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"Gas alam merupakan bahan bakar yang lebih menjanjikan untuk berbagai aplikasi di kendaraan bermotor. Harganya yang lebih murah dari bensin atau solar, dan berpengaruh sedikit merugikan ke lingkungan tetapi memberikan keuntungan dalam hal kebersihan dan keamanan. Kendaraan berbahan bakar gas alam mengeluarkan sedikit karbon dioksida (penyebab efek rumah kaca) dan polutan lainnya ke udara bila dibandingkan dengan kendaraan berbahan bakar bensin. Namun, energi yang rendah membuat gas alam kurang aplikasinya sebagai bahan bakar mobil. Satu liter minyak bumi pada pembakaran menghasilkan sekitar 3,5 x 104 kJ energi, tapi satu liter gas alam hanya menghasilkan energi 40 kJ pada pembakaran, sekitar 0,1% dari minyak bumi. Dengan demikian, masalah utama menggunakan gas alam sebagai bahan bakar kendaraan adalah penyimpanannya untuk mendapatkan kepadatan energi yang tinggi. Sebuah alternatif sistem penyimpanan NG bertekanan rendah (3,5-4 MPa) adalah dengan adsorpsi (Adosrbed Natural Gas / ANG), merupakan pilihan yang seimbang dari segi biaya kompresi dan kapasitas penyimpanan. Adsorpsi merupakan fenomena fisik yang terjadi antara molekul-molekul gas atau cair dikontakkan dengan suatu permukaan padatan. Pada penelitian ini akan dibahas mengenai pengaruh keadaan temperature terhadap proses adsorpsi selama masuknya gas, serta pengaruh laju aliran massa terhadap proses keluarnya gas pada sistem penyimpanan ANG.

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Natural gas is a fuel with rather promising application in all automotive vehicles. It costs less then gasoline or diesel, and has less adverse effect on the environment which provides benefits as cleanliness and safety. Vehicles fuelled with natural gas emit less carbon dioxide (chiefly greenhouse gas) and other pollutants into the air when compared to gasoline-fed vehicles. However, the low energy density of natural gas retards its wide application as automobile fuel. One liter of petroleum on combustion produces about 3.5 x 104 kJ energy, but one liter of natural gas produces only 40 kJ energy on combustion, which approximately 0.1% of petroleum. Thus, the major problem for using natural gas as a vehicle fuel is its storage to obtain high-energy density.

An alternative low-pressure (3.5'4 MPa) system for storing NG is the storage by adsorption (Adosrbed Natural Gas / ANG), which constitutes a good conciliatory choice between compression costs and storage capacity. Adsorption is a physical phenomenon that occurs between the molecules of gas or liquid contacted with a solid surface. In this work, comparative experiments were carried out to study the thermal effect of the adsorption heat during charge and massflow rate effect on the discharge performance of an adsorbed natural gas (ANG) storage system."

"The potential of carbon nanotubes (CNTs) produced in our laboratory to be used for hydrogen storage was tested in this study. The test includes the determination of the hydrogen gas adsorption capacity and the dynamics of the adsorption and desorption of hydrogen on CNTs at isothermal temperature of 25oC and pressures of 0–1,000 psia. A similar test was also conducted on commercial CNTs obtained from the Chinese Academy of Sciences for comparison. The results showed that the hydrogen adsorption capacity of the local CNTs is lower than that of commercial CNTs. At pressures around 960 psia, the adsorption capacities of local and commercial CNTs are 0.09% and 0.13% weight, respectively. In general, the hydrogen adsorption data of both the adsorbents can be represented well by the Langmuir model, with less than 3% absolute average deviation (AAD). The dynamics of adsorption and desorption can be represented well by the Gasem and Robinson model with less than 2% AAD. The adsorption and desorption processes on both local and commercial CNTs occurred very quickly. At the highest pressure (960 psia), the adsorption and desorption equilibriums on the local CNTs were reached in approximately 30 s, while on commercial CNTs, they were reached in 2 s. The rates of the adsorption equilibriums on both local and commercial CNTs increase at a higher pressure. In the desorption process, while the equilibrium time is reached slightly faster at a higher pressure on commercial CNTs, the time is almost similar at all pressures for local CNTs."

"Karena kurangnya kuantitas dan kualitas dari sumber air eksisting UI, PDAM Tirta Asasta, UI berencana untuk membangun SPAM untuk memenuhi kebutuhan lingkungan kampus UI sendiri. Salah satu parameter kualitas air yang diatur pada PP No. 82 Tahun 2001 sebagai baku mutu untuk air baku Instalasi Pengolahan Air Minum adalah logam berat, salah satunya yaitu tembaga. Keberadaan logam ini tinggi pada kandungan sedimen, dan dapat terlepas menuju air. Oleh karenanya, eksperimen ini dilaksanakan untuk mengetahui pengaruh/dampak parameter fisik-lingkungan danau berupa pH, temperatur, dan konsentrasi amonia terhadap terjadinya desorpsi logam tembaga di sedimen Danau Salam UI. Eksperimen awalnya dilakukan dengan pengambilan sampel sedimen dan sampel air. Sampel sedimen dan air dikumpulkan dari 3 titik di dekat posisi inlet IPAM yang direncanakan berdasarkan Rencana Induk Sistem Penyediaan Air Minum UI (RISPAM UI). Dari hasil dari pengujian, didapat konsentrasi tembaga di sedimen, dari 83.1 mg/Kg hingga 92.7 mg/Kg. Selanjutnya, dilakukan eksperimen desorpsi dan dianalisa menggunakan metode regresi linear. Diketahui bahwa pH merupakan parameter yang paling berpengaruh dalam terjadinya proses desorpsi tembaga pada sedimen Danau Salam. Hasil regresi linear, nilai koefisien pH, temperatur, dan konsentrasi amonia adalah -0.0072, -0.0042, dan 0.0003. Nilai pH menunjukkan kemiringan (slope) tertinggi, diikuti dengan temperatur, lalu konsentrasi amonia.

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Due to the lack of quantity and quality from UI's existing water source, PDAM Tirta Asasta, UI plans to build SPAM to meet the needs of the UI campus environment itself. One of the water quality parameters regulated in PP. 82 of 2001 as the quality standard for raw water for Drinking Water Treatment Plants is heavy metals, including copper, cobalt and lead. The presence of these metal is high in sediment content, and could be released into water. Therefore, this experiment was conducted to determine the effect / impact of the physical parameters of the lake environment in the form of pH, temperature and ammonia concentration on the occurrence of copper desorption in the sediments of Lake Salam UI. Initial experiments were carried out by taking sediment samples and water samples. Sediment and water samples were collected from 3 points near the IPAM inlet position which was planned based on the Master Plan for Drinking Water Supply System UI (RISPAM UI). From the test results, the copper concentration in the sediment was obtained, from 83.1 mg / Kg to 92.7 mg / Kg. Furthermore, a desorption experiment was carried out and analyzed using linear regression methods. It is known that pH is the most influential parameter in the process of copper desorption in the Salam Lake sediments. The results of linear regression, the coefficient values for pH, temperature, and ammonia concentration are -0.0072, -0.0042, and 0.0003. The pH value shows the highest slope, followed by temperature, then the ammonia concentration."

"A study research of absorption-of lead metal in liquid by chiken eggshell and lime as comparision substance has be conducted. This research absorpstion capacity,and Pb desorption with saturated NH4CL

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"Peningkatan populasi manusia menyebabkan kebutuhan pangan meningkat. Untuk menjaga pertumbuhan dan kualitas tanaman sebagai sumber pangan, maka pemberian pupuk perlu dioptimalkan. Urea, sebagai pupuk nitrogen yang paling umum digunakan, memiliki potensi untuk meningkatkan produktivitas pertanian. Namun, urea cepat terdegradasi di tanah sehingga tidak terserap optimal oleh tanaman, sehingga diperlukan pendekatan baru seperti mekanisme slow-release fertilizer (SRF) yang dapat memenuhi kebutuhan nutrisi tanaman sekaligus menjaga keseimbangan lingkungan dari nutrisi yang berlebih. Penelitian ini, memanfaatkan fly ash sebagai sumber silika untuk sintesis silika mesopori sebagai SRF. Sintesis silika mesopori menggunakan surfaktan CTAB (Cetyltrimethylammonium bromide) sebagai template dan dilakukan variasi pH 6,8 dan 10 untuk mempelajari pengaruh pH dan CTAB terhadap karakteristik silika mesopori. Penggunaan CTAB menghasilkan ukuran partikel yang seragam dan luas permukaan yang lebih baik. Silika mesopori yang disintesis dengan CTAB pada pH 10 memiliki luas permukaan terbesar, yaitu 1351 m2/g dengan ukuran partikel 138,97 nm. Silika mesopori yang disintesis memiliki kemurnian 93-97%. Silika mesopori menunjukkan kemampuan adsorpsi urea dengan kinetika yang mengikuti model pseudo-orde dua. Kinetika release urea dari silika mesopori mengikuti model kinetika orde satu, yang berarti laju pelepasan dipengaruhi oleh konsentrasi urea yang tersisa dalam silika. Silika mesopori mampu mengadsorpsi urea hingga 565,83 mg/g dan mampu melepaskan urea sebesar 88% dalam 96 jam.

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The growing population leads to an increased demand for food. To ensure the growth and quality of plants as a food source, the application of fertilizers needs to be optimized. Urea, the most used nitrogen fertilizer, has the potential to boost agricultural productivity. However, urea degrades quickly in the soil, limiting its absorption by plants. Therefore, new approaches such as slow-release fertilizer (SRF) mechanisms are necessary to meet the nutritional needs of plants while maintaining environmental balance. This study explores the use of fly ash as a source of silica for the synthesis of mesoporous silica as SRF. The synthesis of mesoporous silica utilized the surfactant CTAB (Cetyltrimethylammonium bromide) as a template and varied pH at 6, 8 and 10 to investigate the impact of pH and CTAB on the characteristics of mesoporous silica. The use of CTAB resulted in uniform particle size and improved surface area. Mesoporous silica synthesized with CTAB at pH 10 exhibited the largest surface area at 1351 m2/g with a particle size of 138.97nm. The synthesized mesoporous silica demonstrated a purity of 93-97%. Mesoporous silica can absorb up to 565.83 mg/g of urea and release 88% of urea within 96 hours. The kinetics of urea adsorption follow the pseudo-second-order model. Urea release from mesoporous silica follows a first-order kinetic model, indicating that the release rate is influenced by the remaining urea concentration."

"Penggunaan bahan bakar minyak (BBM), seperti bensin, solar, minyak tanah, mengakibatkan peningkatan produksi untuk bahan bakar minyak, sehingga ketersediaan minyak bumi yang ada semakin menipis, selain itu hasil pembakaran pada kendaraan bermotor menghasilkan polusi udara yang menjadi salah satu faktor pemanasan global. Masalah tersebut perlu dipecahkan dengan cara mencari energi alternatif yang lebih bersih dengan nilai oktan tinggi serta ketersediaanya di alam masih banyak yaitu gas alam dengan komposisi utama gas metana (CH4). Sebagai tempat penyimpanan digunakan compressed natural gas (CNG) dengan tabung bertekanan 20 MPa. Adsorbed natural gas (ANG) merupakan solusi untuk mengurangi tekanan dalam tabung sekitar 3,5 - 4 MPa memanfaatkan proses adsorpsi menggunakan karbon aktif. Adsorpsi adalah fenomena fisik yang terjadi antara molekul-molekul gas atau cair dikontakkan dengan suatu permukaan padatan. Dalam penelitian ini, dirancang tabung alat uji adsorpsi metana serta sistem adsorpsi dan desorpsi yang diaplikasikan untuk tabung tersebut.

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The consumption of oil fuel, such as gasoline, solar and kerosene demand an increasing production of the oil fuel itself, so its availability are getting decreased every moment. Beside that, the combustion waste in motor vehicle produce air pollution which is one of the main factor in global warming. To overcome this problem, we should find a cleaner alternative energy with a higher octane value and still much available in the nature. One of this alternative energy is a natural gas with the main composition consist of methane (CH4). But to store this compressed natural gas (CNG), a 20 MPa of pressure vessel is needed. Adsorbed natural gas (ANG) is a solution to reduce the pressure in the tube of about 3.5 to 4 MPa by utilizing the process of adsorption using activated carbon. Adsorption is a physical phenomenon that occurs between the molecules of gas or liquid contacted with a solid surface. In this study it will be designed an adsorption and desorption system for methane as well as the pressure vessel used for testing it."

"Limbah katalis dari proses steam reforming dimana menggunakan katalis berbasis nikel yaitu NiO/Al2O3 memiliki kandungan berbahaya karena dapat mencemarkan lingkungan dan juga bersifat karsinogenik. Oleh sebab itu, diperlukan solusi untuk menanggulangi limbah tersebut agar keberadaan kandungan nikel dalam katalis dapat diserap dan dipergunakan kembali dalam bentuk logam murni. Penelitian ini bertujuan untuk melakukan pengambilan kembali logam nikel dari spent catalyst NiO/Al2O3 dengan menggunakan kitosan sebagai adsorben. Hasil penelitian menunjukkan kondisi optimum proses leaching diperoleh pada konsentrasi H2SO4 1M, waktu kontak 90 menit dan temperatur 80°C. Optimum dari proses adsorpsi dengan kitosan diperoleh pada pH 4,3, waktu adsorpsi 90 menit, dan perbandingan solid-liquid 1:100. Pada desorpsi penggunaan asam H2SO4 1,5 M sebagai stripping agent dalam waktu 90 menit mampu mengekstrak logam nikel dari kitosan secara optimum. Kondisi optimum proses electrowinning diperoleh pada rapat arus 140,8 mA dalam waktu 90 menit.

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Catalyst wastes from steam reforming process which use catalyst with nickel base, NiO/Al2O3, has dangerous contents which are carcinogenic and could pollutes the environment. Thus, the environment needs solutions to overcome the problems which could turn the existing of nickel from wastes to be reused as a pure nickel metals. The purpose of this research is to recovery nickel from spent catalyst NiO/Al2O3 using chitosan as the adsorbent. The results show the optimum conditions of leaching process are at concentration of H2SO4 1M, operation time 90 minutes and temperature at 80°C. Meanwhile, the optimum of adsorption process using chitosan are at pH 4.3, adsorption time 90 minutes, and ratio of solid and liquid 1:100. For stripping process, the using of sulfate acid 1.5 M as the stripping agent could optimally extract nickel metal from chitosan. The electro winning optimum conditions are at 140.8 mA and in 90 minutes as the operation time."

"ABSTRAKSistem pendingin adsorpsi merupakan salah satu solusi terkait permasalahan lingkungan yang ditimbulkan oleh pendingin konvensional. Walaupun pendingin adsorpsi menghasilkan COP yang rendah dibandingkan dengan pendingin konvensional, berbagai usaha telah dilakukan untuk meningkatkan performa dari sistem pendingin adsorpsi. Penelitian ini bertujuan untuk mengetahui pengaruh dari waktu siklus adsorpsi/desorpsi dan temperatur inlet chilled water pada performa dari chiller adsorpsi dengan dua bed modular adsorber dan menggunakan dua jenis silica gel sebagai adsorben dan air sebagai adsorbate. Chiller diuji pada setting kondisi temperatur hot water inlet dan cooling water inlet sebesar 75-80oC dan 30oC. Waktu siklus adsorpsi/desorpsi dan temperatur inlet chilled water divariasikan untuk mengetahui pengaruhnya terhadap performa chiller adsorpsi dan untuk memperoleh kondisi optimal berkaitan dengan performa. Hasil eksperimen menunjukkan bahwa setting temperatur inlet chilled water yang lebih rendah menghasilkan performa yang lebih baik pada chiller adsorpsi. Nilai Coefficient of Performance COP dan kapasitas pendinginan maksimum diperoleh sebesar 0.59 dan 3.9 pada saat waktu adsorpsi/desorpsi selama 600s dan setting temperatur inlet chilled water 11 oC.

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ABSTRACTcooling system is one solution related to environmental problems caused by conventional cooling system. Although the adsorption cooling produces a low COP compared to conventional cooling, various efforts have been made to improve the performance of the adsorption cooling system. This study aims to determine the effect of adsorption desorption time and chilled water inlet temperature on the performance of the adsorption chiller with two bed modular adsorber and using two types of silica gel as adsorbent and water as adsorbate. Chiller tested on the setting of hot water inlet temperature conditions and cooling water inlet of 75 80oC and 30oC. The adsorption desorption time and chilled water inlet temperature varied to determine the effect on the performance of the adsorption chiller and to obtain optimal conditions with respect to performance. Experimental results show that the lower temperature inlet setting of chilled water resulted better performance of the adsorption chiller. Coefficient of Performance COP value and maximum cooling capacity were obtained at 0.59 and 3.9 at the time of adsorption desorptiom during 600s and chilled water inlet temperature 11 oC. "

"This book presents several aspects of research on mathematics that have significant applications in engineering, modelling and social matters, discussing a number of current and future social issues and problems in which mathematical tools can be beneficial. Each chapter enhances our understanding of the research problems in a particular an area of study and highlights the latest advances made in that area. The self-contained contributions make the results and problems discussed accessible to readers, and provides references to enable those interested to follow subsequent studies in still developing fields. Presenting real-world applications, the book is a valuable resource for graduate students, researchers and educators. It appeals to general readers curious about the practical applications of mathematics in diverse scientific areas and social problems."

"Pada penelitian ini, material oksida perovskit CaFeO3 (CF), CaFe0.8Mg0.2O3 (CFM-82), CaFe0.8Mg0.1Zn0.1O3 (CFMZ-811), dan CaFe0.8Zn0.2O3 (CFZ-82) telah disintesis menggunakan metode reaksi padat dan dipreparasisebagai membran dengan metodedry-pressing. Fe2O3 yang digunakan sebagai prekursor didapatkan dari pengolahan limbah mill scale dan semua prekursor dievaluasi kemurniannya menggunakan instrumentasi X-Ray Fluoresence(XRF). Perilaku desorpsi gas O2 dari serbuk oksida perovskit dievaluasi menggunakan instrumentasi Temperature-Programmed Desorption of Oxygen (O2-TPD). Nilai kapasitas adsorpsi oksigen (mmol/g) menurun sesuai urutan berikut: CFM-82>CFMZ-811>CFZ-81>CF. Data O2-TPD selanjutnya digunakan dalam estimasi nilai oxygen vacancies. Struktur kristal dari serbuk oksida perovskit dievaluasi menggunakan instrumentasi X-Ray Diffraction (XRD) dan analisa Rietveld refinement dilakukan menggunakan software HighScore PlusTM. Konfirmasi stoikiometrik dari serbuk oksida perovskit dievaluasi menggunakan instrumentasi XRF. Densitas dan porositas membran perovskit dievaluasi menggunakan metode Archimedes. Kekuatan struktural dari membran perovskit dievaluasi menggunakan uji kekerasan Vickers dengan penurunan nilai Vicker Hardness sebagai berikut: CFM-82>CFZ-81>CF>CFMZ-811. Studi perilaku desorpsi oksigen dari oksida perovskit CF, CFM-82, CFMZ-811, dan CFZ-82 pada penelitian ini dilakukan untuk mengevaluasi potensi keempat material tersebut sebagai membran transport oksigen.

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In this research, CaFeO3 (CF), CaFe0.8Mg0.2O3 (CFM-82), CaFe0.8Mg0.1Zn0.1O3 (CFMZ-811), and CaFe0.8Zn0.2O3 (CFZ-82) perovskite oxide materials was synthesized using solid state reaction and prepared asdense ceramic membranes using dry-pressing method. Fe2O3 used as a precursor was obtained from mill scale waste tratment and the purity of every precursor was evaluated using XRF. Oxygen desorption properties of the perovskite oxide powders was evaluated using O2-TPD with oxygen adsorption capacity decreasing in the order of CFM-82>CFMZ-811>CFZ-81>CF. Estimation of oxygen vacancies was conducted from O2-TPD data. Stoichiometric confirmation and crystal structure of perovskite oxide powders was evaluated using XRF and XRD analysis. Rietveld refinement was performed by using High Score PlusTM. Density and porosity of perovskite membranes was evaluated by using Archimedes Method. Structural strength of perovskite membranes was evaluated by using Vickers Hardness Test with the decreasing of Vickers Hardness value in the order of CFM-82>CFZ-81>CF>CFMZ-811. Study on oxygen desorption properties of CF, CFM-82, CFMZ-811,and CFZ-82 was conducted to evaluate the potential of each membranes to be used as oxygen transport membrane materials."