Evaluasi kecepatan pertumbuhan kristal pada reaksi diikuti kristalisasi pada pembuatan amonium sulfat dari amonia dan asam sulfat

ABSTRACT Chemical reaction followed by crystallization is industrially important because numerous materials are marketed in crystalline form. Its wide use has twofold advantages. Firs!, a crystal formed from an impure solution such as a reaction mixture is usually pure and second, crystalline form has preferable condition for packaging and storing. Beside the good yield and high purity, the most important objective of designing a crystallizer is to control the size range of the crystalline product. Crystal size distribution depends on nucleation and growth rates. When supersaturation can be kept low, such as in fluid-fluid reaction controlled by mass transfer rate. nucleation rate is low enough to be neglected and growth rate dominates the process. A model based on the concept of population density is proposed and then used to evaluate the growth rate. Based on the model proposed and the growth rate obtained, crystal size distribution can be predicted. The growth is assumed to follow LIL Law which states that the growth is independent of the crystal size. The model is verified using plant data from ZA III Plant of P.T. Petrokimia Gresik. It is found that in the operating conditions applied, the crystalline ammonium sulphate grows at constant rate of 0.0511 mm/hour. Having relatively small deviation between data and calculated results of mass fractions at any crystal size ranges, the model can well describe the process

Hidrolisis Pestisida Sumithion Dalam Air.

ABSTRACT The hydrolysis of sumithion in the presence and absence of single metal ion was investigated. The variables studied pH of the liquid and ion concentration. The reaction was carried out in a batch reactor. Eventhough neither pH nor were temperature was controlled, their variations were relatively small. If there was small variation, the average value was taken. The reaction was found to be pseudo first order with respect to sumithion. In the absence of ion, the hydrolysis product detected was 3-metil-4-nitrophenot Based on the observation that sumithion was stable at acid condition but unstable at base condition, it was concluded that the hydrolysis was catalyzed by base. Furthermore, ferric ion did not affect reaction rate observed. However, the presence of this ion inhibited degradation of intermediate product (demetilated fenitrothion or demetilated fenitrooxon). On the other hand, metal ion e.g. Cu2+, strongly promoted the hydrolysis of sumithion, and the intermediate products found were 3-metil-4-nitrophenol, a benzoic compound and an unknown product (demetilated fenitrothion or demetilated fenitrooxon). This ion also promoted the degradation of the intermediate products. The effect of pH and this ion concentration was well correlated with the equation: -031 kobs = 0,0148 + 48,1683[0H- + 5,2.106[M ]1\u2775 Key word: Pestisida, Sumithion, Hidrolisi

KNOWLEDGE MANAGEMENT DALAM PENINGKATAN KUALITAS LAYANAN KESEHATAN, SUATU TINJAUAN LITERATUR

Pengetahuan adalah aset tidak berwujud organisasi yang dapat memberikan keuntungan komparatif bagi mereka yang memilikinya. Rumah Sakit merupakan organisasi yang kompleks, unik, padat karya dengan latar belakang profesional yang beragam. Bersifat kompleks sebab terdapat permasalahan yang sangat rumit dan unik karena melibatkan proses yang menghasilkan jasa medis dan keperawatan sekaligus perhotelan dalam bentuk pelayanan kepada para pasien. Upaya sistematis meningkatkan pemanfaatan pengetahuan perusahaan melalui praktik manajemen informasi dan pembelajaran perusahaan untuk mencapai keunggulan kompetetitif berkelanjutan dikenal dengan istilah Knowledge Management. Artikel ini menyajikan review sistematis terhadap jurnal-jurnal yang membahas knowledge management di bidang kesehatan menggunakan google scholar untuk periode 10 tahun (2009-2019). Artikel yang disertakan diberi analisis konten kualitatif. Kami mengambil 64 artikel yang 10 artikelnya memenuhi syarat untuk dianalisis. Sebagian besar penelitian (n=6) menggunakan metodologi kualitatif. Proses yang digunakan untuk tinjauan literatur ini sangat sistematis dan terdiri dari: pencarian, skrining, ekstraksi data, sintesis, dan pelaporan dan diseminasi. Manajer yang bergerak dibidang kesehatan harus berupaya menggunakan KM melalui upaya mengelola pengetahuan sebagai aset, dimana dalam berbagai prakteknya terjadi diseminasi pengetahuan dengan melibatkan seluruh elemen organisasi,manajemen, pasien, dokter dan perawat, serta ditunjang dengan teknologi informasi, struktur dan kepemimpinan. knowledge management yang berhasil harus berpusat pada pasien untuk mendapatkan keunggulan bersaing berkelanjutan perusahaan

Karakteristik Bio-Oil Hasil Pirolisis Ampas Tebu (Bagasse)

Bagasse is a waste of sugar mills that can be utilized for a variety of chemicals. The purposes of this study are to determine the percentage of the compounds and physical properties of bio-oil, to determine the effect of variations of particle size and heating rate on the yields of bio-oil. Pyrolysis has been carried out in a reactor made of steel pipe type 5737 with dimension: diameter 7.62 cm and length 37 cm in length. The reactor was inserted into the furnace with a diameter of 15.24 cm and a length of 40 cm. One hundred and fifty grams of bagasse (Saccarum oficinarum L) has been inserted into the reactor without the presence of oxygen at atmospheric pressure. Pyrolysis has been carried out at the particle size of (-20+25) mesh, (-25+30) mesh, (-30+35) mesh , (-35+40) mesh, and -40 mesh and electrical voltage of 100, 105, 115, and 120 volt. Produced bio-oil has the following properties: brown color, pH of 2.96 to 3.03, viscosity of 1.3306 to 1.5101 cp, and density of 1.03 to 1.5 g/mL. The largest content of the compound is acetic acid (59,72%). The highest yields percentage of the particle size is (40,32%) on (-20+25 mesh) and highest yields percentage electrical voltage is 38,82% on 105 volt

Kinetika Reaksi Etanolisis Minyak Jarak Dengan Katalisator Kalium Hidroksid Dalam Sebuah Reaktor Alir Tangki Berpengaduk = Kinetics of Ethanolysis of Castor Oil Using Potassium Hydroxide as Catalyst in A Continuous Stirr

ABSTRACT In a lot of researches on alcoholysis of castor oil and other vegetable oils, the steps of mono- and diglycerides formation on reaction rate were not considered. The reaction was evaluated with the assumption that all of the three fatty acid groups in a glyceride molecule were attacked by ethanol at the same time. This research would verify that the reaction of the three fatty acid groups proceeds step by step. Four kinetics models of ethanolysis of castor oil were then established based on the reaction steps of the fatty acid groups. The ethanolysis of castor oil using potassium hydroxide as catalyst was initiated by heating castor oiI in a tank flow reactor equipped with initial ethanol feed heater, peristaltic pumps, rotameters, condenser, mechanical stirrer, digital thermometer, product withdrawal, and a water bath. At the same time, ethanol containing potassium hydroxide was heated in another vessel. As soon as the reaction temperature was reached, the, two reactants were quickly mixed. Afterwards, the castor oil and the ethanol containing the catalyst were pumped into the reactor continuously, and the product was constantly withdrawn. The glycerol concentration in the product was analyzed spectrophotometrically until steady state condition was reached. Then, the concentration of glycerol at steady state condition was reanalyzed using acetin method, while ethyl ricinoleate concentration was indirectly determined by measuring the increase of the hydroxyl groups in the glyceride using a method for determination of acetyl value. The data obtained were glycerol and ethyl ricinoleate concentrations in the product of various residence time and catalyst concentrations. The ratio of the ethyl ricinoleate formed to the glycerol produced was greater than three. This proved that the reaction of fatty acid groups in castor oil ethanolvsis proceeded in steps. The reaction rate constant of the secondary group was somewhat greater than those of the primary groups. Hence, it was apparent that the secondary fatty acid group was a bit more reactive than the primary ones. Furthermore, based on the analysis of the effect of catalyst concentration on the reaction rate constants for the primary and secondary groups, it could be concluded that the kinetics model assuming step by step attack on the fatty acid groups (model In) was the most logically acceptable model among the four models proposed. Keywords: kinetics models of castor oil ethanolysis, mono- and diglycerides formation, reactivity of fatty acid groups, step by step attack on the fatty acid group

Pemodelan Dekomposisi Ammonium Carbamate pada Tekanan Tinggi di Pabrik Urea

Urea acts as a nitrogen-based fertilizer to boost crop production and prevent a worldwide hunger crisis. Considering ways to make urea production in existing plants more environmentally friendly, a detailed study has been conducted on the high-pressure stripper, in which the equipment uses intensive energy to decompose ammonium carbamate. The mathematical model was prepared using the two-film theory. The UNIQUAC and Redlich-Kwong equations of state have been used to express nonideality in the NH3-CO2-H2O-urea system under high pressure and temperature circumstances. Due to the lack of transport properties in extreme conditions, the properties were estimated using a theoretical method. The present study obtained the mass-transfer coefficient in dimensionless form  and . Moreover, the heat-transfer coefficient was calculated using the Chilton-Colburn analogy. The proposed model result matches what is expected with the commercial plant data. Furthermore, with less than 5% relative deviations, the model deserves significant consideration for any practical use in high-pressure stripper simulatio

Dewaxing Solar Dengan Penambahan Mek Tinjauan Termodinamis

In the petroleum industries, wax precipitation is undesirable because it may cause plugging in the pipelines and process equipment. So, the amount of wax in petroleum products should be kept relatively small and it can be achieved by dewaxing. The system in dewaxing is assumed to be a ternary system with the pseudo components of alifatics (wax or paraffins and naphtenes), ketones (MEK), and aromatics. Numerous activity coefficient models were used to predict the solid-liquid equilibrium in dewaxing of diesel fuel with MEK. The models were Unifac, Regular solution, and Two Suffix Margules. In one operation, 15 mL of diesel fuel was mixed with 37.5 mL of MEK (pure or mixed with benzene) and chilled to the desired temperature in a silindrical tube with 2.9 cm of inside diameter, 3.25 cm of outside diameter and 12.25 cm of length. After equilibrium condition was attained, a liquid sample was taken and its composition was analyzed using ASTM D 1319-98. Experimental results showed that pseudo ternary approximation could well predict the equilibrium. It was further observed that Uriifac model with 7.6% of error was better than Regular solution model with 12.3% of error. Two Suffix Margules model gave very good result but it used one adjustable parameter, so it could be used only in this system. Keywords : dewaxing, diesel fuel, ternzodynami

Laporan Penelitian Kerjasama Antar Perguruan Tinggi (Pekerti) Karakteristik Produk Pirolisis Dari Sekam Padi, Tongkol Jagung, Dan Serbuk Gergaji Kayu Jati Menggunakan Katalis Zeolit

Menurut BPS (2009), Indonesia memiliki sawah seluas 12,84 juta hektar yang menghasilkan padi sekitar 63,84 juta ton. Kadar sekam padi terhadap berat padi keseluruhan sekitar 15 - 20%. Ini berarti limbah sekam padi yang dihasilkan bangsa Indonesia sekitar 8,2 – 10,9 ton/tahun. Berdasarkan data dari Perum Perhutani Jawa Tengah,mengatakan bahwa produksi kayu jati di Jawa Tengah keadaan Februari Tahun 2011 adalah sebesar 35.654 m3. Produksi kayu jati untuk wilayah Surakarta sebesar 2.500 m3. Berdasarkan uraian di atas potensi limbah yang besar dari serbuk sekam padi, serbuk gergaji kayu jati dan kayu glugu ini hanya sedikit yang baru dimanfaatkan secara optimal. Karenanya peneliti tertarik untuk melakukan penelitian karakteristik produk pirolisis dari serbuk sekam padi, serbuk gergaji kayu jati, dan kayu glugu dengan menggunakan katalis zeolit. Pada penelitian tahun pertama akan dilakukan pirolisis dari kayu jati, sekam padi, dan glugu. Penelitian dimulai dengan me-design dimensi alat pirolisis, melakukan penelitian pendahuluan. Dari penelitian tahun pertama ini akan diperoleh hasil pirolisis dari masing-masing bahan yang terdiri dari asap cair dan bio-char. Setelah penelitian selesai dilakukan uji sifat fisik dan kimia dari asap cair dan bio-char tersebut. Uji terdiri dari uji massa jenis, viskositas, pH, komposisi, dan warna serta nilai kalor. Berdasarkan penelitian yield asap cair tertinggi sebesar 44,75% pada pirolisis sekam padi pada suhu 600oC sedangkan pada variasi perbandingan katalis diperoleh yield sebesar 44,74% pada perbandingan sekam padi : zeolit = 1 : ¼. Yield char tertinggi sebesar 58,14% pada pirolisis kayu glugu pada suhu 450°C sedangkan pada variasi perbandingan katalis diperoleh yield sebesar 64,87% pada perbandingan kayu jati dan kayu glugu: zeolit = 1 : 1/8. Yield gas tertinggi sebesar 24,50% pada pirolisis kayu jati pada suhu 450oC sedangkan pada variasi perbandingan katalis diperoleh yield sebesar 30,35% pada perbandingan sekam padi : zeolit = 1 : 1. Kadar CO2 tertinggi sebesar 35,6625% pada pirolisis kayu glugu . Senyawa terbanyak pada asap cair adalah asam asetat (25,71%), asam metakrilat 24,91%, dan krotanaldehida (21,39%)

Keseimbangan Ion Pada Koagulasi Protein Ampas Tahu

Protein coagulation is one of the important steps in solid protein production. These products are usually used in food industries as functional ingredients add,...d to the food in order to emulsify, to form foams or gels, to bind water, to control color etc. Due to the amphoteric properties of the protein molecules, protein solubility is very influenced by pH. The purpose of this experiment was to obtain a mathematical model which can be used to determine the effect of pH on protein solubility. Because the ionic equilibrium constants are influenced by temperature, this study also includes the effect of temperature. Soybean curd waste was used to test the model. The process took place in an extraction flask provided with stirrer and the pH was fixed at a certain value. The temperature of the solution was kept constant at the desired value using a waterbath. The experiment was carried out for 45 minutes and equilibrium was assumed to be achieved. The precipitate was then filtered. The protein contents in the filtrate were analyzed using UV/Visible spectrofotometer accurding to Lowry method. Compared with the experimental data, the model can qualitatively predict the solubility of protein and quantitatively predicts the isoelectric point. Keywords : Ionic equilibrium, pH, protein, solubility

Perpindahan Panas Pada Packed Bed:Konduktivitas Panas Efektif Dan Koefisien Perpindahan Panas Pernukaan Dinding

Heat transfer in packed beds was studied by flowing air through a tube filled with spherical steel and glass particles, while steam as a heat source was flown through the jacked. It was assumed that the fluid temperature were equal to that of the solid particles (pseudo-homogeneous model). The bed temperatures at various height and radii were measured for various air flow rate and particles size. The mathematical model was solved numerically. Based on the experimental data and the mathematical model proposed, the heat transfer parameters, which were effective thermal conductivity (k,) and heat transfer coefficient on the surface wall (h,â), were evaluated by numerical least squares. The mathematical model turned out to be able to simulate the heat transfer process. The empirical equation was developed to correlate the Reynolds number and the ratio of particles diameter to the ratio of effective thermal conductivity to gas conductivity, and to the Nusselt number