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"In this investigation, SnO2-glass composites were produced by mixing SnO2 and amorphous silica xerogel (SX) extracted from sago waste ash. The composition was prepared by adding 5 mol% of SnO2 into SX; the samples were dry pressed and sintered in a temperature range between room temperature and 1500oC. Their properties were characterized on the basis of the experimental data obtained using Archimedes’ principle, X-ray diffraction (XRD), Fourier transformed infra-red (FTIR), and a scanning electron microscopy (SEM). It was found that the bulk density increased along with the sintering temperature. In the temperature range from 1300oC to 1500oC, the glass ceramic reached a bulk density of about 2.5 g/cm3. The results of the interpretation of XRD patterns, FTIR spectra, and SEM images allow us to conclude that this increase in density was due to an increased degree of crystallinity of SnO2 in the silica xerogel composite."

"ABSTRAKStudy Magnetoimpedance material nano soft magnetic Fe-(Al,Ga)-(P,C,B,Si),yang merupakan material amorf berbasiskan Fe dalam bentuk pita dengan lebar 4mm dan tebal 40 µm yang dipreparasi dengan metode melt-spinning dan diberikanperlakuan panas melalui teknik joule heating dilakukan dengan tujuan untukmengetahui hubungan magnetoimpedance dari material ini dengan struktur mikronyabaik sebelum ataupun setelah mengalami perlakuan panas serta bagaimanapengaruhnya terhadap sifat-sifat magnetik yang sudah ada.Karakterisasi struktur terhadap sampel dari material ini menunjukkan bahwaperlakuan annil melalui teknik joule heating sampai 1.6 A pada sampel menyebabkanterjadinya relaksasi struktural yang membuat penurunan anisotropi dan berakibat padapeningkatan sifat kemagnetan lunak dari sampel.Pengaruh medan magnet luar terhadap sampel pada frekuensi rendahmenyebabkan terjadinya pengurangan nilai impedansi dari sampel."

"ABSTRAKPenelitian tentang bahan amorphous soft magnetic yang lelah diketahui memilikisifat unggul sekarang ini dilakukan sangat intensif. Hal ini dimotivasi tentangluasnya aplikasi bahan ini pada berbagai teknologi seperti sensor yang sensitif.Bahan amorphous soft magnetic ini karena memiliki permeabilitas tinggi,korsivitas rendah dan magnetostriksi kecil, telah diselidiki menunjukkanfenomena magnetoimpedance, yaitu adanya perubahan nilai impedansi bahan biladialiri arus listrik AC dan dibawah pengaruh medan magnet luar.Pada penelitian ini diselidiki beberapa bahan amorphous soft magnetic yaituFe73Al5Ga2P11-xC5B4Six ( x = 1,3 ) Finemet, dan Fe86Cu1Zr7B6 atau nanoperm,untuk mengetahui adanya fenomena magnetoimpedance dengan cara mengalirkanarus AC pada bahan dan memberikan pengaruh magnet luar yang bersumber darikumparan yang berarus listrik. Selanjutnya diukur impedansinya dengan RLCmeter ketika medan magnet luar belum diberikan maupun ketika diberi medanmagnet luar. Dari pengukuran tersebut dibuat hubungan antara impedansi ( Z )terhadap frekuensi, dan medan magnet luar ( H ) untuk mengetahui adanyafenomena magneto impedansi.Karena pada penelitian ini frekuensi yang diberikan antara 100 KHz sampaimaksimum 1 MHz dan medan magnet luar maksimum 2800 A/m, maka fenomenamagnetoimpedansi yang muncul tidak terlalu besar. Diperoleh Sampel Si-1menunjukkan perubahan magnetoimpedansi yang terbesar karena dari hasil XRDdiperoleh bahwa Si-1 mempunyai ukuran butir terkecil, berarti paling amorf."

"kerak silika merupakan masalah utama yang dominan terjadi pada lapangan panasbumi yang didominasi oleh brine (liquid dominated). Kerak silika tidak dapat dihilangkan baik dengan cara kimia, fisika maupun mekanik sehingga biasanya yang dilakukan adalah upaya menghambat. Untuk itulah maka dilakukan pengujian inhibitor antiscale menggunakan campuran polimer asam poliakrilat (PAA) dan asam borat (BA). Pengujian dilakukan menggunakan pipa uji dan pipa blank. Pipa uji menmpunyai dua tempat pengambilan sampel (port) yaitu port untuk injeksi di hulu dan port sampling di hilir Sedangkan untuk pipa blank hanya terdapat pipa port sampling di hilir. Pengambilan sampel dilakukan 1 hari setelah injeksi untuk memastikan terjadi homogenisasi antara inhibitor dan brine di pipa uji. Pengambilan sampel dilakukan setiap hari dan dianalisa di lab PT Geodipa Energi Unit Dieng. Campuran inhibitor di variasikan perbandingan konsentrasi 10 ppm:8 ppm, 15 ppm:5 ppm, dan 20 ppm:3 ppm hingga didapat kondisi optimum yang mampu menghambat pencegahan pembentukan kerak silika. Setiap variasi perbandingan konsentrasi dilakukan selama 7 hari dengan pengambilan sampel sebanyak 5 kali selama 5 hari. Setelah dilakukan pengujian maka untuk campuran asam poliakrilat dan asam borat dengan perbandingan 10 ppm dan 8 ppm memiliki efektifitas sebesar 67,22%. Sedangkan untuk perbandingan 15 ppm dan 5 ppm memiliki efektifitas 44,54%. Untuk perbandingan konsentrasi 20 ppm dan 3 ppm memiliki efektifitas 54,94%."

"Dengan semakin menipisnya cadangan energi dunia, dan rusaknya lingkungan hidup yang mengakibatkan pemanasan global, sudah semestinya untuk mencari alternatif pembuatan alat mesin pendingin yang hemat energi dan ramah lingkungan. Alat tersebut adalah mesin pendingin adsorpsi. Mesin pendingin adsorpsi memerlukan pasangan adsorbat dengan adsorben yang ideal. Proses adsorpsi dan desorpsi adalah salah satu cara atau metode yang efektif untuk membuat siklus pendingin. Adsorpsi adalah fenomena fisik yang terjadi antara molekul-molekul gas atau cair dikontakkan dengan suatu permukaan padatan, untuk itu perlu penelitian karakteristik lebih lanjut adsorbat uap-air dengan silika gel sebagai adsorben pasangannya. Karakteristik adsorpsi merupakan salah satu parameter yang menentukan kemampuan adsorben menyerap adsorbat. Di dalam penelitian ini silika gel merek Merck KGaA digunakan sebagai adsorben dan uap-air menjadi adsorbatnya. Pengujian kapasitas penyerapan uap-air terhadap silika gel sebagai adsorben pasangannya dilakukan dengan alat uji adsorpsi kinetik untuk mengetahui karakteristik adsorpsi. Alat uji adsorpsi kinetik dirancang dan dibuat dengan metode volumetrik dapat digunakan mengukur tekanan dan temperatur per detik. Perhitungan data unjuk kerja alat uji adsorpsi kinetik mengunakan persamaan gas ideal untuk menghitung kapasitas dan laju penyerapan. Dari hasil uji dengan alat adsorpsi kinetik, kapasitas penyerapan uap-air terhadap silika gel (SiO2) 0,197 mg/gadsorben pada tekanan 39,083 mbar dengan temperatur 30°C dan 0,296 mg/gadsorben pada tekanan 38,925 mbar dengan temperatur 32°C sedangkan pada kondisi isotermal temperatur 35°C memiliki kapasitas penyerapan 0,9 mg/gadsorben.

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By distinction of the world resource energi, and environmentally break down could be impact to global warming and. It need to look for the alternative one to make the environmentally ? friendly of refrigeration machine and power saver, that called adsorption refrigeration. The adsorption refrigeration need the ideal adsorbent and adsorbate pair. The adsorption and de-sorption process is one of the effective method to generate the refrigeration cycle. The adsorption is physical phenomena that occurs between gas molecules or liquid that contact over the surface, hence it is important to study the characteristic of water vapor towards silika gel and its adsorbate. The adsorption characteristic is the parameter to determine the capable of adsorbent to adsorb adsorbate.

In this study the silika gel Merck KGaA type used as adsorbent and water vapor as its adsorbate. The experimental of water vapor capacity adsorption over the silika gel carried out by adsorption kinetic apparatus. The adsorption kinetic apparatus designed by volumetrik method, that could be used to measure pressure and temperatur persecond. The calculation data performance of this adsorption kinetic using the gas ideal equation. From the experimental data found the capacity of adsorption is 0,197 mg/gradsorben for 30°C and 0,296 mg/gradsorben for isotermal of 32°C and the biggest capacity is 0,9 mg/gradsorben at isotermal 35°C."

"The synthesis of silica from rice husk ash has been studied. The purification has been done by adding acid solution and by heating. The sample heated in the temperature range of 700 - 1000°C. The characterization was done by means of the X- Ray diffraction, Electron microscope and X-ray Fluorescence. The results show the RHA after burning contain 59.72 % wt, after heating the weight fraction of silica increase, 700°C around 84.59%, 850°C around 85.75 % and 1000°C around 87.55 %. Electron microscope shows the evolution of microstructure on heating. From the evolution of impurity elemens in the RHA, it is concluded that the increased of silica contained is due to decrease of potassium contain in the RHA."

"The series of hybrid organic-inorganic silica materials have been prepared by introducing organic ligands materilas based on sol-gel processing of alkoxysilanes for potential applications in membrane design for pervaporation....."

"[ ABSTRAK Kaca merupakan sumber silika amorphous yang baik serta memiliki komposisi kimia dan reaktivitas yang tepat untuk melakukan reaksi Pozzolan. Sehingga muncul lah ide untuk menggunakan kaca sebagai agregat kasar pada beton. Pada penelitian ini, sampel yang dibuat adalah dua jenis beton, yaitu Portland dan Geopolimer dengan variasi substitusi kaca sebanyak 0%, 25%, 50%, 100%. Pengujian yang dilakukan adalah uji tekan dan pengamatan foto makro. Komposisi beton, sejarah perlakuan, dan suhu curing memberi pengaruh signifikan pada nilai kuat tekan yang dihasilkan. Kesimpulan yang didapatkan adalah beton Portland dan beton geopolimer dengan substitusi kaca sebesar 50% memiliki kuat tekan tertinggi, dan pasta geopolimer dapat melekat pada kaca namun pasta semen tidak.

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ABSTRACT

Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not., Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.]"