Diethylaminoethanol Research Articles

Experimental Study on CO2 Absorption in Novel Biphasic Solvents and CO2 Desorption by Novel Direct Non-Aqueous Gas Stripping Process

In this work, we proposed aqueous blends of 2-(diethylamino)-ethanol (DEEA) and monoethanolamine (MEA) or 2-((2-aminoethyl) amino) ethanol (AEEA) as the biphasic solvent for CO2 capture. Aqueous DEEA-AEEA solvent maintained an effective CO2 loading range (0.86-3.15 mol/kg) that gives two phases at 40 ℃. During the two-phase formation, more than 95% of absorbed CO2 concentrated in the lower phase and the weight percentage of the lower phase was found to increase with increased total CO2 loading. Quantitative 13C NMR analysis indicated that AEEA reactions with CO2 dominate at the beginning of CO2 absorption and the reaction products are in forms of carbamates. Then DEEA starts to react with CO2 and the reaction products are bicarbonate and carbonate. Analysis on the phase split behavior indicated that CO2 products of carbamates and HCO3-/CO32- migrated to the lower phase while DEEA and unreacted AEEA migrated to the upper phase.

Novel Biphasic Solvent with Tunable Phase Separation for CO2 Capture: Role of Water Content in Mechanism, Kinetics, and Energy Penalty

The biphasic solvent-based absorption process has been regarded as a promising alternative to the monoethanolamine (MEA)-based process because of its high absorption capacity, phase separation behavior, and potential for conserving energy for CO2 capture. A trade-off between the absorption capacity and phase separation ratio is critical for developing an advanced biphasic solvent. Typically, water content in the biphasic solvent can be manipulated to tune the phase separation behavior. To explore the relationship between water content and phase separation behavior, an inert organic solvent, 1-methyl-2-pyrrolidinone, was added as a substitute for water in a biphasic solvent, specifically a triethylenetetramine (TETA) and 2-(diethylamino)ethanol (DEEA) blend. Moreover, the water content-kinetics and thermodynamics relationships were also evaluated. Experimental results revealed that reducing the water content was beneficial for phase separation but adverse for adsorption capacity. Kinetic analysis indicated that the water content did not significantly affect the rate of CO2 absorption at a rich loading. Furthermore, the regeneration heat decreased with the water content. The regeneration heat of TETA-DEEA with a water content of 20 wt % was almost 50% less than that of MEA solution. 13C nuclear magnetic resonance analysis revealed that the water content did not affect the reaction mechanism between CO2 and amines.

Thermodynamic modelling of CO2 absorption into aqueous solutions of 2-diethylaminoethanol, piperazine, and blended diethylaminoethanol with piperazine

In this study, the Deshmukh–Mather (D-M) model was used to evaluate the equilibrium behaviour of CO2 + diethylaminoethanol (DEAE) + H2O, CO2 + piperazine (PZ) + H2O, and CO2 + DEAE + PZ + H2O systems. The binary interaction parameters of the model for mentioned systems were obtained by using experimental solubility data from the literature. The ability of the model to predict the concentration profiles for all chemical species present in the liquid phase at different concentrations of amine solution was tested. The excess properties such as Gibbs energy, enthalpy, and heat capacity as a function of the CO2 loading of the amine were obtained. The solution pH and activity coefficients were also investigated. The results of thermodynamic modelling indicated that the D-M model predicted the experimental data with average absolute relative deviations (AARDs) of 7.15%, 11.3%, and 8.65%, respectively, for the CO2 + DEAE + PZ + H2O, CO2 + PZ + H2O, and CO2 + DEAE + H2O systems. The model applied in this study can be used for process simulation based on the rate-based or equilibrium-stage models of CO2 absorption with DEAE + PZ solutions.

New solvent blends for post-combustion CO2 capture

In the current work five different solvent blends are experimentally studied and the reboiler duties are calculated using the so-called short-cut method. Tertiary amines, 2-(diethylamino)ethanol (DEEA), 3-(Diethylamino)-1,2-propanediol (DEA-12PD), 2-[2-(Diethylamino)ethoxy]ethanol (DEA-EO), 1-(2-Hydroxyethyl)piperidine (12HE-PP) are blended with 3-(Methylamino)propylamine (MAPA) and ethanolamine (MEA). The first results from simple solvent screening are given and the cyclic capacities are calculated based data at 40 °C and 80 °C. Then, five solvent systems are chosen for vapor–liquid equilibrium characterization. The vapor–liquid equilibrium data are then used to estimate cyclic capacities at more realistic temperatures, between 40 °C and 120 °C and by using a short-cut method proposed in the literature the reboiler duties of the characterized solvents are estimated. Finally, the potential of the studied systems is discussed. Several of the characterized blends showed reboiler duties around 2.5 MJkgCO2−1.

Thermal stability and corrosion of tertiary amines in aqueous amine and amine-glycol-water solutions for combined acid gas and water removal

Thermal stability and corrosion of seven tertiary amines (20 wt.%) solutions in water and water-glycol [ethylene glycol (MEG)/tri-ethylene glycol (TEG)] loaded with CO2 in stainless steel reactors has been studied for combined acid gas removal along with hydrate control. The pKa of the tested amines varied from 7.85 to 9.75. Titration and inductivity coupled plasma mass spectrometry (ICP-MS) are used to quantify the remaining alkalinity and metal concentrations in amine solutions respectively. The presence of MEG and TEG profoundly influenced the amine stability. Triethanolamine had the highest thermal stability. Furthermore, the results also show that an increase in pKa generally decreases corrosion. 3-(Diethylamino)-1,2-propanediol (DEA-1,2-PD) has the lowest corrosion in water and water-TEG solutions while 2-(Diethylamino)ethanol (DEEA) has the least corrosion in water-MEG solutions.

Kinetics and new mechanism study of CO2 absorption into water and tertiary amine solutions by stopped‐Flow technique

The objective of the present work was to find the accurate kinetic models and mechanism for CO2 absorption into tertiary amine solution, aiming at understanding the contribution of the CO2 reaction with H2O, OH−, and tertiary amines on the overall reaction rate. First, the kinetics of CO2 absorption into water instead of a buffer solution were studied using the stopped‐flow technique at 293–313 K, with initial CO2 molar concentration of 1.1–37.3 mM. The experimental first‐order reaction rate constant () was determined to be about 1000 times larger than the value for CO2 absorption into buffer solution reported in the reference. The was then correlated by a proposed semiempirical model and a simplified theoretical model, giving the activation energy for CO2 reacting with H2O as fitted by the simplified theoretical model in good agreement with the value of previous research. Also, the pH values and hydroxyl ion concentrations of aqueous Diethylaminoethanol (DEEA) solutions were determined at 293–313 K, with DEEA molar concentration of 0.1–0.4 M and CO2 loading of 0–0.626 mol/mol. In addition, the observed first‐order reaction rate constant ( k0_DEEA) of binary DEEA‐H2O solution with DEEA molar concentration of 0.1–0.4 M reacting with CO2 was determined at 293–313 K. It should be pointed out that the kinetic experiments of CO2 absorption into DEEA solution was done with the molar ratio of DEEA to CO2 fixed at 20. The values of k0_DEEA were then fitted and predicted by four models (i.e., termolecular model, base‐catalyzed model, the improved model, and Khalifah model). The results show the improved model and Khalifah model can predict k0_DEEA well with an average absolute relative difference (AARD) <5%. The predicted results indicate that the contribution of OH− to k0_DEEA cannot be ignored for the absorption of CO2 into tertiary amine solutions, and could be responsible for 50–70% of the total absorption reaction rate. Furthermore, the k0 value of CO2 absorption into aqueous triethanolamine and CO2‐loaded DEEA solution were further investigated and comprehensively discussed, suggesting that both pK a and the CO2 solubility affect k0, with pK a having a much more significant effect. © 2018 American Institute of Chemical Engineers AIChE J, 65: 652–661, 2019

In vitro antioxidant and immunostimulating activities of polysaccharides from Ginkgo biloba leaves

Ginkgo biloba leaves (GBLs) are used as herbal dietary supplements and medicine worldwide. In this study, crude GBL polysaccharides (GBPSs) were extracted and further purified on a DEAE (diethylaminoethanol) Sepharose Fast Flow column to obtain GBPS-2 and GBPS-3. The molecular weights of GBPS-2 and GBPS-3 were 672 and 723 kDa, respectively. GBPS-2 and GBPS-3 were typical acidic heteropolysaccharides, composed of mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara) (molar ratio: 0.08:0.12:0.16:0.06:0.11:1.00:0.32) and Man, Rha, GlcA, GalA, Gal, and Ara (molar ratio: 0.92:1.00:0.83:0.11:0.42:0.23), respectively. GBPS-2 and GBPS-3 exhibited limited scavenging abilities for the hydroxyl and 2,2‑diphenyl‑1‑picrylhydrazyl radicals as well as noticeable scavenging effects on superoxide radicals and 2,2′‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid) radicals. Furthermore, GBPS-2 and GBPS-3 significantly increased the phagocytosis of macrophages and promoted the production of NO, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Thus, GBPS-2 and GBPS-3 exhibit potential application as functional food supplements.

Purification and identification of an aflatoxin B1 degradation enzyme from Pantoea sp. T6

Aflatoxin B1 (AFB1) is a secondary metabolite produced by Aspergillus flavus and other fungi. Soil, crops, food, feed, etc. were susceptible to aflatoxin B1 contamination, which caused adverse economic and health consequences. It is necessary to search for microorganisms or microbial enzymes that can degrade AFB1. The degradation activity of AFB1 by cell-free supernatant (68.30%) of isolate Pantoea sp. T6 was significantly higher (P < 0.05) than viable bacterial cells (4.87%) and intracellular cell extracts (3.68%). The supernatant's AFB1 degradation activity was reduced from 68.30% to 5.33% in treatment with protease K and sodium dodecyl sulphate (SDS). An extracellular enzyme from the supernatant was secreted by Pantoea sp. T6 and was named as Pantoea aflatoxin degradation enzyme (PADE), which was obtained using Diethylaminoethanol (DEAE)-Sepharose chromatography. PADE was further purified by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The PADE, outer membrane protein A, was identified by mass spectrometry and molecular mass was 38180.1Da. The optimum temperature and pH for the reaction of PADE with AFB1 were 40 °C and 7.0, respectively. These finding showing that the PADE, which was isolated from the supernatant of Pantoea sp. T6, has the ability to degrade AFB1, and may have potential application for aflatoxin B1 reduction in the food and feed industry.

PDNA capture using grafted adsorbents

AbstractBACKGROUND‘Expanded’ composite materials are of interest as an alternative, or as a supplement, to packed‐bed chromatography during bioproduct recovery and purification. Functionalized non‐woven fabrics and mega‐porous bodies are examples of systems that showed promise. However, there is scarce information on their suitability to capture and release plasmid DNA (pDNA), an important type of product employed in gene therapy.RESULTSComposite adsorbents were prepared using either chemical (CG‐DEAE‐NW) or gamma‐irradiated graft‐polymerization (GIR‐DEAE‐MP), and subsequently modified to have diethylamino ethanol (DEAE) functionality. Capture experiments showed that pDNA can actually reversibly bind to the two mentioned adsorbents, with capacity values of 2.4 and 1.3 mg per mL, respectively. These values are in the range of what can be expected from commercial beaded adsorbents but lower that the values expected from monoliths.CONCLUSIONSExpanded materials, due to their high voidage, may present limited capacity for pDNA. However, such materials are able to bind proteins and other contaminants from bacterial lysate, opening the way for their utilization in the ‘negative’ mode. © 2018 Society of Chemical Industry

Equilibrium solubility of CO2 in aqueous binary mixture of 2-(diethylamine)ethanol and 1, 6-hexamethyldiamine

CO2 solubility data are important for the efficient design and operation of the acid gas CO2 capture process using aqueous amine mixture. 2-(Diethylamino)ethanol (DEEA) solvent can be manufactured from renewable sources like agricultural products/residue, and 1,6-hexamethyldiamine (HMDA) solvents have higher absorption capacity as well as reaction rate with CO2 than conventional amine-based solvents. The equilibrium solubility of CO2 into aqueous binary mixture of DEEA and HMDA was investigated in the temperature range of 303.13-333.13 K and inlet CO2 partial pressure in the range of 10.133-20.265 kPa. Total concentration of aqueous amine mixtures in the range of 1.0-3.0 kmol/m3 and mole fraction of HMDA in total amine mixture in the range of 0.05-0.20 were taken in this work. CO2 absorption experiment was performed using semi-batch operated laboratory scale bubble column to measure equilibrium solubility of CO2 in amine mixture, and CO2 absorbed amount in saturated carbonated amine mixture was analyzed by precipitation-titration method using BaCl2. Maximum equilibrium CO2 solubility in aqueous amine mixture was observed at 0.2 of HMDA mole fraction in total amine mixture with 1.0 kmol/m3 total amine concentration. New solubility data of CO2 in DEEA+HMDA aqueous mixtures in the current study was compared with solubility data available in previous studies conducted by various researchers. The study shows that the new absorbent as a mixture of DEEA+HMDA is feasible for CO2 removal from coal-fired power plant stack gas streams.

Equilibrium Solubility of CO2 in Aqueous Blend of 2-(Diethylamine)ethanol and 2-(2-Aminoethylamine)ethanol

New experimental CO2 solubility data at equilibrium in an aqueous blend of 2-(diethylamino)ethanol (DEEA) and (2-aminoethyl) ethanolamine (AEEA) have been illustrated for the concentration of CO2 in the inlet gas stream ranging from 10.132 to 20.265 kPa and aqueous amine blend temperature ranging from 303.14 to 333.14 K. Total concentrations of aqueous blend were taken in the range of 1.0–3.0 kmol/m3 and mole fraction of AEEA in total amine blend in the range of 0.02–0.20. Experiments were carried out in a semibatch operated laboratory scale gas–liquid bubbling absorber, and analysis of liquid phase CO2 as a saturated liquid was done by titration method. The equilibrium CO2 solubility in DEEA + AEEA blend was found to be a maximum at the value of 0.843 mol CO2/mol amine with AEEA mole fraction in total amine of 0.2 at 1 kmol/m3 total concentration of amine mixture and 303.14 K. New solubility data of CO2 in the present work was compared with existing literature data. An empirical correlation was developed...

Measurement of Solubility and Physical Properties of Aqueous Solution of 2-(Diethylamino)ethanol for CO2 Capture

Nowadays, climate change is the main concern due to the huge amount of carbon dioxide (CO2) emitted into the atmosphere. The sources of this gas are from power generation and natural gas processing. Now, the effective technology to remove CO2 is absorption with amine solutions. The conventional amine solution is monoethanolamine (MEA). However, it also has some disadvantages like low capacity and high energy requirement for regeneration. To overcome these drawbacks, novel solvents have been developed to improve the performance for CO2 capture. Consequently, the objectives of this work are to measure the solubility of CO2 in an aqueous solution of 2-(Diethylamino)ethanol (DEAE) as a novel solution at the temperature from 30 °C to 80 °C, CO2 partial pressures ranging from 5 to 100 kPa and concentration from 3 to 5 M and to measure the physical properties such as density and viscosity from 0-1 mole fraction. The solubility results of CO2 in DEAE solution are compared with those of aqueous solution of MEA. For solubility, the results report that DEAE provides higher performance which is up to 861% higher than that of MEA. For physical properties, the results present that the densities of DEAE decrease with an increase in mole fraction and temperature. Also, the viscosities of all range of mole fraction of DEAE decrease as temperature increases. However, the viscosities increase with mole fraction of DEAE up to 0.4 and becomes lower. This means that DEAE process can be designed and applied for the absorption equipment to save more energy and cost for carbon capture.

Induced Degradation of Anthraquinone-Based Dye by Laccase Produced from Pycnoporus sanguineus (CS43)

In this study, in-house isolated laccase isoforms, i.e., Lac-I and Lac-II of the basidiomycete Pycnoporus sanguineus (CS43), were evaluated in relation to their Remazol Brilliant Blue R (RBBR) dye degradation capacity. A modified Dhouib medium additionally supplemented with 3% ethanol as a secondary inducer was used to propagate P. sanguineus CS43 for enhanced production of laccase under liquid state fermentation. The crude laccase extract was purified by passing through ion exchange diethylaminoethanol (DEAE)-Sepharose and gel filtration-based Sephadex G-200 column chromatography. The purified laccase fractions were subjected to the electrophoresis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed two laccase isoforms Lac-I and Lac-II with 66 and 68 kDa, respectively. To explore the industrial applicability, for RBBR dye, degradation efficiencies ranged from 82 to 88% after 3 h of incubation for both; Lac-I and Lac-II at both concentrations were recorded. However, with 8 U/mL, the degradation ranged between 70 to 80% during the first 5 min of incubation. Enhanced degradation of RBBR dye was obtained in the presence of violuric acid and N-hydroxypthalamide as laccase mediators. Finally, using RBBR as a substrate kinetic characterization of both Lac-I and Lac-II isoforms was performed that revealed K m (0.243 and 0.117 mM for Lac-I and Lac-II) and V max (1.233 and 1.012 mM/Sec for Lac-I and Lac-II) values, respectively.

Enhanced corrosion resistance of metal surfaces by film forming amines: A comparative study between cyclohexanamine and 2-(diethylamino)ethanolbased formulations

The use of recycled process water in steam crackers leads to the accumulation of corrosive impurities, hence the need for adequate treatment. Two corrosion inhibitor formulations containing N-[(9Z)−9-octadecen-1-yl]−1,3-propanediamine (N-oleyl-1,3-propanediamine) with either cyclohexanamine (CHA) or 2-(diethylamino)ethanol (DEAE) were compared for their performance. Electrochemical impedance spectroscopy and visual observations showed that the two formulations offered comparable protection against corrosion. Bengal Rose testing and experiments conducted using a quartz-crystal microbalance with dissipation monitoring (QCM-D) indicated that the two formulations yielded similar coverage of the metal surfaces, and that the kinetics of mass adsorption were also similar. QCM-D data further suggested that the films formed with the two formulations had similar rigidity, and contact angle measurements indicated that they formed films with comparable hydrophobicity, which were equally effective in isolating the metal surfaces from water.

A modeling-optimization framework for assessment of CO2 absorption capacity by novel amine solutions: 1DMA2P, 1DEA2P, DEEA, and DEAB

In this study, a modeling-optimization framework was developed to assess absorption capacity of CO2 by four promising tertiary amines in CO2 capture, namely, 1-dimethylamino-2-propanol (1DMA2P), 1-diethylamino-2-propanol (1DEA2P), 2-(diethylamino)ethanol (DEEA), and 4-diethylamino-2-butanol (DEAB). The purpose of this developed framework is to study the simultaneous effect of all solubility parameters including CO2 partial pressure, temperature, and amine concentration on the absorption capacity in terms of CO2 loading. In this framework, an orthogonal array design (OAD) method (a statistical method) was used for optimization, and Kent-Eisenberg (K-E), modified Kent-Eisenberg (M-K-E), and Deshmukh-Mather (D-M) models (thermodynamic models) were applied to predict CO2 loading of amine solutions. In addition, the back-propagation neural network model was applied and the results were compared with thermodynamic models. The D-M model was used to predict the response values (CO2 loading) in the OAD method. The results showed that the D-M model was superior to other thermodynamic models in the prediction of CO2 loading data with average absolute relative deviations (AARDs) of 2.89%, 3.59%, 1.76%, and 2.3% for DEEA, 1DMA2P, DEAB, and 1DEA2P solutions, respectively. The OAD results showed that all solubility parameters had significant effects on CO2 loading, and the statistically significant order of parameters affecting absorption capacity was CO2 partial pressure > amine concentration > temperature.

Mass transfer characteristics of CO2 absorption into a phase-change solvent in a wetted-wall column

CO2 from coal-fired flue gas is one of the main components of greenhouse gases. Using phase change absorbents as a solvent can effectively decrease the consumption of regeneration energy for CO2 capture process. This study employed a mixed solution of diethylenetriamine (DETA) and diethylaminoethanol (DEEA) as the new phase change absorbent for CO2 absorption. The impact of the phase change behavior on the mass transfer characteristics of CO2 absorption was investigated in a wetted-wall column. Effects of the temperatures, CO2 loadings, and gas flow rate on the mass transfer coefficient were also conducted. The results indicated that temperature and CO2 loading had relatively remarkable effects on the total mass transfer coefficient; whereas the gas flow rate had a smaller effect. Kinetic analysis revealed that the mass transfer resistance of CO2 absorption into the DETA/DEEA phase change absorbent mainly concentrated at the liquid film side. The findings provide a theoretical reference for the development of new CO2 phase change absorption technology.

Study of CO2 Absorption into Phase Change Solvents MAPA and DEEA

This work provides new data for carbon dioxide (CO2) absorption into phase change solvent systems consisting of an aqueous solution of 2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA). The variables related to CO2 absorption are studied and a Lewis cell type apparatus is taken into use. The latter was first validated with experiments of CO2 absorption into aqueous methyl diethanolamine (MDEA) solutions. Experiments are carried out for the determination of apparent kinetic absorption constant and absorption rate of CO2 for aqueous DEEA/MAPA mixtures. The determined kinetic constants (0.008–0.007 mol·(m3·s)−1 for MAPA/DEEA between 308 and 318 K and 0.0184–0.0022 m3·(mol·s)−1 for MDEA between 296 and 318 K) are compared to the literature where available. The phenomena related to phase change solvent absorption are carefully studied. A relation between total CO2 loading and absorption rate is observed, and reasons behind the dependency and the phenomena are analyzed.

Development of a non-sulphite oxygen scavenger for monoethylene glycol (MEG) used as gas hydrate inhibitor

The maximum limit for dissolved oxygen in monoethylene glycol (MEG) used as gas hydrate inhibitor is usually set to 10–20 ppb. Exposure to low quality blanket gas or leaks may lead to oxygen levels up to 1 000 ppb. Oxygen scavenging is an attractive means to reduce the concentration, but oxygen scavengers (OSs) developed for water treatment have limitations in MEG solutions. They react slowly in MEG at low temperature when the pH is less than 9 and some of them are incompatible with other production chemicals. Screening of commonly used reducing agents in lean (90%) MEG showed that erythorbic acid was more effective than the alternatives at pH approximately 8. Adding manganese (II) as a catalyst and diethylaminoethanol (DEAE) improved the performance considerably. The final OS formulation contained 17% erythorbic acid, 25% DEAE and 0.5% MnCl2. It worked well in MEG solutions at 20 and 50 °C when erythorbic acid was converted to erythorbate. When dosed to give 200 ppm erythorbate in solution, it successfully decreased the oxygen concentration from 1 000 to 10 ppb in less than 30 min. The performance was also satisfactory in lean MEG with moderate concentrations of an imidazoline based corrosion inhibitor.

CO2 Capture by Aqueous 3-(Methylamino)propylamine in Blend with Tertiary Amines: An NMR Analysis

Aqueous 3-(Methylamino)propylamine (MAPA) in blend with 2-(Diethylamino)ethanol (DEEA) and other tertiary amines, which mainly differ from DEEA in the number of hydroxyl functions (-OH) and/or in the length and structure of their alkyl chain, are investigated. After absorption of carbon dioxide (CO2) at 40°C, quantitative 13C NMR experiments are performed to calculate the concentration of the species in each blend at equilibrium, together with qualitative NMR experiments for signal assignment. Speciation and absorption capacity data are discussed in terms of chemical structure and basicity of the tertiary amines.In general, it is observed that, at increasing pKa of the tertiary amines (decreasing number of –OH on the structure), there is a decrease of MAPA and primary and secondary MAPA carbamates, and an increase of MAPA dicarbamate, (bi)carbonate and of the absorption capacity. Within the molecules with the same number of –OH but differently branched, some exceptions are found.

Investigation of CO2 Regeneration in Single and Blended Amine Solvents with and without Catalyst

Various single and blended amines (namely, MEA(monoethanolamine), MEA-DEEA (2-diethylamino ethanol), MEA-MDEA (methyldiethanolamine), MEA-1DMA2P (1-dimethylamino-2-propanol)) with three types of catalysts (H-ZSM-5, MCM-41 and SO42–/ZrO2) were studied to determine the respective roles of catalyst and solvent in heat duty and CO2 desorption rate with an initial CO2 loading of 0.5 mol CO2/mol amine at 371 K. The results show that performance of the three catalysts in all the four investigated aqueous solution systems followed the trend: H-ZSM-5 > MCM-41 > SO42–/ZrO2. These results highlight the fact that even though HZSM-5 has moderate acidic sites as compared to MCM-41 and SO42–/ZrO2, its large B/L acid sites ratio coupled with mesopore surface area had the best performance. Furthermore, based on this study, the blended system of aqueous 5 M MEA+1 M MDEA with H-ZSM-5 provided the best approach for solution regeneration because the strong electron withdrawing chemical structure of MDEA.