was also decreased with changes the wave mode from continuous to pulse. Photocatalytic activity was also evaluated resulting in particles synthesized by continuous mode had the highest methylene blue degradation degree following by on:off=3:1, and on:off=2:1 modes. [ABSTRACT FROM AUTHOR]

Zirconium oxide fine particles were synthesized by flame assisted spray pyrolysis using zirconium chloride solution as precursor. Propane gas and air were used as a fuel and an oxidizer, respectively. The ratio of flow rate of oxidizer and fuel was maintained constant at 10:1 to ensure a complete combustion. Increasing fuel flow rate led to the increase of temperature distribution in the flame reactor. The intensity of XRD patterns increased with temperature and precursor concentration. Phase composition of zirconium oxide produced by this process consisted of monoclinic and tetragonal phases. The volume fraction of monoclinic phase of zirconium oxide increased with temperature and precursor concentration. The morphology particles observed by SEM resulted in spherical particles with size in the submicron range depending on the precursor concentration. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) or (Ca10(PO4)6(OH)2 has been widely used in orthopedics and dental applications for human bone implant and teeth filler due to their biocompatibility and osteoconductive properties. Fine to nanoparticles of HA with appropriate stoichiometry and purity are preferred because they enhance densification and bioactive properties. Here, we reported the synthesis of hydroxyapatite particles in a diffusion flame reactor. LPG mainly consisting of butane and propane was used as fuel and compressed air was used as oxidizer and carrier gas. The effects of urea adding into precursor on morphology and crystallinity of the generated particles were investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe particles morphology and crystallinity, respectively. Purity of the generated particles was analyzed quantitatively from XRD pattern using Rietveld method. Spherical shape of particles morphology was obtained for particles synthesized without urea added into precursor. Increasing fuel flow rate and urea concentration led to further disintegration of the generated particles. Nano sized particles were generated using fuel flow rate of 1 L/min and 30 w% concentration of urea added into precursor. However, increasing urea concentration led to the increase of tricalcium phosphate as a further reaction of hydroxyapatite for flame generated by using LPG as fuel of 1 L/min. [ABSTRACT FROM AUTHOR]