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Energy is a need of society and industry which is increasing every year. However, the world's oil reserves continue to run low, so the development of renewable alternative energy is needed. One of the new renewable energies that can... more
Energy is a need of society and industry which is increasing every year. However, the world's oil reserves continue to run low, so the development of renewable alternative energy is needed. One of the new renewable energies that can be developed is vegetable fuel or biofuel. Biodiesel which is a type of biofuel is being widely produced recently. The cetane number determines the quality of biodiesel. Solketal is an additive added to biodiesel to increase the cetane number. The ketonation reaction was used in this study to obtain the solketal. In the manufacture of solketal a catalyst is needed to speed up the reaction and increase conversion. Phosphotungstic Woifram Acid (PWA) is a heterogeneous catalyst chosen because it can be separated from solution. Based on the results of the study, the optimal time for making solketal was 4 hours and the highest solketal conversion was at a reaction temperature of 60oC with a constant reactant mole ratio of 1:3:1 and a percentage of 2% cata...
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Hydrogen fuel cells proton exchangemembrane fuel cell (PEMFC) is currently still in development and commercialization. Several barriers to the commercialization of these Nafion membrane as electrolyte is its very sensitive to humidity... more
Hydrogen fuel cells proton exchangemembrane fuel cell (PEMFC) is currently still in development and commercialization. Several barriers to the commercialization of these Nafion membrane as electrolyte is its very sensitive to humidity fluctuation. Nafion must be modified by making a composite Nafion-SiO 2 -HPA to increase electrolyte resistance against humidity fluctuations during the cell used. Research carried out by mixing Nafion solution with Tetra Ethoxy Ortho Silicate (TEOS) and conductive materials is phosphotungstic acid (PWA) by varying the ratio of Nafion, TEOS and PWA. The membrane is produced by heating a mixture of Nafion, TEOS and PWA by varying the evaporation temperature, time and annealing temperature to obtain the transparentmembrane. The resultingmembrane was analyzed its physical, chemical and electrochemical properties by applying the membrane as electrolyte of PEMFC at various humidity and temperature of operation. The results showed that at low temperatures (30-90) °C and high humidity at 100 %RH, pure Nafion membrane is better than composite membrane (Nafion-SiO 2 -PWA), but at low humidity condition composite membrane is better than the pure Nafion membrane. It can be concluded that the compositemembranes of (Nafion-SiO 2 -PWA) can be used as electrolyte of PEMFC operated at low humidity (40 %RH) and temperature between (30-90) °C. Keywords: Membrane, Nanocomposite, Nafion-SiO 2 -PWA, PEMFC, Humidity.
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Plastic waste has become a global problem because it causes environmental pollution. This is because plastic waste is difficult to decompose. There have been numerous solutions proposed, one of which is theuse of bioplastics. In this... more
Plastic waste has become a global problem because it causes environmental pollution. This is because plastic waste is difficult to decompose. There have been numerous solutions proposed, one of which is theuse of bioplastics. In this research, the bioplastics were made from third- generation biomass, namely the eucheuma cottoni. Eucheuma cottoni is contains biopolymer carrageenan, a carbohydrate with unit structures consisting of d-galactose and 3,6 anhydrogalactose with glycosidic bonds. Goal this research is study the effects of sorbitol plasticizer content and bioplastics manufacturing temperature on bioplastics, tensile strength, elongation, and biodegradation rate. The bioplastics were made by extracting 10 grams of eucheuma cottoni powder in 200 ml of distilled water. The algae extract was added with sorbitol (plasticizer) and heated at various temperatures from 45°C until 60°C. The mixture was poured into a mold tin and dried in the oven to a constant weight. The resulting bi...
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The Ngebel geothermal area is morphologically in several volcanic cones arranged as lava domes, volcanic hills, and lake craters. Volcanic cones are composed of lava, pyroclastic falls, pyroclastic flows, volcanic cones such as Jeding... more
The Ngebel geothermal area is morphologically in several volcanic cones arranged as lava domes, volcanic hills, and lake craters. Volcanic cones are composed of lava, pyroclastic falls, pyroclastic flows, volcanic cones such as Jeding Volcano, Kemlandingan Volcano, Manyutan Volcano, and Ngebel Volcano. The magmatism activity that occurs in this area is andesitic-dacitic and also forms a geothermal system. This geothermal system is estimated to produce 50 MWe. During the formation of a geothermal system, hydrothermal fluids interact with the surrounding rock. Based on the results of geological mapping, petrographic analysis, and analysis of rare earth elements. In general, the results of rock-fluid interactions show a decrease in the concentration of rare earth elements, both light and heavy REE elements, from andesite basaltic samples to cold water samples. However, an unexpected reduction from 10 times chondrite to 0.3 times chondrite from hot water to cold water. This research wil...
Research Interests: Geology, Geochemistry, Petrography, Volcano, Basalt, and 3 moreLava Dome, Lava, and geothermal gradient
Abstract Polymer electrolyte membrane based on Nafion and zirconium oxide (ZrO 2) was developed via film casting method. The content of ZrO 2 (1.0, 2.0, and 3.0 wt.%) was incorporated with Nafion solution to prepare Nafion-ZrO 2 composite... more
Abstract Polymer electrolyte membrane based on Nafion and zirconium oxide (ZrO 2) was developed via film casting method. The content of ZrO 2 (1.0, 2.0, and 3.0 wt.%) was incorporated with Nafion solution to prepare Nafion-ZrO 2 composite membranes. Recast ...
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Abstrak PRODUKSI BATIK RAMAH LINGKUNGAN DI DUSUN KALIAJIR KIDUL KELURAHAN KALITIRTO,KECAMATAN BERBAH, SLEMAN DAERAH ISTIMEWA YOGYAKARTA Mahreni, Wasir Nuri, Tutik Muji Setyoningrum The natural dye now growing rapidly along with public... more
Abstrak PRODUKSI BATIK RAMAH LINGKUNGAN DI DUSUN KALIAJIR KIDUL KELURAHAN KALITIRTO,KECAMATAN BERBAH, SLEMAN DAERAH ISTIMEWA YOGYAKARTA Mahreni, Wasir Nuri, Tutik Muji Setyoningrum The natural dye now growing rapidly along with public awareness to induce negative impact of the batic industry. Wealness of batural dye is unstable. Research and development to produce a stable natural dye is still underway. Particullary natural dye to use as a textile and batik dye. Producing batik uses batural dye is more difficult than to produce synthetic dte. So the price is more . expensive. Barrier constranint need to have to find a way out. In this study attempt to use a ne technology that uses technique stamp in order to save time in producing batik The purpos of this study was to produce batik using blue colour of the plant Indigofera tinctoria,the brown colour of the fruit plants Jolawe, brown colour of Mahoni ang green colour of the micture of Indigo and Jo;awe. The result showed that the col...
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The eggs produce waste in the form of eggs shell. One alternative to reduce the waste is by processin g the egg shell into hydroxy apatite powder. Eggshell is one of the largest sources of calcium carbonate , with 95% of composition. The... more
The eggs produce waste in the form of eggs shell. One alternative to reduce the waste is by processin g the egg shell into hydroxy apatite powder. Eggshell is one of the largest sources of calcium carbonate , with 95% of composition. The characteristics of hy droxy apatites that allowed to be used as biomateri als including the mass ratio of Ca:P should have a valu e of 1.67 and have a crystalline structure. In the first step, the eggs shell reacted with hydrochloric acid . Solution formed to the base condition to get the calcium deposits, which then reacted with sodium ph osphate to produce hydroxy apatite deposition. The deposition which formed then dried and heated for f orming the hydroxy apatite crystals. The hydroxy apatite crystals are analyzed by X-Ray Difractometr y (XRD) and Energy Dispersive Spectroscopy X-ray (EDS). From the analysis results, the mass ratio of Ca:P respectively for samples A (0.8 gr CaCO 3 1 mol 20ml HCl and 0.3 mol Na 3PO 4), C (0.8 gr CaCO 3 1 mol 20ml...
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Membran komposit telah digunakan dalam proses pemisahan komponen untuk menghasilkan komponen tulen dan sebagai elektrolit. Membran nafion sebagai elektrolit dalam sel fuel membrane penukar ion atau Proton Exchange Membrane Fuel Cell... more
Membran komposit telah digunakan dalam proses pemisahan komponen untuk menghasilkan komponen tulen dan sebagai elektrolit. Membran nafion sebagai elektrolit dalam sel fuel membrane penukar ion atau Proton Exchange Membrane Fuel Cell (PEMFC) mempunyai kelemahan yaitu konduktiviti Proton dan prestasi selnya akan turun apabila kandungan air di dalam air akan menurun. Bagi mengatasi masalah tersebut, kajian dengan cara menambahkan komponen yang bersifat hidrokofis dan kondukviti tinggi ke dalam kluster polimer nafion telah dilaksanakan. Kajian ini adalah untuk menghasilkan membran nanokomposit campuran nafion-SiO2-PWA menggunakan kaedah sol-gel fasa larutan. Antara parameter yang dikaji adalah suhu penyejatan pelarut, suhu dan waktu penyepuhlindapan dan nisbah TEOS/nafion. Kajian penentuan sifat membran yang dihasilkan adalah morfologi, sifat termal, struktur kimia terbentuk, kandungan kimia, dan kejernihan membran. Prestasi membran komposit sebagai elektrolit dilakukan dengan menggunak...
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Penelitian ekstraksi kurkumin dari kunyit dengan pelarut etanol telah dilakukan dalam kolom yang diisi dengan kunyit sebagai unggun tetap dan pelarut mengalir secara kontinyu dari atas kolom. Kurkumin yang terekstrak dari kunyit dianalisa... more
Penelitian ekstraksi kurkumin dari kunyit dengan pelarut etanol telah dilakukan dalam kolom yang diisi dengan kunyit sebagai unggun tetap dan pelarut mengalir secara kontinyu dari atas kolom. Kurkumin yang terekstrak dari kunyit dianalisa setiap waktu tertentu dengan mengukur indek biasnya dengan menggunakan alat Refraktometer. Pengamatan dihentikan setelah konsentrasi kurkumin di dalam pelarut tetap. Penelitianini dilakukan untuk menentukan model perpindahan massa padat-cair dengan mengamati variable kecepatan aliran pelarut, diameter kolom, dan tinggi unggun. Model matematis disusun berdasarkan neraca massa kurkumin yang bergerak dari dalam padatan ke permukaan kemudian mendifusi ke dalam aliran pelarut yang bergerak dari atas ke bawah kolom dapat dinyatakan dengan persamaan sebagai berikut :D_AB (d^2 CA)/(dZ^2 )+V (dCA)/dZ+KCA (HXA-CA)=∈(dCA)/dt; (dXA)/dt=-KCA/ρB (CA*-CA).Penyelesaian persamaan diatas dengan cara eksplisit dan optimasi didapatkan harga KCA yang diperoleh antara 0...
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Nafion-Silica oxide (SiO2)-Phosphotungstic acid (PWA) composite membrane have been synthesized using solution phase sol-gel method. The effect of the weight ratio of Nafion:SiO2:PWA to the electrochemical properties of composite membrane... more
Nafion-Silica oxide (SiO2)-Phosphotungstic acid (PWA) composite membrane have been synthesized using solution phase sol-gel method. The effect of the weight ratio of Nafion:SiO2:PWA to the electrochemical properties of composite membrane when applies as electrolyte in the PEMFC was investigated using Fuel Cell Test System (FCTS) at temperature of range of 80 – 90 oC and 40% relative humidity (RH). The weight ratio of the composite membrane samples varied in the range of 100:2.88:1.15, 100:4.33:1.73 and 100:5.76:2.30 and designated as NS10W, NS15W and NS20W, respectively. The aim of the experiment was to insert the inorganic hygroscopic and high conductivity filler like PWA and SiO2 in the Nafion matrix to order to improve the water retention, proton conductivity (σ), hydrogen crossover (β), and thermal stability in addition to increase PEMFC performance at elevated temperature and low RH condition. The result showed when appropriately embeded in the Nafion cluster, the hydrated PWA ...
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NANOCOMPOSITE ELECTROLYTE MEMBRANE FOR MODERATE TEMPERATURE AND LOW RELATIVE HUMIDITY HYDROGEN PROTON EXCHANGE MEMBRANE FUEL CELL (HPEMFC) APPLICATlON Mahreni, A.B. Mohamad, A.A.H. Kadhum, W.R.W. Daud Department of Chemical Engineering... more
NANOCOMPOSITE ELECTROLYTE MEMBRANE FOR MODERATE TEMPERATURE AND LOW RELATIVE HUMIDITY HYDROGEN PROTON EXCHANGE MEMBRANE FUEL CELL (HPEMFC) APPLICATlON Mahreni, A.B. Mohamad, A.A.H. Kadhum, W.R.W. Daud Department of Chemical Engineering -Faculty of Technology Industry- University Pembangunan Nasional Yogyakarta-Indonesia Institute of Fuel Cell- Universiti Kebangsaan Bangi - Malaysia 43600 Nowadays PEMFC with hydrogen fuel has developed to commercialize to replace the conventional machine. Several limitations in PEMFC commercialization are its low efficiency, viability of hydrogen fuel supply and problem of controlling fuel and water as reaction products. Effective effort to increase efficiency and water management include elevating temperature of PEMFC operation near water boiling point to increase energy produced, prevent water flooding, enhanced cooling efficiency and also the possibility to use hydrogen and air under lower humidity in order to make simples PEMFC design. But at ele...
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Waste of chemical laboratory without dilution was analyzed and it was found that pH = 5.5 while (COD=171 717 mg/L) and BOD = 10500.1 mg/L) . This research carried out to reduce COD and BOD using flocculation and coagulation processes.... more
Waste of chemical laboratory without dilution was analyzed and it was found that pH = 5.5 while (COD=171 717 mg/L) and BOD = 10500.1 mg/L) . This research carried out to reduce COD and BOD using flocculation and coagulation processes. Research has been done by mixing the waste with Alum in a flask equipped with a stirrer. Waste is stirred for 15 minutes at a constant speed of 150 rpm. After that the pH of the waste is increased by adding Calcium hydroxide Ca(OH)2 so as to achieve a certain pH. The addition of alum and Ca(OH)2 caused the formation of flock. The flock formed more and more, and left without stirring for 24 hours for maximum flock formation. Further separation of flock using a filter. The COD-BOD of the supernatant is analized. The purpose of the study to determine the pH and the ratio of alum:waste to the reduction of are greatly affect the reduction of COD/BOD. Reduction of COD/BOD highest achieved at pH 12.2 and the ratio of alum/waste is 1/0 (ml/ml) ( COD reduction ...
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Metal-organic of skeletons (MOFs) is a group compound that consists of an ion or metal group coordinated by organic ligands to make many-dimensional structured. MOFs are subclass by coordinated polymer with specialties porous structured.... more
Metal-organic of skeletons (MOFs) is a group compound that consists of an ion or metal group coordinated by organic ligands to make many-dimensional structured. MOFs are subclass by coordinated polymer with specialties porous structured. MOFs have a wide surface, flexible structure, and similar pore size. This MOFs many implicated in the industry for example to absorption of CO2 gas, saving energy, separation process, biomedical, sensors, and catalysts, etc. The goal of this paper is to compare the synthesis process of MOFs with some methods. Like solvothermal/hydrothermal, mechanochemical, microwave-assisted, sonochemical, electrochemical, and layer by layer synthesis. Moreover, it is to know the implementation of MOFs as a heterogeneous catalyst in the chemical industry. Based on the review paper conducted we know that MOFs synthesis with the used sonochemical method is well better than other methods. It is because the sonochemical method needs short crystallization time and eco-f...
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Abstract. Sacharomyces cerevisiae (FNCC-3049) have been produced in the flour banana skin culture in the aerobic condition at room temperature. The parameters studied were the ratio of starter to the volume of medium, to the number of... more
Abstract. Sacharomyces cerevisiae (FNCC-3049) have been produced in the flour banana skin culture in the aerobic condition at room temperature. The parameters studied were the ratio of starter to the volume of medium, to the number of cells generated. The research was conducted through several steps including: (i) the breeding, (ii) preparation of banana flour skin, (iii) hydrolysis, (iv) inoculation, (v) fermentation and (vi) separation of the product. Analysis of cell numbers using haemacytometer. Growth of cells is done by inserting inoculants into each 200 ml of sterile fermentation culture at a various ratio of starter/culture. Air flowed into the culture and the fermentation performed for 24 hours. Analysis of cell number is conducted for every 3 hours until 24 hours. After 24 hours, cells were separated by centrifugation and dried at 40oC and then weighted. At incubation time of 9 hours the number of cells found = 106.11. In these conditions obtained dry weight of the product is 51.9052 grams. Keyword: S. Cerevisiae, banana skin, aerobic fermentation.
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Bio refinery process has an important role in the ethanol production made of the renewable resources especially agricultural waste (lignocelluloses). Lignocelluloses (woods, grass, leaves) usually consist of (i) lignin, (ii) cellulose,... more
Bio refinery process has an important role in the ethanol production made of the renewable resources especially agricultural waste (lignocelluloses). Lignocelluloses (woods, grass, leaves) usually consist of (i) lignin, (ii) cellulose, (iii) hemicelluloses and, (iv) other small molecules such as tannins, turpentine, waxes and fats. Lignin is a part of the non biodegradable lignocelluloses, non sugar compound, and must be separated before the cellulose and hemicelluloses could be use as starting materials in the ethanol production. Delignification process using conventional method as well as explosive steam process fibres (SEF) is the heating process of lignocelluloses in the alkaline solution at high temperature and pressure (2120C and 20 atm). The result is a fibre (cellulose and hemicelluloses) and lignin-containing solution that has been fragmented. SEF process leaves chemical waste and is not economic. In addition, the residual lignin that is deposited on the surface of the fibr...
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Being one of the dangerous substances found in household water. Metal Fe is an one of the dangerous substance can be found in household water, metal Fe needs to be removed in order to have clean waters. Among many methods available, this... more
Being one of the dangerous substances found in household water. Metal Fe is an one of the dangerous substance can be found in household water, metal Fe needs to be removed in order to have clean waters. Among many methods available, this research will focus on adsorption. Bioadsorbent made from brown algae (sargassum sp) without chemical activation and with CaCl and HCl as activator will be used in this experiment. In order to have the bioadsorbent, brown algae will be burned using furnace an then some samples will be activated using CaCl2 and HCl on various concentration (0.4 ; 0.6 ; 0.8 ; 1) mol/L. 10 gram of bioadsorbent will be used on 100 ml of untreated water and the process will take two hours. Bioadsorbent will adsorp metal Fe substance and will reduce metal Fe content level to 1 mg/L to qualify the criteria of clean water according to Peraturan Kementrian Kesehatan RI No. 416/MENKES/PER/IX/1990. The best result from this experiment reduce metal Fe content from 2.5 mg/L to 0...
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Ekonomi berbasis hidrogen belum dapat direalisasikan pada saat ini karena beberapa hambatan di antaranya belum tersedianya infrastruktur dan belum ekonomis. Sementara hidrogen belum dapat tersedia, biodisel merupakan bahan bakar... more
Ekonomi berbasis hidrogen belum dapat direalisasikan pada saat ini karena beberapa hambatan di antaranya belum tersedianya infrastruktur dan belum ekonomis. Sementara hidrogen belum dapat tersedia, biodisel merupakan bahan bakar terbarukan banyak mendapatkan perhatian untuk mengurangi ketergantungan terhadap bahan bakar fosil. Perkembangan sintesis biodiesel memfokuskan kepada efesiensi produksi dan mengurangi efek negatif terhadap lingkungan. Dalam penelitian ini telah dilakukan produksi biodiesel dari minyak sawit menggunakan katalis padat kalsium oksida (CaO) yang dibuat dari kulit telur. Tujuan penelitian ini untuk mempelajari kinerja katalis dalam reaksi transesterifikasi minyak sawit dan metanol dengan mempelajari pengaruh perbandingan katalis/minyak pada perbandingan minyak:metanol tetap terhadap ester yang dihasilkan. Penelitian dilakukan melalui tahap kalsinasi kulit telur untuk menghasilkan CaO. Tahap berikutnya adalah mengaplikasikan CaO yang dihasilkan sebagai katalis bi...
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Penelitian ini dilakukan untuk mempelajari pengaruh volume dan pH media terhadap kecepatan pertumbuhan sel ragi (Sacharomyces cerevisiae) dalam tahap inokulasi di dalam media tepung kulit pisang. Penelitian dilakukan melalui beberapa... more
Penelitian ini dilakukan untuk mempelajari pengaruh volume dan pH media terhadap kecepatan pertumbuhan sel ragi (Sacharomyces cerevisiae) dalam tahap inokulasi di dalam media tepung kulit pisang. Penelitian dilakukan melalui beberapa tahap yaitu tahap persiapan bahan baku, tahap pembibitan (seeding) dan tahap inokulasi. Inokulasi dilakukan di dalam volume media tepung kulit pisang yang volumenya divariasi (40-200 ml) pada pH (3 sampai dengan 5). Inkubasi dilakukan selama 24 jam. Setiap 3 jam jumlah sel dianalisis menggunakan haemocytometer untuk menentukan jumlah sel dan kecepatan pertumbuhan sel. Hasil pengamatan menunjukkan bahwa pada daerah pH (3-5) dan volume media (40-200) ml, pola pertumbuhan sel melalui beberapa tahap yaitu tahap lag, tahap percepatan pertumbuhan, tahap ekponensial, tahap stagnan dan tahap kematian. Volume media terbaik adalah 160 ml dan pH terbaik adalah pada pH=5. Pada kondisi ini menghasilkan jumlah sel terbanyak yaitu 106,07. Dari data yang diperoleh dapa...
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Curcuma (Curcuma xanthorrhiza roxb) currently used as traditional medicine and as a dye. If the Curcuma will be saved then the water content should not be more than 10-11%. The advantages of drying using a glass plate covered with double... more
Curcuma (Curcuma xanthorrhiza roxb) currently used as traditional medicine and as a dye. If the Curcuma will be saved then the water content should not be more than 10-11%. The advantages of drying using a glass plate covered with double collector type can reduce the water content below 10-11 %, reduced drying time and produce dust-free product. The experiment is carried out by inserting curcuma that has been in the form of thin slices into the dryer. Dryers are equipped with several sensors those are (temperature, relative humidity, weight scale and the intensity of sun light) sensors. Measurements of those parameters are performed every interval of 5 minutes. The intensity of sunlight during the day it changes that followed by changes of relative humidity of air (RH) and the rate of water evaporation. Effect of RH, the intensity and temperature in the dryer to the drying characteristic is correlated using mathematical model. There are three common mathematical models used in this ...
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ESTERIFICATION OF OLEIC ACID, STEARIC ACID AND ISOPROPIL ALCOHOL FOR LUBRICANT BASE.Uncontrolled spill of petroleum base lubricant has been polluted the environment. An alternative of biodegradable and environmental friendly lubricant is... more
ESTERIFICATION OF OLEIC ACID, STEARIC ACID AND ISOPROPIL ALCOHOL FOR LUBRICANT BASE.Uncontrolled spill of petroleum base lubricant has been polluted the environment. An alternative of biodegradable and environmental friendly lubricant is needed to substitute petroleum based lubricant. Biolubricant can be made from plant or animal oil, or synthetic lubricant that meets biodegradability criteria and nontoxic to human and environment. The aim of this research is to produce ester from Oleic acid, Stearic acid and Isopropyl alcohol as a base stock for lubricant. Range of time in reaction was set 3,4, and 5 hour. Stearic acid was varied 11-15 gram, Oleic acid 85- 89 ml, and IPA 10-15 ml. The resulting products of ester were confirmed by FTIR. Kinematic viscosity, Pour point, Freezing pont are evaluated by ASTM analyses. Ester produced from 12 gr oleic acid, 88 ml of oleic acid and 5 mil of IPA at room temperature is still in liquid phase, with kinematic viscosity at 100oCis larger than 4,...
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Biohydrogen and bioacetic acid are very important chemicals. Both of these chemicals can be produced through anaerobic fermentation by using Bacillus circulans. Bacillus sp can be isolated from biogas solid sludge by growing it in the... more
Biohydrogen and bioacetic acid are very important chemicals. Both of these chemicals can be produced through anaerobic fermentation by using Bacillus circulans. Bacillus sp can be isolated from biogas solid sludge by growing it in the modified media. The isolation was carried out by boiling the biogas sludge for 2 hours. After it boiled, only the spores-producing microbes would survive, such as Bacillus sp and Clostridium sp. Therefore, spores were grown in hydrogen media with glucose as a carbon source, for 72 hours, in anaerobic conditions and at 60 °C. During the growth, hydrogen produced was analyzed by using gas chromatography (GC), whereas metabolite liquid products were analyzed by using HPLC to determine the composition of organic acids and other products quantitatively. Finally, the identification of microbes producing hydrogen was conducted through the PCR test. The results of the analysis proved that the microbes matched to Bacillus circulans with 97% similarity. The resu...
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Sel bahan bakar hidrogen adalah alat yang dirancang untuk mengubah energi elektrokimia menjadi energi listrik secara langsung dengan bahan bakar berupa gas hidrogen.Sel terdiri dari pasangan elektrode (anode dan katode)yang dipisahkan... more
Sel bahan bakar hidrogen adalah alat yang dirancang untuk mengubah energi elektrokimia menjadi energi listrik secara langsung dengan bahan bakar berupa gas hidrogen.Sel terdiri dari pasangan elektrode (anode dan katode)yang dipisahkan oleh membran elektrolit. Sel bahan bakar bekerja dengan menggunakan gas hidrogen atau gas lain yang mudah teroksidasi yang dimasukkan di sisi anode sebagai sumber elektron/ Elektron ini dipisahkan dengan ion hidrogen dengan menggunakan membran elektrolit yang permeabel terhadap muatan positif. Selanjutnya elektron dilewatkan melalui serangkaian alat listrik untuk menghasilkan energi listrik. Di sisi katode dimasukkan oksigen dari udaraIon oksigen, elektron dan ion hidrogen bergabung menjadi molekul air yang kemudian dikeluarkan dari sisi katodesebagai produk samping sel.Cara perakitan membran dan elektrod dengan tahap tahap sebagai berikut: Yang pertama membuat elektrode (anode dan katode), membuat lapisan difusi, pelapisan lapisan difusi dan elektrode...
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Abstract. Sacharomyces cerevisiae (FNCC-3049) have been produced in the flour banana skin culture in the aerobic condition at room temperature. The parameters studied were the ratio of starter to the volume of medium, to the number of... more
Abstract. Sacharomyces cerevisiae (FNCC-3049) have been produced in the flour banana skin culture in the aerobic condition at room temperature. The parameters studied were the ratio of starter to the volume of medium, to the number of cells generated. The research was conducted through several steps including: (i) the breeding, (ii) preparation of banana flour skin, (iii) hydrolysis, (iv) inoculation, (v) fermentation and (vi) separation of the product. Analysis of cell numbers using haemacytometer. Growth of cells is done by inserting inoculants into each 200 ml of sterile fermentation culture at a various ratio of starter/culture. Air flowed into the culture and the fermentation performed for 24 hours. Analysis of cell number is conducted for every 3 hours until 24 hours. After 24 hours, cells were separated by centrifugation and dried at 40oC and then weighted. At incubation time of 9 hours the number of cells found = 106.11. In these conditions obtained dry weight of the product...
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PERFORMANCE IMPROVEMENT OF PROTON EXCHANGE MEMBRANE FUEL CELL USING SOL-GEL CASTING TECHNIQUE Mahreni Akhmad, Abu Bakar Muhamad, Abdul Amir H. Kadhum,Wan Ramli Wan Daud Department of Chemical & Process Engineering, Faculty of Engineering,... more
PERFORMANCE IMPROVEMENT OF PROTON EXCHANGE MEMBRANE FUEL CELL USING SOL-GEL CASTING TECHNIQUE Mahreni Akhmad, Abu Bakar Muhamad, Abdul Amir H. Kadhum,Wan Ramli Wan Daud Department of Chemical & Process Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia Email: mahreni@vlsi.eng.ulan.my Abstract The sol-gel casting techniqu has been used for (he fabrication of membrane electrode assemblies . (MEA) as a means for better distribution of metal catalyst. such as Pt, residing on the membrane surfaee. This in itself will nraM the catalyst used to be more efficient. The precursor contained Tetra Ethoxy Onbo Silicate (TEOS) as the silica source and Phosphotungsticacid (PWA) as the proton conductive material. The electrolyte me.nbrane, Nofion JJ2 was Impregnated with the precursor solution containing PWA and TEOS before its coated with the catalyst ink to produce the electrodes. The electrodes were fused with the gas diffusion layers (GDL) by hot press a! 12Cf'C and pressur...
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APLIKASI MEMBRAN NANOKOMPOSIT SEBAGAI ELEKTROLIT SEL BAHAN BAKAR HIDROGEN PADA PROTON EXCHANGE MEMBRANE FUEL CELL . Sel bahan bakar hidrogen jenis Proton Exchange Membrane Fuel Cell ( PEMFC ) saat ini masih dalam pengembangan dan... more
APLIKASI MEMBRAN NANOKOMPOSIT SEBAGAI ELEKTROLIT SEL BAHAN BAKAR HIDROGEN PADA PROTON EXCHANGE MEMBRANE FUEL CELL . Sel bahan bakar hidrogen jenis Proton Exchange Membrane Fuel Cell ( PEMFC ) saat ini masih dalam pengembangan dan komersialisasi. Beberapa hambatan komersialisasi di antaranya membran Nafion sebagai elektrolit sangat sensitif terhadap kelembaban. Maka Nafion harus dimodifikasi dengan cara membuat komposit Nafion-SiO 2 - HPA dengan tujuan meningkatkan ketahanan elektrolit terhadap fluktuasi kelembaban selama sel digunakan. Penelitian dilakukan dengan mencampur larutan Nafion dengan tetra etoksi orto silikat ( TEOS ) dan bahan konduktif phosphotungstic acid ( PWA ) dengan memvariasi perbandingan Nafion, TEOS dan PWA . Membran dihasilkan dengan cara memanaskan campuran Nafion, TEOS dan PWA dengan memvariasi suhu penguapan, waktu dan suhu annealing sehingga didapatkan membran dengan penampakan transparan. Membran yang dihasilkan dianalisis terhadap sifat fisika, kimia dan...
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Coal liquefaction is a process of converting solid coal fuel into liquid fuel. This process is developed by various countries to overcome the scarcity of liquid fuels; therefore, this coal liquefaction is very useful for countries that... more
Coal liquefaction is a process of converting solid coal fuel into liquid fuel. This process is developed by various countries to overcome the scarcity of liquid fuels; therefore, this coal liquefaction is very useful for countries that have few petroleum reserves yet, have large coal reserves. There are two coal liquefaction techniques, namely direct coal liquefaction (DCL) and indirect coal liquefaction (ICL). In ICL, there is a gasification process that usually develops products, generating Fischer-Tropsch (F-T) liquid, methanol (CH 3 OH/MeOH), and dimethyl ether (CH 3 OCH 3 /DME). On the other hand, DCL involves a hydrogenation reaction to produce synthetic gasoline and diesel, which is the same as LPG, a hydrocarbon fuel product similar to hydrocarbon fuel derived from petroleum. This paper discusses the ICL and DCL coal liquefaction techniques, including the process stages, the type of catalyst used, and the products resulted from these techniques.
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Abstrak Teknologi membran telah diaplikasikan di berbagai bidang terutama di bidang teknologi pemisahan. Teknologi pemisahan dengan membran merupakan teknologi baru yang diharapkan dapat mengatasi permasalahan yang timbul pada teknologi... more
Abstrak Teknologi membran telah diaplikasikan di berbagai bidang terutama di bidang teknologi pemisahan. Teknologi pemisahan dengan membran merupakan teknologi baru yang diharapkan dapat mengatasi permasalahan yang timbul pada teknologi pemisahan konvensional. Keuntungan menggunakan membran diantaranya untuk mengurangi pencemaran lingkungan dan konsumsi energi, karena pemisahan dengan membran berlangsung pada temperatur dan tekanan yang relatif rendah serta tidak menggunakan aditif kimia. Penelitian ini bertujuaun untuk mengetahui kinerja membran membran distilasi tioe direct contact (DCMD) untuk desalinasi larutan NaCl dengan mengamati fluks permear dan persen rejeksi sebagai fungsi parameter kecepatan umpan, temperatur dan konsentrasi umpan. Penelitian dilakukan dengan menggunakan membran hidropobik dari bahan polipropilen bentuk modul shell dan tube yang mempunyai ukuran diameter pori 0,2 µm, porositas 0,7 diameter dalam fiber 0,3 mm, diameter luar fiber 0,6mm diameter dalam shel...
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Guru adalah komponen penting didalam pendidikan. Guru terlibat langsung dalam proses pendidikan dan pembentukan karakter dan aklak siswa. Mengingat perkembangan akhlak siswa yang saat ini semakin memprihatinkan, sebagaimana munculnya... more
Guru adalah komponen penting didalam pendidikan. Guru terlibat langsung dalam proses pendidikan dan pembentukan karakter dan aklak siswa. Mengingat perkembangan akhlak siswa yang saat ini semakin memprihatinkan, sebagaimana munculnya banyak keluhan dari orang tua tentang anak yang sulit diatur. serta sering tidak menghiraukan orang tua bahkan justru lebih mementingkan bermain daripada belajar. Dari hasil pengamatan pra survey yang penulis lakukan di SMPN I TBT SATAP PENUMANGAN Kecamatan Tulang Bawang Barat Kabupaten Tulang Bawang Barat, penulis menemukan sebuah permasalahan tentang penangan pembinaan Akhlak yang dilakukan oleh guru untuk para siswa di SMPN I TBT SATAP PENUMANGAN. Melihat hal tersebut penulis merasa tertarik untuk melakukan pengamatan lebih jauh tentang bagaimana upaya penanaman pendidikn akhlak yang dilakukan oleh guru terhadap anak di SMPN I TBT SATAP PENUMANGAN, Oleh karena hal tersebut maka Fokus penelitian dalam penulisan tesis ini adalah, 1) Bagaimana perencana...
Isolation of Hydrogen Producing Bacteria from Sludge of Anaerobic Biogas Reactor Mahreni, Yanisworo Wijaya Ratih, Siti Diyar Kholisoh, Harso Pawignyo Abstract Hydrogen-producing bacteria can be found in the activated sludge generation... more
Isolation of Hydrogen Producing Bacteria from Sludge of Anaerobic Biogas Reactor Mahreni, Yanisworo Wijaya Ratih, Siti Diyar Kholisoh, Harso Pawignyo Abstract Hydrogen-producing bacteria can be found in the activated sludge generation from anaerobic waste treatmen process. Mokrobes in it consists of acetogenesis, methanogenesis and hydrogen-producing bacterisa such as Bacillus and clostridium. The purpose of the study was to isolate, characterize and identify a hidrogen-producing bacteria, using a gas chromatograph (GC-Shimadzu). Organics acid and ethanol productions were analyzed by HPLC. Whereas reducing sugar was analysis by DNs method. Isolateds identification was done based in the 16S rDNA gene sequences. Fave isolates using liquid minerals medium (HM medium). Based on examination on the similarities of the isolates morphology obtained, three isolated have been selected. The were BYM1, BYM2 and BYM3. According to the squence of their 16S-rDNA, the BYM1, BYM2 and BYM3 were ident...
Slack wax merupakan produk samping proses dewaxing. Kandungan minyak di dalam slack wax masih cukup tinggi kira-kira 8,5 % berat. Agar supaya wax dari slack wax ini dapat digunakan untuk keperluan industri, maka harus diolah lebih lanjut... more
Slack wax merupakan produk samping proses dewaxing. Kandungan minyak di dalam slack wax masih cukup tinggi kira-kira 8,5 % berat. Agar supaya wax dari slack wax ini dapat digunakan untuk keperluan industri, maka harus diolah lebih lanjut dengan tujuan untuk mengurangi kandungan minyaknya sampai dengan harga yang ditentukan yaitu 0,5 % berat. Proses pengambilan minyak dapat dilakukan dengan menggunakan cara ekstraksi dengan menggunakan pelarut selektif. Kemudian antara phase minyak dan phase wax dipisahkan dengan cara filtrasi. Tujuan penelitian ini untuk mencari kondisi terbaik proses ekstraksi slack wax dengan menggunakan pelarut Metil Iso Butil Keton (MIBK) dengan mengamati variable perbandingan pelarut : slack wax, waktu dan suhu ekstraksi terhadap kandungan minyak di dalam wax. Penelitian dilakukan dengan mencampurkan slack wax dengan pelarut kemudian diaduk dan dipanaskan pada suhu tetap selama waktu tertentu. Kemudian pengaduk dihentikan dan campuran didinginkan sampai wax mem...
Proton conductivity of Nafion membranes and series as well as perfluorosulfonic acid (PFSA) produced by Dow and Aciplek are strongly depend to the water content or water relative humidity on the membrane surface. At low relative humidity... more
Proton conductivity of Nafion membranes and series as well as perfluorosulfonic acid (PFSA) produced by Dow and Aciplek are strongly depend to the water content or water relative humidity on the membrane surface. At low relative humidity and high temperature condition, membrane dehydrated, membrane shrinking and the conductivity reduced dramatically. At high temperature and high relative humidity membrane sweeling was occured. Shringking and swelling cauce cell performance reduction. To overcome the problem, a hygroscopic and highly conductive component is introduce in the cluster of the Nafion polymer matrix. The aim of this study is prepared the nanocomposite membrane using Nation•Si02-PWA mixture in a given composition. The performance of the composite membrane as electrolyte was examined by attaching electrode on both side of composite membrane electrolyte and placing them in a single PEMFC at 60-90°C temperature, 1-2 atm pressure, and 40-100% humidity. Transparent composite mem...
ZAT WARNA ALAMI (REVIEW) Oleh Mahreni Natural dye is caloring material made from plant (roots, thrunks, leaves, flowers and fruits). It is biodehradable in nature, or able to be decomposed by microorganisms. It is also non toxic,making it... more
ZAT WARNA ALAMI (REVIEW) Oleh Mahreni Natural dye is caloring material made from plant (roots, thrunks, leaves, flowers and fruits). It is biodehradable in nature, or able to be decomposed by microorganisms. It is also non toxic,making it save to use as a food coloring material, medicine, dye, batik, and for caloring cosmetics. The weaknesses of natural dye, are inherently unstable and easliy oxidized (changing color when heated). The instability of these natural dye, restricts their use in industries, and also an obstacle to commercialize them. A long with the wordwide paradigm back to nature, natural dye are increasingly in demand to be researched and produced because they have promising market opportunities. Backed up by Indonesias natural resources which make this country potential as a manufacturer of natural colors, it is important to review several things concerned with the commercialization of natural dyes. The purposes of this paper are to explore the possibility of produci...
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Sulfur is a component present in coal whose composition is about 1-2% by weight. When coal is used as an energy source it will liberate sulfur oxide or SOx gas. SOx is a highly toxic gas and one of the gases that causes acid rain.... more
Sulfur is a component present in coal whose composition is about 1-2% by weight. When coal is used as an energy source it will liberate sulfur oxide or SOx gas. SOx is a highly toxic gas and one of the gases that causes acid rain. Therefore, coal desulfurization is very important to reduce the environmental impact caused by SOx. In this research, coal desulfurization has been conducted using Alkyl-alginate surfactant as surface tension reduction agent in coal washing process. The objective of this study was to determine the concentration of surfactant in washing water and to determine the rate of water flow containing surfactant on the percentage of sulfur reduction. The material used in this research was Indonesian coal from South Sumatera. The selected flow rate variations were 750, 1250, 1500, 2500 and 3750 (ml/min) and surfactant concentrations in range of (0.0625, up to 0.375) grams/liter). The results showed that the largest percentage of coal sulfur reduction obtained at a fl...
Abstrak Tumbuhan laut memiliki keunggulan dibandingkan dengan tumbuhan darat. Hal ini dikarenakan tumbuhan laut memiliki senyawa-senyawa yang dapat melindungi tumbuhan dari kondisi lingkungan dengan intensitas sinar UV yang tinggi dan... more
Abstrak Tumbuhan laut memiliki keunggulan dibandingkan dengan tumbuhan darat. Hal ini dikarenakan tumbuhan laut memiliki senyawa-senyawa yang dapat melindungi tumbuhan dari kondisi lingkungan dengan intensitas sinar UV yang tinggi dan kadar garam yang tinggi sehingga tumbuhan laut dapat beradaptasi dengan baik. Alga coklat (Sargasum sp) adalah salah satu jenis rumput laut mengandung antioksidan alami yang disebut Fucoidan. Dalam penelitiain ini kami memproduksi antioksidan (focoidan) yang terdapat dalam rumput laut coklat (Sargasum sp) dengan menggunakan ektraksi menggunakan pelarut etanol. Ativitas antioksidan dianalisis menggunkan penangkapan radikal bebas dengan 2,2-diphenyl-1 1-picylhydrazyl (DPPH). Dalam penelitian ini tujuan yang akan dicapai adalah produksi antioksidan dari Sargasum sp dengan pelarut etanol dengan mempelajari pengaruh rasio Sargasum Sp dan solvent (F/S), waktu ekstraksi (θ) yang dapat menghasilkan aktivitas antioksidan terbaik. Ganggang coklat dicuci dan dibe...
Investigation of the single cell Proton Exchange Membrane Fuel Cell (SCPEMFC) using a series of Nafion-SiO2-PWA composite membranes as electrolyte have been carried out using the Arbin Fuel Cell Test System (FCTS). PEMFC performance and... more
Investigation of the single cell Proton Exchange Membrane Fuel Cell (SCPEMFC) using a series of Nafion-SiO2-PWA composite membranes as electrolyte have been carried out using the Arbin Fuel Cell Test System (FCTS). PEMFC performance and proton conductivity of the composite membrane have been determined over a temperature range of 30-90 o C at pressure 1-1.7 atm at 40% RH. Analysis with FCTS showed that higher current density was yielded by composite membrane (82 mAcm -2 at 0.6 V for NS15W) than with the Nafion membrane (30 mAcm -2 at 0.2 V) at 90 o C. Hence the composite is potentially a good candidate to substitute Nafion membrane especially for the electrolyte of PEMFC operating at higher temperature range and lower RH.
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Indonesian coal consumption is dominated by a low-grade coal quality, and supplied from local coals mining which was composed of lignite. A technological breakthrough has to be main objective to convert low grade coal into upper-class... more
Indonesian coal consumption is dominated by a low-grade coal quality, and supplied from local coals mining which was composed of lignite. A technological breakthrough has to be main objective to convert low grade coal into upper-class coal. This paper reports on improving the quality of lignite coal by washing with biosurfactant. Di-alkyl carbohydrates were tested on coal sizes of 80, 64, 16 and 6 mesh. The optimum biosurfactant applied to increase the calorific value derived from brown algae, namely isopropyl stearate alginate (ISA) 0.5%. This was able to improve a calorific value of lignite coal up to 27722.74% or increased by 11%. The size of the coal also affects the calorific value of lignite coal. Four coal sizes applied in the study (80, 64, 16, and 6 mesh), indicates coal size 80 mesh has given the best calorific value improvement. Conversely, the smaller of the coal size, increase biosurfactant absorption. Thus, improve the washing capability of biosurfactants.
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Surfactant (surface active agent) has capability todecrease surface tension, interfacial tension and increase emulsion stability. Most of surfactant used in industry is produced from petroleum based. As petroleumis limited resources, the... more
Surfactant (surface active agent) has capability todecrease surface tension, interfacial tension and increase emulsion stability. Most of surfactant used in industry is produced from petroleum based. As petroleumis limited resources, the development of surfactant using renewable resources is more needed. Macro algae containrich of polysaccharides such as agarose, carrageenans, and alginates. Some research has been done to study the production of new bio surfactant through the reaction of these polysaccharides with alcohol and lipid acid to promote high hydrophobic and hydrophilic site. Thispaper compared the production and the characterization of new biosurfactant, di-alkyl carbohydrate, from various macro algae such as brown algae (Sargasum sp), red algae (Euchema cottonii),and green algae. The main process was the extraction of polysaccharides at temperature of 80˚C, followed by esterification. Result indicated that all surfactant produced could create oil inwater emulsion system....