ORIGINAL_ARTICLE
Multidimensional Dynamic Modeling of Milk Ultrafiltration Using Neuro-Fuzzy Method and a Hybrid Physical Model
Prediction of the dynamic crossflow ultrafiltration rate of a protein solution such as milk poses a complex non-linear problem as the filtration rate has a strong dependence on both the solution physicochemical conditions and the operating conditions. As a result, the development of general physics-based models has proved extremely challenging. In this study an alternative dynamic neuro-fuzzy model for milk ultrafiltration that describes the variation in dynamic permeate flux decline with temperature, transmembrane pressure (TMP), fat percentage, pH and molecular weight cut off (MWCO) has been developed with the experimental data of the pilot spiral wound membrane test rig. By increasing the temperature, TMP, and pH the permeate flux is increased, and by increasing fat concentration the permeate flux is decreased. The MWCO variation indicates a paradoxical permeate flux. Additionally, a hybrid physical model for dynamic prediction of total resistance in the milk ultrafiltration by combination of two neuro-fuzzy (ANFIS) models and a physical model (BLA model) is developed. By increasing the TMP and fat concentration, the total resistance is increased. But by increasing the pH and temperature, the total resistance is decreased. Also, MWCO variation indicates a paradoxical total resistance value.
https://www.ijche.com/article_11277_3fbec4119781253ec322843eeb2feabf.pdf
2008-04-01
3
22
Ultrafiltration
Dynamic Modeling
Milk
Neuro-Fuzzy
Hybrid Model
ORIGINAL_ARTICLE
Solid Phase Equation of State Application for Wax Formation Prediction in Petroleum Mixtures
Precipitation ofsolid paraffins is one ofthe most common problems in the oil industry, imposing high operating costs. There have been a great many efforts for the prediction of solid paraffins precipitation up to now. Most of them were based on activity coefficient models accounting to solid phase non-ideality or the multi-solid model to calculate the number ofprecipitated solid phases. In this work, solid phase behavior is predicted by a solid equation of state. At first, by using the thermodynamic method (subcoled liquid) for pure solid phase fugacity from pure liquid fugacity, the solid EOS parameters are tuned. The tuned solid EOS can then be directly applied for the prediction of the amount of precipitated solid paraffins (waxes) in the oil samples. The proposed equations system in this work is solved by a proper mathematical method. The obtained results of wax precipitation in this work are in good agreement with the experimental data.
https://www.ijche.com/article_11278_87f159b6c52c03ab4f4796329e4e7022.pdf
2008-04-01
23
33
Solid Paraffin
Solid Phase Equation of State
Wax Precipitation
Multisolid model
ORIGINAL_ARTICLE
Surfactant Remediation of LNAPL Contaminated Soil; Effects of adding alkaline and foam producing substances
Uncontrolled release of light non aqueous phase liquids (LNAPL) such as diesel, gasoline, fuel oils and lubricating oils from transporting vehicles, pipeline and underground storage tanks (UST) could lead to the migration of contaminants to the subsurface soil and ground water. There is a high interfacial tension (IFT) between LNAPL molecules and water molecules that makes water a non-efficient cleaning material for removing LNAPL from the soil. Nowadays, surfactants (surface active agents) can promote the enhanced removal of LNAPL from the subsurface through mobilization and solubilization. Encouraging results were achieved from laboratory and field results. The aim of this study is to improve the clean up efficiency of surfactant-flooding for two different surfactants; Triton X-100 and Sodium Dodecyl Sulfate which are known as mobilizing and solubilizing surfactants, respectively, by adding alkaline (increasing pH) and foam producing substances. It is shown here that adding alkaline improves the performance of Triton X-100 in removing LNAPL from the contaminated soil by about 8 percent, but spoils the remediating capability of Sodium Dodecyl Sulfate by about 3 percent. Also, adding a foaming agent helps the surfactant solution in removing the LNAPLs out of the soil by more than 5 percent.
https://www.ijche.com/article_11279_7f002fe7f048a996c3fdfbde0b5b6385.pdf
2008-04-01
34
44
LNAPL
Surfactant
Remediation
Alkaline
Foam
ORIGINAL_ARTICLE
Preparation and Characterization of Polyaniline/CaCO3 Composite and its Application as Anticorrosive Coating on Iron
Composites of polyaniline with calcium carbonate particles (PANI/CaCO3) with different CaCO3 content (0-40 %w/w) were prepared. Two different methods of in situ polymerization and solution mixing were used for PANI/CaCO3 composite preparation. The composite was characterized using FT-IR, SEM, electrical conductivity measurement and cyclic voltammetry techniques. The incorporation of CaCO3 particles in polyaniline matrix in both methods of composite preparation was confirmed by FTIR results. Electrical conductivity measurements showed that the conductivity of the composite decreases by increasing the CaCO3 loading in polyaniline. Also, the anticorrosive property of the PANI/CaCO3 composite coating on iron samples was investigated in various corrosive environments. According to the results, the corrosion rate or corrosion current of PANI/CaCO3 composite coated iron coupons was much lower (96.75%) than polyaniline coated samples. Also, results showed that the corrosion current of composite coated samples varies with the variation of the CaCO3 content in composite coating, and the optimum CaCO3 content of composite coating to achieve the best anticorrosive performance on iron is 10 %w/w.
https://www.ijche.com/article_11280_3aa51a8ca0f3c4aa5e8e7fdda6930339.pdf
2008-04-01
45
54
Composite
Conducting polymers
Polyaniline
Calcium Carbonate
corrosion
ORIGINAL_ARTICLE
Phase Inversion in a Batch Liquid – Liquid Stirred System
"> Phase inversion phenomenon occurs in many industrial processes including liquidliquid dispersions. Some parameters such as energy input or the presence of mineral compounds in the system affect this phenomenon. The aim of this research is to study the speed of rotation or energy input at a range of 400 to 800 rpm in a batch liquid-liquid system containing toluene and water. The presence of sodium chloride and magnesium sulphate in the system was also studied. It was shown that the increase of energy input had a more obvious effect on oil in water (O/W ) dispersion at lower values of holdup. It was also shown that the ambivalence (o/w → w/o) region of the phase inversion curve shifted downward and became wider as a result of the decrease in interfacial tension. It was observed that inorganic salt, used in both single and dual (mixed) shapes, enhanced phase inversion for O/W dispersion. Therefore, the greater the ionic strength of salt, the greater the tendency to phase inversion is.
https://www.ijche.com/article_11281_489c622670d25bba2627004e56aa29ce.pdf
2008-04-01
55
63
phase inversion
Holdup
ambivalence region
delay time
O/W dispersion
ORIGINAL_ARTICLE
The Effects of SiO2 and Al2O3 Binders on the Activity and Selectivity of Bifunctional Fe/HZSM-5 Catalyst in Fischer-Tropsch Synthesis
"> The influence of SiO2 and Al2O3 binders on the catalyst performance and products selectivity of the precipitated Fe-Cu-K catalyst physically mixtured with HZSM-5 was studied in a fixed bed tubular reactor. The iron catalyst was mixed with HZSM-5 zeolite and shaped to cylinders form by alumina and or silica as a binder for increasing the mechanical strength of bifunctional catalyst. The catalyst activity was tested under reaction condition, P=17 bar, T=290 oC , H2/CO=1 and GHSV= 3.07 NL.h-1.g.Fe-1. The results showed that the catalyst activity for Fischer – Tropsch and water gas shift reactions for silica binders is lower than alumina and secondary reactions in the presence of alumina is higher.
https://www.ijche.com/article_11282_98b77e7e552faa5e860ff6a36b2a3382.pdf
2008-04-01
64
70
Fischer – Tropsch synthesis
HZSM5 Zeolite
Iron Catalysts
Silica binder
Alumina binder
Secondary reaction