The role of SiC on the Desorption Temperature of Mg-based Hydrogen Storage Materials Prepared by Intensive Milling Method

Magnesium, theoretically, have the ability to absorb hydrogen in large quantities (~ 7.6 wt%). However, the kinetic reaction is very slow, thereby hindering the application of magnesium for hydrogen storage material. In this paper, we reported a series of preliminary studies on magnesium inserting with silicon carbide (2 wt%)obtain by mechanical milling method. The vibratory mill type apparatus was used for 180 hours. As the results, structural characterization by XRD showed that the crystallite size after milling for 180 hours decreased around tens nanometer. It was also found that the desorption temperature for the sample after 180 milling inform us that the material decomposed at 330°C. It can concluded that Mg catalyzed with 2 wt% of silicon carbide (SiC) can be prepared by vibratory ball milling.

CHARACTERISTICS OF NATURAL MAGNETITE (Fe3O4) FROM BEACH SAND AS CATALYST APPLICATION IN MATERIALS INDUSTRY

An identification of magnetite nanoparticles synthesized from natural iron sand using co-precipitation method has been conducted. The treatment was undertaken at room temperature and the heating used a pair of acid-base compounds, namely HCL as a solvent and NH4OH as a precipitate. Crystal structures, percentages of elements, particle sizes and magnetic characteristics of the materials were characterized by testing XRF, XRD and Permagraph. The results were then compared with the commercial material purchased from Aldrich (with 97% purity). From the results, it was found that the percentage value of the purity of Fe3O4 derived from natural sand before the extraction was 81.42%, and after the extraction it increased to 86.73%. Furthermore, the saturation magnetization (Ms) value for Fe3O4 ferrite from iron sand was 0.29 T, the residual magnetization or Remanen (Br) was 0.081 T, and Coersivity (Hc) was 1.82 kA/m

Adisi Fe2O3 danSiCPada Material MgH2 untuk Aplikasi Tangki Penyimpanan Hidrogen Kendaraan Fuel Cell

The preliminary studies on MgH2 as hydrogen storage material by inserting dual catalysts, iron oxide and silicon carbide (5wt% Fe2O3 and SiC), has been done. The sample was prepared using reactive ball milling technique for 10 hours. The milling process was done under 10 bar hydrogen pressure. Phase investigation using X-ray diffraction showedthat after 10 hours of milling, the MgH2 emerged as the dominant phase and the crystallite size decreased to nanometer scale. The morphological observation obtained by scanning electron microscope showed that the powder material surface is irregular, as a result of repeated during the milling process. Finally,DTA scan showed the onset temperature at 354o Cwhich is still high for the automotive application. Keywords: hydorgen storage, magnesium, metal oxide, silicon carbide, millin

Analysis of Crystallinity and Physical Properties of the Bio-solar Gemstone

Abstract – Bio-solar is one of the natural gemstones found in the province of Aceh in Indonesia. A recent study suggested that this gemstone could be considered as a vesuvianite type of gemstone. Nevertheless, detail information of this bio-solar gemstone is still unknown. We do not know whether the bio-solar gemstone is crystalline or amorphous. The specific gravity and the hardness of this gemstone are also still unknown. This information is essential to determine the quality of a gem. To answer those questions, we have used x-ray diffraction to study the bio-solar gemstone from the province of Aceh in Indonesia. The physical properties (specific gravity and hardness) of this gemstone have also been measured. We found that the bio-solar gemstone is composed by CaO, SiO2, MgO, Al2O3, Fe2O3, and TiO2 phases. Our results revealed that the bio-solar gem is a crystalline material, not amorphous. The average crystallite size of this gemstone is found to be 353 Å (35 nm). Moreover, the specific gravity of bio-solar gemstone is found to be 3.09 – 3.34. Its hardness is 3 to 4 mohs. Thus, the bio-solar is a good quality gemstone. Our finding confirmed that the bio-solar could be classified as a vesuvianite gemstone

Identifikasi Kandungan Unsur pada Pasir Kuarsa Menggunakan Metode X-Ray Flourescence di Kecamatan Samadua, Aceh Selatan : Identification of Elemental Contents in Quartz Sand Using the X-Ray Flourescence Method in Samadua District, South Aceh

Quartz sand is a non-metallic natural resource that can be used to develop various kinds of human needs, however, it is necessary to know in advance the amount and elements contained therein. This research will conduct a study related to the amount of element concentration in quartz sand in Samadua District, South Aceh Regency. The research method used in this research is the X-Ray Fluorescence technique. The results showed that the elements found in the quartz sand samples were Si, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Sr, Ba, and Eu. From these results, there are three elements that have the highest concentration, namely the element Si as much as 62%, Ca as much as 15.7%, and element K as much as 13.7%

Characteristics and Mineral Content of Sediment at Muara Pulau Kayu (MPK) of Southwest Aceh District

Study on sediment characteristics and mineral content at Muara Pulau Kayu (MPK) of Southwest Aceh District was conducted to find a general description of grain size and mineral content regarding to hydro-oceanographic process. Sampling was collected at MPK, Southwest Aceh District during March 2016. Purposive sampling method was used to determine 4 sampling sites covering estuary and beach area. Grain size and mineral content were analyzed with a set of sieves and X-Ray Fluorescence (XRF with standard reference mineral). Observation on the grain roundness and sphericity showed that sediment grains are generally more rounded at beach area. Mineral content at MPK are dominated by Si, Fe, K, Ca and Ti that are categorized into volcanic mineral which conclude that sediment at MPK originated from Mount Leuser which was an active volcano in the past

Penerapan Pembelajaran Kontekstual Untuk Meningkatkan Kemampuan Berpikir Logis Dan Pemahaman Peserta Didik SMP Pada Materi Sifat-sifat Cahaya

Penelitian penerapan pembelajaran kontekstual pada materi sifat-sifat cahaya telah dilakukan di SMP Negeri I Meulaboh, Aceh Barat menggunakan metode eksperimen semu dengan desain pretest dan posttest group. Teknik pengambilan sampel secara purposif dengan membandingkan nilai rata-rata tiap kelas pada mata pelajaran sains. Dua kelas yang memiliki nilai yang sama dipilih sebagai kelas eksperimen dan kontrol. Pengumpulan data kemampuan berpikir logis (KBL) dan pemahaman peserta didik dilakukan melalui pretest dan posttest. Data KBL juga diperoleh dari lembar observasi dalam PBM sains. Uji data pretest KBL dan pemahaman kedua kelas menunjukkan bahwa salah satu data tidak berdistribusi normal, sehingga dipergunakan uji Mann-Whitney untuk menguji hipotesis penelitian. N-gain rata-rata KBL untuk kedua kelas berkategori tinggi dan uji hipotesis diperoleh z-hitung>z-tabel (2,87 > 2,58) yang artinya pembelajaran kontekstual dapat meningkatkan KBL secara lebih baik. Hasil observasi juga menunjukkan bahwa nilai rata-rata KBL pada kelas eksperimen lebih tinggi dari pada kelas kontrol. N-gain rata-rata pemahaman untuk kedua kelas berkategori sedang dan uji hipotesis menunjukkan z-hitung>z-tabel (2,92>2,33) yang artinya pembelajaran konstekstual meningkatkan kemampuan pemahaman peserta didik secara lebih baik. Dari hasil penelitian dapat disimpulkan bahwa pembelajaran kontekstual secara signifikan dapat meningkatkan KBL dan pemahaman peserta didik secara lebih baik pada materi sifat-sifat cahay

The Effect of Magnetite (Fe3o4)catalyst From Iron Sands on Desorption Temperature of Mgh2 Hydrogen Storage Material

One of the future technologies for a safe hydrogen storage media is metal hydrides. Currently, Mg-based metal hydride has a safety factor and efficient for vehicle applications. However, the thermodynamic properties of magnesium hydride (MgH2) found a relatively high temperature. High desorption temperatures caused MgH2 high thermodynamic stability resulting desorption enthalpy is also high. In this study, natural mineral (iron ore) has been extracted from iron sand into powder of magnetite (Fe3O4) and used as a catalyst in an effort to improve the desorption properties of MgH2. Magnetie has been successfully extracted from iron sand using precipitation method with a purity of 85 % , where the purity of the iron sand before extracted was 81%. Then, MgH2-Fe3O4 was milling using mechanical alloying method with a variety of catalysts and milling time. The observation by XRD showed the material was reduced to nanocrystalline scale. MgH2 phase appears as the main phase. DSC test results showed with the addition of Fe3O4, the desorption temperature can be reduced up to 366oC, compared to pure pure MgH2 reached by 409o C. Furthermore, based on gravimetric test, the hydrogen release occurs at a temperature of 388o C, weight loss of 0.66 mg during 16 minutes