Darmawan Hidayat

Synthesis and Dispersion of Nanoparticles, and Indonesian Graphite Processing

Synthesis of nanoparticles and processing of nanocomposites are the essential steps in the application of nanotechnology in various industrial fields including environmental remediation and renewable energy conversion. It is very important to develop their synthesis methods in which nanoparticles having controlled characteristics including size distribution, morphologies, and compositions. Thus, the process needs to be simple, low in cost, and have both continuous operation and high production rate to meet the industrial requirements. The synthesis method for nanoparticles and the development of nanoparticles dispersion technology will be reviewed; nanoparticles synthesis by pulse combustion spray pyrolysis to improve production rate and dispersion of nanoparticles by bead mill method. Furthermore, the availability of the raw materials are also very important to produce the end products economically. The current development on the graphite processing and the future development on the end product in Indonesia will be reviewed.At the request of the authors and Proceedings Editor an updated version of this article was published on 24 September 2013. All changes are restricted to minor updating and editing of references: the scientific content of the paper remains unchanged.Synthesis of nanoparticles and processing of nanocomposites are the essential steps in the application of nanotechnology in various industrial fields including environmental remediation and renewable energy conversion. It is very important to develop their synthesis methods in which nanoparticles having controlled characteristics including size distribution, morphologies, and compositions. Thus, the process needs to be simple, low in cost, and have both continuous operation and high production rate to meet the industrial requirements. The synthesis method for nanoparticles and the development of nanoparticles dispersion technology will be reviewed; nanoparticles synthesis by pulse combustion spray pyrolysis to improve production rate and dispersion of nanoparticles by bead mill method. Furthermore, the availability of the raw materials are also very important to produce the end products economically. The current development on the graphite processing and the future development on the end product in Indone...

Droplet Generation and Nanoparticle Formation in Low-Pressure Spray Pyrolysis

In the present study, we found that pressure-dependent droplet-to-particle formation is important for the control of both droplet and particle characteristics during the production of particles with enhanced properties. Using experimental and simulation approaches, the present study investigated the droplet-to-particle formation of zinc oxide as a model material that was synthesized via low-pressure spray pyrolysis. The size distributions of both the droplets generated under low-pressure and the synthesized particles were measured and compared. The effects of operating conditions, i.e., operating pressure, carrier gas-, and liquid-flow rates, reactor temperature, and precursor concentration, on the characteristics of the generated droplets and synthesized zinc oxide particles were systematically investigated. We found that broad and bimodal droplet size distributions shifted to narrow and monodispersed distributions as chamber pressures were reduced. The low-pressure-synthesized zinc oxide nanoparticles were highly crystallized with unimodal distributions and sizes of approximately 8 nm. Droplet temperature decreased with decreasing chamber pressure, which confirmed both the evaporative cooling of droplets and the formation of smaller droplet sizes. The chamber temperature and droplet size simulation results were in accordance with the experimental results. In conclusion, we found that the chamber pressure is the primary determinant of monodispersity with respect to droplet size distribution and to the size and morphology of the synthesized particles.

Synthesis of lithium cobalt oxide using low-pressure spray pyrolysis

A low pressure spray pyrolysis (LPSP) process was applied to synthesize crystalline lithium cobalt oxide as a battery cathode material via a liquid route. The effects of temperature and pressure of reactor on the synthesized particles characteristics were systematically investigated. Reactor temperatures of 800, 1000 and 1200 °C with pressures of 760 and 300 Torr were applied as operating conditions. The characterizations results show that the synthesized particles were highly crystalline and nearly spherical in shape. The results concluded that the low-pressure spray pyrolysis method has ability in control of particles morphology, crystallinity and atomic lithium-to-cobalt ratio.

MOSFET-based high voltage short pulse generator for ultrasonic transducer excitation

This paper presents the generation of a high-voltage short pulse for the excitation of high frequency ultrasonic transducers. This is highly required in the purpose of various ultrasonic-based evaluations, particularly when high resolution measurement is necessary. A high voltage (+760 V) DC voltage source was pulsated by an ultrafast switching MOSFET which was driven by a pulse generator circuit consisting of an astable multivibrator, a one-shot multivibrator with Schmitt trigger input and a high current MOSFET driver. The generated pulses excited a 200-kHz and a 1-MHz ultrasonic transducers and tested in the transmission mode propagation to evaluate the performances of the generated pulse. The test results showed the generator were able to produce negative spike pulses up to -760 V voltage with the shortest time-width of 107.1 nanosecond. The transmission-received ultrasonic waves show frequency oscillation at 200 and 961 kHz and their amplitudes varied with the voltage of excitation pulse. These result...

Effect of binders on natural graphite powder-based gas diffusion electrode for Mg-air cell

This paper mainly discussed the electrical performance of gas diffusion electrode of Mg-Air Cell. The gas diffusion electrodes (GDE) use a natural graphite powder as catalyst material. The effect of additional binders to the GDE have been investigated to improve electrode performances. Several types of GDE have been developed using binder materials such as epoxy resin, natural clay, carboxymethyl cellulose (CMC) and urea-formaldehyde (UF). By using discharge performance measurement, the characteristics of the as-prepared GDEs are reported.

Development of Indonesia corncob and rice husk biobriquette as alternative energy source

Facing the increasing of fuel price and lacking of world oil resource, research for biobriquette as alternative energy for fossil fuel is conducted. Indonesia has considerable amount of biomass and it is still remain unused that can be used as biobriquette. As the initial research, Garut, Ciamis, and Sumedang district, West Java are selected which have rice husk and corncob commodities. In these disrticts, rice husk and corncob potency are respectively 4,460.73 tons and 3,222.85 tons and potentially result 57,572.86 GJ from husk and 60,911.86 GJ from corncob. To optimize mechanical properties and calorie value of biobriquette, research for calorie content and combination of rice husk and corncob are being conducted with various adhesive content and mixture. The best result of shatter index, durability, and calorie test on the corncob biobriquette is from biobriquette with 6% adhesive with calorie content as 5,516.85 kkal/kg. While the best calorie content for husk biobriquette is 6% adhesive with calorie ...

Improvement on droplet production rate of ultrasonic - nebulizer in spray pyrolysis process

Atomization is an important part in Spray Pyrolysis (SP) process which is applied to synthesize submicron or nano sized particles or to deposit thin film. Ultrasonic Nebulizer (UN) is usually use in SP due to its homogeneous droplets production with size between 1-5 μm. The drawback of the UN is low droplets production rate. In this research, we successfully developed a Digital Ultrasonic Nebulizer (DUN) with high droplets production rate using two ultrasonic traducers with applied frequency of 2.4 MHz. The result of DUN atomization was improved 4-6 fold compare to the conventional UN. The DUN also has an additional digital features such as pushbutton, LCD and microcontroller which is allow to set duration and applied voltage.