EXPERIMENTAL MEASUREMENTS OF FOAMING TENDENCIES IN AQUEOUS GAS SWEETENING SOLUTIONS CONTAINING MDEA OVER A TEMPERATURE RANGE OF 297–358 K AND A PRESSURE RANGE OF 101–500 KPA

This work presents experimental measurements of foaming tendencies and break times for 50 wt% aqueous solutions of MDEA in contact with nitrogen, methane, and ethane gases from atmospheric pressure to 500 kPa and temperatures from 297 to 358 K. The effect of various contaminants including methanol, HEP (1,4- bis-2-hydroxyethyl piperazine), hexane, and carboxylic acids ranging from formic to dodecanoic acid was investigated. Only those systems containing carboxylic acids heavier than valeric acid exhibited foaming. Foaming tendency in systems containing carboxylic acids was worsened by the addition of methanol and HEP, although the difference was moderate. Foaming was shown to be worse at lower pressure and at higher temperature. Foaming in MDEA systems was shown to be substantially worse than that measured previously by McCarthy and Trebble (1996 McCarthy , J. and Trebble , M. A. ( 1996 ). An experimental investigation into the foaming tendency of diethanolamine gas sweetening solutions , Chemi. Eng. Commun. , 144 , 159 – 171 [CSA] [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) for aqueous systems of DEA.     

AN EXPERIMENTAL INVESTIGATION INTO THE FOAMING TENDENCY OF DIETHANOLAMINE GAS SWEETENING SOLUTIONS

The foaming tendency of a 30 weight % solution of diethanolamine (DEA) in distilled water was measured over a temperature range of 20-85°C and a pressure range of 1-3 MPa in the presense of a number of contaminants including carboxylic acids, oils, 1-4 bis (2-hydroxyethyl) piperazine (HEP), methanol, iron sulphide, silicone antifoam, etc. The measurements were conducted using a Jerguson high pressure sight glass contained in an air bath. Foaming was measured at gas rates up to 7.5 standard m³/d using air, nitrogen, carbon dioxide, and ethane. One notable observation was that the addition of most of the contaminants commonly identified as foam promoters did not create a foaming system with a clean 30% DEA solution. In fact, the only solutes that produced significant foaming were the carboxylic acids as noted previously in the literature by Pauley et al. (1989). The addition of contaminants to a foaming system did increase foam heights and stability substantially and results are presented for methanol and HEP addition to a foaming system of DEA-carboxylic acid. The effects of temperature, pressure, and gas flow rates on foam heights and foam break times were measured for a number of systems. Foaming was increased by a higher temperature and by higher pressure and was much more pronounced when carbon dioxide or ethane gases were used     

Back-extraction Of Pu4 From 20% Tributyl Phosphate - 20% Mixed Trialkyl Phosphine Oxides/kerosene In The Presence Of

Back-extraction of Pu^4 +  from a mixture of 20% tributyl phosphate (TBP) and 20% mixed trialkyl phosphine oxides (TRPO) in kerosene in the presence of UO²⁺₂was studied. The back-extractants investigated may be divided into three groups: carboxylic acids and salts, amino polycarboxylates, and phosphonic acid. The distribution coefficients of both Pu^4 +  and UO²⁺₂using a number of different back-extractants were measured and compared. The results obtained suggest that the only practical back-extractants are carboxylic acids. Among the carboxylic acids tested, oxalic acid is suitable when the UO²⁺₂ concentration in the organic phase is less than 2 g/L. For UO²⁺₂concentrations between 2 and 10 g/L, oxalic acid-nitric acid mixtures may be used. For UO²⁺₂concentrations greater than 10 g/L, the only practical back-extractant is glycolic acid. The results obtained here may be used to further develop a new process for separation of Pu^4 +  and UO²⁺₂ from TBP-TRPO/kerosene mixture.     

SOLUBILITY OF NITROUS OXIDE IN AQUEOUS SOLUTIONS OF METHYLDIETHANOLAMINE, DIETHANOLAMINE AND MIXTURES OF METHYLDIETHANOLAMINE AND DIETHANOLAMINE

The solubility of nitrous oxide (N₂O) in aqueous solutions of 0-50 mass % methyldiethanolamine (MDEA), 0-30 mass % diethanolamine (DEA), and 50 mass % total amine with DEA/MDEA weight ratios of 0.04413-0.5883 was measured over the temperature range 293-353 K and at N₂O partial pressures near atmospheric. The solubility data from this work were found to be in fair agreement with the literature where data were available. The N₂O solubility data for the aqueous MDEA and aqueous DEA solutions were fitted using the extended scaled-particle model proposed by Li and Mather (1994) (which was based on the work of Hu et al. (1985)). The parameter estimates obtained from these fits were then used to predict the N₂O solubility in the aqueous DEA + MDEA solutions. The model predictions were found to agree with the experimental data with an average deviation of 3.4%     

AN EXPERIMENTAL STUDY OF GAS HOLDUP IN TWO-PHASE BUBBLE COLUMNS WITH FOAMING LIQUIDS

Gas-liquid upward flow experiments have been performed in two bubble columns of different diameters (0.10 and 0.29 m,) using air as gas phase and several liquids: water, aqueous solutions of ethanol and glycerine, kerosene, and a solution of a surfactant in kerosene. The main goal of the study is the analysis of foaming systems, including the comparison of their behavior with respect to non-foaming systems. The gas holdup was determined experimentally as a function of the gas and liquid superficial velocities in bubbling, churn-turbulent and foaming regimes. It was found that, for foaming systems, semi-batch operation enhances foam formation, yielding higher holdups than those obtained in continuous operation at very low liquid velocities. Opposite to what is observed in non-foaming systems, the liquid superficial velocity affects the gas holdup appreciably in foaming systems. An increase in column diameter results in a decrease in gas holdup for all the systems studied. In aqueous foaming systems, this trend is more drastic since foam is inhibited as the column diameter increases.     

酚醛树脂高温发泡模具设计研究

针对采用常温发泡模具进行高温发泡时,常常产生树脂液溢出量及发泡压力不易控制的问题,设计了高温发泡模具.与常温发泡模具采用堵帽控制发泡压力不同,在高温发泡模具中采用压缩弹簧预紧的放气控制单元对树脂液溢出量及发泡压力进行控制,解决了树脂液溢出量过多的问题,发泡压力可调,模具结构可靠、拆装方便.     

INSIGHT INTO HETEROGENEOUS PHOTOCATALYTIC DEGRADATION OF PHENOL OVER MONTMORILLONITE KSF

The commercially available substance montmorillonite KSF, used as a photocatalyst in heterogeneous systems for degradation of phenol in water, was investigated in this study. Phenol can be photodegradated in montmorillonite KSF suspension under a 250 W metal halide lamp (λ ≥ 365 nm). The photodegradation was dependent on the pH of the solution, and it was more effective for phenol to be degraded at pH 4. Results also indicated that the concentrations of montmorillonite KSF and phenol could affect the degradation rate. The degradation rate of phenol increased with the increasing concentration of clays in aqueous suspensions in the range of 0.25 to 2.0 wt.%, and the initial photodegradation rate of phenol increased with increasing initial concentration of phenol. Furthermore, the removal efficiency of phenol can be enhanced in the presence of carboxylic salts. A preliminary mechanism of the phenol degradation in KSF suspension is suggested that hydroxyl radicals might be photogenerated from water on the surface of KSF, and iron from KSF acts as a photocatalyst by generating hydroxyl radicals.     

EFFECT OF ACETIC ACID ON CO2 CORROSION OF CARBON STEEL IN VAPOR-WATER TWO-PHASE HORIZONTAL FLOW

The effect of acetic acid on the corrosion behavior of X 65 and C 1018 carbon steel in vapor-water two-phase stratified flow (Vsg: 2 m/s; Vsl: 0.1 m/s) at 2 bars total pressure, 1.54 bars CO₂ partial pressure, pH 5.5, and 80°C was studied in a low pressure-high temperature multiphase flow horizontal loop using electrochemical and mass loss techniques. The liquid phase is composed of 1% NaCl aqueous solution containing different concentrations of acetic acid (500 to 5000 ppm total acetic acid), and the gas phase is composed of CO₂-acetic acid-water vapor mixture. The corrosion rates, on both the top and bottom of the line, increase with increase in acetic acid concentration, which was attributed to the contribution of hydrogen ions by the free acetic acid to the cathodic reaction. Partial coverage of the metal surface by FeCO₃ on both the top and bottom of the line is reported to be responsible for the observed localized corrosion. Surface analysis investigated with SEM and XRD is reported.

A vapor-liquid equilibrium model was developed for the system studied.     

THERMODYNAMICS OF ALKANOLAMINE+WATER SYSTEM

Design of gas treating processes requires knowledge of the vapor-liquid equilibrium behavior of the (acid gas + aqueous alkanolamine) system. The present study is focused on thermodynamics and associated nonideal behavior of binary MEA + H₂O, DEA + H₂O, and MDEA + H₂O systems, which is required to predict the vapor-liquid equilibrium of acid gases such as CO₂ and H₂S over aqueous alkanolamine solutions. Determination of binary interaction parameters and analytical prediction of infinite dilution activity coefficient, heats of solution at infinite dilution, the excess Gibbs free energy, and excess enthalpy for nonideal alkanolamine-water systems are the objectives of this study.     

Foaming strategies for bioabsorbable polymers in supercritical fluid mixtures. Part I. Miscibility and foaming of poly(l-lactic acid) in carbon dioxide + acetone binary fluid mixtures

Miscibility and foaming of poly(l-lactic acid) (PLLA) in carbon dioxide + acetone mixtures have been explored over the temperature and pressure ranges from 60 to 180 °C and 14 to 61 MPa. Liquid-liquid phase boundaries were determined in a variable-volume view-cell for polymer concentrations up to 25 wt% PLLA and fluid mixtures containing 67-93 wt% CO₂ over a temperature range from 60 to 180 °C. Even though not soluble in carbon dioxide at pressures tested, the polymer could be completely solubilized in mixtures of carbon dioxide and acetone at modest pressures.Foaming experiments were carried out in different modes. Free-expansions were carried out by exposure and swelling in pure carbon dioxide in a view-cell followed by depressurization. Foaming experiments were also carried out within the confinement of specially designed molds with porous metal surfaces as boundaries to direct the fluid escape path and to generate foams with controlled overall shape and dimensions. These experiments were conducted in pure carbon dioxide and also in carbon dioxide + acetone fluid mixtures over a wide range of temperatures and pressures. Foaming in carbon dioxide + acetone mixtures was limited to 1 and 4 wt% acetone cases. Microstructures were examined using an environmental scanning electron microscope (ESEM). Depending upon the conditions employed, pore diameters ranging from 5 to 400 μm were generated. At a given temperature, smaller pores were promoted when foaming was carried out by depressurization from higher pressures. At a given pressure, smaller pores were generated from expansions at lower temperatures. Foams with larger pores were produced in mixtures of carbon dioxide with acetone.     

RHEOLOGICAL CHARACTERIZATION OF NON-NEWTONIAN FLUIDS WITH A NOVEL VISCOMETER

A hydrostatic head viscometer and its novel viscosity equation were developed to determine flow characteristics of Newtonian and non-Newtonian fluids. The objective of this research is to test capabilities of the hydrostatic head viscometer and its novel non-Newtonian viscosity equation by characterizing rheological behaviors of well-known polyethylene oxide aqueous solutions as non-Newtonian fluids with 60 wt.% sucrose aqueous solution as a reference/calibration fluid. Non-Newtonian characteristics of 0.3-0.7 wt.% polyethylene oxide aqueous solutions were extensively investigated with the hydrostatic head viscometer and its non-Newtonian viscosity equation over a 294-306 K temperature range, a 0.14-40 Reynolds number range, and a 55-784 s^-1 shear rate range at atmospheric pressure. Dynamic viscosity values of 60 wt.% sucrose aqueous solution were determined with the calibrated hydrostatic head viscometer and its Newtonian viscosity equation over a 3-5 Reynolds number range at 299.15 K and atmospheric pressure and compared with the literature dynamic viscosity value.     

Separation of Oleic Acid from Fatty Acid Impurities

Abstract

A method of oleic acid purification is described. The method consists of the following five steps: 1) cooling of the sample to 4°C for a partial separation of palmitic acid by crystallization, 2) distillation at reduced pressure (0.8 mmHg) for removal of lauric and myristic acids, 3) crystallization of stearic and palmitic acids from acetone at -25°C, 4) separation of oleic acid from palmitoleic and linoleic acids by oleic acid crystallization from aqueous methanol solutions at ?10°C, 5) reduced pressure (0.5 mmHg) distillation of the resulting oleic acid sample for removal of water and methanol. By utilizing the procedure described above, a sample containing only 82% oleic acid was refined to a product containing 98.7–98.9% oleic acid.     

DEGRADATION OF AQUEOUS SOLUTIONS OF ALKANOLAMINE BLENDS AT HIGH TEMPERATURE, UNDER THE PRESENCE OF CO2 AND H2S

An experimental study on the degradation of aqueous solutions of alkanolamine blends, under the presence of carbon dioxide and hydrogen sulfide, was carried out. The studied alkanolamines were: diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP). Degradation experiments were carried out at a temperature of 200°C. The mass fraction of DEA and MDEA in the studied aqueous solutions was 10% and 35%, respectively. AMP was incorporated into the MDEA-DEA aqueous solutions, with concentrations of (0-8) mass fraction. Partially degraded alkanolamine aqueous solutions were analyzed, after about 90 hours, by gas chromatography.

It was found that in all the studied alkanolamine aqueous solutions the MDEA degrades more slowly than DEA under the same experimental conditions. Degradation of both alkanolamines was found to be almost independent of the AMP concentration. AMP exhibits an intermediate stability; it is more resistant to degradation than DEA but less than MDEA. In addition, thermal degradation of DEA and MDEA is minimal up to 200°C.     

KINEMATIC VISCOSITIES OF POLYETHYLENE GLYCOL DEXTRAN WATER SOLUTIONS

The kinematic viscosities of aqueous polyethylene glycol and dextran and polyethylene glycol + dextran + water were measured at temperatures of 30, 50, and 70°C. Polyethylene glycol with relative molecular masses of 200 and 1000 and dextran samples with nominal molecular masses of 37 500 and 2 000 000 were used. A one-parameter Grunberg-like equation proposed earlier by one of the present authors was used for estimating the values of viscosity of polyethylene glycol + dextran + water. A disposable parameter for the temperature range was calculated as 0.96 and 1.05 for PEG 200 + dextran 37 500 + water and PEG 1000 + dextran 37 500 + water, respectively, and as 2.74 and 2.80 for PEG 200 + dextran 2 000 000 + water, and PEG 1000 + dextran 2 000 000 + water, respectively. In view of our results, the proposed model works well for systems containing polyethylene glycol and dextran with different molecular masses.     

EXTRACTION EQUILIBRIA OF SILVER WITH A SULFUR-CONTAINING CARBOXYLIC ACID

Abstract

A new carboxylic acid extractant containing a sulfur atom, α-butylthiolauric acid(abbreviated as α-BTLA) was synthesized to investigate the extraction equilibrium of silver(I) from 1 mol/dm³ aqueous ammonium nitrate solution with its toluene solution at 30°C. Moreover, the extraction of silver(I) with palmitic acid in toluene was studied to compare with the extraction properties of α-BTLA. It was found that silver(I) is extracted as AgR×3HR for both carboxylic acids(HR) according to the following equation.

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Extraction equilibrium constants were evaluated as

$     

PHASE EQUILIBRIUM FOR TERNARY LIQUID SYSTEMS OF WATER CARBOXYLIC ACID CHLORINATED HYDROCARBON: THERMODYNAMIC MODELING THROUGH SERLAS

Liquid-liquid equilibrium data of the solubility (binodal) curves and tie-line end compositions are presented for mixtures of [water (1) + formic acid, or acetic acid, or propanoic acid (2) + chlorobenzene, or 1,2-dichloroethane (3)] at T = 293.2 K and P = 101.3 ± 0.7 kPa. A log-basis approach, SERLAS (solvation energy relation for liquid-associated system), has been proposed to estimate the properties and liquid-liquid equilibrium (LLE) of associated systems containing proton-donating and -accepting and polar components capable of a physical interaction through hydrogen bonding or dipole-dipole interaction. The tie lines were also correlated using the UNIFAC-original model. The reliability of the models has been analyzed against the LLE data with respect to the distribution coefficient and separation factor. The proposed model appears to be an improvement in data fit for the ternary systems, yielding a mean relative error of 10.1% for all the systems considered.     

A Simple Direct Casting Route to Ceramic Foams

A simple direct foaming and casting process using ovalbumin-based aqueous slurries for fabricating ceramic and metal foams is demonstrated. Foaming of aqueous ceramic slurries and the foam microstructure were seen to be a strong function of slurry rheology. Setting of foams with ceramic solids loading above 20 vol% was achieved by addition of acid, which also prevented binder migration. Acid addition resulted in excessive shrinkage, causing cracking of foams with ceramic loading below 20 vol%. Addition of sucrose to the slurries suppressed shrinkage leading to defect-free foams with porosity exceeding 95%. Overall porosity and foam microstructure could be controlled through ceramic solids loading, ovalbumin–water ratio, foaming time and sucrose amount, and sintering temperature. The ceramic foams fabricated by the process were strong enough to be green machined to different shapes.     

KINETICS OF SUPERCRITICAL FLUID EXTRACTION OF ETHANOL FROM AQUEOUS SOLUTION

A 1.3 dm³ high-pressure vessel was used to extract ethanol from aqueous solution of 10 wt% using supercritical carbon dioxide as a solvent. Experiments were carried out in a semibatch mode. A mathematical model based on the two-film theory was derived for estimating the over all mass transfer coefficient. The effects of operating variables, including pressure, CO₂ superficial velocity, and agitation rate, on the mass transfer coefficient were investigated. In general, the mass transfer coefficient increased with increasing pressure, CO₂ superficial velocity, and agitation rate. The concentration of ethanol recovered in the collector after 180 minutes reached 50 wt%, starting with a feed of 10 wt% ethanol.     

Clearning performance and foaming properties of lauroylamidopropylbetaine/nonionics mixed systems

Lauroylamidopropylbetaine (LPB) has good cleaning and foaming performance with excellent low skin irritation. We have investigated the relationship between cleaning performance and foaming properties of aqueous solutions containing binary and ternary LPB/nonionic surfactant systems. Foaming properties were evaluated by observing dynamic surface tension and aqueous core thickness of a vertical foam film measured by Fourier transform infrared spectroscopy. The LPB/lauroyldiethanolamide (LDE) system has a positive synergistic effect on cleaning performance and foam stability, estimated from the grease removal test and dishwashing test for a light-duty detergent. However, this system shows very poor initial foam performance in both the sponge test and Ross-Miles foam test. This disadvantage of the LPB/LDE system was improved using C12En (polyoxyethylene dodecyl ethers). Addition of C12En promoted dynamic surface tension lowering, indicating an improvement in the initial foaming performance, while maintaining cleaning performance and foam durability. Thus, the LPB/LDE/C12En ternary system has an excellent cleaning and foam performance as a light-duty liquid detergent.     

羧酸开环法合成1,1-二氨基-2,2-二硝基乙烯的研究

对2一甲基咪唑为反应底物制备1,1一二氨基一2,2．二硝基乙烯(FOx一7)的合成方法进行了实验研究,找到了一种新的合成FOx．7的方法,该方法首次采用低碳有机羧酸与硝化中间体2一(二硝基亚甲基)．4,5．咪唑烷二酮l的反应实现FOx一7的合成,对产物结构进行了表征并对反应奈件进行了优化。开环试剂为甲酸时,最优条件下两步反应(收率分别为20．3％和95．3％)的总收率约为19．3％,与氨水开环法(约13、1％)相比收率有较大幅度提高,通过控制反应时间和结晶时间可对FOx．7的颗粒度进行控制,同时该方法也是制备大颗粒和不同形貌特征FOx一7的有效方法。对开环反应机理进行了探讨,