Arturo Trejo

Solubilities of carbon dioxide and hydrogen sulfide in propylene carbonate, N-methylpyrrolidone and sulfolane

Abstract Gas solubilities of carbon dioxide and hydrogen sulfide have been measured in propylene carbonate, N -methylpyrrolidone and sulfolane at several temperatures ranging from 298 to 373 K and in the pressure range 51–2330 kPa. Values of the Henrys law constant and of heat of solution were derived from the solubility data. The experimental results have been correlated with the Soave-Redlich-Kwong equation of state using a binary interaction parameter.

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

ABSTRACT 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.

Solubility of CO2 in aqueous mixtures of diethanolamine with methyldiethanolamine and 2-amino-2-methyl-1-propanol

Abstract Using the static method with recirculation of the vapor phase, experimental data for the solubility of CO 2 in aqueous mixtures of known composition of diethanolamine (DEA) with methyldiethanolamine (MDEA) and DEA with 2-amino-2-methyl-1-propanol (AMP) have been obtained in the CO 2 partial pressure range 3–3000 kPa. The data for DEA–MDEA solutions were obtained at 313.15 K and are reported at four different compositions: 10 wt.% DEA–15 wt.% MDEA, 10 wt.% DEA–20 wt.% MDEA, 20 wt.% DEA–10 wt.% MDEA and 10 wt.% DEA–35 wt.% MDEA, data for the solution of 10 wt.% DEA–20 wt.% MDEA were also obtained at 393.15 K. The data for DEA–AMP solutions were obtained at 313.15 and 373.15 K and are reported at two different compositions: 25 wt.% DEA–5 wt.% AMP and 20 wt.% DEA–10 wt.% AMP. The results are given as the partial pressure ( p ) of CO 2 against its mole ratio α (mol CO 2 /mol alkanolamine), in the range of temperature studied. The solubility of CO 2 in all the studied systems decreases with an increase in temperature and increases with an increase in the partial pressure of CO 2 , at a given temperature, and it is a strong function of the composition of the blend of alkanolamines in solution. The aqueous mixture with 10 wt.% AMP, at 313.15 K, shows higher capacity to absorb CO 2 than any of the other mixtures studied here. From the experimental solubility results, exothermic values of the enthalpy of solution, Δ H s , were derived.

Determination of the temperature dependence of water solubilities of polycyclic aromatic hydrocarbons by a generator column-on-line solid-phase extraction-liquid chromatographic method.

An improved dynamic coupled column liquid chromatographic (DCCLC) technique for determining water solubility data of hydrophobic compounds is presented. The technique is based on pumping water through a thermostated generator column in order to generate emulsion-free, saturated aqueous solutions of the compound under study. Through a switching valve system the solute in the aqueous solution is extracted and concentrated by an on-line solid-phase extraction process and subsequently eluted and analyzed by high performance liquid chromatography (fluorescence detection coupled to photodiode array detection). The improvements carried out to the original DCCLC technique have given rise to savings in time for the experimental work and increased sensitivity during the detection and quantification stage. Applicability of the method for studying highly hydrophobic substances is demonstrated by determining water solubility of anthracene and pyrene in the temperature range of 8.9-49.9 and 8.5-32.2 degrees C, respectively. The measured water solubilities are in good agreement with the best available literature data. The method has also been applied to the determination of water solubility of m-terphenyl, 9, 10-dihydrophenanthrene and guaiazulene, in the temperature range of 4.8-49.9, 4.8-25.0, and 4.5-29.9 degrees C, respectively. The uncertainty in the Sw values determined in this work ranged from 0.7% to 4.6%. The experimental water solubility data, as a function of temperature, are fitted to the equation In Sw = A + B/T; where Sw and T are given in mole fraction and Kelvin, respectively.

Extraction of Hydrocarbons from Crude Oil Tank Bottom Sludges using Supercritical Ethane

Abstract A custom‐built, solvent recirculating, supercritical fluid extraction (SFE) apparatus was used to study the extraction of hydrocarbons from a crude oil tank bottom sludge (COTBS) with supercritical ethane. The SFE experiments were carried out varying the pressure (10 MPa and 17.20 MPa) and temperature (35°C and 65°C). The yield of the extracted hydrocarbon fraction increased with increase in extraction pressure at constant temperature, and decreased with increase in extraction temperature at constant pressure. The maximum extraction yield was obtained at the pressure and temperature conditions that lead to the highest solvent density. The extracted hydrocarbon fraction was a significantly upgraded liquid relative to the original untreated COTBS.

Removal of polycyclic aromatic hydrocarbons from soil: a comparison between bioremoval and supercritical fluids extraction.

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic substances which are resistant to environmental degradation due to their highly hydrophobic nature. Soils contaminated with PAHs pose potential risks to human and ecological health, therefore concern over their adverse effects have resulted in extensive studies on their removal from contaminated soils. The main purpose of this study was to compare experimental results of PAHs removal, from a natural certified soil polluted with PAHs, by biological methods (using bioaugmentation and biostimulation in a solid-state culture) with those from supercritical fluid extraction (SFE), using supercritical ethane as solvent. The comparison of results between the two methods showed that maximal removal of naphthalene, acenaphthene, fluorene, and chrysene was performed using bioremediation; however, for the rest of the PAHs considered (fluoranthene, pyrene, and benz(a)anthracene) SFE resulted more efficient. Although bioremediation achieved higher removal ratios for certain hydrocarbons and takes advantage of the increased rate of natural biological processes, it takes longer time (i.e. 36 d vs. half an hour) than SFE and it is best for 2-3 PAHs rings.

Liquid—liquid coexistence curves for binary systems

Abstract The liquid—liquid coexistence curves of polar+non-polar binary systems have been determined experimentally. The polar compounds studied were ethanenitrile, methanol and N-methylpyrrolidone, whereas the non-polar compounds were chosen from the n-alkane series. The upper critical solution temperature for each set of mixtures increases with increasing n-alkane chain length, and the critical composition of the polar component also increases in this fashion.

Liquid—liquid equilibria for ternary systems. I. C6-isomers + sulfolane + toluene at 298.15 K

Experimental binodal curved and tie line data have been obtained at 298.15 K for the ternary liquid—liquid equilibria of four C6-isomer+sulfolane+toluene systems, where the isomers studied are n-hexane, cyclohexane, 2-methylpentane and 1-hexene. The tie line data were correlated with the well-known NRTL model. Values of selectivity, distribution coefficient and capacity or solvent power for sulfolane were derived from the equilibrium data.

Gas solubility of hydrogen sulfide and carbon dioxide in mixtures of sulfolane with diethanolamine at different temperatures

Abstract Murrieta-Guevara, F., Rebolledo-Libreros, E. and Trejo, A., 1994. Gas solubility of hydrogen sulfide and carbon dioxide in mixtures of sulfolane with diethanolamine at different temperatures. Fluid Phase Equilibria , 95: 163-174. Experimental equilibrium solubility data are reported for hydrogen sulfide in mixtures of tetramethylene sulfone (sulfolane) with 15, 30 and 50wt.% diethanolamine, and for carbon dioxide in a mixture of sulfolane with 50 wt.% diethanolamine in the temperature range 303.15–373.15 K from 15 up to 2296 kPa of solute partial pressure. The results of the gas solubility measurements are presented as a partial pressure of the solute against its mole fraction in the solvent mixture, and also against its mole ratio with respect to diethanolamine. For a given temperature, the solubility of either solute increases as the pressure increases. The solubility of the hydrogen sulfide increases as the concentration of diethanolamine increases. Exothermic values of the enthalpy of solution for hydrogen sulfide and carbon dioxide were obtained from solubility data.

Gas solubility of carbon dioxide and hydrogen sulfide in mixtures of sulfolane with monoethanolamine

Murrieta-Guevara, F., Rebolledo-Libreros, E. and Trejo, A., 1993. Gas solubility of carbon dioxide and hydrogen sulfide in mixtures of sulfolane with monoethanolamine. Fluid Phase Equilibria, 86: 225-231 The equilibrium solubility of carbon dioxide and hydrogen sulfide in mixtures of tetra-methylene sulfone (sulfolane) with 15 and 30wt.% monoethanolamine was determined experimentally in the temperature range 303.15–373.15 K from 2 to 2210 kPa of partial pressure. The results of the gas solubility measurements are presented as partial pressure of the solute against its mole fraction in the solvent. Values of the enthalpy of solution for carbon dioxide and hydrogen sulfide were derived from the solubility data.