Diisopropanolamine Research Articles

Synthesis and characterization of hyperbranched poly(urea‐urethane)s based on AA* and B2B* monomers

AbstractHyperbranched aromatic and aliphatic poly(urea‐urethane)s were prepared by the one‐pot method using 2,4‐toluylene diisocyanate (TDI), isophorone diisocyanate, and 2(3‐isocyanatopropyl)cyclohexyl isocyanate as AA* monomers and diethanol amine and diisopropanol amine as B2B* monomers. The characteristics of the resulting polymers were very sensitive to slight changes in the reaction conditions, such as temperature, concentration, and type of catalyst used, as can be seen from the results of gel permeation chromatography and differential scanning calorimetry. The structures were analyzed in detail using 1H and 13C NMR spectroscopy. By using model compounds, the different isomeric structures of the TDI polymers were deduced, their percentages of their linear, terminal, and dendritic subunits were calculated, and their degree of branching (DB) was determined. DB values up to 70% were reached depending on the reaction conditions and stoichiometry of the monomers. The number of terminal groups decreased significantly when dibutylamine was used to stop the reaction instead of B2B*, indicating the presence of a significant number of unreacted isocyanate groups in the hyperbranched product when the polyaddition reaction was stopped. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3062–3081, 2004

Characterization and Comparison of the CO2 Absorption Performance into Single and Blended Alkanolamines in a Packed Column

The performance of carbon dioxide (CO2) absorption into aqueous solutions of single and blended alkanolamines was evaluated experimentally in a bench-scale absorber packed with high-efficiency packings. The absorption experiments were conducted under atmospheric pressure, using a feed gas mixture containing 10% CO2 and 90% nitrogen. Monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine (DIPA), methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), and their mixtures including MEA−MDEA, DEA−MDEA, MEA−AMP, and DEA−AMP were tested in this work. The absorption performance was presented in terms of the CO2 removal efficiency, absorber height requirement, effective interfacial area for mass transfer, and overall mass-transfer coefficient (KGae). Comparison of the absorption performance between the tested alkanolamines was made over ranges of operating conditions to establish the correlation between single- and blended-alkanolamine systems.

Solubility of propylene in aqueous alkanolamine solutions

Measurements of the solubility of propylene in aqueous alkanolamine solutions have been made over a range of temperatures from 8 to 100 °C. Concentration of the amines ranged from 0.7 to16.5 mol/l. In all cases, the pressure was high enough to ensure that two phases were present. The amine solutions included monoethanolamine (MEA), diethanolamine (DEA), di-isopropanolamine (DIPA), methyldiethanolamine (MDEA), and Diglycolamine ® (DGA ®). The data have been correlated by a modified Setchenow equation.

Volumetric Properties and Viscosities for Aqueous Diisopropanolamine Solutions from 25 °C to 70 °C

This paper reports the density and viscosity of aqueous diisopropanolamine (DIPA) solutions at five temperatures in the range 25 °C to 70 °C over the whole concentration range. The results are compared with data published in the literature. The derived excess molar volumes, partial molar volumes, the partial molar volumes at infinite dilution, and viscosity deviations were correlated as a function of composition.

COMPARISON OF LEVELS OF SULFOLANE AND DIISOPROPANOLAMINE IN NATURAL WETLAND VEGETATION EXPOSED TO GAS-CONDENSATE CONTAMINATED GROUND WATER

Groundwater containing the process chemicals sulfolane (tetrahydrothiophene 1,1-dioxide) and diisopropanolamine (DIPA) has contaminated a wetland in the vicinity of a sour-gas natural gas processing facility. Of concern is the extent of which these contaminants are taken up by vegetation and the associated risk to wildlife that may eat the plants. All sampled wetland plants contained detectable levels of sulfolane and DIPA. Sulfolane was distributed predominantly in portions of the vegetation above the surface, such as sedges (Carex spp.) flower heads (e.g., 430±80 mg kg−1 wet tissue mass), whereas the levels of DIPA were more evenly distributed and generally lower throughout the plants (e.g., cattail (Typha latifolia) roots, 9.4±1.7 mg kg−1; sedges flower heads, 16±3 mg kg−1). Sulfolane may, therefore, translocate to a greater extent than DIPA in wetland vegetation. A wide range of concentrations covering a factor of 10 was observed for both contaminants in plant tissue collected within close proximity (5–50 cm) of each other. The dose rates received by wildlife eating the plants will thus depend on which parts of specific plants are consumed. Site-specific factors, such as the heterogeneity in the levels of the contaminants, density and type(s) of biomass (e.g., roots, stem, leaves, berries) of specific vegetation in the wetland, must therefore be accounted for to properly assess the fate of sulfolane and DIPA in contaminated wetlands.

LC/MS DETERMINATION OF A SULFOLANE METABOLITE IN WETLAND VEGETATION EXPOSED TO GAS-CONDENSATE CONTAMINATED GROUND WATER

Groundwater containing the process chemicals sulfolane (tetrahydrothiophene 1,1-dioxide) and diisopropanolamine (DIPA) has contaminated a wetland in the vicinity of a sour-gas natural gas processing facility. Residues of the chemicals are found in wetland soil, water and vegetation. While it is known that DIPA undergoes transformation in wetlands plants, little is known regarding the degree of transformation of sulfolane. This is due in part to the lack of analytical methods suitable for the determination of transformation products of sulfolane in vegetation. Described is a new procedure, employing electrospray ionization with reverse-phase liquid chromatography mass spectrometry for the determination of the 3-hydroxysulfolane metabolite in plant tissue. The metabolite was determined using filtered water extracts of the vegetation, preconcentrated using solid-phase extraction with no further clean up or derivatization steps. Under positive ion electrospray conditions, there was preferential formation of a series of adducts with minimal (M+H)+ formation. The same was true for negative-ions, for which the molecular ion was not observed. However, the latter was more selective for crude extracts of vegetation. Quantification was performed using selected ion monitoring of the m/z 197.03 (M+61)− adduct, elucidated as the (M−1)(CN·(H2O)2)− negative-ion. Confirmations were based on comparison of the retention time and product ion scan of an authentic standard. Instrumental detection limits were attainable in the picogram range (50–100 pg injected). Successful application of the procedure is demonstrated for the determination of the metabolite in 22 samples, collected from a sour-gas contaminated wetland and a control site. For roots, shoots, berries, seeds, grasses, and leaves, the recovery was 117±5.6% r.s.d with a detection limit of 50 ng/g. In general, the technique was rugged (based on a study period of 18 months), and relatively fast (∼25 min per sample for a batch of 10 samples). For the study period, it appears that sulfolane is also transformed in the plants in a manner similar to DIPA, suggesting that degradation of both process chemicals occurs in wetland plants.

Solubility of propane in aqueous alkanolamine solutions

Measurements of the solubility of propane in aqueous alkanolamine solution have been made over a range of temperatures from 40 to 75 °C. Concentration of the amines ranged from 0.7 to 16.5 mol/l. In all cases, the pressure was high enough to ensure that two phases were present. The amine solutions included monoethanolamine (MEA), diethanolamine (DEA), di-isopropanolamine (DIPA), methyldiethanolamine (MDEA), and Diglycolamine ® (DGA). The data have been correlated by a modified Setchenow equation.

Volumetric Properties and Viscosities for Aqueous Diglycolamine Solutions from 25 °C to 70 °C

This paper reports the density and viscosity of aqueous diisopropanolamine (DIPA) solutions at five temperatures in the range 25 °C to 70 °C over the whole concentration range. The results are compared with data published in the literature. The derived excess molar volumes, partial molar volumes, the partial molar volumes at infinite dilution, and viscosity deviations were correlated as a function of composition.

Laboratory Evaluations of Factors Affecting Biodegradation of Sulfolane and Diisopropanolamine

Sulfolane and diisopropanolamine (DIPA) are used in the Sulfinol® process to remove hydrogen sulfide from sour natural gas. This process has been used in western Canada since the early 1960s, and contamination of groundwater has occurred from surface spills and from seepage from landfills and unlined process water storage ponds. Aquifer sediments from contaminated and uncontaminated areas, and muds in a wetland downgradient from the contaminated plume, were collected from a gas plant. Vigorously agitated shake-flask cultures and gently agitated 2.5-L microcosms consisting of contaminated sediment, mud and groundwater, or wetland water were used to study the biodegradation of sulfolane and DIPA. The aerobic shake-flask method showed that all five of these materials contained microbial communities that biodegraded both compounds. Microorganisms in all samples, except the uncontaminated aquifer sediment, degraded both compounds in the aerobic 2.5-L microcosms. In general, the biodegradation occurred more rapidly in the shake-flask cultures. The addition of P greatly enhanced the degradation of sulfolane and DIPA, whereas the addition of N yielded little stimulation.

Microbial mineralization of diisopropanolamine

Diisopropanolamine (DIPA) is a "sweetening agent" used to remove hydrogen sulfide from sour natural gas, and it is a contaminant at some sour gas treatment facilities in western Canada. To investigate the biodegradation of this alkanolamine,14C-DIPA was used in anaerobic and aerobic mineralization studies. Between 3 and 78% of the radioactivity from this compound was released as14CO2in sediment-enrichment cultures incubated under nitrate-reducing conditions. Similarly, 12-78% of the label was converted to14CO2in sediment-enrichment cultures incubated under Mn(IV)-reducing conditions. These activities were observed at 8°C, a typical groundwater temperature in western Canada, and at 28°C. In contrast, DIPA-degrading activity was difficult to sustain under Fe(III)-reducing conditions, and <25% of the radioactive label from14C-DIPA was liberated as14CO2. Two mixed cultures and two isolates (both irregular, non-sporeforming, Gram-positive rods) were used to assess aerobic mineralization of14C-DIPA. The aerobic mixed cultures released 73 and 79% of the radioactive label as14CO2, whereas the pure cultures liberated only 39 and 47% as14CO2. Between one-third and one-half of the nitrogen from DIPA was found as ammonium-N in aerobic batch cultures. These results clearly demonstrate that DIPA is mineralized under a variety of incubation conditions.Key words: alkanolamine, biodegradation, diisopropanolamine, mineralization, natural gas.

Ion‐exchange electrospray ionization liquid chromatography mass spectrometry and tandem mass spectrometry of alkanolamines in wetland vegetation exposed to sour‐gas contaminated groundwater

Electrospray ionization with ion-exchange liquid chromatography mass spectrometry was used for the determination of selected alkanolamines in wetland vegetation exposed to sour-gas contaminated groundwater. Analytes were determined using filtered water extracts of the vegetation with no further cleanup, preconcentration or derivatization steps. Quantification was performed using either selected ion monitoring of the protonated molecular ions (MH+) or the loss of water transition in product ion scans. Confirmations were based on comparison of the respective product ion scans with authentic standards. Instrumental detection limits were attainable in the picogram range (20–40 pg) for diisopropanolamine (DIPA), monoethanolamine, diethanolamine, methyldiethanolamine and triethanolamine. Successful application of the procedure is demonstrated for the determination of DIPA in over 50 samples, collected from a sour-gas contaminated wetland and a control site. For roots, shoots, berries, seeds, grasses and leaves, the recovery was 90 ± 25 % relative standard deviation (RSD) with a detection limit of 20 ng/g. In general, the technique was rugged (based on a study period of 18 months in which over 175 runs were conducted), relatively fast (∼25 min per sample for a batch of 10 samples) and gave detection limits a factor of 5 lower than a conventional ion chromatography method. Copyright © 1999 John Wiley & Sons, Ltd.

Ion-exchange electrospray ionization liquid chromatography mass spectrometry and tandem mass spectrometry of alkanolamines in wetland vegetation exposed to sour-gas contaminated groundwater

Electrospray ionization with ion-exchange liquid chromatography mass spectrometry was used for the determination of selected alkanolamines in wetland vegetation exposed to sour-gas contaminated groundwater. Analytes were determined using filtered water extracts of the vegetation with no further cleanup, preconcentration or derivatization steps. Quantification was performed using either selected ion monitoring of the protonated molecular ions (MH+) or the loss of water transition in product ion scans. Confirmations were based on comparison of the respective product ion scans with authentic standards. Instrumental detection limits were attainable in the picogram range (20–40 pg) for diisopropanolamine (DIPA), monoethanolamine, diethanolamine, methyldiethanolamine and triethanolamine. Successful application of the procedure is demonstrated for the determination of DIPA in over 50 samples, collected from a sour-gas contaminated wetland and a control site. For roots, shoots, berries, seeds, grasses and leaves, the recovery was 90 ± 25 % relative standard deviation (RSD) with a detection limit of 20 ng/g. In general, the technique was rugged (based on a study period of 18 months in which over 175 runs were conducted), relatively fast (∼25 min per sample for a batch of 10 samples) and gave detection limits a factor of 5 lower than a conventional ion chromatography method. Copyright © 1999 John Wiley & Sons, Ltd.

Microbial mineralization of diisopropanolamine

Diisopropanolamine (DIPA) is a "sweetening agent" used to remove hydrogen sulfide from sour natural gas, and it is a contaminant at some sour gas treatment facilities in western Canada. To investigate the biodegradation of this alkanolamine, 14C-DIPA was used in anaerobic and aerobic mineralization studies. Between 3 and 78% of the radioactivity from this compound was released as 14CO2 in sediment-enrichment cultures incubated under nitrate-reducing conditions. Similarly, 12-78% of the label was converted to 14CO2 in sediment-enrichment cultures incubated under Mn(IV)-reducing conditions. These activities were observed at 8 degrees C, a typical groundwater temperature in western Canada, and at 28 degrees C. In contrast, DIPA-degrading activity was difficult to sustain under Fe(III)-reducing conditions, and < 25% of the radioactive label from 14C-DIPA was liberated as 14CO2. Two mixed cultures and two isolates (both irregular, non-sporeforming, Gram-positive rods) were used to assess aerobic mineralization of 14C-DIPA. The aerobic mixed cultures released 73 and 79% of the radioactive label as 14CO2, whereas the pure cultures liberated only 39 and 47% as 14CO2. Between one-third and one-half of the nitrogen from DIPA was found as ammonium-N in aerobic batch cultures. These results clearly demonstrate that DIPA is mineralized under a variety of incubation conditions.

Diisopropanolamine Biodegradation Potential at Sour Gas Plants

AbstractThe potential for aerobic and anaerobic biodegradation of a sour gas treatment chemical, diisopropanolamine (DIPA), was studied using contaminated aquifer materials from three sour gas treatment sites in western Canada. DIPA was found to be readily consumed under aerobic conditions at 8°C and 28°C in shake flask cultures incubated with aquifer material from each of the sites, and this removal was characterized by first‐order kinetics. In addition, DIPA biodegradation was found to occur under nitrate‐, Min(IV)., and Fe(III)‐reducing conditions at 28°C, and in some cases at 8°C, in laboratory microcosms, DIPA loss corresponded to consumption of nitrate, and production of Mn(II) and Fe(II) in viable microcosms compared to corresponding sterile controls. A threshold DIPA concentration near 40 mg/L was observed in the anaerobic microcosms. This report provides the first evidence that DIPA is biodegraded under anaerobic conditions, and our data suggest that biodegradation may contribute to DIPA attenuation under aerobic and anaerobic conditions in aquifers contaminated with this sour gas treatment chemical.

Sorption of sulfolane and diisopropanolamine by soils, clays and aquifer materials

The natural gas sweetening chemicals, sulfolane and diisopropanolamine (DIPA), are highly water soluble and have leached into the ground water from landfills and spills at some sour gas processing plant sites in western Canada. This paper reports on the results of batch equilibration studies designed to evaluate sulfolane and DIPA sorption parameters, which are of relevance to modeling fate and behavior of these compounds in the saturated zone. The sorbents included aquifer materials from three plant sites, reference montmorillonite and kaolinite, and six soils of various clay and organic matter contents. The DIPA sorption isotherms were curvilinear, the slope decreasing with increasing concentration. DIPA adsorption by montmorillonite decreased as the solution concentration of K 2SO 4 increased, consistent with a cation-exchange reaction. A decrease in pH from 8.3 to 6.8 produced a slight increase in DIPA adsorption by montmorillonite. X-ray analysis of DIPA-saturated montmorillonite showed that DIPA enters the interlayer space of the mineral. The sulfolane sorption isotherms were linear and sulfolane sorption by the aquifer materials was very low ( K d<1 l/kg), whereas DIPA uptake was somewhat higher ( K d<4 l/kg). Both compounds were sorbed more by clay minerals than by organic matter and cation exchange capacity was a reasonable predictor of the sorption of sulfolane and DIPA by soils and aquifer materials with low contents of organic C (<1 g/100 g). DIPA desorption from montmorillonite was low relative to adsorption, and some hysteresis was found for some aquifer materials in the desorption of DIPA. Based on estimates of retardation, sulfolane was predicted to move farther than DIPA under the conditions at plant sites.

Simultaneous evaluation of cell viability by neutral red, MTT and crystal violet staining assays of the same cells

By combining three separate toxic assays, the neutral red (NR), MTT and crystal violet staining assays (CVS), we developed a convenient assay method, the NMC assay, in which the NR, MTT and CVS assays are performed consecutively on the same cultured HeLa cells. The NMC assay is performed as follows: the cultured HeLa cells are first treated with NR, and thereafter with MTT; the NR extracted with 30% methanol and the MTT extracted with isopropanol are measured spectrophotometrically (NMC-NR and NMC-MTT assays); the residual cells adhered on the microplate are then stained with crystal violet (NMC-CVS assay). The absorbance values in each of the NMC assay correlated with the viable cell count, as when the assays were performed individually. The EC 50 values of sodium lauryl sulfate (SLS) obtained by the NMC-NR, NMC-MTT and NMC-CVS assays in the HeLa cells were also in agreement with that obtained by each individual assay. Some chemicals, namely monensin, diisopropanol amine and antimycin A, gave different dose–cell viability curves in the NMC-NR, NMC-MTT and NMC-CVS assays depending on their specific mechanisms of action.

Kinetics of carbon dioxide absorption in aqueous solutions of diisopropanolamine

A bubble column absorber was used to investigate kinetics of the reaction between carbon dioxide and aqueous solutions of diisopropanolamine (DIPA), by means of gas absorption experiments. These were conducted in the temperature range of 20 to 40°C, with DIPA concentrations from 5 to 500 mol/m3, and CO2 partial pressures between 5 and 101 kPa. A model based on the Danckwerts' surface reneval theory was used to analyze the experimental results and to determine the rate constant. The obtained data support the assumption of a second-order overall reaction, with the rate constants being well correlated by the Arrhenius equation:

Simultaneous Absorption of Hydrogen Sulfide and Carbon Dioxide into di‐isopropanolamine Solution

AbstractThe simultaneous absorption of hydrogen sulfide and carbon dioxide into di‐isopropanolamine (DIPA) solution was investigated in a 183 cm long, 2.72 cm OD wetted‐wall column at atmospheric pressure. The influence of liquid flow rate, gas flow rate, temperature and liquid concentration on the absorption rate, overall gas‐phase mass transfer coefficient and selectivity factor were studied at a constant gas feed ratio. The results show that the absorption rate of CO2 increases rapidly with increasing liquid flow rate (the Reynolds number of the turbulent liquid film ranges from 2600 to 4350) but increases moderately with increasing gas flow rate (G = 18‐91 L/min), indicating that it is liquid‐phase mass transfer controlled. In contrast, the absorption rate of H2S increases very slowly with increasing liquid flow rate but increases rapidly with increasing gas flow rate, indicating that it is gas‐phase mass transfer controlled. The absorption rate of CO2 also increases with increasing temperature (26‐80°C) but H2S absorption rate decreases with increasing temperature. When the concentration of DIPA solution increases from 0.2 to 2.6 mol/L, the absorption rate of both CO2 and H2S increases but with a larger rate of increase for CO2 For selective H2S removal, it is preferable to operate at low liquid and high gas flow rates, low temperatures and low DIPA concentrations.

Thermodynamics of ionization of aqueous alkanolamines

We have made electrochemical measurements with a glass electrode that have yielded pK values at T = 298.15 K for monothanolamine (MEA), triethanolamine (TEA), diisopropanolamine (DIPA), and methyldiethanolamine (MDEA) relative to the already well-known pK for diethanolamine (DEA), with all pK values referring to equilibria of the type AmH+(aq) = Am(aq) + H+(aq) in which Am(aq) represents an alkanolamine in aqueous solution and AmH+(aq) represents the corresponding protonated alkanolamine. We have also made calorimetric measurements leading to ΔH0 values for dissociation of the protonated species of all five of these alkanolamines in aqueous solution at T = 298.15 K. These pK and ΔH0 values have led to ΔG0 and ΔS0 values for the corresponding dissociation reactions of all five AmH+(aq) species.

Simultaneous mass transfer of H 2S and CO 2 with complex chemical reactions in an aqueous di-isopropanolamine solution

The absorption of H 2S and CO 2 into an aqueous di-isopropanolamine (DIPA) solution was studied experimentally and theoretically as an example of simultaneous mass transfer with complex reversible reactions. The absorption phenomena were classified into three regimes: (1) negligible mutual interaction between the CO 2 and H 2S absorption, (2) intermediate interaction, and (3) extreme interaction leading to forced desorption of one of the gaseous components, while based on its overall driving force absorption would be expected. The key parameter largely determining the transitions between these regimes is the extent of depletion of the alkanolamine in the penetration zone. In order to study these phenomena, simultaneous absorption experiments were carried out in each of the three regimes mentioned above using a stirred cell reactor and for some experiments a wetted wall column. The experimental results were evaluated by means of a numerical solution of the penetration model description of simultaneous mass transfer with complex reactions (Cornelisse et al., Chem. Eng. Sci., 35 (1980) 1245). Recently we derived a numerical film theory description, which has also been incorporated in the evaluation. The measured hydrogen sulphide fluxes fall between film and penetration theory calculations, whereas the CO 2 fluxes are closer to the film theory.