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نویسندگان: 

ZHOU Q. | BAI H. | XIE G.

نشریه: 

VIRTUAL

اطلاعات دوره: 
  • سال: 

    621
  • دوره: 

    1
  • شماره: 

    1
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    3
  • بازدید: 

    209
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 209

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نویسنده: 

YOUSEFI AMIRI T. | MOGHADDAS J.S.

اطلاعات دوره: 
  • سال: 

    2009
  • دوره: 

    6
تعامل: 
  • بازدید: 

    169
  • دانلود: 

    0
چکیده: 

IN THE PRESENT WORK, SOME AFFECTED PARAMETERS ON THE LIQUID PHASE MIXING IN THE PROPOSED JET MIXED GAS- LIQUID SYSTEM WERE STUDIED EXPERIMENTALLY. IN THIS TWO-PHASE MIXING SYSTEM, INSTEAD THE IMPELLER IN CONVECTIONAL STIRRED TANKS THE JET FLUID HAS BEEN USED AS A MIXER. IN THE MIXING VESSEL THE JET FLOW AND GAS FLOW ARE COUNTERCURRENT. THE STUDIED PARAMETERS INCLUDED AERATION RATE, JET FLOW RATE AND NOZZLE DIAMETER. THE CREATED FLOW PATTERN EXTRACTED FOR EACH CONDITION AND RESULTS OFTEN ANALYZED ON THE BASIS OF THEM. IT IS OBTAINED, ON THE BASIS OF JET REYNOLDS NUMBER AND THE AMOUNT OF JET TRAVELLING IN THE VESSEL, INCREASING OF AERATION RATE HAVE DIFFERENT EFFECTS ON THE PERFORMANCE OF MIXING. GENERALLY FOUR DIFFERENT TRENDS FOR VARIATION OF MIXING TIME WITH INCREASING OF AERATION RATE ARE OBSERVED. DECREASING OF NOZZLE DIAMETER AT CONSTANT JET FLOW RATE OR INCREASING OF JET FLOW AT CONSTANT NOZZLE DIAMETER CONTINUOUSLY DECREASES THE MIXING TIME. TOO, COMPARISON OF THE JET MIXED SYSTEM RESULTS WITH THE RESULTS OF SIMILAR MECHANICALLY STIRRED SYSTEM SHOWS THE IMPROVING OF LIQUID PHASE MIXING IN THE JET MIXED SYSTEM.

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بازدید 169

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نویسنده: 

GHANADZADEH H.

اطلاعات دوره: 
  • سال: 

    2004
  • دوره: 

    9
تعامل: 
  • بازدید: 

    157
  • دانلود: 

    0
چکیده: 

THE DETERMINATION REGION OF SOLUBILITY OF METHANOL WITH GASOLINE OF HIGH AROMATIC CONTENT WAS INVESTIGATED EXPERIMENTALLY AT TEMPERATURE OF 298.2 K. A TYPE 1 LIQUIDLIQUID PHASE DIAGRAM WAS OBTAINED FOR THIS TERNARY SYSTEM. THESE RESULTS WERE CORRELATED SIMULTANEOUSLY BY THE UNIQUAC MODEL. THE VALUES OF THE INTERACTION PARAMETERS BETWEEN EACH PAIR OF COMPONENETS IN THE SYSTEM WERE OBTAINED FOR THE UNIQUAC MODEL USING THE EXPERIMENTAL RESULT. THE ROOT MEAN SQUARE DEVIATION (RMSD) BETWEEN THE OBSERVED AND CALCULATED MOLE PERCENTS WAS 2.86 FOR METHYLCYCLOHEXANE + METHANOL + ETHYLBENZENE. THE MUTUAL SOLUBILITY OF METHYLCYCLOHEXANE AND ETHYLBENZENE WAS ALSO INVESTIGATED BY THE ADDITION OF METHANOL AT 298.2 K.

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اطلاعات دوره: 
  • سال: 

    2008
  • دوره: 

    5
  • شماره: 

    2
  • صفحات: 

    55-63
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    277
  • دانلود: 

    0
چکیده: 

Phase inversion phenomenon occurs in many industrial processes including liquid - iquid 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.

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بازدید 277

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اطلاعات دوره: 
  • سال: 

    2006
  • دوره: 

    11
  • شماره: 

    2
  • صفحات: 

    202-206
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    140
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 140

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اطلاعات دوره: 
  • سال: 

    1386
  • دوره: 

    26
  • شماره: 

    1
  • صفحات: 

    39-49
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    1162
  • دانلود: 

    179
چکیده: 

وارونگی فاز در پراکندگی های مایع ـ مایع، پدیده ای است که در بسیاری از فرایندهای صنعتی روی می دهد، اما مکانیسم های حاکم بر این پدیده و چگونگی اثر پارامترهای فیزیکی و هندسی روی آن به خوبی درک نشده است. در این مقاله اثر سرعت هم زدن، نوع سیستم شیمیایی و وجود نمک های معدنی روی این پدیده در ظرف های هم زن دار و در حالت ناپیوسته بررسی شده است. به منظور بررسی پدیده وارونگی، از یک سیستم مجهز به هم زن با دور متغیر و برای مشاهده آن از یک هدایت سنج استفاده شده است. نتیجه ها نشان می دهد که با افزایش سرعت هم زدن، پراکندگی های فاز آلی در آب در مقدارهای کم تری از کسر حجمی فاز پراکنده وارونه می شود، در حالی که پراکندگی های آب در فاز آلی گرایش معکوسی را نشان می دهد. همچنین مشاهده شده است که کاهش کشش بین سطحی پراکندگی باعث انتقال مرزهای ناحیه دوسوگرایی به سمت پایین و پهن شدن آن می شود. افزودن نمک به فاز آبی نیز روی رفتار وارونگی فاز اثر گذار بوده و باعث آسان شدن وارونگی فاز در پراکندگی های فاز آلی در آب شده است، هر چه نمک اضافه شده از قدرت یونی بالاتری برخوردار باشد، این تاثیر بیشتر خواهد بود.

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نویسندگان: 

Yanli Zhang | Dongguang Li

اطلاعات دوره: 
  • سال: 

    2022
  • دوره: 

    41
  • شماره: 

    12
  • صفحات: 

    4228-4233
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    29
  • دانلود: 

    0
چکیده: 

Phase diagrams for the ternary (neopentyl glycol + sodium formate + water) system were measured. Phase equilibrium data were obtained at different temperatures of 333. 15, 343. 15, and 353. 15 K. The effect of temperature on the liquidliquid phase equilibrium was studied and the length and slope of the tie-line at different temperatures for the conjugate phase were investigated. It was found that the tie-line length decreases and the two-phase area is slightly reduced by increasing temperature. The three fitting parameters of the Merchuk and Pirdashti equations were obtained with the temperature dependence expressed in the linear form, respectively. Compared with the Pirdashti equation, the binodal curves were described satisfactorily with the Merchuk equation, further, the plait points at various temperatures were estimated by extrapolation. The Othmer-Tobias and Hand models were used for the correlation of the phase equilibrium behavior. The correlation coefficients of the models were obtained for the corresponding temperatures. The results showed that it was well fitted with the Othmer-Tobias model by contrast with the Hand model

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اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    11
  • شماره: 

    4
  • صفحات: 

    1087-1101
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    344
  • دانلود: 

    0
چکیده: 

In the past decade, liquid-phase microextraction (LPME), which can also be called solvent microextraction, has emerged as a minimal organic solvent-based sample preparation approach. The main advantages of this method include versatility, simplicity and effectiveness of its extraction procedures at reducing sample complexity, as well as the convenience of liquid sample concentration and injection techniques. LPME is based on the distribution of analytes between the organic solvent and the aqueous solution. Hitherto, several different LPME modes have been developed. Some of the described methodologies usually offer slow extraction kinetics due to the low contact surface between the sample and the extractant phase. Since the introduction of dispersive liquidliquid microextraction, a number of studies have been focused on the features of emulsification in preconcentration techniques. Emulsification enhances the surface area between the extraction solvent and aqueous sample by the efficient dispersion (chemically assisted or by the use of an external energy source) of the extractant in the sample. In this paper we review the emulsification-based liquid-phase sample preparation techniques. A brief practical and theoretical description of each technique and some applications are given.

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بازدید 344

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نویسندگان: 

GERMAN R.M.

اطلاعات دوره: 
  • سال: 

    1990
  • دوره: 

    26
  • شماره: 

    -
  • صفحات: 

    23-33
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    164
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 164

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اطلاعات دوره: 
  • سال: 

    2013
  • دوره: 

    16
تعامل: 
  • بازدید: 

    124
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

HYDROCHLOROTHIAZIDE (HCTZ) IS A THIAZIDE DIURETIC AND ANTIHYPERTENSIVE DRUG USED IN THE TREATMENT OF OEDEMA ASSOCIATED WITH CONJESTIVE HEART FAILURE AND RENAL AND HEPATIC DISORDERS [1]. THE AIM OF THE PRESENT INVESTIGATIONS IS TO INTRODUCE LIQUID-LIQUID MICROEXTRACTION WITH HOLLOW FIBERS (HF-LPME) IN HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC) HAS BEEN APPLIED AS A NEW, FAST, SIMPLE AND EFFICIENT PROCEDURE FOR THE DETERMINATION OF HCTZ IN HUMAN URINE SAMPLE. THE TARGET COMPOUNDS WERE EXTRACTED FROM 24-ML AQUEOUS SAMPLE (DONOR SOLUTION, PH 12.0) THROUGH A MICROFILM OF ORGANIC SOLVENT (1-OCTANOL), IMMOBILIZED IN THE PORES OF A HOLLOW FIBER WITH 8.4 CM LENGTH FIXED ONTO THE TIP OF THE SYRINGE NEEDLE, WHICH WAS DIRECTLY IMMERSED INTO THE SAMPLE [2]. AFTER A PRESCRIBED PERIOD OF TIME, THE ACCEPTOR SOLUTION INSIDE THE FIBER WAS WITHDRAWN INTO THE MICROSYRINGE AND DIRECTLY INJECTED INTO THE HPLC SYSTEM FOR ANALYSIS. FACTORS RELEVANT TO THE EXTRACTION PROCEDURE WERE STUDIED: CHOOSING THE SUITABLE EXTRACTION SOLVENT, PH VALUE OF THE SAMPLE SOLUTION, THE EFFECT OF IONIC STRENGTH (WHICH FOUND THAT THE CONCENTRATION OF NACL SLIGHTLY DECREASES THE EXTRACTION EFFICIENCY), THE STUDY OF ION PAIR EFFECT (ALIQUAT-336 ADDED INTO THE EXTRACTION SOLVENT) [3], IT SHOWED THAT THE SIGNAL OF THE ANALYTE WAS INCREASED BY INCREASING THE CONCENTRATION OF ALIQUAT-336 UP TO 2% (V/V). THE STIRRING OF 800 RPM AND THE EXTRACTION TIME OF 90 MIN WERE CHOSEN AS THE OPTIMUM CONDITIONS.QUANTITATIVE PARAMETERS UNDER THE OPTIMIZED CONDITIONS WERE CALCULATED. LDR OVER THE RANGE OF 1.0-100MG L-1 OF HCTZ, R2 0.9933, LOD 0.5MG L-1, RSD% FOR FOUR REPLICATE MEASUREMENTS OF 25.0MG L-1 WAS 7.4%. UP TO 126-FOLD ENRICHMENT OF ANALYTES WAS DEFINED. IN ORDER TO ASSAY THE APPLICABILITY OF THE NEWLY DEVELOPED EXTRACTION SYSTEM, TAP WATER AND URINE SAMPLES WERE EXTRACTED AND ANALYZED AND MORE THAN 85% RELATIVE RECOVERY OF THE ANALYTE IN URINE SAMPLE WAS ACHIEVED. THE PRESENT STUDY EXHIBITED EXCELLENT PERFORMANCE OF THE CARRIER BASED HF-LPME TECHNIQUE FOR THE ANALYSIS AND EXTRACTION OF TRACE LEVELS OF HCTZ. THE PROPOSED METHOD PROVIDED HIGH PFS FOR THE TARGET ANALYTE, ALONG WITH AN EXCELLENT CLEAN-UP CAPABILITY. THE WHOLE OPERATION IS VERY CONVENIENT TO HANDLE BECAUSE THE RECEIVING PHASE IS PROTECTED BY THE HOLLOW FIBER.

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