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Abstract
Kinetics of the monoethanolamine vapor adsorption on the surface of silica previously deposited onto quartz plate was examined by the piezoelectric microweighing. With the assumptions which are in accord with the experimental data, the kinetic equation of the process was obtained and thus the adsorption and desorption constants were found. The structure of the possible adsorption complexes was studied in the framework of the quantum-chemical MNDO method and the conclusion was made that the two-center adsorption of the monoethanolamine on the silica surface proceeds as a two-stage process with the participation of both functional groups. The bonding is mainly effected owing to the proton-acceptor properties of amine groups.
Abstract
Determination of milligram amounts of monoethanolamine with zinc/II/ by radiometric titration is described.
Carbon dioxide absorption by MEA
A preliminary evaluation of a bubbling column reactor
Abstract
Biogas generally contains significant quantities of carbon dioxide in addition to methane. A bubbling column reactor operating at atmospheric pressure is proposed for cheap separation and a Mettler RC1 reaction calorimeter was used to build a simplified empirical model for measuring the molar heat of solubility of CO2 in aqueous solutions of monoethanolamine (MEA). Determinations were performed in 12 mass% MEA solutions regenerated at atmospheric pressure and reflux temperature for 3 h. Flows of CO2 from 174 to 917 mL min−1 were used at a reactor temperature of 283 to 353 K.
Abstract
Thermal behaviour of ammonium (NH4alg), mono- (MEAalg), di- (DEAalg) and triethanolammonium (TEAalg) salts of alginic acid (Halg) was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Salts were prepared by the direct reaction of alginic acid with the ammonium hydroxide and with the respective ethanolamines. After preparation the compounds were lyophilized during 24 h and characterized by FTIR spectroscopy and elemental analysis (C, H and N). Under air the compounds exhibited three successive thermal decomposition steps: dehydration, decomposition of the polymeric matrix and finally, burning of carbonaceous residue. Under nitrogen two steps (dehydration and decomposition) were observed. The stability order of this series of compounds was: TEAalg this series of compounds was: TEAalg<DEAalg<NH4alg<Halg≈MEAalg. DSC curves between –50 and 150C did not show any thermal events suggesting that after lyophilization probably non-freezing type water is present in the system.
Use of the NRTL equation for simultaneous correlation of vapour-liquid equilibria and excess enthalpy
Applications to aqueous alkanolamine systems
Abstract
The NRTL model has been used to correlate the data for the aqueous alkanolamine systems of (MEA+H2O), (DEA+H2O) and (MDEA+H2O). The model was successfully applied to correlate simultaneously the excess enthalpy, vapour-liquid equilibria, and low temperature activity coefficients. A large database of data was collected for the investigation and it covers a wide range of composition, temperature and pressures. It was found that the form of the binary interaction parameters used by Posey (1996) with a variable non-randomness parameter gave the best results.
yet. Experimental Materials The following materials were used to prepare the sol:zinc acetate dihydrate (Zn(OOCCH 3 ) 2 ·2H 2 O, 98 %, Aldrich), monoethanolamine (MEA, Merck), 2-methoxyethanol (Merck) and
Absorption heats of hydrogen sulphide in aqueous solutions of monoethanolamine, diethanolamine and triethanolamine were determined by calorimetry. The measured enthalpies were compared to those calculated on the basis of solubility measurement and to the enthalpies of protonation of hydrogen chloride at 25‡.
Summary
A simple and reliable sampling system for 3H and 14C in airborne release from nuclear facilities was designed. The sampling system can collect 3H and 14C simultaneously with a condensation technique using a commercially available cold trap equipment and a CO2 absorption technique using an organic alkali monoethanolamine solution, respectively. In situ performance tests for the effluent from a reprocessing plant showed that the system has high and stable efficiencies for collecting 3H and 14C for a one-week batch sampling at a sampling flow rate of 0.4 l . min-1. These collection techniques also provided a simple procedure of following sample preparation for activity measurements by liquid scintillation counting. The detectable concentrations of the proposed monitoring method were 3.0 Bq . m-3 for 3H and 1.6 Bq . m-3 for 14C, respectively. The sensitivity would be on an acceptable level for routine monitoring of airborne release at nuclear facilities.
Abstract
TMA has been used to investigate the thermomechanical behaviour of six series of elastomers in connection with their chemical constitution and physical structure. The elastomers, were synthesized from an NCO-terminal pre-polymer, based on oligo (ethylene adipate), 1,4-butanediol and 2,4-toluylene diisocyanate, by curing with systems of two agents: a bifunctional one (1,4-butanediol, bistethylene glycol)terephthalate, or monoethanolamine), and a trifunctional one (1,1,1-trimethylolpropane or diethanolamine). The TMA results are presented as due to the superposition of the chemical cross-linking and the physical network, formed through microphase segregation. The TMA suggests that diethanolamine unexpectedly acts as a chain extender, rather than a cross-linking agent.
examined samples were also studied by XRD and CHNS techniques. Experimental Materials Bentonite clay with a cation exchange capacity (CEC) of 0.928 meq/g, monoethanolamine (MEA), diethanolamine (DEA) and
