The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
C A Loto - One of the best experts on this subject based on the ideXlab platform.
-
corrosion behaviour of s43035 ferritic stainless steel in hot sulphate chloride solution
Journal of materials research and technology, 2017Co-Authors: Roland Tolulope Loto, C A LotoAbstract:Abstract The corrosion resistance of S43035 ferritic stainless steel at elevated temperatures of 308 K, 328 K, 348 K and 378 K was studied through potentiodynamic polarization test and optical microscopy analysis in 2 M H 2 SO 4 at 0%, 1%, 3.5% and 6% NaCl. Results show that increase in temperature and NaCl generally hinders the formation of the passive film. Changes in corrosion rate from 308 K to 378 K at 0% NaCl was marginal. Metastable pitting was absent until 378 K due to increased electrolytic action of SO 4 2− ions. In the presence of chlorides at 308 K metastable pitting is visible delaying the formation of stable passive film. Passivation behaviour was absent at temperatures above 308 K due to polarization similar to carbon steels and a strong decrease in hydrogen evolution over potential especially at 1% and 3.5% NaCl. Optical images showed mild deterioration at 378 K from 0% NaCl and the formation of corrosion pits at 308 K and 378 K from 6% NaCl. Negative Enthalpy Value at 0% NaCl implies exothermic nature of the steel corrosion reaction. Addition of chlorides changed the steel corrosion reaction to endothermic. Increase in NaCl concentration caused a decrease in activation energy and increase in entropy Values due to decrease in passivation of the alloy and consequently increase in corrosion rate. Statistical analysis through ANOVA at confidence levels of 95% and 97.5% showed the strong influence of temperature variation on corrosion rate with F -Values of 5.256 at 50.8% in contrast to the NaCl concentration whose Value was below the significance level.
Mitsuhiro Shibayama - One of the best experts on this subject based on the ideXlab platform.
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
Kenta Fujii - One of the best experts on this subject based on the ideXlab platform.
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
-
conformational equilibrium of bis trifluoromethanesulfonyl imide anion of a room temperature ionic liquid raman spectroscopic study and dft calculations
Journal of Physical Chemistry B, 2006Co-Authors: Kenta Fujii, Toshiyuki Takamuku, Takao Fujimori, Ryo Kanzaki, Yasuhiro Umebayashi, Shin Ichi IshiguroAbstract:The structure of bis(trifluoromethanesulfonyl) imide (TFSI-) in the liquid state has been studied by means of Raman spectroscopy and DFT calculations. Raman spectra of 1-ethyl-3-methylimidazolium (EMI+) TFSI- show relatively strong bands arising from TFSI- at about 398 and 407 cm-1. Interestingly, the 407 cm-1 band, relative to the 398 cm-1 one, is appreciably intensified with raising temperature, suggesting that an equilibrium is established between TFSI- conformers in the liquid state. According to DFT calculations followed by normal frequency analyses, two conformers of C2 and C1 symmetry, respectively, constitute global and local minima, with an energy difference 2.2−3.3 kJ mol-1. The wagging ω-SO2 vibration appears at 396 and 430 cm-1 for the C1 conformer and at 387 and 402 cm-1 for the C2 one. Observed Raman spectra over the range 380−440 cm-1 were deconvoluted to extract intrinsic bands of TFSI- conformers, and the Enthalpy of conformational change from C2 to C1 was evaluated. The Enthalpy Value is...
Kei Hashimoto - One of the best experts on this subject based on the ideXlab platform.
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
-
acid base property of protic ionic liquid 1 alkylimidazolium bis trifluoromethanesulfonyl amide studied by potentiometric titration
Journal of Molecular Liquids, 2013Co-Authors: Kei Hashimoto, Kenta Fujii, Mitsuhiro ShibayamaAbstract:Abstract We report the acid–base property of typical protic ionic liquid, 1-alkylimidazolium bis(trifluoromethanesulfonyl)amide ([CnImH+][TFSA−], n: alkyl-chain length), investigated by potentiometric titration. The equilibrium constant, Ks = [CnIm][HTFSA] on the autoprotolysis reaction (CnImH+ + TFSA− ⇄ CnIm + HTFSA) was successfully determined for n = 2 and 4 systems using an ion-selective field effect transistor (IS-FET) electrode. The pKs Values for n = 2 and 4 were estimated to be 12.3 and 12.6 mol2 dm− 6, respectively, indicating that the autoprotolysis reaction is almost independent of the alkyl chain length. Temperature dependence of the potentiometric titration was also performed to obtain the reaction Enthalpy. The Enthalpy Value, 41 kJ mol− 1, obtained here is appreciably smaller than that for ethylammonium nitrate (83 kJ mol− 1).
Roland Tolulope Loto - One of the best experts on this subject based on the ideXlab platform.
-
corrosion behaviour of s43035 ferritic stainless steel in hot sulphate chloride solution
Journal of materials research and technology, 2017Co-Authors: Roland Tolulope Loto, C A LotoAbstract:Abstract The corrosion resistance of S43035 ferritic stainless steel at elevated temperatures of 308 K, 328 K, 348 K and 378 K was studied through potentiodynamic polarization test and optical microscopy analysis in 2 M H 2 SO 4 at 0%, 1%, 3.5% and 6% NaCl. Results show that increase in temperature and NaCl generally hinders the formation of the passive film. Changes in corrosion rate from 308 K to 378 K at 0% NaCl was marginal. Metastable pitting was absent until 378 K due to increased electrolytic action of SO 4 2− ions. In the presence of chlorides at 308 K metastable pitting is visible delaying the formation of stable passive film. Passivation behaviour was absent at temperatures above 308 K due to polarization similar to carbon steels and a strong decrease in hydrogen evolution over potential especially at 1% and 3.5% NaCl. Optical images showed mild deterioration at 378 K from 0% NaCl and the formation of corrosion pits at 308 K and 378 K from 6% NaCl. Negative Enthalpy Value at 0% NaCl implies exothermic nature of the steel corrosion reaction. Addition of chlorides changed the steel corrosion reaction to endothermic. Increase in NaCl concentration caused a decrease in activation energy and increase in entropy Values due to decrease in passivation of the alloy and consequently increase in corrosion rate. Statistical analysis through ANOVA at confidence levels of 95% and 97.5% showed the strong influence of temperature variation on corrosion rate with F -Values of 5.256 at 50.8% in contrast to the NaCl concentration whose Value was below the significance level.