Thermodynamic insights into Henry's constant in hyperthermal oxidation of silicon for fabricating optical waveguides

Hyperthermal oxidation of silicon is envisaged to be an alternative to silicon-on-insulator (SOI) waveguide fabrication for photonic integrated circuit (PIC) devices, and thus the local oxidation of silicon (LOCOS) technique has attracted attention.

Experimental and numerical study of the polyurethane foaming process using high-pressure CO2

A simulation of simultaneous bubble nucleation and growth was performed for polyurethane/CO2 physical foaming process. The single-factor and comprehensive effects of viscoelastic properties, Henry’s constant, CO2 diffusion coefficient and surface tension on the cell morphology were numerically analyzed. The results show that the cell density of PU foam ( N0) increases and its average cell diameter ( Dv) reduces with increased Henry’s constant and slower gas diffusion. Both N0 and Dv reduces with the curing degree ( α). In addition, the effects of α and foaming conditions on the cell structure were experimentally investigated. With an increase of α at foamable range, Dv decreases continuously and N0 increases first and then declines. With increasing saturation pressure and depressurization rate or decreasing temperature, N0 increases and Dv reduces. There is an intrinsic correlation between the simulated and experimental variables, and the results of the simulation and experiment are generally consistent.

Analysis and Interpretation of Pressure-Decay Tests for Gas/Bitumen and Oil/Bitumen Systems: Methodology Development and Application of New Linearized and Robust Parameter-Estimation Technique Using Laboratory Data

Summary Diffusion mixing is a dominant process in the absence of convective mixing in various reservoir processes, such as carbon dioxide (CO2) flooding of fractured reservoirs, heavy-oil and bitumen recovery, solution-gas-drive processes, and the gas-redissolution process in a depleted reservoir. In these processes, the diffusivity governs the rate and extent of mixing of light hydrocarbons/nonhydrocarbons with the oil that enhances the oil recovery through in-situ viscosity reduction. It is one of the key parameters for the design and understanding of displacement processes. Because of its significance in various aspects of oil-recovery processes, several experimental and theoretical studies were recently performed on the measurement of gas diffusivity in oils. Experimental work most commonly uses the pressure-decay (PD) concept because of its simplicity and the potential extraction of other necessary parameters, such as Henry's constant. However, the parameter estimation from these tests is dependent on nonlinear regression, which might have several issues such as nonconvergence, nonuniqueness or multiplicity in solution, and high sensitivity toward noise and the time span of the data. Therefore, in this paper, Ratnakar and Dindoruk (2015) is extended and New experimental data are provided from a PD test for CO2 diffusion into bitumen at 80°C and approximately 700 psi. A robust inversion technique for parameter estimation is presented for exponentially decaying late-transient data, which can be used with any PD model used in the literature. The validity and applicability of the inversion technique is demonstrated against numerical data that are generated for a PD system by solving a diffusion model with continuity in the state variable (using Henry's constant) and molar flux at the gas/oil interface. Most importantly, the issues with the nonlinear-regression technique are resolved using the linearized technique. The inversion technique presented in the work is dependent on a combination of linear regression and numerical integration using a modified, more-convenient form of the fundamental equations rather than a nonlinear regression on the fundamental equations as derived. This integral-based linear representation avoids the multiple solutions and can be used with limited data sets and/or when noise in the experimental data is significant, especially in industrial-grade experiments.

Pengukuran konstanta henry toluen dan benzen dalam minyak dan air dengan kolom gelembung

Determination of Henry’s constant for toluene and benzene in oils and water were carried out in a bubbling bottle with diameter of 3 cm. Air containing toluene vapour or benzene vapour was bubbled through 50 mL absorbing liquid. The gas flow rate was 13.6 mL/min. By measuring the concentration of toluene or benzene in the inlet and outlet gas stream, we were able to calculate their concentrations in absorbing liquid. We found that the value of Henry’s constant of toluene in lubrication oil and palm oil at 30 oC were 155 and 145 respectively (H= CG/CL, with CG in mol/L and CL in mol/L). We also found that the absorption capacities were in the order (from the highest) of: lubrication oil, palm oil, and sunflower oil. Henry’s constant of toluene in water was at about 4 which was much lower than those of oils.Keyword: absorption, Henry’s constant, toluene, benzene, producer gas AbstrakPengukuran konstanta Henry sistem toluen dan benzen dalam minyak dan air dilakukan melalui percobaan absorpsi di dalam sebuah kolom gelembung dengan diameter 3 cm. Minyak sawit, minyak bunga matahari, minyak pelumas dan air digunakan sebagai absorben. Toluen dan benzen dipilih sebagai tar model. Gas model yang tersusun dari udara dan uap toluen atau benzen digelembungkan ke dalam absorben 50 mL. Absorpsi dilakukan pada suhu 30 dan 60 oC dan laju alir gas model 13,6 mL/min. Analisa dilakukan terhadap konsentrasi aliran gas model sebelum dan sesudah absorpsi. Analisa tersebut dilakukan dengan kromatografi gas Shimadzu GC-8APF. Konstanta Henry dihitung sebagai H=CG/CL dan H=P/CL. Nilai 1/H sistem toluen-minyak pelumas dan toluen-minyak sawit pada suhu 30 oC dan laju alir gas 13,6 mL/min berturut-turut adalah 155 dan 145 (untuk CG dalam mol/L dan CL dalam mol/L). Merujuk pada nilai-nilai konstanta Henry hasil percobaan, minyak pelumas dan minyak sawit merupakan cairan penyerap yang paling cocok untuk toluen dan benzen sebagai representasi tar dalam gas hasil gasifikasi. Urutan besarnya kapasitas absorpsi cairan penyerap terhadap toluen dan benzen adalah sebagai berikut (berturut-turut dari yang besar): minyak pelumas, minyak sawit, minyak bunga matahari dan air. Konstanta Henry toluen dalam air berada pada kisaran 4, yang menunjukkan bahwa kapasitas absorpsi toluen dalam air lebih rendah dibandingkan kapasitas absorpsi toluen dalam minyak.Kata Kunci: absorpsi, konstanta Henry, toluen, benzen, gas produser

Measurements of Hydrogen Solubility in Nitrobenzene/Aniline Mixtures

Measurements of hydrogen solubility in various nitrobenzene-aniline mixtures were conducted in an autoclave reactor with a stirrer and control of temperature. The solubility of hydrogen was measured at 7 different values of temperature (30 °C, 40 °C, 50 °C, 90 °C, 130 °C, 170 °C, 210 °C, respectively), 3 values of stirrer rotation speed (1200 rpm, 1600 rpm, 2000 rpm, respectively) and a range of pressure of 20 ‒ 30 bar. Moreover, pure aniline, pure nitrobenzene and their mixtures with different concentrations were used. In the next step, values of Henry’s constant were calculated. Based on experimental data a dependence of Henry’s constant on temperature for pure aniline and pure nitrobenzene was proposed. Additionally, for each temperature correlations between Henry’s constant and aniline’s concentration in mixture of nitrobenzene-aniline were found.

Pengaruh Suhu pada Esterifikasi Amil Alkohol dengan Asam Asetat Menggunakan Asam Sulfat sebagai Katalisator

Ester compounds are widely used as solvents, artificial aroma materials, and precursors of pharmaceutical ingredients. One of the ester compounds widely used in the chemical industry is amyl acetate. Amyl acetate can be synthesized by esterification of amyl alcohol and acetic acid, which is a liquid-liquid heterogeneous reaction. This study aims to study the kinetics of this particular reaction focusing on the effect of temperature. The catalyst used in this study was sulfuric acid. The mole ratio of acetic acid to amyl alcohol used was 2: 5. Reaction was run at constant temperature in a three-neck flask as a batch reactor. The acetic acid and sulfuric acid were first put into the reactor and heated while stirring. After reaching a certain temperature, the preheated amyl alcohol was added into the reactor. During reaction, the temperature was maintained at the desired temperature. The reactants and products involved in this reaction were immiscible. The product phases were separated and then the remaining acetic acid content in the water-soluble phase was analyzed by volumetric method. The study was carried out in 4 variations of temperature i.e. 70, 80, 90, and 100C. The results of experimental data analysis showed that the reaction will be faster when the temperature is higher. The mass transfer from the acetic acid phase to the amyl alcohol phase increased with the increase of temperature. The value of the reaction rate constant, the overall mass transfer coefficient, and the Henry’s constant were evaluated by the parameter fitting method using the MATLAB program. Based on the evaluation at the highest reaction temperature 100oC, the rate constant was 0,0134 mL.mole-2s-1, the mass transfer coefficient was 0,3180 L s-1, and the Henry’s constant was 0,0174 (mole/L)A in phase II/(mole/L)A in phase I. Keywords: esterification, immiscible, amyl acetate, mass transfer Senyawa ester banyak dipakai sebagai solven, bahan aroma buatan, dan prekursor bahan-bahan farmasi. Salah satu senyawa ester yang banyak digunakan dalam industri kimia dalah amil asetat. Ester amil asetat dapat disintesis melalui reaksi esterifikasi dengan bahan baku amil alkohol dan asam asetat. Reaksi ini merupakan reaksi heterogen cair-cair. Penelitian ini bertujuan untuk mempelajari kinetika reaksi tersebut, terutama pengaruh variabel suhu. Untuk mempercepat laju reaksi ditambahkan asam sulfat. Perbandingan mol pereaksi asam asetat:amil alkohol yang digunakan sebesar 2:5. Reaksi dijalankan dalam reaktor batch dan suhu dijaga konstan. Reaktan dan katalisator dicampur dalam labu leher tiga. Asam asetat dan asam sulfat dituangkan ke dalam reaktor, dipanaskan dan diaduk sampai suhu tertentu. Selanjutnya amil alkohol yang telah dipanaskan sebelumnya hingga suhu tertentu dituangkan. Selama reaksi suhu dipertahankan konstan. Reaktan dan produk yang terlibat dalam reaksi ini berupa campuran immiscible. Produk yang terdiri dari dua fase dipisahkan antar fasenya kemudian fase yang larut dalam air dianalisis kadar asam asetat sisanya dengan metode volumetri. Reaksi dilakukan masing-masing pada suhu 70, 80, 90, dan 100oC. Hasil analisis menunjukkan bahwa reaksi akan semakin cepat apabila suhu semakin tinggi. Transfer massa dari fase asam asetat ke fase amil alkohol semakin besar pula dengan adanya kenaikan suhu. Nilai konstanta kecepatan reaksi, koefisien transfer massa overall, dan konstanta Henry dievaluasi dengan metode fitting parameter menggunakan program MATLAB. Berdasarkan evaluasi pada suhu reaksi tertinggi yaitu 100oC diperoleh nilai konstanta kecepatan reaksi sebesar 0,0134 mL.mol-2s-1, koefisien transfer massa overall sebesar 0,318 mL s-1, dan konstanta Henry sebesar 0,0174 (mol/L)A di fase II/(mol/L)A di fase I. Kata kunci: esterifikasi, immiscible, amil asetat, transfer massa