Monoethanolamine Concentration Research Articles

Surface coating method for cement-based materials to improve chloride ion penetration resistance using amine-based CO2 solvent

The application of coatings on concrete surfaces serves as a protective shield, guarding the structure against chlorides and averting corrosion of the reinforcement, consequently enhancing its durability. This study investigates the resistance of cement mortar samples to chloride ion penetration when coated with an amine-based carbon dioxide (CO2) solvent. Various factors, including monoethanolamine (MEA) concentrations of 1, 10, and 30 wt%; water-to-cement ratios (w/cm) of 0.35, 0.4, and 0.5; coating timings on day 3 and day 27; and pre-conditioning methods such as air drying, are investigated for their impact on the performance of chloride penetration resistance. Specifically, pre-conditioning significantly enhanced the performance of the coatings, especially in samples with a higher w/cm. Coatings applied at an early stage demonstrated superior resistance to chloride ion penetration compared to those applied later in the curing process. Moreover, solutions with higher concentrations of MEA, capturing more CO2, encouraged the resistance against chloride penetration by reducing capillary macropores within the cement mortar samples. Diffusivity analysis of the coated surface layer confirmed the efficacy of the CO2-dissolved MEA solution as a barrier against chloride ion penetration. Optimal performance was possibly observed in the samples produced by a w/cm of 0.4 and their treatment with more than 10% MEA concentrations.

Experimental study on the effect of process parameters on postcombustion CO2 capture using rotating packed bed technology

AbstractEnvironmental issues are the most discussed in today's industrialized world, and this has always been associated with the emission of greenhouse gases. CO2 emissions, especially from power plants, are considered the major greenhouse gas source. Capturing CO2 from large emission sources is necessary to address the worst impacts of climate change, including more frequent and severe droughts, heat waves, and intermittent rainfall. Conventional post‐combustion CO2 capture has always been questioned because of its high impact on energy costs. Rotating packed bed technology has shown the potential to reduce the cost of CO2 capture. This paper presents an experimental study on an in‐house designed rotating packed bed absorber for the capture of CO2 from a flue gas stream. Effects of process parameters such as rotating speed, liquid‐to‐gas ratio, and monoethanolamine (MEA) concentration on CO2 capture efficiency and overall volumetric mass transfer coefficient were studied. The study showed that as rotor speed increased, the CO2 capture efficiency increased, this can be attributed to higher rotor speed, resulting in more droplet flow, indicating an increase in the area of contact between the flue gas and the MEA solvent. Also, as the concentration of MEA increased CO2 capture efficiency increased, since an increase in concentration results in an increase in the rate of reaction. Finally, the study showed that a rotating packed bed absorber is an efficient unit for CO2 capture since it enhances mass transfer performance.

Synergistic promoting of CO2 absorption-mineralization by MEA-carbide slag

Thermal amine regeneration CO2 capture with amines is the most widely used technology. However, this method suffers from high energy consumption and amine losses, and captured CO2 storage safety limits its further application. To achieve CO2 capture and utilization with low energy consumption and high efficiency, this study constructed a CO2 synergistic absorption-mineralization reaction system based on monoethanolamine (MEA)-carbide slag (CS). The CO2 capture process and its effects are analyzed. The circulating absorption-mineralization activity of the coal-fired flue gas of the MEA-CS is studied. Compared with other technologies, it has good CO2 coupled absorption-mineralization performance for coal-fired flue gas and promotes the green utilization of CS and produces high-value CaCO3 products. CS can promote MEA recycling, which determines the CO2 absorption. MEA determines the CO2 absorption-mineralization rate; however, the CO2 absorption-mineralization rate does not change when MEA is > 0.1 mol/L. MEA has the best synergistic effect with CS compared to the other amines. After five rounds of experiments, the CO2 capture efficiency of MEA-CS decreases by approximately 3 %. MEA loss leads to a decrease in the CO2 capture efficiency, which includes physical and chemical losses. The main loss of MEA is the physical loss, which can be reduced by low MEA concentrations. The CO2 absorption-mineralization product is CaCO3. Compared with other CO2 capture technologies, the regeneration energy consumption is lower, and the existence of captured CO2 in solid form avoids the problem of CO2 storage and utilization.

What is behind a gas stream scrubbing liquid? Monoethanolamine/water mixtures as seen by dielectric relaxation spectroscopy.

High-quality dielectric data for monoethanolamine (MEA)/water mixtures covering the entire miscibility range are presented. For MEA concentrations c1 ≥ 1 M the obtained complex permittivity spectra, covering the frequency range from 0.05 to 89 GHz, are best described by a sum of four Debye relaxations. Modes at ∼3 GHz and ∼10 GHz are solute-specific. Whilst the first can be assigned to MEA aggregates, the second is a composite arising from "free" MEA dipoles with dynamically retarded water hydrating them. The relaxations at ∼18 GHz and ∼200 GHz essentially reflect the cooperative H-bond fluctuations of more-or-less unperturbed "bulk" water, albeit with minor solute contributions. Evaluation of the bulk-water amplitude reveals that in water-rich mixtures (c1 ≤ 3.5 M) Zt = 3.5 ± 0.2 H2O molecules hydrate a MEA molecule. Then Zt drops linearly, reaching zero for neat MEA. Supported by the literature, this concentration dependence suggests that only H2O molecules H-bonded to the NH2 and OH groups of MEA contribute to Zt. At concentrations beyond hydration shell overlap (c1 ≥ 3.5 M) these H-bonds are gradually eliminated, while new interactions with neighboring MEA molecules are formed. From the evaluation of the MEA-specific amplitudes we conclude that for c1 ≥ 2 M, including neat MEA, ∼35% of the solute molecules are in aggregates, where breaking the intermolecular NH⋯O hydrogen bond determines the dynamics.

РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЙ ПО ОПРЕДЕЛЕНИЮ РАЦИОНАЛЬНОГО СПОСОБА УДАЛЕНИЯ ЗАГРЯЗНЕНИЙ ИЗ МОТОРНОГО МАСЛА БЕЗ ЕГО СЛИВА ИЗ СИСТЕМЫ СМАЗКИ

Contaminants are formed in diesel internal combustion engines of tractors during operation under the influence of high temperatures and loads on the parts of the cylinder-piston group, which then enter the engine oil, which affects the service life of the oil and the characteristics of the machine-tractor unit. An important measure that affects the contamination of parts and the service life of the oil is flushing the lubrication system during routine replacement of used oil. However, for a number of well-known objective and subjective reasons, this technological method is practically not carried out under real operating conditions. Resource-saving technology for flushing the lubrication system with motor oil running in the tractor engine was developed at TSTU. A number of technological methods for cleaning oil from contaminants and resins under the influence of chemical reagents added to the oil, followed by idling the engine, have been developed. The dependences of changes in contamination, base number, viscosity and color of the oil on the cleaning method, the concentration of the addition of urea, monoethanolamine, and isopropanol reagents were obtained. It has been determined that the addition of isopropanol can increase the flash point of the oil. The dependences of the change in base number and viscosity on the concentration of monoethanolamine with isopropanol in the oil have been established. The rational concentration for adding this additive is 2–3% of the oil volume. It was determined that the color of the oil changes from 9 to 4 points per unit. CNT. Research on the use of finely dispersed contaminants as a separating agent and coagulant has established that 3% vol. carbamide dissolved in ammonium hydroxide allows you to get the best result. Research in this area will be continued and requires confirmation in a wide range of oils and the technological state of tractor engines.

New improvement of amine-based CO2 capture processes using heat integration and optimization

The post-combustion capture process (PCCP) using amine-based solvent was the most mature and adequately researched carbon capture and storage (CCS) technology. Monoethanolamine (MEA) solvent regeneration in the stripper (desorption process) usually takes high energy consumption and a MEA make-up is required before re-entering the absorber (absorption process). To improve the CO2 capture efficiency and reduce the overall energy consumption of PCCP, four configurations (Design-1, Design-2, Design-3, Design-4) are presented, where Design-1 is denoted as the base case design. Design-2 is an extension of Design-1 by adding the side intercooler in the absorber. Design-3 is an extension of Design-2 by using internal heat integration in the stripper. Design-4 is an extension of Design-3 by adding the side interheater in the absorber. By using response surface methodology (RSM) in conjunction with central composite design (CCD), operating parameters (MEA solvent flowrate, MEA concentration, pressure) including side intercooler/side interheater locations of Design-2 to Design-4 are optimized. It is successfully validated that the side intercooler absorber could increase the CO2 capture ability by MEA solvent and the side interheater stripper with internal heat integration could effectively reduce energy consumption about 36% to 62%.

CO2 and H2S Absorption in Tofu Liquid Waste Biogas using Packed Bed Scrubber with Variation of MEA Concentration and Flow Rate

Biogas technology has become an alternative fuel that is often used in Indonesia. One of the raw materials for biogas that has the potential and is easy to obtain is waste from the tofu industry. Liquid waste still contains a lot of organic elements. The organic materials contained in the exhaust of the tofu industry are generally very high. The gases commonly found in tofu waste are nitrogen gas (N2), oxygen (O2), hydrogen sulfide (H2S), ammonia (NH3), carbon dioxide (CO2) and methane (CH4). These gases come from the decomposition of organic materials contained in wastewater. So that biogas produced from tofu liquid waste still contains CO2 and H2S gases which are quite high. Therefore, in this study the process of purification or refining of biogas products will be carried out using the absorption method through an absorber column using monoethanolamine (MEA) solution as a chemical absorbent through a 8 mm packed bed scrubber. The results showed that the best biogas flow rate in the purification process which produced the highest CH4 concentration of 95.12% was 40% MEA concentration and 0.8 L/min flow rate. The effect of MEA concentration on biogas purification causes the concentration of CO2 and H2S in the purified biogas to decrease as the MEA concentration increases. The best combination of 0.8 L/min biogas flow rate and 10 mm packing area reduces CO2 and H2S concentrations to 1.88% and 0 ppm.

Hybrid Smart Strategies to Predict Amine Thermal Degradation in Industrial CO2 Capture Processes.

CO2 emission reduction is an essential step to achieve the climate change targets. Solvent-based post-combustion CO2 capture (PCC) processes are efficient to be retrofitted to the existing industrial operations/installations. Solvent degradation (and/or loss) is one of the main concerns in the PCC processes. In this study, the thermal degradation of monoethanolamine (MEA) is investigated through the utilization of hybrid connectionist strategies, including an artificial neural network-particle swarm optimization (ANN-PSO), a coupled simulated annealing-least squares support vector machine (CSA-LSSVM), and an adaptive neuro-fuzzy inference system (ANFIS). Moreover, gene expression programming (GEP) is employed to generate a correlation that relates the solvent concentration to the operating variables involved in the adverse phenomenon of solvent thermal degradation. The input variables are the MEA initial concentration, CO2 loading, temperature, and time, and the output variable is the remaining/final MEA concentration after the degradation phenomenon. According to the training and testing phases, the most accurate model is ANFIS, and the reliability/performance of its optimal network is assessed by the coefficient of determination (R2), mean squared error, and average absolute relative error percentage, which are 0.992, 0.066, and 2.745, respectively. This study reveals that the solvent initial concentration has the most significant impact, and temperature plays the second most influential effect on solvent degradation. The developed models can be used to predict the thermal degradation of any solvent in a solvent-based PCC process regardless of the complicated reactions involved in the degradation phenomenon. The models introduced in this study can be employed for the development of more accurate hybrid models to optimize the proposed systems in terms of cost, energy, and environmental prospects.

Saturation of the MEA solution with CO2: Absorption prototype and experimental technique

The carbon dioxide (CO2) emissions from thermoelectric power plants contribute to global warming. The Monoethanolamine (MEA) solution is the most widely used solvent for CO2 removal processes from these power plants with the disadvantage that it is expensive and corrosive at high concentrations. In this work, an experimental methodology is developed to fix the operating flow ratio (L/G) that ensures the maximum absorption capacity of MEA solution. The absorption system prototype and the experimental saturation technique are detailed. The main parameters of the experimental technique were the amount (0.65 and 1.30 kg) and concentrations (10,15, 20, 25, and 30 wt%) of MEA solution with CO2 inlet gas concentration (12.5 vol%). The experimental technique shows that MEA saturation occurs when the maximum temperature increase in the solution. Continuous tests were developed to operate the absorption system with the maximum absorption capacity of the MEA solution. The results show that the temperature increases in the MEA solution are a function of the flow rates (L/G) and the MEA concentration. Furthermore, the density, viscosity, and refractive index of CO2-free and CO2-saturated MEA solution at concentrations of MEA below 30 wt% are also measured in this work.

Computational Fluid Dynamics Simulation of a Membrane Contactor for CO2 Separation: Two Types of Membrane Evaluation

AbstractTwo different types of hollow‐fiber membrane contactors were used for CO2 separation from the gas stream with monoethanolamine (MEA) absorbent and numerically investigated. After the model validation with experimental data, CO2 removal efficiency, MEA concentration, and pressure drop variation were examined under different conditions by variation of some effective parameters such as gas stream velocity, absorption solution velocity, membrane porosity, and membrane tortuosity. Membrane tortuosity and porosity enhancement led to light decrease and light increase in CO2 removal efficiency, respectively, but gas stream velocity enhancement significantly reduced the CO2 removal efficiency.

Mass transfer enhancement for CO2 chemical absorption in a spiral baffle embedded microchannel

This paper presents an experimental study on CO2 chemical absorption by Monoethanolamine (MEA) solution in microchannel. In particular, a novel spirally distributed baffle structure is proposed to be embedded into the microchannel so as to generate the swirling flow pattern and to enhance the mass transfer. The effect of spiral baffle structure on the two phase flow pattern transition, the CO2 gas void fraction, the pressure drop, and the mass transfer performance are characterized and discussed, under varied gas and liquid flow rates, and MEA concentrations. Results demonstrate that the spiral baffle structure could significantly enhance the gas–liquid mass transfer, with overall liquid side volumetric mass transfer rate (kLa) up to 2.35 s−1 and enhancement number E up to 1.387 at small gas and liquid Reynolds numbers (ReG < 5.5; ReL < 14). New predictive correlations have also been proposed by considering both the structure enhancement factor and the chemical reaction factor.

A Simplified Kinetic Modeling of CO2 Absorption into Water and Monoethanolamine Solution in Hollow-Fiber Membrane Contactors

The absorption of CO2 from CO2-N2 gas mixtures using water and monoethanolamine (MEA) solution in polypropylene (PP) hollow-fiber membrane contactors was experimentally and theoretically examined. Gas was flowed through the lumen of the module, whereas the absorbent liquid was passed counter-currently across the shell. Experiments were carried out under various gas- and liquid-phase velocities as well as MEA concentrations. The effect of pressure difference between the gas and liquid phases on the flux of CO2 absorption in the range of 15-85 kPa was also investigated. A simplified mass balance model that considers non-wetting mode as well as adopts the overall mass-transfer coefficient evaluated from absorption experiments was proposed to follow the present physical and chemical absorption processes. This simplified model allowed us to predict the effective length of the fiber for CO2 absorption, which is crucial in selecting and designing membrane contactors for this purpose. Finally, the significance of membrane wetting could be highlighted by this model while using high concentrations of MEA in the chemical absorption process.

Mass transfer dynamics of single CO2 bubbles rising in monoethanolamine solutions: Experimental study and mathematical model

Carbon dioxide (CO2) absorption into amine-based absorbents is a widely used method for carbon emission reduction to deal with global warming problems. The intensification of the absorption process relies on an in-depth understanding of the mass transfer mechanisms between CO2 gas and the reaction media. However, the influence of products of a chemical reaction on mass transfer dynamics is usually underestimated. In this study, we perform research studies on the absorption process of single CO2 bubbles rising in monoethanolamine (MEA) solutions. Firstly, we perform an experimental study to visualize and measure the spatial position and the diameter of the bubbles using the high-speed camera. We observe a special phenomenon that the CO2 bubble diameter rapidly decreases to a nearly constant value in MEA solutions, and the terminal bubble diameter increases with the MEA concentration. Based on the phenomenon, we divide the absorption process into two stages. One is the mass transfer enhancement stage, where the bubble diameter decreases rapidly. The other is the mass transfer deterioration stage, where the bubble diameter remains almost constant. Furthermore, we propose an elaborate mass transfer dynamics model considering the combined effect of chemical reaction kinetics and reaction-induced bubble surface contamination. Finally, a well-predictive performance by the mass transfer dynamics model is validated by experiment. The findings of this study are of theoretical and practical significance for the mass transfer in gas–liquid reactive flow and multiphase reactor design.

A new look to the old solvent: Mass transfer performance and mechanism of CO2 absorption into pure monoethanolamine in a spray column

The most mature CO2 capture technology is absorption of monoethanolamine (MEA) in packed or spray columns. Typically, an aqueous 30 wt.% MEA solution is used. High MEA concentrations are believed to hinder mass transfer rate due to high viscosity of MEA. We worked, for the first time, on the effects of using pure MEA on overall mass transfer coefficient (KGɑ) and absorption efficiency in a spray column by varying several operational parameters. Image analysis results suggested that interfacial area increased with increasing liquid flow rate. As a result, KGɑ increased. As opposed the belief in literature, KGɑ also increased with increasing MEA concentrations. The highest KGɑ was obtained in this work (11.7 kmol·m−³∙kPa−1∙h−1) is around one order of magnitude higher than most literature studies. Having more MEA molecules on the surface of the droplets led to higher KGɑ. In addition, it was shown that absorption efficiency was largely determined by inlet CO2 to MEA molar ratio. 13C NMR spectra results revealed that similar levels of carbamate were formed for MEA concentrations up to 70 wt.%. A simplified analysis on regeneration heat duty showed that decreasing water amount can lead to 3–10 fold decrease in reboiler energy duty.

Transport properties of mixtures of acid gases with aqueous monoethanolamine solutions: A molecular dynamics study

We investigated the effect of temperature and monoethanolamine (MEA) concentration on the self-diffusivity of acid gases, CO2 , and H2S in aqueous MEA solutions. For this purpose, we computed densities of pure MEA and 30 wt% MEA/water solutions while scaling the LJ energy (ϵ) parameter and point charges of MEA. Results show that with a scaling factor of 0.80 applied to the point charges of MEA, computed densities agree well with the experimental ones from literature. This was tested by computing viscosities and the self-diffusivity of pure MEA and 30 wt% MEA/water solutions and comparing these with experiments. We showed that the scaling factor of 0.80 also works well for predicting transport properties of MEA/water solutions. Finally, we computed self-diffusivities of infinitely diluted CO2 and H2S for temperatures ranging from 293–353 K and MEA concentrations of 10–50 wt%. Our results show that the self-diffusivity of both acid gases depends significantly on the temperature and MEA concentration in the solution. The results of this study will contribute to the development of more efficient acid gas treatment processes.

Optimization of the extraction process of Pinus sylvestris L. pine bark with monoethanolamine

The paper presents the results of optimizing the process of extraction of the bark of Pinus sylvestris L. Scotch pine. The input parameters were the duration of the process and the concentration of the monoethanolamine solution. The experimental data were processed using the STATGRAPHICS® Centurion software package. It has been established that the maximum extraction of extractive substances occurs when the duration of the extraction process is 5 hours with a concentration of monoethanolamine of 5%.

Monoethanolamine Treatment of Fish Wastes and Salmon Guts to Increase It Palmitoylethanolamide and Anandamide Contents

This study was carried out to determine the palmitoylethanolamide (PEA) and arachidonoylethanolamide (AEA) or anandamide contents in selected fish wastes, treating the fish wastes with highest PEA and AEA with different concentration of monoethanolamine (MEA) solution, incubation temperature and time, as well as the ratio of MEA solution to fish waste to further increase its PEA and AEA contents.&#x0D; Based on the results of the preliminary experiment, a fractional factorial design experiments was done with 4 factors including MEA concentration, incubation time, incubation temperature and dosing ratio (MEA solution:salmon guts). The results showed that the MEA content ranged from 2.25 to 8.06 mg/g sample, the PEA content ranged from 17.4 to 300.2 µg/g sample while the AEA content ranged from 1.3 to 19.0 µg/g sample all on a wet weight basis of all the FD treated samples. The FD treated sample with the highest MEA, PEA and AEA using an MEA solution concentration of 250mM from pure MEA chemical, incubation time of 0.5 hour, incubation temperature of 6oC and a dose ratio of 6 mL MEA solution:100 g salmon guts. The MEA, PEA and AEA contents of the different samples were analysed using the Yates algorithm to determine which of the four factors were more important. The results showed that MEA, PEA and AEA contents were significantly affected by the concentration of MEA solution used in dosing the salmon guts, followed by the incubation time and then a slight effect of dosing ratio while the incubation temperature has no significant effect.

Study of molecular interactions of monoethanolamine with some higher alcohols at 298.15 K

Abstract Experimental measurements of the viscosity, density, and ultrasonic parameters of monoethanolamine (MEA) with 1-butanol, 1-pentanol, and 1-hexanol were carried out at 298.15 K. The excess molar volume (V E), viscosity change (Δη), and isentropic compressibility (ΔK s) are calculated using the viscosity, density, and ultrasonic velocity data. A polynomial equation of the Redlich-Kister type was used to fit these values. With increasing mole fraction, the viscosity, the density and the ultrasonic velocity increase. As the concentration of MEA rises, the excess molar volume falls. All V E values for MEA and 1-hexanol are positive, meaning that V E increases. At all concentrations, isentropic compressibility and viscosity change exhibit negative values.

Simulation Assessment of Inlet Parameters and Membrane-Surface-Structure Effects on CO2 Absorption Flux in Membrane Contactors

The management of global carbon dioxide (CO2) emissions is considered one of the main environmental problems facing the modern world. One of the potential techniques for CO2 capture is absorption, using membrane contactor modules. Most of the previous research that dealt with membrane contactor simulations considered the whole membrane surface as the active reaction surface. However, in this paper, a more realistic model of the membrane-contactor module is presented, taking into account the effects of the pore size and surface porosity. CO2 absorption into the monoethanolamine (MEA) solution in hollow fiber membrane-contactor modules was numerically investigated. A computational fluid dynamics simulation was established using essential basic fluid dynamics and mass transfer equations in reactive mode. An algorithmic function was used to present the relations between the CO2 absorption flux and the hollow fiber length, membrane surface pore size, and porosity. The simulation results were compared to previously obtained experimental results without using any fitting parameters, and a good agreement was found with an average error of 8.5%. The validated simulation was then used to predict the effects of the MEA inlet velocity and concentration, the membrane surface pore size, and porosity on the total CO2 absorption flux. A maximum absorption flux of about 1.8 mol/m2·s was achieved at an MEA concentration of 4 M with a pore size of 0.2 microns, a surface porosity of 1%, and an inlet velocity of 0.25 m/s. The extrapolation technique was then used to predict the values of the absorption flux at longer fiber lengths. The concentration profiles around the pores at the gas–liquid contact surface of the membrane were obtained and presented. The proposed model exhibited excellent potential to evaluate the effective reaction surface in hollow fiber membrane contactors. This model could be considered the first step to obtaining accurate predictions of the membrane contactor gas absorption performance based on its surface structure.

Effect and Mechanism of Dual-Official Group of Ethanolamines on the Chemical Mechanical Polishing of Monocrystalline Silicon

Chemical mechanical polishing (CMP) is a key step in semiconductor technology because it is crucial to produce a defect-free and flat enough surface for further processing of microelectronic devices. Silicon (Si) wafer is widely used in integrated circuit (IC) devices, high-density information storage devices, and other advanced applications. In this paper, the effect of different pH and three ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA), on the removal rate of Si was studied. The influence mechanism of MEA and its concentration on Si removal rate and surface quality were mainly investigated. The results show that the removal rate increased first and then decreased with increasing pH value. Among the three ethanolamines, the effect of the removal rate of Si is MEA > DEA > TEA. It may be related to the denser passivation film formed on the Si surface by increased hydroxyl groups in ethanolamines. The removal rate first increased and then decreased slowly with the concentration of MEA increased. The removal rate reached the peak value (6800 Å·min−1) when the MEA concentration was 0.15 wt%. The changing trend of the removal rate of Si is mainly due to the Si-N bond being generated on the polished Si surface by MEA and the ionization properties of MEA, which are indicated through the X-ray photoelectron spectroscopy (XPS) and the Zeta potential measurements. Meanwhile, Si surfaces with low surface roughness and ultra-smooth with the increase of MEA concentration were obtained.