Application of poly(phthalazinone ether sulfone ketone)s to gas membrane separation

A series of poly(phthalazinone ether sulfone ketone) (PPESK) copolymers containing different component ratios of bis(4‐fluorodiphenyl) ketone and bis(4‐chlorodiphenyl)sulfone with respect to a certain amount of 4‐(4‐hydroxyphenyl)‐2,3‐phthalazin‐1‐one were synthesized by polycondensation. Glass transition temperatures of these polymers were adjusted from 263°C to 305°C by changing the ratios of reactants. Gas permeability and selectivity of the dense membranes of the polymers for three kinds of gases (CO₂, O₂, and N₂) were determined at different temperatures. The result indicated that the membrane of PPESK (S/K = 1/1, mol ratio) had an excellent gas separation property. Permeability of the polymer membranes for CO₂, O₂, and N₂ was P = 4.121 barrier, P = 0.674 barrier, and P = 0.0891 barrier, respectively. Separation factors of α and α were 7.6 and 46, respectively. New material was made into a composite membrane with silicone rubber for blocking up leaks and defects on the surface of its nonsymmetrical membrane. As a result of the test, permeability of the composite membrane was J = 7.2 × 10⁻⁶ cm³ (STP) cm⁻² S⁻¹ cm⁻¹ Hg and J = 0.99 × 10⁻⁶ cm³ (STP) cm⁻² S⁻¹ cm⁻¹ Hg, whereas the α was still higher than 7. These showed that PPESKs had a bright prospect as the potential membrane material for high‐temperature gas separation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2385–2390, 1999     

Radiolysis of Fremy's Salt in the Presence of Some Hydrated Electron Scavengers in Alkaline Aqueous Solution

Fremy's salt, ON(SO₃)₂^2?, was irradiated with γ-rays in deaerated alkaline aqueous solutions in the presence of NO₃^?, N₂O. In the presence of N₂O an increase of the G(-ON(SO₃)₂^2? = G from 6.1 to about 6.7 was observed within a limited range of concentration, while with NO₃^? the change is gradual. This is consistent with NO₂ and OH produced, respectively, in the reaction of e_aq^? with Fremy's salt, taking place in one-electron-equivalent processes, and with the assumption that pairs of radicals may originate from water molecules.     

A zeolite/polymer membrane for separation of ethanol-water azeotrope

A novel membrane effective in the separation of ethanol-water mixtures by pervaporation was made by combining zeolite NaA and poly(vinyl chloride) modified by 2-(2′-butoxyethoxy)ethyl thiolate. Under ambient conditions, a separation factor (α) of 29 and pervaporability (P) of 4 × 10^?4 g m^?1 h^?1 were obtained for the azeotropic mixture whereas, in the absence of zeolite, the respective values were 7 and 7 × 10^?5. A mechanism was proposed relating the preferential water transport at ≈? 50% zeolite content to an interfacial “phase” between the zeolite and the modified polymer.     

Ammoxidation of propylene by pulse reaction technique

The ammoxidation of propylene on Fe-Bi-P mixed oxide catalyst was studied at 500 °C by the pulse reaction technique, to examine the effects of P(P = 0–4) and P (P/P = 0–3) on the catalyst activity. Since the ammoxidation of propylene proceeds through consumption of oxygen from the catalyst even in the absence of oxygen, the reduction of catalyst progresses with the number of O₂-free pulse, losing its activity. In the presence of oxygen, however, the conversion of propylene and the selectivities of acrylonitrile, acetonitrile, CO₂, and CO vary with the pulse number, but settle to some steady values corresponding to P/P. It is also found that the conversion and the selectivities depend on the oxidation state of the catalyst, the latter also depending on P/P in the reactants, and that the catalyst working in the flow system may be being reduced to some extent.     

Permeability of dense (homogeneous) cellulose acetate membranes to methane,carbon dioxide,and their mixtures at elevated pressures

Mean permeability coefficients for CH₄ and CO₂ (P̄ and P̄) in cellulose acetate (CA, DS = 2.45) were determined at 35°C (95°F) and at pressures up to about 54 atm (800 psia). The measurements were made with pure CH₄ and CO₂ as well as with CH₄/CO₂ mixtures containing 9.7, 24.0, and 46.1 mol % CO₂. In the measurements with the pure gases, P̄ was found to decrease with increasing pressure, as expected from the “dual-mode” sorption model. By contrast, P̄ passes through a minimum and then increases with increasing pressure, probably due to the plasticization (swelling) of CA by CO₂. The values of P̄ and P̄ determined with the mixtures containing 9.7 and 24.0 mol % CO₂ decrease with increasing total pressure; this behavior is adequately described by the extended “dual-mode” sorption model for mixtures. By contrast, the values of P̄ and P̄ obtained with the mixture containing 46.1 mol % CO₂ pass through a minimum and then increase as the total pressure is raised, probably also due to the plasticization of CA by CO₂. The CO₂/CH₄ selectivity (≡P̄/P̄) of the CA membrances decreases with increasing total pressure and, at constant pressure, decreases with increasing CO₂ concentration in the feed mixture. The effects of exposing the CA membranes to high-pressure CO₂ prior to the permeability measurements (“conditioning” effects) on P̄ and P̄ have also been studied. © 1996 John Wiley & Sons, Inc.     

Composition and temperature effects on air separation through liquid crystalline alkyl cellulose membranes

The air separation through triheptyl cellulose (THC)/ethyl cellulose (EC) blend membranes containing no more than 20 wt % THC at the temperature range from 298 to 358 K was investigated using a variable volume method. The air-separation ability for the THC/EC membranes were greater than that for the THC-free pure EC membrane. P for the THC/EC membranes was between 1.06–8.89 × 10^?9 cm³ (STP) cm/cm² s cmHg and P/P 3.04–3.66. The THC/EC membrane showed a unique trend in its P/P ? P relationship, i.e., the magnitude of P/P increased simultaneously with that of P. The THC/EC membrane yielded a maximum oxygen concentration in the oxygen-enriched air (OEA) of 39.5% at an OEA flux of 6.99 × 10^?4 cm³ (STP)/s cm² for a pressure difference of 0.43 MPa at 358 K. After 300 h of measurement at 0.40 MPa and 313 K, the efficiency of the concentrating oxygen was almost constant. © 1994 John Wiley & Sons, Inc.     

Absorption of NO2/N2O4 in nitric acid

Laboratory-scale measurements were performed on the absorption of NO₂ gas into diluted nitric acid. The concentration of NO₂ gas, which represents an NO₂/N₂O₄ equilibrium, varied from 1000 to 20000 ppm, the carrier gas being nitrogen. The concentration of nitric acid ranged from 15 to 60 mass-%. The absorption experiments were carried out in a double stirred cell, with a defined gas/liquid interface as the mass transfer area. The liquid phase was conducted periodically and the gas phase continuously. Mass flow rates were determined. The well-known film model of absorption was used for analyzing the experimental results. Only the N₂O₄ species was considered to pass the gas/liquid interface. The measured data yielded values of H(k D₁)^1/2 as well as their variation with temperature and nitric acid concentration.     

Gas permeabilities of poly(trimethylsilylpropyne) membranes surface modified with CF4 plasma

Surface fluorination of poly(trimethylsilylpropyne) (PTMSP) membranes by CF₄ plasma was studied. The surface fluorination of the membranes was carried out in an atmosphere of CF₄ in a capacitively coupled discharge apparatus with external electrodes. Dramatic increase in selectivity (P/P) was observed. The effect of fluorination conditions such as duration of treatment and discharge power on the permeabilities of the membranes was studied. X-ray photoelectron spectrometric data of modified PTMSP membranes showed a drastic alternation in the surface layer. The P and P/P of the membranes were observed to be dependent on the F/C atomic ratio. At F/C > 1, the P/P value of the membranes could be more than four. © 1993 John Wiley & Sons, Inc.     

Oxidative coupling of methane over a La2O3/CaO catalyst. Optimization of reaction conditions in a bubbling fluidized-bed reactor

Oxidative coupling of methane over a La₂O₃/CaO catalyst was investigated in laboratory-scale fluidized-bed reactors (ID = 5 and 7 cm) in the following range of reaction conditions: T = 700 – 880°C, P = 41 – 72 kPa and P = 6 – 29 kPa. The maximum C₂₊ selectivity and yield amounted to 73.8% (T = 800°C, X = 13.1%, Y = 9.7%) and 16.0% (T = 840°C, X = 34.0%, S = 47.2%), respectively. Axial gas concentration profiles revealed that C₂₊ selectivity was not only influenced by oxidative consecutive reactions, but also by steam reforming of ethylene. When diluting the catalytic bed (m_cat = 145 g) with quartz (m = 200 and 400 g), a slight decrease of the selectivity (1–2%) was observed. The dilution of the feed gas with nitrogen only led to only a small increase (< 2%) of the C₂₊ selectivity.     

Relationship in polypropylene melt between its linear viscoelasticity and its steady capillary flow properties

It is the object of the present study to obtain clear knowledge of the relations in the polypropylene melt between its linear viscoelasticity and its nonlinear steady capillary flow, paying particular attention to the elastic properties in its capillary flow. By representing the linear viscoelasticity numerically with zero-shear viscosity, η₀, and steady-state compliance, J, evaluation has been made of the properties concerning the elasticity of polymer melt in the capillary flow, such as non-Newtonianity, the entrance pressure loss, the end correction, the Barus effect, and the melt fracture. The steady flow viscosity η, the entrance pressure loss P₀, the critical shear stress, τ_c, and the critical shear rate $\dot \gamma _c$ at which melt fracture begins to occur are subject to η₀ as follows: From the well-known relationship between η and the weight-average molecular weight M?_w, these quantities are governed by M?_w. Meanwhile, for such quantities as structural viscosity index N, end correction coefficient ν, and elastic pressure loss ratio P₀/P, following correlations hold: As η₀ and J are respectively determined mainly by M?_w and the molecular weight distribution MWD, these quantities are governed by both M?_w and MWD. Physical meanings of η₀·J and η₀² · J are, respectively, mean relaxation time and a measure of stored energy in steady flow. The Barus effect has a positive correlation to J, ν, and P₀/P. (The symbol ∝ employed here means positive correlation.)     

Conversion of SO2 into elemental sulfur by using the RF plasma technique

This study demonstrates a new approach for converting SO₂ into elemental sulfur by adding CH₄ in a radio-frequency (RF) plasma reactor. With the applied power (P) of the RF reactor specified at 90 W and operating pressure set at 4000 N/m², it was found that as the CH₄/SO₂ ratio (R) was increased from 0.3 to 1.0, most sulfur-containing products were in the form of elemental sulfur. While R was increased from 1 to 2, the content of elemental sulfur was decreased significantly, but CS₂ was increased dramatically. While R was increased from 2 to 3, both elemental sulfur and CS₂ contents became quite comparable. Nevertheless, it was found that both H₂ and CO (that is, syngas) were the main nonsulfur-containing products under all testing conditions. These results indicate that the use of the RF plasma technique was not only beneficial to convert SO₂, but also was able to convert CH₄ into useful materials. For R = 0 (that is, no CH₄ was introduced), it was found that the SO₂ conversion (i.e., η) = 0.084, indicating that the RF plasma process was inadequate to convert pure SO₂ without adding CH₄ as a reducing agent. While R was increased to 2, it was found that η was improved significantly to 0.968 accompanied with η = 0.999. But as R was increased from 2 to 3, both η and η were slightly decreased. Both η and η also were sensitive to the applied power (P). As P was increased from 15 W to 90 W at R = 2, it was found that both η and η were increased dramatically from 0.247 and 0.320 to 0.968 and 0.999, respectively. But as P was increased from 90 W to 120 W, the increase on both η and η became very limited. Based on these, this study suggests that the operating condition of R = 2 and P = 90 W would be the most appropriate combination for SO₂ conversion. © 2004 American Institute of Chemical Engineers AIChE J, 50: 524–529, 2004     

Sorption and transport properties of the semi‐interpenetrating network based on crosslinked poly(vinyl alcohol) and poly(styrene sulfonic acid‐co‐maleic anhydride) as proton‐conducting membranes

This study investigates the sorption and transport properties of hydrocarbon membranes based on poly(vinyl alcohol) network and poly(styrene sulfonic acid‐co‐maleic acid) (PSSA‐MA). The water and methanol self‐diffusion coefficients through an 80 wt % PSSA‐MA interpenetrating SIPN‐80 membrane measured 3.75 × 10^?6 and 5.47 × 10^?7 cm²/s, respectively. These results are lower than the corresponding values of Nafion® 115 (8.89 × 10^?6 cm²/s for water and 8.63 × 10^?6 cm²/s for methanol). The methanol permeability of SIPN‐80 membrane is 4.1 × 10^?7 cm²/s, or about one‐fourth that of Nafion® 115. The difference in self‐diffusion behaviors of Nafion® 115 and SIPN‐80 membranes is well correlated with their sorption characteristics. The solvent uptake of Nafion® 115 increased as the methanol concentration increased up to a methanol mole fraction of 0.63, and then decreased. However, the solvent uptake of the SIPN‐80 membranes decreased sluggishly as the methanol concentration increased. The λ values of water and methanol (i.e., λ and λ) in Nafion® 115 are quite close, indicating no sorption preference between water and methanol. In contrast, the λ value is only one‐third λ for a SIPN‐80 membrane. Accordingly, the SIPN membranes are regarded as candidates for direct methanol fuel cell applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Liquid–solid mass transfer for cocurrent gas–liquid upflow through solid foam packings

This article presents the liquid–solid mass transfer characteristics for cocurrent upflow operated gas–liquid solid foam packings. Aluminum foam was used with 10, 20, and 40 pores per linear inch (PPI), coated with 5 wt % Pd on γ‐alumina. The effects of gas velocity (u_g = 0.1?0.8 m m s^?1) and liquid velocity (u_l = 0.02 and 0.04 m m s^?1) are studied using the Pd/Bi catalyzed oxidation of glucose. The volumetric liquid–solid mass transfer coefficient, k_lsa_ls, is approximately the same for 10 PPI and 20 PPI solid foams, ranging from 2 × 10^?2 to 9 × 10^?2 m m s^?1. For 40 PPI solid foam, somewhat lower values for k_lsa_ls were found, ranging from 6 × 10^?3 to 4 × 10^?2 m m s^?1. The intrinsic liquid–solid mass transfer coefficient, k_ls, increases with increasing liquid velocity and was found to be proportional to u. Initially, k_ls decreases with increasing gas velocity and after reaching a minimum value increases with increasing gas velocity. The values for k_ls range from 5.5 × 10^?6 to 8 × 10^?4 m m s^?1, which is in the same range as found for random packings and corrugated sheet packings. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Thermal decomposition of potassium persulfate in aqueous solution at 50°C in the presence of ethyl acrylate

Potassium persulfate modes of thermal decomposition and reactions with ethyl acrylate in aqueous solution at 50°C in nitrogen atmosphere have been investigated. It has been found that the rate of persulfate decomposition may be expressed as ?d(S₂O)/dt ∝ (S₂O)^{1.00 ± 0.06} × (M)^0.92±0.05 while the steady state rate of polymerization (R_p) is given by R_p ∝ (S₂O)^{0.50 ± 0.50} × (M)^{1.00 ± 0.06} in the concentration ranges of the persulfate, 10^?3?10^?2 (m/L), and monomer (M), 4.62?23.10 × 10^?2 (m/L), i.e., within its solubility range. In the absence of monomer, the rate of persulfate decomposition was slow and first order in persulfate at the early stages of the reaction when the pH of the solution was above 3.0. The separating polymer phase was a stable colloid at low electrolyte concentrations even in the absence of micelle generators. It has been shown that the oxidation of water soluble monomeric and oligomeric radicals by the S₂O ions in the aqueous phase, viz., \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm M}_j^ \cdot + {\rm S}_2 {\rm O}_8^{2 - } \to {\rm M}_j - {\rm O} - {\rm SO}_3^ - + {\rm SO}_4^{ \cdot - } $\end{document} is not kinetically significant in this system. It has been found that the reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm M} + {\rm S}_2 {\rm O}_8^{2 - } \rightarrow{k}{\rm M} - {\rm O} - {\rm SO}_3^ - + {\rm SO}_4^{ \cdot - } $\end{document} would also lead to chain initiation at the outset of the polymerization reaction. k has been estimated as 5.41 × 10^?5 (L/m/s) at 50°C. Taking k_p as 10³ (L/m/s), k_t has been estimated as 0.168 × 10⁶ (L/m/s). The partition confficient (β) of the monomer between the polymer phase and the aqueous phase was found to be 16 ± 2, at 50°C. The rate constant for persulfate ion dissociation has been found as 1.40 × 10^?6 s^?1 at 50°C.     

Melt viscosity of acrylic copolymers

The melt flow behavior of methyl methacrylate (MMA) copolymerized with methyl acrylate (MA) was measured and analyzed in terms of the molecular structure of the copolymers. Measurement was done by using a capillary rheometer in the shear rate range from 6 × 10⁰ to 3 × 10³ s^?1 and in temperatures from 160°C to 280°C. The Newtonian flow pattern appeared in lower shear rate and higher temperature regions. However, with increasing shear rate at lower temperature, viscosity decreased to a constant slope on a logarithmic scale. The melt fracture arose at the critical shearing stress point S_c of 6 × 10⁶ dyn/cm². A die swell also appeared in the shear rate range larger than 1 × 10⁶ dyn/cm², and its maximum value was two times larger than that of the capillary diameter. The decrease in viscosity with increasing shear rate is explained in terms of the apparent energy of activation in flow E. E also decreases with increasing shear rate. The exponential relation of E to η is maintained in the higher shear rate. The lowering of viscosity in lower shear rate, however, is attributed to not only the change in E but also the change in the volume of flow unit. The melt viscosity increases in inverse proportion to the MA content in the copolymers which form more flexible chains. Syndiotactic form of MMA has increased viscosity, caused by the rigidifying of segmented chains, rather than the strengthening of intermolecular interaction.     

Electrochemical Nanogravimetric Studies of Ruthenium(III) Trichloride Microcrystals

Ruthenium (III) trichlorid solid crystals have been mechanically attached to gold and paraffin-impregnated graphite surfaces and studied in the presence of aqueous solutions of M⁺Cl⁻ electrolytes, where M⁺ = Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺ and K₂SO₄ by cyclic voltammetry and electrochemical nanogravimetry at a quartz crystal microbalance (EQCM). The electrochemical reduction of the layered α-RuCl₃ microcrystals causes drastic changes in the composition and the structure of crystals. The comparison of the current—potential and surface mass change—potential functions belonging to the first reduction-reoxidation cycle with the subsequent ones reveals that the simple intercalation scheme described in the literature cannot be entirely valid. During the first reduction step at ca. 0.2 V vs. SCE the charge consumption is substantially higher than in the course of the further potential cycling, and the simultaneous rapid and intense mass decrease indicates that considerable chemical and structural transformations occurs. Although a loss of the surface mass cannot be entirely excluded, the frequency increase most likely is not related to the dissolution of the microcrystals, however, large amounts of water molecules and—to a much smaller extent—chloride ions leave the crystal phase, and in fact a new material, which remains strongly attached to the gold or graphite surface, is formed. The extremely high frequency change at the first reduction process during the first cycle is most likely related to the stress effect originating in the phase transition of the surface layer and/or the removal of the water rigidly coupled to the surface into voids of the immobilized microcrystals. Depending on the amount of microcrystals on the electrode surface and the experimental conditions (the nature and concentration of the contacting electrolyte, scan rate, and potential range) used, after the “break-in” cycle stable electrochemical and nanogravimetric responses develop. The several reduction and reoxidation pairs of waves in the cyclic voltammograms and the simultaneous mass changes are in connection with the wide variety of intercalation reactions and complex formation during the electrochemical transformations. The mass change was reversible, in general, during reduction mass increase, while during oxidation mass decrease occurred at medium electrolyte concentrations in three or more steps. The mass excursions are rather complicated, involving different mass increase/decrease regions as a function of potential and the composition of the contacting solution. Taking into account the layered structure of RuCl₃, the electrochemical reduction can be explained as an intercalation reaction in that mixed valence intercalation phases with a general formula K Ru [Ru Cl_3z-y (H₂O)_y] • dH₂O are formed from z (RuCl₃ · H₂O). The reduction/reoxidation waves are related to the redox transformations of Ru(III) to Ru(II) sites and the insertion/deinsertion of cations and water molecules, while the composition of the polynuclear complexes and the structure of microcrystals change.     

Solution properties and unperturbed dimensions of poly (vinylpyrrolidone)

The dilute solution properties of nine poly(vinylpyrrolidone) fractions in methanol covering the molecular weight range 6.76 × 10⁴ to 1.02 × 10⁷ were studied. Constants a and K_m of the Mark-Houwink-Sakurada (M.H.S.) equation were found to be 0.60 and 2.64 × 10^?4 respectively using light scattering and intrinsic viscosity data and were compared with the literature values. The second virial coefficient, A₂ decreases gradually as the molecular weight increases while the root-mean-square radius of gyration, ² increases. The dependence of A₂ on molecular weight is in agreement with other flexible polymers dissolved in moderate to good solvents. The unperturbed chain dimension, (r/M) was calculated using the Stockmayer-Fixman (S—F) equation and a value of 4.9 × 10^?17 cm was obtained. The S—F plot slightly bends in the region of high molecular weight which is according to expectation.     

Estimation of the energetic parameters associated with the aerobic degradation of quinoline by Comamonas acidovorans in continuous culture

An estimation of the true growth yields and maintenance coefficients for Comamonas acidovorans DSM 6426 under continuous cultivation on quinoline has been performed. The data were checked for consistency using available electron, carbon and nitrogen balances. The true biomass energetic yields, η_max, and energetic maintenance coefficients, m_e, were estimated using two models based on control of growth rate and control of substrate uptake rate, respectively. The estimations were converted to the various familiar true growth yield and maintenance units such as substrate-based (Y, m_S/X), oxygen-based (Y, m) and carbon dioxide-based (Y, m) units. For the complete mineralization of quinoline by C. acidovorans, values of η_max = 0.371 and m_e = 0·0426 h^?1 were obtained.     

Some observations in the aqueous and emulsion polymerizations of common vinyl monomers initiated by sodium metabisulfite (Na2S2O5) at 50°C

Analytical grade sodium metabisulfite (Na₂S₂O₅) has been found to initiate the polymerizations of methyl methacrylate (MMA) and ethyl methacrylate (EMA) in the aqueous media in the presence and absence of detergents, and of styrene in the presence of detergents only, but it fails to initiate the polymerization of methylacrylate (MA) at low concentrations of the initiator and of acrylonitrile (AN) in the absence of cationic detergent micelles. If a mixture of AN (2.0%, v/v) and metabisulfite (1.60%, w/v) is kept for 16 h at 50°C in the presence of nitrogen, no polymerization occurs, but if a little ferric chloride (0.001%, w/v) is added to this mixture in nitrogen atmosphere, the initiation of AN polymerization is found to occur. MA can be polymerized partly by adding metabisulfite to an aqueous solution of MA and a cationic detergent (above CMC) in the presence and absence of air. Very little polymer is found under similar conditions with AN. No polymerizations were found to occur with any of the above-mentioned monomers if hydroquinone was present in the system. In the Na₂S₂O₅—MMA and Na₂S₂O₅—EMA systems, the average rates of the aqueous polymerizations were found to decrease with the increase of the initiator concentrations (from 1.316 × 10^?3 to 2.63 × 10^?1 m/L) at 50°C in the presence of nitrogen, and to be approximately inversely proportional to the sqare root of the initiator concentrations. It is suggested that the bisulfite (produced by the reaction of S₂O^2?₅ ions with water) adds to vinyl monomers as well as initiaing polymerization reactions by the reduction activation of the monomers in the presence of nitrogen. The presence of bulky groups such as methyl, phenyl, etc., at the β-position of the ethylenic double bond of the monomer, probably prevents or slows down the bisulfite addition reactions due to the steric hindrance, and so the polymerization reactions will predominate in the system of MMA, EMA, and styrene-like monomers. The complex species formed due to the interactions of the cetyltrimethyl ammonium bromide (CTAB) micelles and free CTAB cations with HSO and S₂O ions initiate the polymerizations of MA and of AN in the presence of nitrogen or air. Cationic detergent micelles protect the monomers from the direct attack of the HSO/S₂O ions.     

Equilibrium model for CO2 absorption in an aqueous solution of 2-amino-2-methyl-1-propanol

A semi-empirical gas-liquid equilibrium model for the absorption of CO₂ in aqueous 3M AMP (2-amino-2-methyl-1-propanol) is presented. It applies to high CO₂ loadings (y > 0.5) in the temperature range between 20 and 50 °C, and is based on experimental solubility and pH determinations. For a given amine concentration, it yields the equilibrium partial pressure of CO₂ as a function of only two variables: the CO₂ loading and temperature. The model correlates the expressions for the chemical equilibria involved as follows: p = m y × 10^x, where p is the equilibrium partial pressure, x = logK - pH, m is the amine molarity, y the CO₂ loading, and K is a parameter involving Henry's law constant, H, and the first dissociation constant, K₁, of carbonic acid. pH is found to depend on both temperature and CO₂ loading while logK depends only on the CO₂ loadIng. Correlations for pH and logK are presented. The model fits own data for 3M AMP very well as well as the equilibrium data found in recent literature.