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The Growth Mechanisms of Atomic Layer Deposition: An Overview
Get PDFIn this review, the discussion emphasized on the growth mechanisms of atomic layer deposition which consists of a theoretical model and experimentally growth as well as the measurement testing as evidences. The deposition process description with some testing evidences can be used to facilitate in the effort to understand the basic concept of ALD growth mechanisms. Some metal oxides like Al2O3, HfO2, and TiO2 with these employed precursors are typically used for the detailed illustration during the reaction steps. Although the surface chemistry of ALD process has been well understood, systematic description which combine a theoretical and experimentally growth mechanism is still missing. This paper aims to provide a better understanding of ALD growth mechanisms and surface chemistry which eventually able to contribute on the thin film growth processing
POST-COMBUSTION COAL DESULFURIZATION Review
Get PDFThe sulfur content in coal ranges from 0.5 to 5%, and it is an impurity that must be removed before burning coal, due to the toxic effects and acid rain caused by SO2 gas generated from sulfur oxidation. Sulfur cleaning technology can be carried out on coal before combustion (pre-combustion), and can reduce the inorganic sulfur content by up to 50%; however, it cannot reduce the organic sulfur content. Therefore, the industry relies on post-combustion desulfurization to remove SO2 from the gas from coal combustion. The aim of the coal desulfurization review is to direct desulfurization research to be efficient and effective, as well as to be environmentally friendly. Sulfur in coal consists of organic sulfur and inorganic sulfur. Coal inorganic sulfur consists of pyrite (FeS2), sulfate, and sulfide. The largest composition is pyrite. Organic sulfur consists of hetero-atomic and heterocyclic (thiophenic) macromolecules that bind N and O atoms, aromatic sulfides, and aromatic disulfides (small amounts). Inorganic sulfur can easily be separated from coal by means of flotation, microwave energy, magnetic forces, ultrasonic energy, and as well as microorganisms. Meanwhile, organic sulfur cannot be separated from coal by using the methods used in the inorganic sulfur separation process. Organic sulfur can be removed by chemical and biodesulfurization, however, this process is inefficient for industrial scale. The most recommended method is the absorption of SO2 gas in the gas from coal combustion, or post-combustion desulfurization. Various methods have also been investigated to separate SO2 gas, and more details will be described in this paper
Pemanfaatan Serbuk Kayu Pohon Gayam (Inocarpus Fagiferus) sebagai Bio Adsorbent Penjerap Ion Logam Berat Pb(II) dalam Limbah Cair
No full textTahitian chestnut (Inocarpus fagifer) was utilized as adsorbent to eliminate heavy metal ions in wastewater. In this research, Tahitian chestnut wood sawdust was chemical modified by alkali solution from potassium hydroxide and sodium hydroxide to enhance the adsorption capacity of the sawdust. Furthermore, the effect of pH solution and soaking time to the adsorption capacity of Tahitian chestnut wood sawdust was investigated. Based on the experiment data, it can be concluded that the kinetic of adsorption Pb(II) ions onto the adsorbent Tahitian chestnut wood sawdust was well illustrated by Lagergren 2 nd order mathematic model with the value of determination coefficient (R2 ) was 0,9496.Gayam (Inocarpus fagifer) dimanfaatkan sebagai bahan penjerap alami (bio adsorbent) untuk mengolah limbah cair dengan kandungan ion logam berat. Pada penelitian ini serbuk kayu gayam dimodifikasi kimia dengan larutan basa potasium hidroksida dan sodium hidroksida untuk meningkatkan kapasitas penjerapan. Selain itu kapasitas penjerapan serbuk kayu gayam diteliti terhadap pengaruh pH larutan dan waktu kontak. Berdasarkan data penelitian diperoleh hasil bahwa kinetika proses penjerapan ion Pb(II) ke dalam bio adsorbent kayu gayam dapat diilustrasikan dengan model matematis Lagergren order dua dengan nilai koefisien determinasi (R2) 0,9496
PREPARASI KARBON BERPORI DARI LIMBAH AMPAS KOPI SEBAGAI MATRIKS PADA PEMBUATAN SLOW RELEASE FERTILIZER
Get PDFUrea is one of the fertilizers that are widely used in agriculture. However, the absorption efficiency of urea for plants is currently only around 30%. Therefore, to increase its absorption in plants it is necessary to control the release of urea by making it a Slow Release Fertilizer (SRF) fertilizer. The use of SRF is expected to control the release of nutrients according to the time and amount needed by plants. Natural material which has the potential as a matrix of SRF fertilizer is coffee grounds waste. This research produces carbon from coffee pulp waste which can be used as a matrix in the manufacture of urea SRF fertilizer. With the addition of a matrix of coffee carbon is expected to slow the rate of release of urea into nature. So that the process of absorption of urea into plants will be more leverage. Coffee pulp was pyrolysed with pyrolysis temperature variation (400 - 600oC) using ZnCl2 as activator. The iodine number value of coffee grounds carbon produced decreases with increasing temperature. The addition of carbon coffee grounds can inhibit the release of urea from 81.5% to 26% for 30 days.Urea merupakan salah satu pupuk yang banyak digunakan dalam pertanian. Namun efisiensi penyerapan urea untuk tanaman saat ini hanya berkisar 30%. Oleh karena itu, untuk meningkatkan penyerapannya pada tanaman maka perlu dilakukan pengendalian pelepasan urea dengan membuatnya menjadi pupuk Slow Release Fertilizer (SRF). Penggunaan SRF diharapkan dapat mengendalikan pelepasan unsur nutrisi sesuai dengan waktu dan jumlah yang dibutuhkan tanaman. Bahan alami yang berpotensi sebagai matriks dari pupuk SRF ialah limbah ampas kopi. Penelitian ini menghasilkan karbon dari limbah ampas kopi yang dapat digunakan sebagai matrik dalam pembuatan pupuk SRF urea. Dengan penambahan matrik dari karbon kopi diharapkan dapat memperlambat laju pelepasan urea ke alam. Sehingga proses penyerapan urea ke dalam tumbuhan akan menjadi lebih maksimal. Ampas kopi dipirolisis dengan variasi suhu pirolisis (400 – 600oC) menggunakan ZnCl2 sebagai activator. Nilai iodine number karbon ampas kopi yang dihasilkan menurun dengan naiknya suhu. Penambahan karbon ampas kopi mampu menghambat pelepasan urea dari 81,5% menjadi 26% selama 30 hari
Steam Distillation of Essential Oil from Lemongrass (Cymbopogon citratus) using Microwave Pretreatment
Get PDFEssential oils from lemongrass (Cymbopogon citratus) containing citral are very potential to be used in food and pharmacy industries. The process of isolating essential oils is still constrained by its low yield. In order to increase yield, in this research, isolation of essential oil by steam distillation method was carried out using microwave pretreatment. The results showed that pretreatment using microwave for 2 minutes had the effect of increasing yield up to 1.4 times compared to without pretreatment. The essential oil produced using microwave pretreatment had physical properties (colour, odor, density, and refractive index) similar to those without pretreatment. Composition analysis by GC-MS showed that essential oils extracted using microwave pretreatment and without pretreatment contain geranial (Ecitral or citral-a), neral (Z-citral or citral-b) and mircena as the main components
Biokeramik Hidroksiapatit (HAp) Berbahan Dasar Cangkang Tiram Anodonta nuttaliana dari Danau Poso
Get PDFBioceramic Hydroxyapatite (HAp) was a derivated chemical synthetic compound from calcium phosphate commonly used to care the damage of hard tissues. Bioceramic Hydroxyapatite can synthetized from the compounds which rich with calcium contains. In this study threated the synthesis and physicochemical characterization to the HAp made from Anodonta nuttaliana clam shells obtained from Poso lake. From the characterization of the sample A. nuttaliana shells obtained the water contains 0,50±0,00%; ash contains 0,9827±0,0022g/g; potasium 0,00135±0,0002g/g; calcium 0,0165±0,0034g/g; phosphate 0,1920±0,0424g/g and the ratio of Ca/P 1,9389±0,3039%. The synthesis of HAp by base precipitation method showed the yield of synthesis 95,4320±0,7085% with the characteristic of the HAp showed that the potassium contains 0,0005±0,00004g/g; calcium 0,95476±0,0012g/g; phosphate 0,528±0,0075; ratio of Ca/P 1,0307±0,0932%; porosity 73,9598±1,1320%; swelling ability 9,6067±2,5365%; and biodegradability 8,8206±0,2176%. From the overall results concluded that the A. nuttaliana clam shells was very potential to became a source of Bioceramic Hydroxyapatite (HAp).Biokeramik Hidroksiapatit (HAp) merupakan suatu komponen kimiawi sintetik dari turunan kalsium fosfat yang umumnya digunakan untuk memperbaiki kerusakan jaringan keras. Biokeramik Hidroksiapatit dapat disintesis dari bahan-bahan yang kaya akan kalsium. Pada penelitian ini dilakukan sintesis dan karakterisasi fisikokima HAp dari cangkang tiram Anodonta nuttaliana yang diperoleh dari danau Poso, Sulawesi tengah. Dari hasil karakterisasi sampel cangkang tiram A. nuttaliana diperoleh kadar air 0,50±0,00%; kadar abu 0,9827±0,0022g/g; kadar kalium 0,00135±0,0002g/g; kalsium 0,0165±0,0034g/g; fosfat 0,1920±0,0424g/g dan rasio Ca/P 1,9389±0,3039%. Sintesis HAp dengan metode pengendapan basa menunjukkan yield sintesis sebesar 95,4320±0,7085% dengan karakteristik HAp yang dihasilkan menunjukkan kadar kalium 0,0005±0,00004g/g; kalsium 0,9476±0,0012g/g; fosfat 0,528±0,0075; rasio Ca/P 1,0307±0,0932%; porositas 73,9598±1,1320%; daya kembang 9,6067±2,5365%; dan biodegradabilitas 8,8206±0,2176%. Dari keseluruhan hasil disimpulkan bahwa cangkang tiram A. nuttaliana sangat potensial untuk dijadikan sumber biokeramik hidroksiapatit (HAp)
Influence of Particle Size and Chemical Activation on Rice Husk Biochar as Slow Release Fertilizer
Get PDFNitrogen, Phosphate, and Potassium are important nutritional elements contained in the fertilizers for plants but their presence in the soil could be easily wash out by rain water. Biochar, originated from rice husks with a high absorbance ability, might be able to be used to inhibit the release of those nutrients. This research aims to investigate the influence of biochar size and the HCl chemical activation. Biochar, which has been pyrolyzed, was ground and sieved to obtain powder with the size average equivalent to 0.2735 mm; 0.4485 mm; 0.725mm; and 0.925 mm. The optimized biochar size were opted for later being activated using HCl with a concentration of 3%; 9%; and 15%. The leaching process of fertilizer, aiming to imitate the rain water washing, was performed by pouring water on a daily basis on a sand column with the presence of biochar saturated with colorized fertilizer. The obtained solution were then characterized using Spectrophotometer. The results show that the estimated release time for the case with the absence of biochar is 36 days, in contrast to 55 days for the case with the presence of biochar.
Penurunan Konsentrasi Anion Fosfat dan Sulfat dalam Air Limbah Hasil Proses Pengolahan Senotim dengan Metode Elektrokoagulasi
Get PDFIndonesia has rare earth mineral resources that have the potential to be processed into beneficial products for human life. In the processing of rare earth mineral resources rarely needed waste treatment devices to reduce contaminants in liquid waste process results. The method of processing with the electrocoagulator system is used because its does not require high levels of technology and costs. In research conducted wastewater treatment process results of xenotime by using method of electrocoagulation with variation of voltage and time of contact. Digestion of xenotime sand using concentrated sulfuric acid and in the content of xenotime sand there is a phosphate anion that binds with metal Y, Dy, Gd, La, Ce, Nd. Xenotime wastewater treatment process with electrocoagulation method is set at voltage variation 7V-13V with variation time of 0-120 minutes. The results of analysis with High Performance Liquid Chromatography (HPLC) showed that there is a decrease in the concentration of phosphate and sulfate anions in the filtrate of the processing results of xenotime wastewater using electrocoagulation method. The lowest concentrations of phosphate and sulfate anions occur in the 13 V voltage condition with 120 minutes of 1.180% and 0.564%.Indonesia memiliki sumber daya mineral logam tanah jarang yang berpotensi untuk diolah menjadi produk yang bermanfaat untuk kehidupan manusia dan bernilai ekonomis tinggi. Didalam pengolahan sumber daya mineral logam tanah jarang diperlukan perangkat pengolahan limbah untuk mereduksi kontaminan dalam limbah cair hasil proses, perangkat pengolahan limbah dikembangkan sesuai kebutuhan teknis berdasarkan aspek teknologi dan biaya. Proses pengolahan limbah cair di lingkungan industri kimia saat ini selain masih terpaku pada teknologi yang tersedia, dan membutuhkan bahan kimia pendukung proses pengolahan dengan biaya tinggi. Metode pengolahan dengan sistem elektrokoagulator digunakan karena teknologi elektrokoagulasi tidak membutuhkan tingkat teknologi dan biaya tinggi. Pada penelitian ini dilakukan pengolahan air limbah hasil proses senotim dengan menggunakan metode elektrokoagulasi dengan variasi tegangan dan waktu kontak. Dijesti pasir senotim menggunakan asam sulfat pekat dan di dalam kandungan pasir senotim terdapat anion fosfat yang berikatan dengan logam Y, Dy, Gd, La, Ce, Nd. Proses pengolahan limbah senotim dengan metode elektrokoagulasi diatur pada variasi tegangan 7V-13V dengan waktu 0-120 menit. Hasil analisis dengan HPLC menunjukkan adanya penurunan kadar anion fosfat dan sulfat di dalam filtrat hasil pengolahan limbah senotim dengan menggunakan metode elektrokoagulasi. Konsentrasi anion fosfat dan sulfat terendah terjadi pada kondisi tegangan 13 V dengan waktu 120 menit yaitu 1,18% dan 0,564% dari konsentrasi anion fosfat dan sulfat mula-mula 11,469% dan 0,991
Enhancing coal tailing quality by Flotation Method using Biosurfactant from Lerak (Sapindusrarak De Candole)
Get PDFWasted from coal mining that mixed with the wasted of the coal washing product called Coals Tailing (CT) has a low calorific value,high sulfur and ash content. To upgrade its quality by increasing its calorific value and to reduce environmental pollution by reducing sulfur and its ashes, coal must improve from its impurities, one of which is to try with flotation method. Flotation is a process that describes solids that occur due to differences in surface properties (surface properties). The flotation process takes place in a system consisting of three phases, namely gas phase, liquid, and solid, which are interrelated to complete the appearance (with the help of flotation agent / surfactant) so that discussion occurs between the hydrophobic component (waterproof) and the hydrophilic component (like water). The main objective of the research is to improve the quality of coals tailing (CT), by increasing the calorific value (reducing the content of sulfur, ash, and other impurities) using the flotation method, and using lerak (Sapindus rarak De Candole) as a surfactant. From this research show that an optimal conditions were obtained, at particle size of -80 / + 100 mesh, operating conditions at pH 6, calorific value increased from initially 3230,171 cal/gr to 5035,622 cal/gr, sulfur content decreased according to the optimum condition reached 2026.08 mg /kg, and the ash content decreased from 54.61% to 33.9%. From the results of these research indicate, Lerak as a surfactant is is enhanced to improve the quality of Tailings Coal (CT) by flotation method
Biogas Production from Vegetables and Fruit Wastes Using Anaerobic Floating Bioreactor
Get PDFMarkets and supermarkets are one of the pillars of the country\u27s economy, besides that, they are also the biggest contributors to vegetable and fruit waste which can cause various environmental problems. Therefore, the abundance of vegetable and fruit waste produced by markets and supermarkets can be utilized as environmentally friendly alternative energy, namely biogas. This study aimed to determine the effect of organic loading rate (OLR) on biogas production and gas composition in a continuous anaerobic floating bioreactor using mixed vegetable and fruit waste. A 40-l anaerobic floating bioreactor was utilized and the hydraulic retention time was 10 days; one kg of vegetable and fruit wastes at a 1:1 mass ratio was added with water to 4 l and introduced during 25 days; the daily biogas production was collected in a floating drum and measured as volume. The maximum biogas yield was 0.0452 m3/kg, achieved using the OLR of 0.0125 kg/l.day. The use of OLR of 0.0250, 0.0375 and 0.0500 kg/l.d reached biogas yields of 0.0435, 0.0282, and 0.0163 m3/kg, respectively. The composition of the maximum biogas yield was 68.17% CH4, 19.34% CO2, 1.85% H2S, and 0.64% NH3.