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Thermal degradation of piperazine (PZ) in aqueous and mixed sulfolane (SFL) (30% by weight) + H2O solution as a hybrid context was investigated as a function of temperature and two levels of piperazine concentrations and two levels of carbon dioxide loadings. Degradation of PZ in aqueous solution has been found to be first order. The pseudo rate constants for 5%wt solution of piperazine at 145, 160 and 175 °C in aqueous solution are 2.24 × 10–9, 1.09 × 10–8 and 2.27 × 10–7 and in the hybrid media are 3.56 × 10–8, 7.67 × 10–8 and 1.19 × 10–7 per second, respectively, and the activation energies for the aqueous and hybrid media were estimated 238.71 and 62.77 kJ/mole, respectively. Considering the most abundant degradation products identified; 3-(hydroxyethyl)-2-oxazolidone (HEOD), N,N-bis-(2-hydroxyethyl)-piperazine (BHEP), N,N',N-tris-(hydroxyethyl) ethylenediamine (THEED), 1-[2-[(2-Aminoethyl) amino] ethyl] piperazine (AEAEPZ) and 1-Methylpiperazine (1-MPZ), the degradation pathway of PZ in both media is expected to proceed through ring opening of protonated PZ with the attack of other piperazine molecules on its alpha carbon. The presence of SFL only accelerates the reactions without changing the degradation mechanism. [ABSTRACT FROM AUTHOR]

Given the importance of La3+ ions in various areas of medicine and industry and the effects these ions can have on humans and animals, the analysis of the species is an important area in analytical chemistry. In the light of the efficiency of the ion-selective electrodes in the determinations of traces amounts of various analytes, including rare earth ions and lanthanum, all published reports on the development of La3+ ions were reviewed with a focus on the ionophores incorporated therein, their composition and the response and selectivity behavior of the developed sensors, to provide the readers with insight on the various factors influencing the analytical performance of lanthanum selective sensors ions, which can also be applied to research on the development of other rare earth ion sensors. [ABSTRACT FROM AUTHOR]

In this paper, the experimental solubility of hydrogen sulfide in aqueous N- Methyldiethanolamine + Amine Functionalized UiO-66 (UiO-66-NH2) was studied. UiO-66-NH2 was produced using solvothermal process, and its physicochemical properties were investigated by different techniques including XRD, TGA, TEM, BET, and FTIR to realize its crystalline structure, morphology, thermal stability, and porous structure. The Zeta potential of the solution was turned out to be about 26.6 mV (millivolt), meaning that UiO-66-NH2 particles are moderately stable in aqueous 40 wt.% MDEA. The solubility of hydrogen sulfide has been carried out using the isochoric saturation / or static method in two concentration grades of 0.1 and 0.5 wt.% of UiO-66-NH2 in the aqueous solution of 40 wt.% MDEA known as nanofluid. Experimental measurements were carried out at temperatures of 303.15 through 333.15 K, and pressures up 1100 kPa. Results showed that the addition of UiO-66-NH2 nanoparticles to the MDEA solution altered the results less than 3% , while the mean value of uncertainty reported in this work is about 4% , meaning that the addition of nanoparticles do not have remarkable effect on H2S solubility. In contrast, it causes an increased capacity of CO2 absorption of that solution up to 10%. [ABSTRACT FROM AUTHOR]

In this research, UiO-66-NH 2 was synthesized with solvothermal method and analyzed by XRD, SEM, BET, TGA and IR spectroscopy to understand its crystalline structure, morphology, thermal stability, and porous structure. Mass fraction of 0.1% of UiO-66-NH 2 added to aqueous solution of mass fraction of 40% N-Methyldiethanolamine (MDEA). Measurement of zeta potential showed that UiO-66-NH 2 particles are stable in aqueous mass fraction of 40% MDEA. The solubility of carbon dioxide investigated in aqueous solution of mass fraction of 40% MDEA and the prepared mixture of mass fraction of 0.1% of UiO-66-NH 2 nanofluid in aqueous solution of mass fraction of 40% MDEA at temperatures of 303.15, 313.15, 323.15, and 333.15 K, and carbon dioxide pressures up to 2300 kPa. Results showed that addition of UiO-66-NH 2 nanoparticles to the MDEA solution, increased capacity of CO 2 absorption of solution up to 10%. The solubility of CO 2 increased with increasing partial pressure and decreased with increasing temperature for both systems. [ABSTRACT FROM AUTHOR]

In the present work, the equilibrium solubility of carbondioxidewas measured for three different aqueous mixture of N-methyldiethanolamine (MDEA) and diisopropanolamine (DIPA). The sumof the mass fraction of MDEA and DIPA for each aqueous mixture wasconstant at 100 w= 50. The mass fraction of DIPAwas chosen as 100 w= (1, 3, and 5) for the mixture,respectively. The experimental data were measured for the temperaturerange of (313.2 to 358.2) K and the equilibrium CO2partialpressure of (85 to 3984) kPa. To predict and correlate the equilibriumsolubility behavior of carbon dioxide with an aqueous mixture of MDEAand DIPA, the Deshmukh–Mather model was used. The binary interactionparameters of the model were tuned by regression of experimental data.Having used the tuned parameters, the equilibrium behavior of CO2with relevant aqueous solution was estimated and comparedwith the equivalent experimental values. The average absolute deviation(AAD %) was obtained to be 13.2 % for all data points. [ABSTRACT FROM AUTHOR]

Abstract: Solubility data of CO2 in aqueous N-methyldiethanolamine (MDEA) solutions of concentration (2.52, 3.36, and 4.28)kmol/m3 were obtained at temperatures (313, 323, and 343)K and partial pressures ranging from about (30 to 5000)kPa. A thermodynamic model based on extended Debye–Hückel theory was applied to predict and correlate of CO2 solubility in various aqueous amine solutions. The effect of piperazine (PZ) concentration on CO2 loading in MDEA solutions was determined at PZ concentration (0.36, 0.86, and 1.36)kmol/m3. Using experimental data in various temperatures the interaction parameters of activity coefficient model for these systems were determined. The results show the model consistency with experimental and literature data and PZ is beneficial to the CO2 loading. The comparison of results of this study with previous data work shows the wide range of CO2 loading considered in this work and the better agreement of model with experimental data. The average absolute relative deviation percent (δ AAD) for all data points were 8.11%. [Copyright &y& Elsevier]

A novel approach was examined by addition of amine-modified reduced graphene oxide (rGO) to amine solutions in order to enhance the CO 2 absorption capacity of amine solutions. Amine functionalized reduced graphene oxide (rGO)/methyl diethanolamine (MDEA) nanofluid was prepared for absorption of acid gases (CO 2 , H 2 S). GO was synthesized via a modified hummer method and functionalized through solvothermal method. As-synthesized NH 2 -rGO was characterized by XRD, BET, SEM, FTIR, EDX and XPS analysis to determine the structure. NH 2 -rGO was dispersed in MDEA and displayed excellent stability verified by zeta potential analysis. NH 2 -rGO/MDEA nanofluid showed high absorption capacity toward CO 2 and H 2 S. The absorption capacity of the solution for CO 2 and H 2 S was promoted up to 16.2% and 17.7%, respectively. Solubility results showed a reverse relationship with increasing temperature. Comparison of solubility data revealed that introducing 0.1 wt% NH 2 -rGO to 40 wt% had a greater enhancement relative to introducing 0.1 wt% GO to the same solution., (Copyright © 2018 Elsevier Inc. All rights reserved.)