Joel Reza

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.

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.

EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBONS FROM SOIL USING WATER UNDER SUBCRITICAL CONDITIONS

Water under subcritical conditions (250°C, 4100 kPa) was used to extract polycyclic aromatic hydrocarbons (PAHs) from a Mexican hydrocarbon-contaminated soil. Extraction was carried out by continuously circulating the solvent through the sample contained in an extraction cell. After extraction, the non-extracted PAHs were eluted from the soil and then analyzed by high performance liquid chromatography. The elution and subsequent analysis were carried out by directly coupling the extraction cell, through a switching valve system, to a liquid chromatograph. The elution and analysis process takes place in a closed system that allows a fast, precise, and highly sensitive quantification of the studied compounds. Additional extraction experiments with spiked samples (silicon dioxide and nonpolluted soil) were carried out in order to asses the performance of the method. Extraction recoveries ranged from 95 to 100% with an average uncertainty of ±1.2%. In some cases it was possible to quantitatively extract PAHs at concentrations as high as 8522 mg· kg − 1 .

GAS-LIQUID PRESSURE-TEMPERATURE-COMPOSITION CRITICAL LOCI FOR N-BUTANENITRILE WITH C5 TO C11 N-ALKANES

Gas—liquid critical pressure and critical temperature were determined experimentally throughout the composition range for the seven binary systems comprising the n-alkanes from n-pentane through n-undecane with n-butanenitrile as a common component. Some of these mixtures are known to form a positive azeotrope at temperatures below the normal boiling temperature, and the presence of a minimum temperature in the p—T and T—x critical loci of some of the mixtures indicates that the homogeneous azeotrope is also present in the critical region. Incidentally, experimental vapour pressures are also reported for n-butanenitrile.

Generator column determination of water solubilities for saturated C6 to C8 hydrocarbons

Water solubilities, S w , of C 6 to C 8 saturated hydrocarbons have been determined at 25°C by using a generator column method. The method is based on pumping water through a bed of a high-surface-area packing, coated with the studied compound. As a result of this process a saturated aqueous solution of that compound is generated, which can be analyzed by gas chromatography. Solubility data are reported for: n-hexane, n-heptane, 3-methylhexane, 2,4-dimethylpentane, n-octane, 4-methylheptane, 2,3,4-trimethylpentane and trans-1,3-dimethylcyclohexane. Experimental S w values determined in this work are in good agreement with reported data determined from diffusion experiments where no stirring steps are involved, and are lower than those determined from batch-stirring methods, which suggest that solutions produced by generator columns are free from emulsions. No experimental S w data have been reported previously for 4-methylheptane and trans-1,3-dimethylcyclohexane. The uncertainty in the S w values determined in this work ranged from ± 1.0 to ± 3.7 %.