Studies on lactobionic acid introduced as a synergist in the presence of phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and zinc ions for corrosion control of carbon steel in aqueous environment are presented. The ...Studies on lactobionic acid introduced as a synergist in the presence of phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and zinc ions for corrosion control of carbon steel in aqueous environment are presented. The investigations revealed that lactobionic acid (LBA) acts as an excellent synergist in corrosion inhibition. Optimum concentrations of all the three components of the ternary formulation are established by gravimetric studies. Potentiodynamic polarization studies indicate that the new ternary system is a mixed inhibitor. Impedance studies show that a protective film is formed on the metal surface in the presence of the inhibitor formulation. The film is found to exhibit its protective nature even at higher temperatures up to 60 ~C. Analysis of the protective film by X-ray photoelectron spectroscopy (XPS) and reflection absorption Fourier transform infrared (FTIR) spectroscopy infers the presence of Zn(OH)2, oxides and hydroxides of iron and the inhibitor molecules in the surface film probably in the form of a complex, [Zn(II)-PBTC-LBA]. The morphological studies by scanning electron microscopy (SEM) and the topographical studies by atomic force microscopy (AFM) also indicate the presence of protective film on the metal surface. A plausible mechanism of corrosion inhibition is proposed.展开更多
A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari ear...A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari earthquake(Maharashtra,India).Palynological studies of the sediments indicate their age as Early Permian(Asselian,298-295 Ma) for deposition.Transmission electron microscope studies reveal that the spherule from the infratrappeans,is having a similar composition to that of the Neoarchean amphibolite to granulite facies mid crustal basement.The spherule is non-spherical in nature,containing mostly FeO(10.70±0.20 wt.%),CaO(13.8±0.5 wt.%),Al203(7.78±0.30 wt.%),MgO(6.47±0.3 wt.%),Si02(47,46±0.50 wt.%),Ti02(2.47±0.3 wt.%).K20(1.89±0.20 wt.%).and Cl(0.33±0.05 wt.%).Since the Fe composition of the spherule is almost same as the basement rock(10.5 wt.%),and the chlorine content is also in the same range as the basement(0.04-0.24 wt.%),it would suggest possibility of an extraterrestrial impact over the Indian terrain during the erstwhile Gondwana sedimentation period that may be associated with the Permian-Triassic mass extinction,the most severe one in the Earth's history.展开更多
Optical absorption and fluorescence spectra of Sm3+-doped zincfluorophosphate glasses with molar composition of 44P2O5+17K20+9Al2O3+(30-χ)ZnF2+χSm2O3 (χ=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol...Optical absorption and fluorescence spectra of Sm3+-doped zincfluorophosphate glasses with molar composition of 44P2O5+17K20+9Al2O3+(30-χ)ZnF2+χSm2O3 (χ=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 2.0 and 3.0 mol.%) referred as PKAZFSm were prepared by melt quenching technique and were characterized through Raman, absorption, emission and decay curve analysis. From the absorption spectra, Judd-Ofelt intensity parameters were determined and were used to predict radiative properties such as transition probabilities (AR, radiative lifetimes (τR), branching ratios (βR), effective bandwidths (△λeff) and stimulated emission cross-section (σ(λp)) for the excited 4G5/2 luminescent level. The decay curve for the 4G5/2 level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the 4G5/2 level increased with increase in Sm3+ ions concentration accompanied by decrease in lifetime due to energy transfer processes among the Sm3+ ions. The non-exponential decay curves was well fitted to the generalized Inokuti-Hirayama model for S=6, indicating that the energy transfer among optically active ions was of dipole-dipole interaction. The cross-relaxation mechanism responsible for the quenching of lifetimes and the effect of variation of concentration on the spectroscopic properties were also discussed.展开更多
文摘Studies on lactobionic acid introduced as a synergist in the presence of phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and zinc ions for corrosion control of carbon steel in aqueous environment are presented. The investigations revealed that lactobionic acid (LBA) acts as an excellent synergist in corrosion inhibition. Optimum concentrations of all the three components of the ternary formulation are established by gravimetric studies. Potentiodynamic polarization studies indicate that the new ternary system is a mixed inhibitor. Impedance studies show that a protective film is formed on the metal surface in the presence of the inhibitor formulation. The film is found to exhibit its protective nature even at higher temperatures up to 60 ~C. Analysis of the protective film by X-ray photoelectron spectroscopy (XPS) and reflection absorption Fourier transform infrared (FTIR) spectroscopy infers the presence of Zn(OH)2, oxides and hydroxides of iron and the inhibitor molecules in the surface film probably in the form of a complex, [Zn(II)-PBTC-LBA]. The morphological studies by scanning electron microscopy (SEM) and the topographical studies by atomic force microscopy (AFM) also indicate the presence of protective film on the metal surface. A plausible mechanism of corrosion inhibition is proposed.
基金PLANEX,Physical Research LaboratoryISRO-Space Application center,Ahmedabad for financial supportingsupported by the CSIR-Emeritus Scientist project sanctioned to O.P.Pandey
文摘A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari earthquake(Maharashtra,India).Palynological studies of the sediments indicate their age as Early Permian(Asselian,298-295 Ma) for deposition.Transmission electron microscope studies reveal that the spherule from the infratrappeans,is having a similar composition to that of the Neoarchean amphibolite to granulite facies mid crustal basement.The spherule is non-spherical in nature,containing mostly FeO(10.70±0.20 wt.%),CaO(13.8±0.5 wt.%),Al203(7.78±0.30 wt.%),MgO(6.47±0.3 wt.%),Si02(47,46±0.50 wt.%),Ti02(2.47±0.3 wt.%).K20(1.89±0.20 wt.%).and Cl(0.33±0.05 wt.%).Since the Fe composition of the spherule is almost same as the basement rock(10.5 wt.%),and the chlorine content is also in the same range as the basement(0.04-0.24 wt.%),it would suggest possibility of an extraterrestrial impact over the Indian terrain during the erstwhile Gondwana sedimentation period that may be associated with the Permian-Triassic mass extinction,the most severe one in the Earth's history.
基金supported by Department of Atomic Energy-Board of Research in Nuclear Sciences(DAE-BRNS)government of India(2009/34/36/BRNS/3174)
文摘Optical absorption and fluorescence spectra of Sm3+-doped zincfluorophosphate glasses with molar composition of 44P2O5+17K20+9Al2O3+(30-χ)ZnF2+χSm2O3 (χ=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 2.0 and 3.0 mol.%) referred as PKAZFSm were prepared by melt quenching technique and were characterized through Raman, absorption, emission and decay curve analysis. From the absorption spectra, Judd-Ofelt intensity parameters were determined and were used to predict radiative properties such as transition probabilities (AR, radiative lifetimes (τR), branching ratios (βR), effective bandwidths (△λeff) and stimulated emission cross-section (σ(λp)) for the excited 4G5/2 luminescent level. The decay curve for the 4G5/2 level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the 4G5/2 level increased with increase in Sm3+ ions concentration accompanied by decrease in lifetime due to energy transfer processes among the Sm3+ ions. The non-exponential decay curves was well fitted to the generalized Inokuti-Hirayama model for S=6, indicating that the energy transfer among optically active ions was of dipole-dipole interaction. The cross-relaxation mechanism responsible for the quenching of lifetimes and the effect of variation of concentration on the spectroscopic properties were also discussed.