Mochamad Zainuri

Synthesis of SiO2 nanopowders containing quartz and cristobalite phases from silica sands

Abstract In this study, extraction and synthesis of SiO2 nanoparticles from silica sands have been conducted by means of two different methods, i.e. dry method (method 1) and hydrothermal process (method 2). The basic difference between the two methods is in the extraction step. The two methods were compared in terms of being more efficient, economical, and superior in obtaining SiO2 nanoparticles. The SiO2 nanoparticles were characterized in terms of phase purity, crystallinity, Si-O functional bonding as well as particles size and morphology. The most interesting fact in this study was the formation of both quartz and cristobalite phases within all prepared SiO2 nanoparticles.

Various Magnetic Properties of Magnetite Nanoparticles Synthesized from Iron-sands by Coprecipitation Method at Room Temperature

Natural sand-based magnetite nanoparticles have been succesfully synthesized by coprecipitation method at room temperature. Magnetite nanoparticles were investigated by X-ray Diffractometer (XRD) and Vibrating Sample Magnetometer (VSM). The morphology of magnetite nanoparticles has been evaluated by Transmission Electron Microscopy (TEM). Qualitative analysis of XRD data reveals that the structure of magnetite nanoparticles have the same phase of ICSD No. 82237. On the other hand, quantitative analysis shows that the crystallite size of magnetite nanoparticles have ranges between 8.89 nm to 12.49 nm. The average diameter of magnetite nanoparticles increase with the increase the stirring rate of reaction when the stirring rate is lower than 1000 rpm, while the crystallite size of magnetite particles decrease with the increase the stirring rate when the stirring rate is higher than 1000 rpm. The stirring rate of reaction influence the the magnetic properties of magnetite nanoparticles. The results of the best magnetic respon are revealed for the stirring rate of 1000 rpm with the larger the crystallite size of magnetite nanoparticles due to its stronger saturation magnetization.

Synthesis of microforsterite using derived-amorphous-silica of silica sands

Synthesis of microforsterite (Mg2SiO4) has been successfully done by a simple method benefiting of the local silica sands from Tanah Laut, Indonesia. The starting material was amorphous silica powder which was processed using coprecipitation method from the sands. The silica powder was obtained from a series of stages of the purification process of the sands, namely magnetic separation, grinding and soaking with HCl. The microforsterite synthesis followed the reaction of stoichiometric mole ratio mixing of 1:2 of the amorphous silica and MgO powders with 3 wt% addion of PVA as a catalyst.The mixture was calcined at temperatures between 1150-1400°C with 4 hours holding time. XRD data showed that calcination at a temperature of 1150°C for 4 hours was optimum where the weight fraction of forsterite can reach as much as 93 wt% with MgO as the secondary phase and without MgSiO3. SEM photograph of the microforsterite showed tapered morphology with a relatively homogeneous distribution.

Microstructure and Magnetic Properties of Barium Hexaferrite Produced by Sol Gel Auto Combustion for Radar Absorber Material (RAM) Application

Barium hexaferrite (BaFe12O19) with hexagonal structure has been known as the high performance magnetic for Radar Absorber Material (RAM). Barium hexaferrite (BaM) was synthesized by sol gel auto combustion to get an homogeneous nanoparticle of BaM. Barium hexaferrites obtained from solution mixture between barium nitrate and ferri nitrate nonahidrat with precipitation of ion barium (Ba2 +) and ferri (Fe3 +) by solution of sodium hydroxide. Sample prepared with mol ratio of Fe / Ba 11 then added ammoniac in order that pH varies become 7,5; 9; and 11. Citric acid added in order that happen process of combustion. The stirring time was varieties by 1, 2, 3 hours. The effect of pH, stirring time, microstructure, phase,and magnetic properties were investigated using X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and a vibrating sample magnetometer (VSM). The results showed that the highest coercivity was 0.6 Tesla and the smallest crystal size 414.409 nm was obtained for pH 7.5 and stirring time 2 hours. The largest magnetic saturation 55.54 emu /g was reached for pH 7.5 with stirring time 1 hour

Magneto-elasticity in hydrogels containing Fe3O4 nanoparticles and their potential applications

The magnetic hydrogels have been fabricated via standard method of polymer preparation. Hydrogels were the mixture of polyvinyl alcohol (PVA) and water by certain ratio of mass. Magnetism in hydrogels was presented by introduction of magnetic Fe3O4 nanoparticles with crystal size ranging from 11 nm to 15 nm, prepared by coprecipitation technique from iron-sands. According to the magnetic induction experiment, it has shown that the magneto-elasticity of gels containing Fe3O4 of around 2.5% – 15% tends to decrease as increasing Fe3O4 concentration. The magneto-elasticity responses of the gels clearly form hysteresis in the increasing and decreasing applied magnetic field, where in turn open the potential applications of these magnetic hydrogels.

Effect of calcination temperature on the photocatalytic activity of TiO2 powders prepared by co-precipitation of TiCl3

The adsorption of basic dye methylene blue (MB) onto titanium dioxide (titania) powder that were prepared by coprecipitation method of TiCl3 and NH4OH as iniatial material with different calcination temperature was studied to examine the photocatalytic activity. Synthesis process carried out by the solution pH was adjusted to be 8. Effect of calcination temperature on the titania powder were characterized with Differential Scanning Calorimetry/Thermogravimetry (DSC/TG), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The result of TG and XRD showed that the NH4Cl decomposed between 235-372°C. The XRD result showed that the anatase TiO2 only contained a single phase when the calcination temperature of the precursor at 800°C, and over which it began to grow rutile phase. The influence of synthesis condition on the photocatalytic activity of TiO2 powder was determined by the photodegradation of MB dye under UV light.

Synthesis of LiFePO4/C composites based on natural iron stone using a sol gel method

Synthesis of LiFePO4/C composites has been carried out using a sol gel method. The Fe precursor was made from a natural iron stone of Tanah Laut, South Kalimantan, while the other raw materials were commercial Li2CO3 powder and NH4H2PO4 powder with HCl and water as solvents. Citric acid was used as the carbon source in the synthesis. This study used a molar ratio of 1:1:2 for Li:Fe:P with variation of added citric acid of 1.5 and 2.5 g. The solutions were dried in air at 100°C. The dried powders were characterized using DSC-TGA and then calcined at 600 and 700°C under argon environment for 10 hours. The calcined powders were characterized by X-ray diffractometry (XRD), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), and LCR meter. It was found that the samples contained LiFePO4 as the dominant phase and LiFeP2O7 and Fe2O3 as secondary phases. The analysis showed that the addition of citric acid influenced the electronic conductivity of the composites. A Rietveld relative weight fraction of...

Interfacial reactions and wetting in Al-Mg sintered by powder metallurgy process

Was conducted to analyze the effect of temperature variation on the bonding interface sintered composite Al-Mg and analyze the effect of variations of the density and hardness sinter. Research carried out by the base material powders of Al, Mg powder and solvent n-butanol. The method used in this study is a powder metallurgy, with a composition of 60% volume fraction of Al - 40% Mg. Al-Mg mixing with n-butanol for 1 hour at 500 rpm. Then the emphasis (cold comression) with a size of 1.4 cm in diameter dies and height of 2.8 cm, is pressed with a force of 20 MPa and held for 15 minutes. After the sample into pellets, then sintered at various temperatures 300 °C, 350 °C, 400 °C and 450 °C. Characterization is done by using the testing green density, sintered density, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), vickers microhardness, and press test. XRD data analysis done by using X’Pert High Score Plus (HSP) to determine whether there is a new phase is formed. Test results show that the sin...

Influence of pH on the formulation of TiO2 powder prepared by co-precipitation of TiCl3 and photocatalytic activity

Titanium dioxide (titania) nanoparticle were synthesized by coprecipitation process of titanium trichloride (TiCl3) in aqueous medium, with NH4OH as pH regulator. The pH solution was varied during the synthesis process between pH 3-8.4, and all samples were calcined temperature at 400°C for 3 hours. Characteristics and properties of the TiO2 powder were investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). XRD results show that the single-phase rutile formed when the pH is less than 5, anatase single phase formed began pH 8, and the pH of the solution between 5-8 formed mixed phase rutile-anatase-brookite, rutile-brookite or anatase-brookite. Methylene Blue (MB) photodegradation test were performed in order to evaluate photocatalytic activity. Nanoparticles TiO2 rutile, anatase phase, and mixed phase rutile-brookite, anatase-brookite used to test the photocatalytic activity by measuring the absorbance spectrum photodegradation using UV-Vis spectrometer. The test results showed th...

Synthesis of nano-forsterite powder by making use of natural silica sand

Nano-forsterite powder with natural silica sand and magnesium powder as the raw materials have been succesfully synthesized. The silica sand was purified followed by a coprecipitation process to obtain colloidal silica. The magnesium powder was dissolved in a chloric acid solution to obtain MgCl2 solution. The nanoforsterite powder was synthesised using a sol-gel method which included the mixing the colloidal silica and the MgCl2 solution with various aging and filtering processes. The samples were dried at 100 °C using a hot plate and then the dried powders were calcinated at 900 °C for 2 hours. The samples were characetised for their elements and phase compositions using X-ray Flourescence (XRF) and X-ray Diffraction (XRD) methods, respectively. The diffraction data were qualitatively analyzed using Match!2 software and quantitatively using Rietica software. The crystallite size was verified using Transmission Electron Microscopy (TEM). Results of XRD data analysis showed that the forsterite content rea...