Poor Desorption Research Articles

Effect of sterically hindered amines on the cycling capacity of biphasic absorbents for industrial CO2 capture

The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO2 capture. However, most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase. To the issues, a novel pentamethyldiethylenetriamine (PMDETA)-2-amino-2-methyl-1-propanol (AMP)/diethylenetriamine (DETA)-sulfolane biphasic solvent was developed. The mechanism of AMP affecting CO2 recycling capacity was analyzed. By adjusting the ratio of AMP and DETA, the absorption and desorption performance were balanced, and the recycling capacity and renewable energy consumption of the absorbent were improved. For the P2.4A0.8D0.8S2 biphasic solvent, the CO2 loading of the rich phase was 5.87 mol/L, and the proportion of the rich phase volume ratio was 35%, which surpasses most reported biphasic solvents. The viscosity of the absorbent significantly decreased from 527.00 mPa·s to 92.26 mPa·s, attributed to the beneficial effect of AMP. Thermodynamic analysis showed that the biphasic solvent produced a lower regeneration energy consumption of 1.70 GJ/t CO2, which was 57% lower than that of monoethanolamine (MEA). Overall, the PMDETA-AMP/DETA-sulfolane biphasic solvent exhibited cycle capacity, which provided new insights for the designing of biphasic solvent.

Modified Clinoptilolite for the Removal of Rhodamine B Dye from Wastewater

This study reveals the modification of the surface area of natural zeolite Clinoptilolite (CLN) by implementing the ion exchange method. The ammonium chloride cation exchange method was adopted and was followed by calcination at 450 °C for 5 h. This procedure helps to increase the surface area of CLN and also enhances its adsorption efficiency. The modifications of the CLN were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis. The efficiency and adsorption capacity of the modified CLN were determined by the adsorption of a Rhodamine B (Rh B) dye from an aqueous medium. The comparative analysis of the adsorption efficiency of raw CLN and the modified CLN revealed an enhanced adsorption of Rh B by the modified CLN at pH = 10. For desorption, different solvents were used. The results showed good desorption in ethanol and methanol, and poor desorption in acidic (HCl) and basic (NaOH) solutions. The kinetic study of the adsorption of Rh B by the modified CLN helped us to conclude that the adsorption follows a pseudo-second-order kinetics. For the surface study and to understand the mechanism of adsorption, several isotherm models were applied to the adsorption data at equilibrium. The data showed consistency with the Freundlich adsorption isotherm confirming that the process took place at its heterogeneous surface. The experimentally calculated adsorption capacity of the modified CLN was 2.81 mg g−1, showing a comparable value to certain other common adsorbents. Therefore, the modified CLN may also be considered a cost-effective and promising adsorbent for the removal of Rh B dye from wastewater.

Enhanced cyclic durability of low-cost Ti–V–Cr hydrogen storage alloys by elemental alloying

Low-cost low vanadium (low-V) hydrogen storage materials have high reversible capacities (>2.0 wt%) under moderate conditions, however, they suffer from drastic capacity decay during cycling. In this work, a series of TiCr1.1M0.1(V–Fe)0.6 (M = Mn, Mo and Nb) alloys are prepared by elemental alloying on the basis of the low-cost, low-V alloy TiCr1.2(V–Fe)0.6 alloy, and the modification mechanism of the elemental alloying on the cycling durability of the alloy is systematically investigated. In 100 cycles, the results demonstrated that the original alloy TiCr1.2(V–Fe) 0.6 suffered from poor desorption capacity (1.13 wt%) and lowly capacity retention rate (60.43%). Compared to the addition of Mn and Nb, TiCr1.1Mo0.1(V–Fe)0.6 obtained higher cyclic hydrogen storage capacity (1.32 wt%) and capacity retention (68.04%). In addition, it is found that the addition of Mo can inhibit the formation of the secondary phase during the cycling, and the abundance of the C14 Laves phase maintained at only 2.47% after 100 cycles. According to the microstructural analysis of the alloys during cycling, it is found that the decrease in grain size, the accumulation of micro strain and dislocation density, and the degree of particle pulverization seriously affect the cycling durability of the alloys, resulting in a drastic decrease in the dehydrogenation cycling capacity. Finally, it should be noted that although the improvement in cycle durability with Mo alloying is limited, it is still a positive reference for developing low-cost low-V alloys with good cycle durability.

Engineering P-Fe2O3-CoP nanosheets for overall freshwater and seawater splitting

Tailoring surface composition and coordinative environment of catalysts in a nano-meter region often influence their chemical performance. It is reported that CoP exhibits a low dissociation ability of H–OH, originating from the poor desorption of intermediate species. Herein, we provide a feasible method to construct P-Fe2O3-CoP nanosheets through a gas-phase phosphorization process. P doping induces the formation of interfacial structure between Fe2O3 and CoP and the generation of defective structures. The resulting P-Fe2O3-CoP nanosheets afford high freshwater/seawater oxidation activity (250/270 mV@10 mA/cm2) in 1 mol/L (M) KOH, which is even lower than commercial RuO2. Compared with CoP||CoP, P-Fe2O3||P-Fe2O3, and Co3O4||Co3O4, the assembled P-Fe2O3-CoP||P-Fe2O3-CoP exhibits the superior water/seawater electrolysis performance with 1.61/1.65 V@10 mA/cm2. The synergistic effect of P doping, defective structure, and heterojunction leads to high water oxidation efficiency and water splitting efficiency.

Photoelectrochemical reforming of glycerol by Bi2WO6 photoanodes: Role of the electrolyte pH on the H2 evolution efficiency and product selectivity

Photoreforming of biomass derivatives is a promising strategy for the production of green hydrogen and chemicals. Herein, nanocrystalline Bi2WO6 photoanodes were applied for the first time for the conversion of glycerol in different pHs. Different from TiO2 photoanodes, the photocurrent for Bi2WO6 films is relatively independent of the applied potential, which is attributed to the preferential glycerol oxidation in detriment of water oxidation. Impedance measurements reveal that photocurrent is limited by the charge transfer on the Bi2WO6 surface and is partially inhibited by the poor desorption of glycerol oxidation products. At pH 6, photocurrents up to 0.69 mA cm−2 are reached with a faradaic efficiency for H2 evolution of 100% and 41% selectivity for formate production. In acid media, this selectivity increases to 88%, but the photocurrent decreases 50%. In alkaline media, glycerol oxidation is facilitated and photocurrents up to 0.80 mA cm−2 are reached at the cost of poor product selectivity.

Adsorption of dissolved gas molecules in the transformer oil on silver-modified (002) planes of molybdenum diselenide monolayer: a DFT study

High-sensitivity gas sensor is a crucial online monitoring device to ensure the safe operation of the transformer. In this paper, based on density functional theory, an Ag–MoSe2 monolayer system was established by investigating four different positions of Ag doping to adsorb the dissolved gas (H2, C2H2, CH4, CO and CO2) in transformer oil. The sensing properties of adsorption system for different dissolved gas were studied via the analysis of adsorption energy (E ad), charge transfer, density of state, energy band, lowest unoccupied molecular orbit, highest occupied molecular orbit, and desorption time. Finally, Ag–MoSe2 had good adsorption and desorption properties for CO and CH4 at room temperature, and could be used as a sensor material for the two gases detection. It had strong adsorption and poor desorption performances for C2H2 at room temperature, which could serve as C2H2 scavenger, and simultaneously had good adsorption and desorption performance at a temperature of 358 K, therefore it could be used as a candidate material to detect C2H2 at high temperatures. Ag–MoSe2 had a weak interaction with H2 and CO2, thus was not suitable for detecting the two gases. The results indicated that Ag–MoSe2 had excellent potential in detecting dissolved gases in transformer oil.

NO₂ Gas Sensor Based on SnSe/SnSe₂p-n Hetrojunction.

Air pollution is a big concern as it causes harm to human health as well as environment. NO₂ can cause several respiratory diseases even in low concentration and therefore an efficient sensor for detecting NO₂ at room temperature has become one of the priorities of the scientific community. Although two dimensional (2D) materials (MoS₂ etc.) have shown potential for NO₂ sensing at lower temperatures, but these have poor desorption kinetics. However, these limitations posed by slow desorption can be overcome, if a material in the form of a p-n junction can be suitably employed. In this work, ~150 nm thick SnSe₂ thin film has been deposited by thermally evaporating in-house made SnSe₂ powder. The film has been studied for its morphological, structural and gas sensing applications. The morphology of the film showed that the film consists of interconnected nanostructures. Detailed Raman studies further revealed that SnSe₂ film had 31% SnSe. The SnSe-SnSe₂ nanostructured sensor showed a response of ~112% towards 5 ppm NO₂ at room temperature (30 °C). The response and recovery times were ~15 seconds and 10 seconds, respectively. Limit of detection for NO₂ was in sub-parts per million (sub-ppm) range. The device demonstrated a better response towards NO₂ compared to NH₃, CH₄, and H₂. The mechanism of room temperature fast response, recovery and selective detection of NO₂ independent of humidity conditions has been discussed based on physisorption, charge transfer, and formation of SnSe-SnSe₂ (p-n) nano-junctions. Depositing a nanostructured film consisting of nano-junctions using an industrially viable thermal evaporation technique for sensing a very low concentration of NO₂ is the novelty of this work.

Below-room-temperature solution-grown ZnO porous nanosheet arrays with ppb-level NO2 sensitivity under intermittent UV irradiation

It is difficult for a chemiresistive metal oxide gas sensor to operate at room temperature due to the poor desorption ability of the adsorbed gases during recovery. UV irradiation helps to clean the surface of metal oxides, but it is also unfavorable for gas adsorption. In this work, intermittent UV irradiation, i.e., UV on (off) before (after) exposure to a target gas, is found to remarkably enhance the sensitivity of ZnO toward NO2. Porous nanosheet arrays of ZnO have been in-situ grown on the sensor chip in an alkaline bath at a low temperature of 8 °C. Heterogeneous growth of nanosheet arrays and homogeneous growth of nanosheet-constructed spheres take place on the substrate and in the bulk solution, respectively. The as-grown ZnO nanosheet arrays contain not only macropores between nanosheets but also mesopores within the nanosheets, which endow them superior NO2 sensing properties under intermittent UV irradiation. The growth kinetics of ZnO porous nanosheet arrays and the mechanism of the NO2 sensing under intermittent UV irradiation have been elaborated.

Characteristics of carbon dioxide desorption from MEA-based organic solvent absorbents

The fundamental characteristics of CO2 desorption from absorbents were assessed to highlight the importance of CO2 desorption in a CO2 absorption field. Four monoethanolamine (MEA)-based absorbents were tested for their absorption and desorption performances, including MEA/water, MEA/ethanol, and two kinds of MEA/ethanol/water. MEA/ethanol exhibited a higher absorption rate, higher regeneration fraction, and lower desorption temperature for CO2 desorption as compared to others. Compared with MEA/water, MEA/ethanol had a 20 °C lower desorption temperature, 41.72 % higher average desorption rate (in the first 20 min) and 5.52 percentage points higher regeneration fraction. MEA/ethanol/water showed very poor desorption performance, with regeneration fractions between 64–82 %. The desorption energy requirement of MEA/ethanol is significantly lower than that of MEA/water with all absorbent CO2 loading ratios. At the CO2 loading of 0.07 mol CO2/mol MEA, the desorption energy requirement of MEA/ethanol was 80 % less than that of MEA/water. For all absorbents, the desorption process took 3–5 times longer than that required for the absorption equilibrium to be reached, and absorbent CO2 loading had a significant influence on CO2 absorption with a higher absorption rate at lower CO2 loading. The results also indicated that adding organic solvents such as ethanol could reduce the desorption energy consumption and desorption temperature, which is conducive to absorption and also important for selecting the right absorbent.

Macro, colloidal and nanobiochar for oxytetracycline removal in synthetic hydrolyzed human urine

Macro (BC), colloidal (CBC) and nanobiochar (NBC) were examined for the particle size effect for adsorptive removal of oxytetracycline (OTC) and co-occurring nutrients, which are present in synthetic hydrolyzed human urine. The surface morphologies and functionality of biochars were characterized using Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area and Fourier Transform Infra-Red (FTIR) Spectroscopy. Experiments for the removal of OTC were performed at the natural pH (pH 9.0) of hydrolyzed human urine using solid-solutions of 3 types of chars (1 g/L) with a contact time of 5 h, at initial OTC concentration of 50 mg/L where isotherm experiments were investigated with OTC concentrations from 25 to 1000 mg/L. The highest maximum adsorption capacity of 136.7 mg/g was reported for CBC, while BC reported slightly low value (129.34 mg/g). Interestingly, NBC demonstrated a two-step adsorption process with two adsorption capacities (16.9 and 113.2 mg/g). Colloidal biochar depicted the highest adsorption for NH4+, PO43−, and SO42− nutrients. All 3 types of chars showed strong retention with a poor desorption (6% in average) of OTC in synthetic hydrolyzed urine medium. CBC and NBC demonstrated both physisorption and chemisorption, whereas the OTC removal by BC was solely via physisorption. Nevertheless, CBC biochar demonstrated the best performance in adsorptive removal of OTC and nutrients in hydrolyzed human urine and its capability towards wastewater treatment. As the removal of nutrients were low, the treated urine can possibly be used as a safe fertilizer.

Preparation and Evaluation of Methacrylate-based Reversed-phase Sorbents for Solid-phase Extraction of Polar Compounds

In solid-phase extraction (SPE), hydrophilic-lipophilic balance (HLB) type sorbents prepared by copolymerization with divinylbenzene (DVB) and polar monomers are widely used. The hydrophobicity of the HLB-type sorbents depends on DVB as the main component, and the extraction efficiency for polar compounds is enhanced by interaction with the polar groups introduced by polar monomers. On the other hand, high adsorption ability, due to the hydrophobicity of DVB, adversely affects the rapid elution of trapped compounds. In this study, the non-aromatic sorbents that has high adsorption ability for polar compounds, and can rapidly elute polar compounds including aromatic rings were developed. Porous polymer particles were prepared with trimethylolpropane trimethacrylate (TMPT), and the solid-phase extraction characteristics were evaluated. By optimizing the pore characteristics of TMPT-type sorbent, it was possible to effectively extract the nucleobases and nucleosides whose extraction efficiency was comparable to that of the commercial HLB-type sorbent. Furthermore, in order to improve the hydrophobicity of the TMPT-type sorbents, non-aromatic sorbents copolymerized with stearyl methacrylate (SMA) were prepared. However, the adsorption abilities of the TMPT-type sorbent could not be improved. The adsorption and desorption properties of the non-aromatic sorbents were evaluated using the TMPT-type sorbent. The aromatic polar compounds were able to be strongly sorbed to the TMPT-type sorbent, but they could be rapidly eluted by low concentration organic solvent as eluent. These results suggest that the TMPT-type sorbents are useful for a solid-phase extraction of the polar compounds and will solve the problem of the poor desorption in the HLB-type sorbents containing DVB.

Small gas adsorption on Co–N4 porphyrin-like CNT for sensor exploitation: a first-principles study

Using first-principles theory, we investigated the adsorption performance of CoN4-CNT towards six small gases including NO, O2, H2, H2S, NH3, and CH4, for exploiting its potential application for chemical gas sensors. The frontier molecular orbital theory was conducted to help understand the conductivity change of the proposed material at the presence of gas molecules. The desorption behavior of gas molecules from CoN4-CNT surface at ambient temperature was analyzed as well to determine its suitability for sensing application. Results show that CoN4-CNT is a promising material for O2 and NH3 sensing due to their desirable adsorption and desorption behaviors while not appropriate for sensing NO due to the poor desorption ability and for sensing CH4 and H2 given the poor adsorption behavior. Our calculation would provide a first insight into the CoN4-embedded effect on the structural and electronic properties of single-walled CNT, and shed light on the application of CoN4-CNT towards sensing of small gases.

A first-principles insight into Pd-doped MoSe2 monolayer: A toxic gas scavenger

Using first-principles theory, we investigate the Pd-doping effect on the geometric and electronic behaviors of MoSe2 monolayer, and the adsorption behavior of Pd-MoSe2 monolayer upon four toxic gases, namely NO, NO2 SO2 and H2S. Desorption property of Pd-MoSe2 monolayer upon four gases at diverse temperatures is analyzed as well to help explore its potential application. For Pd dopant adsorption onto MoSe2 monolayer, somewhat n-type doping is determined, which accounts for the increased conductivity for intrinsic MoSe2 monolayer. The strong adsorption ability and poor desorption performance of Pd-MoSe2 monolayer upon four gases indicate its large potential as gas scavenger to remove these toxic gases from their surroundings. Moreover, it could be explored as a gas sensor for detection of NO, NO2 and H2S as well, given the obvious change in conductivity after gas adsorption based on band structure analysis. Our calculations would be beneficial to understand the TM doping effect on intrinsic MoSe2 monolayer and to provide a first insight into the potential application as gas sensor or sweeper for Pd-MoSe2 monolayer.

Effect of Ultrasonic Microdroplet Generation in the Low-Temperature Plasma Ionization-Mass Spectrometry

Low-temperature plasma (LTP) ionization is one of the ambient ionization methods typically used in mass spectrometry (MS) for fast screening of chemicals with minimal or no sample preparation. In spite of various advantages of LTP ionization method, including simple instrumentation and in-situ analysis, more general applications of the method are limited due to poor desorption of analytes with low volatilities and low ionization efficiencies in the negative ion mode. In order to overcome these limitations, an ultrasonic vibrator of a commercial hand-held humidifier was interfaced with an LTP ionization source, which generated microdroplets from sample solutions and assisted with LTP ionization. Ionization behaviors of various chemicals in microdroplet-assisted LTP (MA LTP) were tested and compared with typical LTP ionization from dried samples applied on a surface. MA LTP efficiently ionized small organic, amino, and fatty acids with low volatilities and high polarities, which were hardly ionized using the standard LTP method. Facile interaction of LTP with ultrafine droplets generated by ultrasonic resonator allows efficient ionization of relatively non-volatile and polar analytes both in the positive and negative ion modes.

Mild electrokinetic treatment of cadmium-polluted manure for improved applicability in greenhouse soil.

Applications of cadmium (Cd) and salinity-containing manures contribute to Cd pollution and salinization in greenhouse soils. In this study, chicken manure polluted with Cd (5.6mg/kg) was mildly electrokinetically treated (0.25V/cm) for 48h with intermittent replacement of catholyte with 20mM acetic acid solution to remove Cd and salinity for application without need of post-treatment in greenhouse soil. The electrokinetic treatment created pH conditions mainly ranging from 5.0 to 8.0 within the manure for minimizing re-precipitation of desorbed Cd and evaporative loss of ammonium. However, without manure pre-acidification, electrokinetic treatment resulted in negligible removal of total Cd but 61.7% of increase in the small fraction of exchangeable Cd, due to poor desorption but enhanced formation of exchangeable Cd. In contrast, manure pre-acidification with 20mM acetic acid favored Cd desorption, leading to electrokinetic removal of exchangeable, carbonate-bound, and total Cd by 32.2%, 34.5%, and 14.5%, respectively. Mild electrokinetic treatment of manure with and without pre-acidification resulted in similar removal of salinity (72.3% and 68.0%), similar pH condition (7.2 and 7.4), and basically same evaporative loss of ammonium (14.6% and 14.2%). Overall, the mild electrokinetic treatment considerably lowered the risk of Cd and the salinity from the pre-acidified manure for improved applicability in greenhouse soil, and more studies are needed to enhance the performance of electrokinetic Cd removal from manure.

Solvent desorption of asphaltenes from solid surfaces

ABSTRACTThe main goal of this paper is to compare the ability of different organic solvents to desorb asphaltenes from stainless steel surfaces. The asphaltenes were extracted from a North Sea crude oil by precipitation. The organic solvents are characterized based on their Hansen solubility parameters (HSPs). The adsorption of asphaltenes was followed by means of a Quartz Crystal Microbalance with Dissipation (QCM-D). The asphaltene desorption efficiency of the solvents tested varied between 20% and 70%, with pyridine as the most efficient solvent. Carbon disulfide was found to be a poor desorption solvent, indicating the importance of solvent polarity. A simple model based on the HSPs seemed to give a good quantitative explanation of experimental desorption experiments.

Peltier Heating-Assisted Low Temperature Plasma Ionization for Ambient Mass Spectrometry

Low temperature plasma (LTP) ionization mass spectrometry (MS) is one of the widely used ambient analysis methods which allows soft-ionization and rapid analysis of samples in ambient condition with minimal or no sample preparation. One of the major advantages of LTP MS is selective analysis of low-molecular weight, volatile and low- to medium-polarity analytes in a sam- ple. On the contrary, the selectivity for particular class of compound also implies its limitation in general analysis. One of the critical factors limiting LTP ionization efficiency is poor desorption of analytes with low volatility. In this study, a home-built LTP ioniza- tion source with Peltier heating sample stage was constructed to enhance desorption and ionization efficiencies of analytes in a sam- ple and its performance was evaluated using standard mixture containing fatty acid ethyl esters (FAEEs). It was also used to reproduce the previous bacterial identification experiment using pattern-recognition for FAEEs. Our result indicates, however, that the bacterial differentiation from FAEE pattern recognition using LTP ionization MS still has many limitations.

Continuous cycling of an asymmetric capacitive deionization system: An evaluation of the electrode performance and stability

Capacitive deionization (CDI) shows great promise as an energy efficient water treatment technology. However, much of the research has focused on brackish water desalination and/or NaCl removal while ignoring other ions that may pose challenges for CDI and should be addressed. In this work, we studied the effects of modifying operational parameters in a CDI system operating in a continuous adsorption/desorption cycle using CaSO4, as well as other electrolytes. Low-cost, high surface area carbons coated with two different metal oxides (SiO2 on the cathode and Al2O3 on the anode) were employed as electrodes in the CDI reactor. Two ion adsorption mechanisms, electrosorption in the electrochemical double layer (EDL) and specific adsorption on the oxide surfaces and carbon support, appeared to play a role in the ion removal process. During regeneration of the electrodes, poor CaSO4 desorption likely associated with specific adsorption on the metal oxide coatings, along with diffusional issues, led to salt accumulation on the electrodes. Electrode regeneration values above 95% were obtained when chloride-containing electrolytes were employed, indicating that SO42− interactions were the main cause of the poor desorption. The mode of regeneration also strongly influenced ion desorption kinetics and charge efficiencies during subsequent removal cycles. Long-term experiments revealed that oxidation of the anode affected the electrosorption of ions and induced acidification of the solution.

Critical evaluation of ninhydrin for monitoring surgical instrument decontamination

New Department of Health (England) Choice Framework for Local Policies and Procedures guidance (CFPP 0101) still states that ninhydrin can be used to check for efficient protein removal from surgical instruments processed in sterile services departments (SSDs). With the potential transfer of variant Creutzfeldt-Jakob disease (vCJD) via surgical procedures it is necessary to re-evaluate recommended methods for protein detection. This paper reports studies on the sensitivity and applicability of ninhydrin for detecting proteins in laboratories and SSDs. The efficiency of protein removal by swabbing was also evaluated. Ninhydrin showed poor sensitivity toward proteins. Limits of detection for bovine serum albumin (BSA) in solution were 205 μg/mL compared with arginine 6 μg/mL. A commercial kit could detect neither rat brain homogenate nor BSA at <1000 μg protein pipetted directly into the vials. Swabbing with water-wetted rayon swabs was inefficient at removing protein (50 μg) from instruments (N = 6) with 32 ± 4% BSA and 61 ± 5% fibrinogen remaining bound. Swabs dipped in 0.5% detergent (Triton X-100) solution had slightly better removal efficiency with 20 ± 3% BSA and 24 ± 2.8% fibrinogen remaining. Ninhydrin kits, currently used in SSDs, are ineffective at detecting residual proteins due not only to the insensitivity of ninhydrin towards proteins but also to the poor desorption of adhered proteins by swabbing. Overall ninhydrin, either as a laboratory reagent or as supplied in protein detection kits, does not provide sensitive detection of proteins and generates high numbers of false negatives when used in decontamination practices.

Understanding Precipitation in Amino Acid Salt systems at Process Conditions

Rapid screening experiment has been used to acquire first-hand information on the precipitation characteristics of 14 aqueous amino acid salt systems. Absorption tests at 40°C have shown that at high concentrations, amino acid salt systems forms precipitate in the presence of CO2 resulting to 2 or 3 solid-liquid phase formation. Potassium salt of the amino acid salts generally showed better reaction kinetics than their sodium salt counterparts. 5m’ KSar and 4.3m’ KPro showed significantly higher reaction kinetics while 5m’ KSar, 5m’ KAla, 4.5m’ KSer, 5m’ KL-Ala were observed to have an upward shift in absorption rate at some point during absorption resulting to increased loading. Application of the conventional stripping process in the screening test, i.e. heating up the absorption solution to 80oC showed poor desorption characteristics for the precipitating amino acid salt solutions. Qualitative 13C NMR studies was used to identify the chemical species in the phases, 3-phase in 5m’ KSar and 2-phase in 4.5m’ KSer. The NMR results show that each phase contains HCO3 -/CO32- and carbamate fractions at varying degree.