Indonesia adalah negara dengan potensi alam yang melimpah, khususnya bahan tambang (mineral), diantaranya material-material dengan kandungan oksida yang mempunyai prospek aplikasi sebagai material cerdas (misalnya SiO2, CaCO3, Al2O3,TiO2, dsb). Tujuan dari penelitian ini adalah mencari atau mengidentifikasi kandungan unsur oksida didalam bahan alam jenis batuan atau pasir kuarsa dengan kemurnian tinggi (> 50%), khususnya sebagai sumber oksida SiO2 (silica) dan CaCO3 (calsite). Selanjutnya bahan-bahan tersebut akan diproses dengan milling proses serbuk (ukuran mikron) untuk, peningkatan kemurnian tinggi dan pengecilan ukuran pada orde nanometer. Identifikasi awal adalah melakukan uji difraksi Sinar-X (XRD) dan analisisnya (kualitatif) serta uji flouresensi sinar-X (XRF). Telah dilakukan uji XRD dan XRF pada sampel batuan yang diambil dari daerah Tulungagung, onik dari pulau Bawean-Gresik, dan pasir dari Tuban dan Sumenep. Hasil difraksi sinar X (XRD) bahan alam (batuan dan pasir) yang diambil sebagai sampel yang diambil dari beberapa daerah tersebut, diperoleh bahwa Batu_1(onik) dan Batu_2(putih) menunjukan bahwa sampel tersebut mempunyai fase dominan struktur kristal Calsite (CaCO3), dan untuk pasir dari Tuban dan Sumenep mempunyai fase dominan quartz (SiO2), demikian. Dan hasil XRF menunjukan kandungan CaCO3 pada sampel batuan (onik) cukup tinggi (98,23%), dan untuk sampel pasir (Tuban dan Sumenep) menunjukan kandungan oksida quartz (SiO2) dengan kemurnian yang tinggi (65,9 -76,8 %), dengan impuritas terbanyak CaO dan Fe2O3 (20-28%).
Pemurnian, ekstrak dan sintesis nanosilika dari bahan dasar pasir kuarsa yang diambil di daerah Bancar Tuban (utara Pulau Jawa-Indonesia) telah dilakukan pada penelitian ini. Secara fisik pasir Bancar Tuban mempunyai bentuk butiran agak kasar dan berwarna kuning cerah. Pasir Bancar mempunyai unsur atom Si (69%Wt), dan unsur atom pengotor dominan adalah Ca (7,5%wt) dan K (4,8%wt). Pola difraksinya menunjukan intesistas dominan terjadi pada sudut (2 theta) ~26o, fase quartz (paling stabil di alam). Ukuran serbuk pasir yang telah dihaluskan sekitar 5-50 mikrometer. Sintesis nanosilika berbasis pasir alam digunakan metode basah, yang terdiri dari dua proses, yaitu: (1) serbuk pasir diproses dengan metode hidrotermal dengan menggunakan senyawa alkali (NaOH) dengan molaritas 7M, hingga diperoleh larutan bening sodium silikat (Na2O.xSiO2), dan (2) larutan sodium silikat berperan sebagai prcursor diproses dengan metode co-presipitasi, larutan sodium silikat dititrasi dengan HCl 2 M hingga diperoleh bubur silicite Si(OH)4. Produk akhir berupa serbuk silika dengan struktur amorf dan kristal (quartz); kemurnian (%Wt Si) mencapai 95,7% dan analisis marfologi menunjukan bahwa partikel SiO2 cenderung membentuk aglomerasi dan ukuran partikel yang tidak beraglomerasi teramati berukuran sekitar ~58 nm.
<pre>Calcium oxide (CaO) and calcium carbonate (CaCO3) are widely used in industry. CaO and CaCO3 can be synthesized or derived from limestone. The purpose of this study to determine the characteristics of CaO calcined limestone from Ambunten Sumenep. Lime in calcined at 850 ° C for 6 hours. Characterization of X-ray fluorescence (XRF) was conducted to determine the chemical composition of limestone, X-ray diffraction test (XRD) to find the lime crystalline phase and FTIR test to determine the absorption of wave number. XRF test results showed that the limestone chemical composition consisted of Ca of 95.37% as the dominant element, Mg of 4.1%, Fe 0.17% and Y by 0.39%. The XRD test results showed that the limestone crystal phase is ankerite (Ca [Fe, Mg] [CO3] 2) and after the calcined phase calcination is vaterite (Ca [OH] 2), calcite (CaO) and calcite (CaCO3). While the FTIR test results show that the CaO spectra are seen at 3741.24, 1417.12 and 874.14 cm</pre><sup>-1</sup><pre>.</pre>
Sintesis dan karakterisasi komposit PANi-SiO 2 dengan pengisi gel SiO 2 telah dilakukan dengan menggunakan metode polimerisasi in-situ. Gel SiO 2 disintesis dari silika hasil pemurnian pasir Bancar Tuban menggunakan metode kopresipitasi dengan variasi sebanyak 5gr, 10gr dan 15 gr. Selanjutnya PANi-Gel SiO 2 disintesis dengan 2 jenis metode yaitu metode stirrer dan ultrasonik. Pada penelitian ini komposit PANi-gel SiO 2 dikarakterisasi menggunakan X-ray Diffratometer (XRD), Fourier Transform Infrared (FTIR) dan SEM-EDX. Hasil karakterisasi menunjukkan bahwa fasa terbentuk selama sintesis PANi-gel SiO 2 adalah semikristalin (amorf + kristal). Dalam pengamatan secara mikrostruktur, penambahan gel SiO 2 dalam proses sintesis komposit PANi-SiO 2 mempengaruhi sifat dan struktur kehomogenan dari komposit PANi-SiO 2 menjadi lebih homogen. Kehomogenan struktur komposit PANi-SiO 2 ditandai dengan jarak antar partikelnya yang sempit dan persebaran unsur Si yang merata dalam komposit PANi-SiO 2 ketika variasi kandungan Si pada gel SiO 2 semakin banyak. Sedangkan berdasarkan metode yang digunakan untuk mensintesis komposit PANi-SiO 2 didapatkan hasil bahwa komposit PANi-SiO 2 metode stirrer memiliki struktur yang lebih homogen daaripada komposit PANi-SiO 2 metode ultrasonik.
In this research ZrO2 has been synthesized from Kereng Pangi zircon sand in Central Kalimantan through alkali fusion-coprecipitation method. Firstly, zircon sand (ZrSiO4) was purified to reduce impurities by magnetic separation, cleaned using an ultrasonic cleaner, soaked/leached with HCl 2 M for 12 hours and leached with HCl at 60 ºC for 3 hours. Secondly, alkali fusion was done with KOH as an alkali. This product was then washed by water and dried before leached with HCl 30% at 90 ºC for 30 minutes to precipitate and seperate Silica from Zircon. ZrO2 filtrate (ZrOCl2) precipitated with NH4OH at pH 4, pH 7, and pH 10 forms Zr(OH)4 gel. Zr(OH)4 gel was dried and characterized by DTA-TGA, which was then followed by calcination based on DTA TGA results at temperature ranges of 550 ºC - 700 ºC to produce ZrO2. XRD results show that single tetragonal phase of ZrO2 is formed in all variations of pH precipitation and calcination temperature. An analysis using MAUD software show that crystal size reduces as the increase in precipitation of pH. The crystal size results are 110 nm, 66 nm and 48 nm at pH 4, pH 7 dan pH 10 at 700 ºC, respectively. Moreover, XRF results show that ZrO2 with purity is at around 95.8 % at pH 4 and 96.3 % at pH 7 and pH 10.
A set of ceramic powders has been synthesized using a "bottom-up" approach which is denoted here as the dissolution method. The raw materials were metal powders or minerals. The dissolution media were strong acid or base solutions. In the case of metallic raw materials, magnesium and titanium powders were separately dissolved in hydrochloric acid to obtain their precursors. They were then dried, washed, and calcined in air at various temperatures to produce pure MgO and TiO 2 nano-powders. Pure MgTiO 3 nano-powders by mixing the precursors at the stoichiometric ratio and calcining the dried mixture at a temperature as low as 700°C have also been successfully synthesized. In the mineral case, local zircon sand was used as the raw material. A standard procedure to extract the "clean" and pure zircon powder was applied which included washing, magnetic separation, and reactions using hydrochloric acid and sodium hydroxide. A pure zircon nano-powder was obtained by applying mechanical ball-milling to the zircon powder. The zircon powder was also chemically dissociated to give amorphous silica (SiO 2 ), cristobalite, amorphous zirconia (ZrO 2 ), and nanometric tetragonal zirconia powders.
The thermomechanical properties of polyethylene glycol (PEG) composites filled with various zircon sizes were studied. The zircon powders were derived from natural (well-known as puya) sand collected from Kereng Pangi, Central Kalimantan, Indonesia. The effects of the zircon size and content were examined to understand the thermomechanical properties of the composites using dynamic mechanical analysis in shear mode. Pure zircon powders with micron to nanometer sizes were prepared. The microzircon powders were prepared by heating zircon at 500, 1000, and 1200 C. Moreover, the nanozircon powders were prepared by a wet milling method with milling times of 5, 10, and 15 hours. Furthermore, the composites were prepared by a wet mixing method. According to elemental analysis of scanning electron microscopy/energy dispersive X-Ray spectroscopy (SEM/EDX) data, it was found that the various zircon sizes caused different distribution effects, that is, in general, the smaller the size was, the better the distribution. Filler size variation also affected the thermomechanical properties of the composites. The addition of microzircon heated at 1200 C had the lowest storage moduli (G'), that is, 154.90 MPa and 155.55 MPa for 5 wt.% and 10 wt.%, respectively. Moreover, the maximum value of G' was obtained for the composite with the addition of nanozircon milled for 10 h (Z10h), that is, 679.27 MPa and 706.37 MPa for 5 and 10 wt.%, respectively. The addition of nanozircon slightly reduced roomtemperature G', presumably due to the agglomerated filler, as confirmed by the SEM/EDX data. Moreover, a decrease in zircon size caused an increase in the melting temperature (T m ) of the matrix. In contrast, 15 h of milling had a minor effect on T m and G', whereas the loss modulus (G") decreased with the addition of nanozircon. The effects of filler size on the thermomechanical properties of PEG/zircon composites are discussed in detail. K E Y W O R D Snano-and micron-sized filler, PEG, thermomechanical properties, zircon
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