Increasing Amine Concentration Research Articles

Corrosion Investigation of Carbon Steel in Different Amine-Based CO2 Removal System

The steel industry is a major source of CO2 emissions, which is affecting the corrosion behavior of carbon steel. The corrosion behavior of carbon steel (C1018) absorbed for CO2 removal is examined in different blends of amine solution by adding a heat-stable salt neutralizer and increasing amine concentration. Corrosion of carbon steel using different methyldiethanolamine (MDEA)/ (5% piperazine amine solution) which had 26% amine solution that contained heat stable amine salts treated with neutralizer at 80 °C and CO2 loading was investigated. The effect of the treated solutions on the corrosion behavior was observed using either the K2CO3 treatment solution to reach 30% amine or increasing the concentration to 33% amine solution using weight loss, potentiodynamic polarization, cyclic voltammetry, and impedance measurements. A visual examination of the corroded samples of the different amine solutions was performed. XRD for phase identification and SEM for microstructure examination were used to describe the corroded surfaces and analyze the corrosion products on the specimen surfaces under different conditions. After nine days in the 30% amine solution, these analyses showed the formation of the FeCO3 protective layer. The carbon steel in 30% amine solution provides better protection, and the lowest corrosion resistance (39.9 µm/Y).

Thermodynamic evaluation of inhibitors for methane-hydrate formation

The present paper presents an experimental study on the thermodynamic effect of three amines including (3-Aminopropyl)triethoxysilane (APTES), (3-Aminopropyl)triethoxysilane (APTMS), and Triethylenetetramine (TETA) on methane hydrates. Hydrate-Liquid-Vapour Equilibrium (HLwVE) data for methane hydrate were evaluated in the presence of 7 wt% and 20 wt% APTES, APTMS, and TETA, and with pressure ranging from 2.0 to 9.0 MPa. The thermodynamic effect of these amines on methane-hydrate formation has been investigated via measuring the methane-hydrate dissociation temperature, in applying an isochoric pressure-search method. The results reveal that APTES, APTMS, and TETA effectively shift the hydrate equilibrium curve to higher-pressure and lower-temperature regions for the methane + amine + water system. All of these three show thermodynamic-inhibition effects similar to the lower-concentration case (7 wt%), but with increasing concentration to 20 wt% for the thermodynamic-inhibition effect in the order APTES > APTMS > TETA. The average hydrate-suppression temperature (ΔT), as a ‘signature’ of thermodynamic-inhibition effect on methane hydrates measured for 7 wt% APTES, APTMS and TETA was 1.5, 1.5, and 1.3 K, respectively. ΔT increased with increasing amine concentration; these values were 5, 4.3, and 3.2 for 20 wt% APTES, APTMS, and TETA, respectively. Hydrate-onset time was further delayed due to the synergistic inhibition effect of inhibitors. The results show that these amines have a kinetic effect on gas-hydrate formation, such as for methane-hydrate formation in presence of APTMS: here, the hydrate formed after several cycles with the help of the memory effect. Moreover, the inhibition impact of these amines was compared with conventional hydrate thermodynamics, and found to be in the range of some and similar to ethylene glycol at 5 wt%. Furthermore, the addition of 5 wt% APTMS to sea salt not only enhances the thermodynamic inhibition effect, but also inhibits kinetically the formation of methane hydrate. For modelling of methane-hydrate dissociation conditions, the solid-solution theory of van der Waals and Platteeuw was applied for the hydrate phase along with the Peng–Robinson equation of state for the gas phase. Taken together, this study elucidates a novel class of thermodynamic hydrate inhibitors, which can control methane-hydrate formation efficiently.

Nucleophile-Controlled Halide Release from the Substitution Reaction of Haloketone for Facet Tuning and Manganese Doping in CsPbCl3 Nanocrystals.

Halide content of the reaction medium not only enhances the brightness of CsPbCl3 nanocrystals but also, control the shape modulations as well as doping Mn(II) in these host nanocrystals. Correlating both the shape effect and doping, herein, an in situ reaction of nucleophile-controlled halide release was explored for monitoring facets modulations and doping in CsPbCl3 nanocrystals. This was performed using alkyl amine as nucleophile which reacted with α-halo ketone, phenacyl chloride, to release chloride ions. Increase in amine concentration which released more Cl ions, reduced the possibility of shape transformation from perfect to truncated cubes during annealing. Similarly, for Mn(II) doping, the dopant photoluminescence intensity remained directly proportional to the amount of introduced amine nucleophiles. Quality of both doped and undoped nanocrystals obtained in this procedure remained unparallel and the method provided a strong correlation of rate of halide release with both facet modulations and doping in these nanocrystals.

The effect of alkanolamine mixtures on CO2 absorption efficiency in T-Shaped microchannel

In this investigation, removal of CO2was carried out using aqueous mixtures of MEA + DEA and MEA + TEA in a T-shaped microchannel. For this purpose, the effect of parameters temperature, amine concentration in the solvent, the volume percent of amines in the solvent, the gas flow rate, and the liquid flow rate was investigated by the central composite design method. The results of experiments indicated that increasing the operating temperature did not have a significant effect on CO2 removal efficiency in both mixtures. However, the CO2 removal efficiency increases with increasing amine concentration, the volume percent of the amine in the solvent, and the liquid flow rate, but the CO2 removal efficiency decreases significantly as the gas flow rate increases. Under optimal conditions, the maximum removal coefficient of CO2 obtained by MEA +DEA and MEA+TEA aqueous mixtures is 97.9% and 91.9%, respectively. Besides, the maximum volumetric overall gas-phase mass transfer coefficient under operation condition of the experiment was obtained to be 110 and 67.5 (kmol/ m3 h kpa), respectively It indicates that compared to other mass transfer devices, using microchannel in the CO2 absorption process significantly increases the volumetric overall gas-phase mass transfer coefficient and provides a new approach to obtained high absorption percentage.

Viscosity, density, and derived thermodynamic properties of aqueous 2-(ethylamino)ethanol (EAE), aqueous aminoethylethanolamine (AEEA), and its mixture for post-combustion CO2 capture

In the present study, viscosity and density of aqueous 2-(ethylamino)ethanol (EAE), aqueous aminoethylethanolamine (AEEA), and aqueous EAE + AEEA blend were measured in the temperature range of 293.15 K to 333.15 K at atmospheric pressure. Concentration of aqueous amines was used upto 30 wt% that is usually applicable for CO2 absorption from flue gases in post combustion CO2 capture process. EAE/AEEA weight ratio was 9/1, 8/2, and 7/3 in the aqueous EAE + AEEA blend. Viscosity of all mixtures increased by increasing amine concentration and decreased by increasing temperature of samples. Experimental viscosity data were correlated to newly proposed models and average absolute deviation (AAD) % was 1.515, 2.027, and 2.889 for viscosity of EAE + H2O, AEEA + H2O, and EAE + AEEA + H2O, respectively. Density of aqueous EAE and aqueous EAE + AEEA blend (at fixed EAE/AEEA weight ratio) decreased by increasing amount of amine in the mixture but aqueous AEEA showed increased density by increasing concentration of AEEA. Excess molar volume (VE) calculated for all aqueous mixtures and VE of aqueous EAE and aqueous AEEA was fitted in Redlich-Kister equation. Density of aqueous EAE + AEEA blend was correlated to a new empirical model and AAD % for this model was 0.018. Isobaric thermal expansion coefficient (αp) of binary and ternary solutions was calculated from density versus temperature data. Activation molar enthalpy (∆H∗), activation molar entropy (∆S∗), and activation molar Gibbs free energy (∆G∗) at 298.15 K for aqueous EAE, aqueous AEEA, and aqueous EAE + AEEA blend were calculated using viscosity and density data on the basis of Eyring theory of liquid viscosity.

Proton-transfer in 1,1,3,3 tetramethyl guanidine by means of ultrasonic relaxation and Raman spectroscopies and molecular orbital calculations.

In this work, we report on the structure and dynamics of the 1,1,3,3 tetramethyl guanidine (TMG) aqueous solutions in a wide concentration and temperature range by combining vibrational and ultrasonic spectroscopies. The experimental Raman spectra have been compared with the corresponding spectra obtained by ab initio quantum mechanical and density functional theory electronic structure calculations. This comparison indicated that only a single mechanism occurs when dissolving TMG in water and this is the proton transfer reaction, while the formation of byproducts during hydrolysis of TMG is dubious. This observation is further supported by the concentration dependence of the Raman spectra. The analysis of the ultrasonic relaxation data also revealed that the system exhibits a single relaxation process associated with this proton transfer reaction. It has been also observed that both relaxation amplitude and frequency exhibit a clear monotonous increase with increasing amine concentration in the solutions supporting the concept of the proton transfer reaction. The corresponding activation enthalpy was estimated directly from the temperature dependence of the acoustic data and found equal to ΔH*=5.56±0.34kcal/mol, which seems to be reasonable for hydrogen-bond formation. Furthermore, the concentration dependence of the acoustic parameters and kinematic viscosity data has been used as a probe for the molecular association in these solutions. The results have been discussed in relation to the ability or inability of water molecules to form stable clathrates after the addition of amine molecules in the solutions.

Density, Speed of Sound, Viscosity, and Surface Tension of Hexamethylenetetramine Aqueous Solutions from T = (293.15 to 323.15) K

The present research work analyzes the behavior of aqueous solutions of hexamethylenetetramine, determining several physical properties such as density, speed of sound, viscosity, and surface tension. Besides the importance of these properties, they allow the type of interactions between solute and solvent molecules to be analyzed. The study consisted of the evaluation of the influence of amine concentration and temperature upon these properties. An increase in amine concentration causes an increase in density, viscosity, and speed of sound and a decrease in isentropic compressibility and surface tension. On the basis of experimental data of isentropic compressibility and surface tension the presence of temperature resistant structure has been determined.

The study of kinetics of CO2 absorption into 3-dimethylaminopropylamine and 3-diethylaminopropylamine aqueous solution

In this work, the stopped-flow technique is used to determine the kinetics data in terms of pseudo first-order rate constants (k0) for the homogenous reaction of CO2 into aqueous solutions of 3-dimethylaminopropylamine (DMAPA) and 3-diethylaminopropylamine (DEAPA) as amine concentrations ranged from 0.05 kmol/m3 to 0.15 kmol/m3 and temperature ranged from 293 K to 313 K. It is found that k0 increased with increasing temperature and with increasing amine concentration. The mechanism of the pseudo first-order chemical reaction hypothesis is applied to interpret the experimental data. The Arrhenius expressions as k2=8.69×109×exp(−4226.2/T) for DMAPA and k2=7.21×1012×exp(−6162.9/T) for DEAPA are obtained. The results show that the experimental CO2 absorption rates exhibited good agreement with predicted CO2 absorption rates with an average relative deviation (ARD) of 2.34% and 7.53%, respectively. Finally, the interaction of tertiary amine groups with primary amine groups and the effect of molecular structure on the interaction are discussed by comparing the CO2 absorption and desorption performances in five different systems (MEA, DEEA, MEA + DEEA, DMAPA, DEAPA). It is found that the intermolecular interaction of amino groups is stronger than that of intramolecular interaction.

Extractive Separation of Pentanedioic Acid by Amberlite LA-2 in Various Solvents

Reactive extraction of pentanedioic acid using Amberlite LA-2 in different diluents, such as hexane, methylbenzene, kerosene, 4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, n-hexanone, 3-methyl-1-butanol, n-octanol, n-nonanol, and n-decanol, respectively, was studied. At lower amine concentrations, KD values of less than 1 were obtained but it improves as amine concentration was raised. Increase in amine concentration was found to increase the KD by 80–85% in inert diluents (hexane, methylbenzene and kerosene). In the chosen ketones, the extraction percentage follows the following trend 4-methyl-2-pentanone > DIBK > n-hexanone. Among the various diluents used, higher KD was obtained when alcohols were used as diluents. Mass action equilibria, linear solvation energy relationship modeling, and differential evolution (DE) was applied for estimating the model parameter and compare the model values with the experimental results of extraction equilibria.

Self-assembly of polyethyleneamine-intercalated H2Ti2O5 nanoparticles into spherical agglomerates

Abstract

Solubility of heptane in aqueous solutions of methyldiethanolamine (MDEA)

New experimental solubility data of heptane in aqueous amine solutions is presented. Simple equilibrium cells were used to measure the solubility of heptane in aqueous amine systems in the range: 298–328 K. Aqueous liquid samples were analyzed using a gas chromatograph. It was observed that heptane solubility in Methyldiethanolamine (MDEA) solutions increased with increasing temperature. Also, increasing amine concentration in the tested solution, the solubility of heptane increased. Simple models were developed in order to represent the activity coefficient of heptane in the aqueous MDEA solution in the range of 40–50 wt % MDEA. The Henry's law-based model allowed for a more direct comparison between the solubilities in pure water and in the aqueous solution of MDEA. The obtained heptane solubility data were compered to predicted data using group contribution equation of state model (GCA-EoS).

Experimental and theoretical investigation of the reaction between CO$_{2}$ and carbon dioxide binding organic liquids

The reaction kinetics of CO$_{2}$ absorption into new carbon dioxide binding organic liquids (CO$_{2}$BOLs) was comprehensively studied to evaluate their potential for CO$_{2}$ removal. A stopped-flow apparatus with conductivity detection was used to determine the CO$_{2}$ absorption kinetics of novel CO$_{2}$BOLs composed of DBN (1,5-diazabicyclo[4.3.0]non-5-ene)/1-propanol and TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene)/1-butanol. A modified termolecular reaction mechanism for the reaction of CO$_{2}$ with CO$_{2}$BOLs was used to calculate the observed pseudo-first-order rate constant k$_{0}$ (s$^{-1})$ and second-order reaction rate constant k$_{2}$ (m$^{3}$/kmol.s). Experiments were performed by varying organic base (DBN or TBD) weight percentage in alcohol medium for a temperature range of 288-308 K. It was found that k$_{0}$ increased with increasing amine concentration and temperature. By comparing using two different CO$_{2}$BOL systems, it was observed that the TBD/1-butanol system has faster reaction kinetics than the DBN/1-propanol system. Finally, experimental and theoretical activation energies of these CO$_{2}$BOL systems were obtained and compared. Quantum chemical calculations using spin restricted B3LYP and MP2 methods were utilized to reveal the structural and energetic details of the single-step termolecular reaction mechanism.

Syntheses of Mg–Al–NO3layered double hydroxides with high crystallinity in the presence of amines

In the present work, layered double hydroxides of Mg–Al were synthesized with nitrate interlayer anions in the presence of different types of amines such as ethylenediamine, dimethylamine, and trimethylamine, without a N2atmosphere, from a homogeneous solution using the coprecipitation method. The concentration of the different types of amines and pH of the solution were adjusted to produce high-purity and -crystallinity samples. The structure and morphology of layered double hydroxides were characterized and investigated by powder X-ray Diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis techniques. The analyses showed that with increasing amine concentration, both crystallinity and purity of the samples increase at pH 10.5.

Solubility of Hexane in Aqueous Solutions of Methyldiethanolamine

This paper presents new experimental solubility data of hexane in aqueous amine solutions. A set of simple thermodynamics equilibrium cells were used to measure the solubility of hydrocarbons in aqueous amine systems in the range 298 K to 333 K. Analyses of aqueous liquid samples are performed using a gas chromatograph. It was observed that hexane solubility in methyldiethanolamine (MDEA) solutions increased with increasing temperature. Also, increasing amine concentration in the test solution increased the solubility of hexane. A simple model is developed in order to represent the activity coefficient of hexane in the aqueous MDEA solution in the range of 40 wt % to 50 wt % MDEA.

Sorption of Ionizable Organic Amines on Soil and Their Effects on Phenanthrene Sorption

Sorption of four ionizable organic amines, n-hexylamine, trimethylamine, 1-naphthylamine, and phenylamine, on a soil sample were measured, and their effects on the sorption of phenanthrene (PHE) to the same adsorbent were studied. The aim of this study was to better clarify sorption mechanisms of chemicals with different polarity and ionization characteristics in a single-solute system and in a polar/nonpolar binary system. In the single system, cationic organic amines exhibited greater sorption than those in a neutral form, and the sorption increased with hydrophobicity for amines with the same form. In the binary system, the sorption of PHE was promoted in the presence of n-hexylamine and the solid-water distribution coefficient (K d) increased with increasing amine concentrations. This may be explained by the elevated amount of hydrophobic organic sites provided by the head-on adsorption of cationic n-hexylamine to the negatively charged sorbent surface, which are probably more favorable for the sorption of PHE compared with natural organic matters. Contrarily, the neutral amine, 1-naphthylamine, might compete with PHE for the mutually available hydrophobic sites and hence inhibited PHE sorption. On the other hand, both trimethylamine and phenylamine had little effects on PHE sorption due to their relatively high solubility and weak hydrophobicity. Therefore, either in single or binary system, both the form and the solubility/hydrophobicity of the compound play important roles in the sorption of ionizable organic amines and their effects on the sorption of nonpolar co-solute.

Experimental study of the kinetics of the homogenous reaction of CO2 into a novel aqueous 3-diethylamino-1,2-propanediol solution using the stopped-flow technique

In this work, the stopped-flow technique was used to determine the kinetic parameters in terms of pseudo first-order rate constants (k0) for homogenous reaction of CO2 into aqueous 3-diethylamino-1,2-propanediol (DEA-1,2-PD) solutions as temperature ranged from 293 to 313K and amine concentrations ranged from 0.20kmol/m3 to 1.00kmol/m3. It was found that k0 increased with increasing amine concentration and temperature. Both the base-catalyzed hydration and the termolecular models were applied to interpret the experimental data. The results showed that the predicted CO2 absorption rates exhibited good agreement with experimental data with an absolute average deviation (AAD) of 5.7% and 3.8% with respect to base-catalyzed hydration and the termolecular model, respectively. Furthermore, the pKa of DEA-1,2-PD was experimentally determined over the temperature range from 298 to 318K. The relationship between experimentally measured second-order reaction rate constants (k2) and pKa was correlated using the Brønsted relationship. The results suggest that the Brønsted relationship for DEA-1,2-PD developed in this work can predict the reaction rate constant very well with an AAD of 0.8%.

EIS Study of Amine Cured Epoxy-silica-zirconia Sol-gel Coatings for Corrosion Protection of the Aluminium Alloy EN AW 6063

The organic-inorganic hybrid sol-gel films, the structure of which comprises interconnected inorganic and organic networks have been reported as an environmentally friendly anti-corrosion pre-treatment for several metals, including aluminium alloys. In this paper, an epoxy-silica-zirconia hybrid sol-gel coating was synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium npropoxide (TPOZ) precursors and applied to EN AW-6063 alloy by dip-coating. To promote the organic network formation through the epoxy group polymerization at room temperature, two types of amine crosslinkers were added during synthesis: diethylenetriamine (DETA), in different concentrations, and a tri-functional aminosilane. The evolution of the curing process and the corrosion behaviour of the coated aluminium alloy specimens were evaluated by Electrochemical Impedance Spectroscopy (EIS) in 0.5 M NaCl. The morphology and surface chemistry of the hybrid coatings were characterized by Energy Dispersive Spectroscopy (EDS) coupled with Scanning Electron Microscopy (SEM) and by Fourier Transform Infrared Spectroscopy (FTIR). The results obtained revealed that the sol-gel coatings with lower amine ratios required longer curing times, but showed the best anticorrosive performance with time. The increase in amine concentration has led to a more cross linked organic network, resulting in higher initial coatings resistance; however it has turned coatings more hydrophilic, prone to rapid degradation in water.

Effect of Alkylamine Chain Length on the Critical Micelle Concentration of Cationic Gemini Butanediyl-α, ω-bis(dimethylcetylammonium bromide) Surfactant

Herein we report the effect of chain length of alkyl amines on the critical micelle concentration (CMC) of cationic gemini surfactant butanediyl-α, ω-bis(dimethylcetylammonium bromide) (abbreviated as C16-C4-C16). The CMC of different mixtures has been measured by surface tension using a du Noüy tensiometer in aqueous solution at 303 K. A synergistic effect was observed in all instances that were found to be correlated with chain length. It was found that the CMC of C16-C4-C16 decreased with increasing amine concentrations and the extent of effect followed the sequence: octylamine (C8NH2) > heptylamine (C7NH2) > hexylamine (C6NH2) > pentylamine (C5NH2) > butylamine (C4NH2). C20 (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m), ratio of C20 and CMC, maximum surface excess (Γmax) and minimum surface area per molecule (Amin) were evaluated from surface tension versus log C (C is concentration) plots. Mixed micelles were formed with the gemini surfactant and the CMC values of the mixtures were used to compute βm (the interaction parameter for mixed micelle formation in aqueous medium), βσ (the interaction parameter for mixed monolayer formation at the aqueous solution/air interface), and the activity coefficients (f1 and f2). The standard Gibbs energy of adsorption () was also evaluated.

Mixed Micellization of Cationic Gemini Surfactants with Primary Linear Alkylamines

AbstractDue to the potential use of amines as co‐surfactants in microemulsions, the effect of adding alkylamines (C4–C8NH2) on the aggregation properties of cationic gemini surfactants [pentanediyl‐1, 5‐bis(dimethylcetylammonium bromide) and hexanediyl‐1, 6‐bis(dimethylcetylammonium bromide), referred to as 16‐5‐16 and 16‐6‐16 compounds] has been studied using tensiometry at 303 K. Data on critical micelle concentration (CMC), the surface properties C20 (the surfactant concentration required to reduce the surface tension by 20 mN/m), Гmax (maximum surface excess), Amin (minimum surface area per molecule) evaluated from the surface tension versus surfactant concentration plot, the interaction parameters βσ (for mixed monolayer formation at the aqueous solution/air interface), and βm (for mixed micelle formation in aqueous medium) are reported. A synergistic interaction was observed both in the micelle as well as at interface, as evident from interaction parameters. Theoretical models of Clint, Rubingh and Rosen were used to explain and compare the results. More synergistic interaction was observed in 16‐5‐16 as compared to 16‐6‐16. The CMC values of 16‐s‐16 (s = 5, 6) decreased with increasing amine concentrations and the extent of the effect followed the sequence: octylamine > heptylamine > hexylamine > pentylamine > butylamine.

Equilibrium study on reactive extraction of propionic acid with N1923 in different diluents

The equilibrium for the propionic acid extraction by N1923 in three diluents, represented as proton-donator (n-octanol), polar (butyl acetate), inert (hexane) types, have been studied. The diluents had a significant influence on the equilibrium. The loading ratio, Z, was employed to investigate the effect of diluents on the extraction efficiency. When Z exp was lower than 1, N1923 extraction followed the order: n-octanol > butyl acetate > hexane. When the loading ratio Z exp was higher than 1, the order changed to: butyl acetate > hexane > n-octanol. Equilibrium complex constants K 11, K 21, K 31 have been estimated. The results showed that K 11 was much higher than K 21 and K 31, demonstrated K 11 as the dominant factor in the extraction process. Comparing the values of K 11 of all the three diluents, the following order was observed: n-octanol > butyl acetate > hexane. The influence of amine concentration on the extraction equilibrium constant in different diluents was also investigated. The extraction equilibrium constant K 11 decreased with the increase of amine concentration in n-octanol. When hexane and butyl acetate were used as diluent, the extraction equilibrium constant K 11 increased slightly with the increase of amine concentration.