Aqueous Solutions Of Piperazine Research Articles

Correlation of CO 2 solubility in N-methyldiethanolamine + piperazine aqueous solutions using extended Debye–Hückel model

Solubility data of CO 2 in aqueous N-methyldiethanolamine (MDEA) solutions of concentration (2.52, 3.36, and 4.28) kmol/m 3 were obtained at temperatures (313, 323, and 343) K and partial pressures ranging from about (30 to 5000) kPa. A thermodynamic model based on extended Debye–Hückel theory was applied to predict and correlate of CO 2 solubility in various aqueous amine solutions. The effect of piperazine (PZ) concentration on CO 2 loading in MDEA solutions was determined at PZ concentration (0.36, 0.86, and 1.36) kmol/m 3. Using experimental data in various temperatures the interaction parameters of activity coefficient model for these systems were determined. The results show the model consistency with experimental and literature data and PZ is beneficial to the CO 2 loading. The comparison of results of this study with previous data work shows the wide range of CO 2 loading considered in this work and the better agreement of model with experimental data. The average absolute relative deviation percent ( δ AAD) for all data points were 8.11%.

Influence of fluorocarbon flat-membrane hydrophobicity on carbon dioxide recovery

The influence of hydrophobicity in flat-plate porous poly(vinylidene fluoride) (PVDF) and expended polytetrafluoroethylene (PTFE) membranes on CO 2 recovery using aqueous solutions of piperazine (PZ) and alkanolamine is examined. Experiments were conducted at various gas flow rates, liquid flow rates, and absorbent concentrations. The CO 2 absorption flux increased with increasing gas flow rates and absorbent concentrations. When using 2-amino-2-methyl-1-propanol (AMP) or AMP + PZ aqueous solution as absorbent, this process was dominantly governed by gas film layer diffusion and membrane diffusion. The diffusion resistance of the membrane phase was only important when using N-methyldiethanolamine as the sole absorbent. The water contact angle increased initially with increasing plasma working power and reached at steady state value of 155° beyond 100 W. The elemental fluorine-to-carbon ratio (F/C) and water contact angle of the PVDF membrane increased with increasing treatment time and reached a plateau after 5 min of CH 4 plasma (100 W). Increases in the CO 2 absorption fluxes of 7% and 17% were observed for plasma-treated PVDF membranes in comparison to non-treated PVDF and PTFE, respectively, when using 1 M AMP as absorbent. The membrane mass transfer coefficient, k m , for plasma-treated PVDF membranes increased from 2.1 × 10 −4 to 2.5 × 10 −4 m s −1. Membrane durability was greatly improved by CF 4 plasma treatment (100 W/5 min) and comparable to that of PTFE membranes.

Absorption of carbon dioxide by mixed piperazine–alkanolamine absorbent in a plasma-modified polypropylene hollow fiber contactor

This paper examines the enhancement of hydrophobic plasma treatment on the performance of polypropylene (PP) hollow fibers in a gas absorption membrane (GAM) process using aqueous solutions of piperazine (PZ) and alkanolamine. Experiments were conducted at various gas flow rates, liquid flow rates, and absorbent concentrations. The CO 2 absorption flux increased with increasing gas flow rates and absorbent concentrations. The diffusion resistance of the liquid phase was only important when using 2-amino-2-methyl-1-propanol (AMP) or methyldiethanolamine (MDEA) as the sole absorbent. The diffusion resistance in the gas boundary layer is always dominant in the hollow-fiber CO 2 absorption processes. The water contact angle and roughness of the PP membrane increased by plasma treatment in CF 4. We show that the wetting ratio of the PP membranes decreased from 0.0674% to 0.027% after plasma treatment, when using mixed AMP–PZ solution as the absorbent. An 8% increase in the CO 2 absorption flux was observed for plasma-treated PP hollow fibers in comparison to non-treated fibers when using 1.0 mol/dm 3 AMP as the absorbent. Membrane durability was greatly improved by the treatment of plasma with CF 4 (20 W/5 min). The membrane mass transfer coefficient k m for plasma-treated PP membranes was comparable to that of polytetrafluoroethylene (PTFE) membranes.

Post-combustion CO2 capture in coal-fired power plants: Comparison of integrated chemical absorption processes with piperazine promoted potassium carbonate and MEA

Abstract A thermodynamic and economic comparison of post-combustion CO2 capture processes using aqueous solutions of piperazine (PZ) promoted potassium carbonate (K2CO3) and monoethanolamine (MEA) based on fair boundary conditions and constant assumptions using rigorous thermodynamic models is described. In contrast to a first preliminary comparison, it is shown that under the stated assumptions and considered boundary conditions, a 7 m MEA solution performs better in both thermodynamic and economic terms than aqueous solutions of K2CO3 and PZ.

Kinetics of the Absorption of Carbon Dioxide into Mixed Aqueous Solutions of Piperazine and Triethanolamine

The reaction kinetics of the absorption of CO2 into mixed aqueous solutions of piperazine (PZ) and triethanolamine (TEA) are investigated using the wetted wall column at temperatures of 303.2 to 313.2 K. The physical properties such as density and viscosity of the aqueous alkanolamine solutions, and the solubility and diffusivity of the nitrous oxide in aqueous alkanolamine solutions are also measured. The N2O analogy is applied to estimate the solubilities and diffusivities of CO2 in aqueous amine systems. Based on the pseudo-first-order for CO2 absorption, the overall pseudo first-order reaction rate constants were determined from the kinetics measurements. For CO2 absorption into mixed aqueous solutions of PZ and TEA, it is found that the addition of small amounts of PZ to aqueous TEA solutions has a significant effect on the enhancement of the CO2 absorption rate. For the CO2 absorption rate model, a second-order reaction rate model is applied for both reactions of CO2 with PZ and TEA. The overall absolute percentage deviation for the calculation of the apparent rate constant kapp was 4.6% for the kinetics data measured. The model is satisfactory in representing the CO2 absorption into mixed aqueous solutions of PZ and TEA.

Absorption of carbon dioxide into aqueous solutions of piperazine activated 2-amino-2-methyl-1-propanol

In this work, new experimental data on the rate of absorption of CO 2 into piperazine (PZ) activated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) are reported. The absorption experiments using a wetted wall contactor have been carried out over the temperature range of 298–313 K and CO 2 partial pressure range of 2–14 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt%, keeping the total amine concentration in the solution at 30 wt%. The CO 2 absorption into the aqueous amine solutions is described by a combined mass transfer-reaction kinetics-equilibrium model, developed according to Higbie's penetration theory. Parametric sensitivity analysis is done to determine the effects of possible errors in the model parameters on the accuracy of the calculated CO 2 absorption rates from the model. The model predictions have been found to be in good agreement with the experimental results of rates of absorption of CO 2 into aqueous (PZ+AMP). The good agreement between the model predicted rates and enhancement factors and the experimental results indicates that the combined mass transfer-reaction kinetics-equilibrium model with the appropriate use of model parameters can effectively represent CO 2 mass transfer in PZ activated aqueous AMP solutions.

CO 2/H 2 separation by facilitated transport membranes immobilized with aqueous single and mixed amine solutions: Experimental and modeling study

An experimental and theoretical analysis to separate CO 2 using facilitated transport membranes immobilized with different aqueous single and mixed amine solutions have been performed. The membranes containing monoethanolamine (MEA), diethanolamine (DEA), monoprotonated ethylenediamine (EDAH +) and piperazine (PZ), as well as aqueous blends of PZ with MEA, DEA or EDAH + were considered. The aqueous solution of PZ showed the highest CO 2 permeation rate with respect to other single amine solutions. Therefore blends of PZ with MEA, DEA and EDAH + increased the permeance of carbon dioxide through mixed amine membranes. Facilitated transport of carbon dioxide across a liquid membrane containing aqueous single and mixed amine solutions have been numerically modeled in which the reversible reaction A (CO 2) + 2B (amine) ⇔ AB (carbamate) + BH (protonated amine) occurs inside the liquid membranes. The current numerical solution predicts the facilitated factor of CO 2 through the immobilized membrane and is based on the dimensionless, nonlinear diffusion–reaction transport problem, allowing unequal diffusivities of complexes and carrier and cases of zero and nonzero permeate side solute concentrations. In comparison with the numerically calculated results, the results obtained were found to be in well agreement although improved estimation of physicochemical parameters would substantially improve the model predictions.

Diffusion Coefficients of N2O in Aqueous Piperazine Solutions Using the Taylor Dispersion Technique from (293 to 333) K and (0.3 to 1.4) mol·dm−3

The diffusion coefficients of N2O in aqueous piperazine (PZ) solutions have been determined using the Taylor dispersion technique over a temperature range from (293 to 333) K and a concentration range from (0.3 to 1.4) mol·dm−3 PZ. The experimental results have been compared to literature values. Diffusion coefficients of N2O in aqueous PZ solutions can be estimated by using a modified Stokes−Einstein relation with sufficient accuracy for engineering purposes. The diffusion coefficient of CO2 in an aqueous PZ solution can be estimated by means of the “N2O analogy”. The use of the Taylor dispersion technique for determination of gas diffusivities in liquids is given in detail.

Densities, Viscosities, and Liquid Diffusivities in Aqueous Piperazine and Aqueous (Piperazine + N-Methyldiethanolamine) Solutions

Densities and viscosities of aqueous solutions containing both piperazine (PZ) and N-methyldiethanolamine (MDEA) have been determined at a temperature range from (293.15 to 323.15) K. The concentrations of MDEA have been kept constant at (1, 2, 3, and 4) mol·dm−3 with the concentration of PZ varying from (0 to 1) mol·dm−3. Liquid diffusivities of aqueous PZ solutions have been determined using the Taylor dispersion technique over a temperature range from (293.15 to 368.15) K and concentrations from (0 to 1.5) mol·dm−3. At infinite dilution, the method proposed by Othmer & Thakar can be used to estimate the liquid diffusivities, and a modified Stokes−Einstein relation can be used to predict the diffusivities at higher concentrations. Liquid diffusivities of both PZ and MDEA have been determined in aqueous solutions containing 4.0 mol·dm−3 MDEA and (0, 0.5, and 1.0) mol·dm−3 PZ at a temperature range from (298.15 to 368.15) K. The liquid diffusivities can be estimated by a modified Stokes−Einstein relation.

Absorption of carbon dioxide by the absorbent composed of piperazine and 2-amino-2-methyl-1-propanol in PVDF membrane contactor

This paper tests the performance of microporous polyvinylidinefluoride (PVDF) hollow fiber in a gas absorption membrane process (GAM) using the aqueous solutions of piperazine (PZ) and 2-amino-2-methyl-1-propanol (AMP). Experiments were conducted at various gas flow rates, liquid flow rates and absorbent concentrations. Experimental results showed that wetting ratio was about 0.036% when used with the aqueous alkanolamine solutions, while that was 0.39% with aqueous piperazine solutions. The CO 2 absorption rates increased with increasing both liquid and gas flow rates at N Re < 20. The increase of the PZ concentration showed an increase of absorption rate of CO 2. The CO 2 absorption rate was much enhanced by the addition of PZ promoter. The resistance of membrane was predominated as using a low reactivity absorbent and can be neglected as using absorbent of AMP aqueous solution. The resistance of gas-film diffusion was dominated as using the mixed absorbents of AMP and PZ. An increase of PZ concentration, the resistance of liquid-film diffusion decreased but resistance of gas-film increased. Overall, GAM systems were shown to be an effective technology for absorbing CO 2 from simulated flue gas streams, but the viscosity and solvent–membrane relationship were critical factors that can significantly affect system performance.

Kinetics and modeling of carbon dioxide absorption into aqueous solutions of piperazine

In this work, the kinetics of the reaction between CO 2 and aqueous piperazine (PZ) have been estimated over the temperature range of 298–313 K from the absorption data obtained in a wetted wall contactor. The absorption data are obtained for the PZ concentrations of 0.2– 0.8 kmol m - 3 and for CO 2 partial pressures up to 5 kPa. A coupled mass transfer-kinetics-equilibrium mathematical model based on Higbie's penetration theory has been developed with the assumption that all reactions are reversible. The model is used to estimate the rate constants from the experimental data for absorption of CO 2 in aqueous PZ. The estimated rate constants of this study are in good agreement with those reported in the literature.

Physical Solubility and Diffusivity of N2O and CO2 in Aqueous Solutions of Piperazine and (N-Methyldiethanolamine + Piperazine)

In this work, the physical solubility and diffusivity of N2O in aqueous solutions of piperazine (PZ) and an aqueous blend of N-methyldiethanolamine (MDEA) and piperazine have been measured over a range of temperatures and at atmospheric pressure. For the binary mixtures, the mass percents of PZ used are (1.74 to 12) %. For the ternary mixtures, the total amine strength in the solution has been kept at 30 mass %. The “N2O analogy” is then used to estimate the physical solubility and diffusivity of CO2 in aqueous PZ and PZ-blended aqueous MDEA solutions. The experimental physical solubility and diffusivity data have been correlated as a function of temperature and concentration of amine and compared with the available data in the literature.

Kinetics of absorption of carbon dioxide in aqueous piperazine solutions

In the present work the absorption of carbon dioxide into aqueous piperazine (PZ) solutions has been studied in a stirred cell, at low to moderate temperatures, piperazine concentrations ranging from 0.6 to 1.5 kmol m - 3 , and carbon dioxide pressures up to 500 mbar, respectively. The obtained experimental results were interpreted using the DeCoursey equation [DeCoursey, W., 1974. Absorption with chemical reaction: development of a new relation for the Danckwerts model. Chemical Engineering Science 29, 1867–1872] to extract the kinetics of the main reaction, 2 PZ + CO 2 → PZCOO - + PZH + , which was assumed to be first order in both CO 2 and PZ. The second-order kinetic rate constant was found to be 70 m 3 mol - 1 s - 1 at a temperature of 298.15 K , with an activation temperature of 4.1 × 10 3 K . Also, the absorption rate of CO 2 into partially protonated piperazine solutions was experimentally investigated to identify the kinetics of the reaction 2 PZH + + CO 2 → H + PZCOO - + PZH 2 2 + . The results were interpreted using the Hogendoorn approach [Hogendoorn, J., Vas Bhat, R., Kuipers, J., Van Swaaij, W., Versteeg, G., 1997. Approximation for the enhancement factor applicable to reversible reactions of finite rate in chemically loaded solutions. Chemical Engineering Science 52, 4547–4559], which uses the explicit DeCoursey equation with an infinite enhancement factor which is corrected for reversibility. Also, this reaction was assumed to be first order in both reactants and the second-order rate constant for this reaction was found to be ( 0.28 ± 0.10 ) m 3 mol - 1 s - 1 at 298.15 K.

Solubility of Carbon Dioxide in Aqueous Solutions of Piperazine in the Low Gas Loading Region

The solubility of carbon dioxide in aqueous solutions of piperazine was determined at low gas loadings (stoichiometric molar ratios of carbon dioxide to piperazine between about 0.05 and 0.95) and temperatures between (313 and 393) K by means of headspace gas chromatography. The stoichiometric molality of piperazine amounted to about (1 and 2) mol·(kg of water)-1 {mass fraction of piperazine ≈ (8 and 15) %} at T ≈ 313 K and to about (2 and 4) mol·(kg of water)-1 {mass fraction of piperazine ≈ (15 and 26) % } at T ≈ (353 and 393) K. The partial pressure of carbon dioxide was between about (0.1 and 95) kPa. A thermodynamic model for describing the vapor−liquid equilibrium (which applies Pitzer's molality scale based equation for describing the Gibbs excess energy of the aqueous phase) is revised and extended using the new data.

Investigations on the structures and performances of a polypiperazine amide/polysulfone composite membrane

Abstract A polypiperazine amide (PA) composite membrane was prepared by interfacial polymerization using a trimesoyl hexane solution as the oil phase and a piperazine aqueous solution as the water phase on a polysulfone ultrafiltration substrate. The surface was inspected by attenuated total reflection–Fourier transform infrared spectroscopy, showing that a polyamide layer was formed. The molecular structure of polypiperazine amide was simulated using Materials Studio as a plane molecule with hexagon rings of 1.5 nm in diameter of the inscribed circle. Incorporating the result of wide angle X-ray diffraction pattern, the supermolecular structure of the PA was predicted as an irregular laminated structure. This model appears good according to the performance of the membrane. Also investigated was the morphology of the membrane by scanning electron microscope, showing a dense layer of 300 to 400 nm on the porous substrate. The composite membrane obtained is a high-performance nanofiltration membrane.

Density and Viscosity of Aqueous Solutions of Piperazine and (2-Amino-2-methyl-1-propanol + Piperazine) from 298 to 333 K

The densities and viscosities of aqueous solutions of piperazine (PZ) and aqueous blends of 2-amino-2-methyl-1-propanol (AMP) and piperazine have been measured at (298, 303, 308, 313, 318, 323, 328, and 333) K. The experiments covered the concentration range of (0.2 to 0.8) mol·L-1 piperazine (mass fraction piperazine (1.74 to 6.88) %) for the (PZ + water) system and mass fraction of (2 to 8) % for piperazine-activated blended AMP solutions. The results are compared with the available data in the literature. The experimental density and viscosity data were correlated as a function of temperature and concentration of amine.

Solublity of N2O in and Density, Viscosity, and Surface Tension of Aqueous Piperazine Solutions

Solublity of N₂O in and Density, Viscosity, and Surface Tension of Aqueous Piperazine Solutions

Solubility of N2O in and Density, Viscosity, and Surface Tension of Aqueous Piperazine Solutions

The physical solubility of N2O in and the density and viscosity of aqueous piperazine solutions have been measured over a temperature range of (293.15 to 323.15) K for piperazine concentrations ranging from about (0.6 to 1.8) kmol·m-3. Furthermore, the present study contains experimental surface tension data of aqueous piperazine solutions at temperatures of (293 and 313) K and at concentrations of (0.5, 1.0, and 1.5) kmol·m-3 piperazine in water.

Solubility of carbon dioxide in aqueous piperazine solutions

AbstractIn the present work, new experimental data are presented on the solubility of carbon dioxide in aqueous piperazine solutions, for concentrations of 0.2 and 0.6 molar piperazine and temperatures of 25, 40, and 70°C respectively. The present data, and other data available in the literature, were correlated using a model based on the electrolyte equation of state (EoS), as originally proposed by Fürst and Renon. The final model derived, containing only seven adjustable (ionic) parameters, was able to describe the available experimental solubility data (&gt;150 data points for total and/or CO2 partial pressure) with an average deviation of 16%. © 2005 American Institute of Chemical Engineers AIChE J, 2005

Kinetics of the absorption of carbon dioxide into mixed aqueous solutions of 2-amino-2-methyl-l-propanol and piperazine

The reaction kinetics of the absorption of CO 2 into aqueous solutions of piperazine (PZ) and into mixed aqueous solutions of 2-amino-2-methyl-l-propanol (AMP) and PZ were investigated by wetted wall column at 30–40 °C. The physical properties such as density, viscosity, solubility, and diffusivity of the aqueous alkanolamine solutions were also measured. The N 2O analogy was applied to estimate the solubilities and diffusivities of CO 2 in aqueous amine systems. Based on the pseudo-first-order for the CO 2 absorption, the overall pseudo first-order reaction rate constants were determined from the kinetic measurements. For CO 2 absorption into aqueous PZ solutions, the obtained second-order reaction rate constants for the reaction of CO 2 with PZ are in a good agreement with the results of Bishnoi and Rochelle (Chem. Eng. Sci. 55 (2000) 5531). For CO 2 absorption into mixed aqueous solutions of AMP and PZ, it was found that the addition of small amounts of PZ to aqueous AMP solutions has significant effect on the enhancement of the CO 2 absorption rate. For the CO 2 absorption reaction rate model, a hybrid reaction rate model, a second-order reaction for the reaction of CO 2 with PZ and a zwitterion mechanism for the reaction of CO 2 with AMP was used to model the kinetic data. The overall absolute percentage deviation for the calculation of the apparent rate constant k app is 7.7% for the kinetics data measured. The model is satisfactory to represent the CO 2 absorption into mixed aqueous solutions of AMP and PZ.