The biosorption potential of different types of carbohydrate biomass is investigated to evaluate ... more The biosorption potential of different types of carbohydrate biomass is investigated to evaluate their application to purify water contaminated by vanadium in environmentally-relevant oxidation states (VIV and VV). Spectroscopic studies are done by electron paramagnetic resonance (EPR), vanadium nuclear magnetic resonance (51V NMR), circular dichroism (CD) and electronic absorption in the visible range (Vis). Both D-galacturonic acid and D-glucuronic acids are major components of plant cellular wall polysaccharides. The ...
Water pollution by heavy metals represents a serious problem around the world. Among various trea... more Water pollution by heavy metals represents a serious problem around the world. Among various treatment techniques for water remediation, adsorption is an effective and versatile method due to the low cost, effectiveness and simplicity. Chitosan is a cationic polysaccharide with an excellent adsorption capacity of heavy metal ions. Chitosan has a high molybdate adsorption capacity (265±1mgg(-1)) at 20°C and pH 2.7. Participation of hydroxyl groups in the adsorption of molybdate anions was confirmed by FT-IR analysis. SEM images showed that morphological surface changes happen after Mo(VI) adsorption. Continuous adsorption data were best fitted by Modified Dose- Response model. Scale-up of continuous processes was achieved applying bed depth service time (BDST) model. Application of chitosan in molybdate removal from real groundwater samples suggest that this polysaccharide is a good option to be used for household purposes.
Equilibrium studies of BMXD complexation with copper(II) and glycylglycine were performed by pote... more Equilibrium studies of BMXD complexation with copper(II) and glycylglycine were performed by potentiometric and UV–visible titration. The equilibrium constants determined by potentiometry for the ternary system are: [LCu2P3+]/[LCu24+][P−]=8.11(3), [LCu2HP4+]/[LCu2P3+][H+]=5.39(2), [LCu2H−1P2+][H+]/[LCu2P3+]=−6.33(2), [LCu2(OH)H−1P+][H+]/[LCu2H−1P2+]=−8.20(1) and [LCu2(OH)2HH−1P][H+]/[LCu2(OH)H−1P−1]=−10.33(3), which are in good agreement with the values determined by UV–visible titration. The species formed were confirmed by electrospray mass spectrometry. The association constants, determined by kinetic
ABSTRACT The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically st... more ABSTRACT The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in aqueous solution. Measurements were carried out at 20.0 and 25.0±0.1°C and the ionic strength was maintained at 0.100 M with NaNO3. The potentiometric curves showed the release of four protons in addition to the carboxylic one, leading to the formation of complexes with different degrees of deprotonation. Since the first chelate was completely formed at low pH, competition equilibria involving ethylenediaminetetraacetic acid or nitrilotriacetic acid ligands were used to calculate the corresponding equilibrium constant. Coordination bonding sites for metal–ligand interactions were inferred from 13C NMR spectroscopy. According to the obtained results, the complex formed at acid pH would present a carboxylate coordination and those formed at high pH would involved a bonding with the oxygens of carbons 2, 3, 4 and 5. On the other hand, the complex Bi(C6H9O7)·H2O was isolated and characterized by elemental and thermogravimetric analyses and by Fourier transform infra-red (FT-IR) spectroscopy. While the thermogravimetric analyses confirmed the water content in the solid complex, the IR spectra showed a monodentate carboxylate coordination.
A quantitative study of the equilibria involved in the interaction of Cu(II) ion with D-glucohept... more A quantitative study of the equilibria involved in the interaction of Cu(II) ion with D-glucoheptonic, D-gluconic, D-galactonic, D-ribonic, D-glucuronic, and D-galacturonic acids in aqueous medium has been carried out by means of potentiometric measurements of hydrogen ion concentrations at a constant temperature of 20 °C and an ionic strength of 0.10 (NaNO3). The equilibrium data were processed with the FORTRAN computer program BEST. It was found that Cu(II) interacts with D-aldonic acids to form 1:1, 2:2, and 1:2 (M/L) complexes. The copper(II) complexes with D-galacturonic and D-glucuronic acids are considerably weaker than those of D-aldonic acid. Possible structures of the complex species formed are discussed.
Journal of the Chemical Society, Perkin Transactions 2, 1977
Page 1. 1977 685 Oxidative Decarboxylation of Aldonolactones by Ceriurn(iv) Subhate in Aqueous Su... more Page 1. 1977 685 Oxidative Decarboxylation of Aldonolactones by Ceriurn(iv) Subhate in Aqueous Sulphuric Acid ; Synthesis of D-Arabinose By Luis F. Sala, Alicia Fernhndez Cirelli, and Rosa M. de Lederkremer,' Departamento ...
The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in ... more The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in aqueous solution. Measurements were carried out at 20.0 and 25.0±0.1°C and the ionic strength was maintained at 0.100 M with NaNO3. The potentiometric curves showed the release of four protons in addition to the carboxylic one, leading to the formation of complexes with different degrees of deprotonation.
The biosorption potential of different types of carbohydrate biomass is investigated to evaluate ... more The biosorption potential of different types of carbohydrate biomass is investigated to evaluate their application to purify water contaminated by vanadium in environmentally-relevant oxidation states (VIV and VV). Spectroscopic studies are done by electron paramagnetic resonance (EPR), vanadium nuclear magnetic resonance (51V NMR), circular dichroism (CD) and electronic absorption in the visible range (Vis). Both D-galacturonic acid and D-glucuronic acids are major components of plant cellular wall polysaccharides. The ...
Water pollution by heavy metals represents a serious problem around the world. Among various trea... more Water pollution by heavy metals represents a serious problem around the world. Among various treatment techniques for water remediation, adsorption is an effective and versatile method due to the low cost, effectiveness and simplicity. Chitosan is a cationic polysaccharide with an excellent adsorption capacity of heavy metal ions. Chitosan has a high molybdate adsorption capacity (265±1mgg(-1)) at 20°C and pH 2.7. Participation of hydroxyl groups in the adsorption of molybdate anions was confirmed by FT-IR analysis. SEM images showed that morphological surface changes happen after Mo(VI) adsorption. Continuous adsorption data were best fitted by Modified Dose- Response model. Scale-up of continuous processes was achieved applying bed depth service time (BDST) model. Application of chitosan in molybdate removal from real groundwater samples suggest that this polysaccharide is a good option to be used for household purposes.
Equilibrium studies of BMXD complexation with copper(II) and glycylglycine were performed by pote... more Equilibrium studies of BMXD complexation with copper(II) and glycylglycine were performed by potentiometric and UV–visible titration. The equilibrium constants determined by potentiometry for the ternary system are: [LCu2P3+]/[LCu24+][P−]=8.11(3), [LCu2HP4+]/[LCu2P3+][H+]=5.39(2), [LCu2H−1P2+][H+]/[LCu2P3+]=−6.33(2), [LCu2(OH)H−1P+][H+]/[LCu2H−1P2+]=−8.20(1) and [LCu2(OH)2HH−1P][H+]/[LCu2(OH)H−1P−1]=−10.33(3), which are in good agreement with the values determined by UV–visible titration. The species formed were confirmed by electrospray mass spectrometry. The association constants, determined by kinetic
ABSTRACT The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically st... more ABSTRACT The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in aqueous solution. Measurements were carried out at 20.0 and 25.0±0.1°C and the ionic strength was maintained at 0.100 M with NaNO3. The potentiometric curves showed the release of four protons in addition to the carboxylic one, leading to the formation of complexes with different degrees of deprotonation. Since the first chelate was completely formed at low pH, competition equilibria involving ethylenediaminetetraacetic acid or nitrilotriacetic acid ligands were used to calculate the corresponding equilibrium constant. Coordination bonding sites for metal–ligand interactions were inferred from 13C NMR spectroscopy. According to the obtained results, the complex formed at acid pH would present a carboxylate coordination and those formed at high pH would involved a bonding with the oxygens of carbons 2, 3, 4 and 5. On the other hand, the complex Bi(C6H9O7)·H2O was isolated and characterized by elemental and thermogravimetric analyses and by Fourier transform infra-red (FT-IR) spectroscopy. While the thermogravimetric analyses confirmed the water content in the solid complex, the IR spectra showed a monodentate carboxylate coordination.
A quantitative study of the equilibria involved in the interaction of Cu(II) ion with D-glucohept... more A quantitative study of the equilibria involved in the interaction of Cu(II) ion with D-glucoheptonic, D-gluconic, D-galactonic, D-ribonic, D-glucuronic, and D-galacturonic acids in aqueous medium has been carried out by means of potentiometric measurements of hydrogen ion concentrations at a constant temperature of 20 °C and an ionic strength of 0.10 (NaNO3). The equilibrium data were processed with the FORTRAN computer program BEST. It was found that Cu(II) interacts with D-aldonic acids to form 1:1, 2:2, and 1:2 (M/L) complexes. The copper(II) complexes with D-galacturonic and D-glucuronic acids are considerably weaker than those of D-aldonic acid. Possible structures of the complex species formed are discussed.
Journal of the Chemical Society, Perkin Transactions 2, 1977
Page 1. 1977 685 Oxidative Decarboxylation of Aldonolactones by Ceriurn(iv) Subhate in Aqueous Su... more Page 1. 1977 685 Oxidative Decarboxylation of Aldonolactones by Ceriurn(iv) Subhate in Aqueous Sulphuric Acid ; Synthesis of D-Arabinose By Luis F. Sala, Alicia Fernhndez Cirelli, and Rosa M. de Lederkremer,' Departamento ...
The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in ... more The system formed between bismuth(III) ion and d-gluconic acid was potentiometrically studied in aqueous solution. Measurements were carried out at 20.0 and 25.0±0.1°C and the ionic strength was maintained at 0.100 M with NaNO3. The potentiometric curves showed the release of four protons in addition to the carboxylic one, leading to the formation of complexes with different degrees of deprotonation.
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