Documents disponibles écrits par cet auteur

Bromate ion-exchange properties of crystalline akaganéite / Ramesh Chitrakar in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2107–2112 Titre : Bromate ion-exchange properties of crystalline akaganéite Type de document : texte imprimé Auteurs : Ramesh Chitrakar, Auteur ; Satoko Tezuka, Auteur ; Akinari Sonoda, Auteur Année de publication : 2009 Article en page(s) : p. 2107–2112 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crystalline  akaganéite  Ion-exchange  properties  BrO3− Résumé : We synthesized crystalline akaganéite (β-FeOOH; Cl− type) by hydrolysis of FeCl3 solution at 100 °C and examined the ion-exchange properties with BrO3−. The uptake rate of BrO3− was so fast that equilibrium was attained in 60 min. The uptake was significantly dependent on pH, showing a maximum uptake at pH ≈ 4. From distribution coefficients (Kd) determined with a mixed solution (BrO3−, Cl−, CO32−, and SO42−; each concentration = 0.1 mmol/dm3), crystalline akaganéite showed the highest selectivity toward BrO3−. The BrO3− uptake was fitted well with the Langmuir model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011038 [article] Bromate ion-exchange properties of crystalline akaganéite [texte imprimé] / Ramesh Chitrakar, Auteur ; Satoko Tezuka, Auteur ; Akinari Sonoda, Auteur . - 2009 . - p. 2107–2112. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2107–2112 Mots-clés : Crystalline  akaganéite  Ion-exchange  properties  BrO3− Résumé : We synthesized crystalline akaganéite (β-FeOOH; Cl− type) by hydrolysis of FeCl3 solution at 100 °C and examined the ion-exchange properties with BrO3−. The uptake rate of BrO3− was so fast that equilibrium was attained in 60 min. The uptake was significantly dependent on pH, showing a maximum uptake at pH ≈ 4. From distribution coefficients (Kd) determined with a mixed solution (BrO3−, Cl−, CO32−, and SO42−; each concentration = 0.1 mmol/dm3), crystalline akaganéite showed the highest selectivity toward BrO3−. The BrO3− uptake was fitted well with the Langmuir model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011038

Calcined Mg–al layered double hydroxides for uptake of trace levels of bromate from aqueous solution / Ramesh Chitrakar in Industrial & engineering chemistry research, Vol. 50 N° 15 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9280-9285 Titre : Calcined Mg–al layered double hydroxides for uptake of trace levels of bromate from aqueous solution Type de document : texte imprimé Auteurs : Ramesh Chitrakar, Auteur ; Akinari Sonoda, Auteur ; Yoji Makita, Auteur Année de publication : 2011 Article en page(s) : pp. 9280-9285 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Aqueous  solution  Uptake  Calcination Résumé : Layered double hydroxides of Mg and Al (Mg-Al LDH) were synthesized with OH-, Cl-, or CO32- as charge compensating anions. The materials were calcined at 500 °C in air. The bromate uptakes of calcined and uncalcined LDH materials were investigated from 0.78 μmol/dm3 bromate solution. Results show that uncalcined LDH exhibited no bromate uptake, although calcined LDH exhibited bromate uptake: the initial bromate concentration of 0.78 μmol/dm3 decreased to less than 0.078 μmol/dm3, the maximum contaminant level established for bromate in drinking water. The rate of bromate uptake of calcined LDH was slow to attain equilibrium in 48 h. The bromate uptake data of calcined LDH agreed well with the Freundlich model. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395872 [article] Calcined Mg–al layered double hydroxides for uptake of trace levels of bromate from aqueous solution [texte imprimé] / Ramesh Chitrakar, Auteur ; Akinari Sonoda, Auteur ; Yoji Makita, Auteur . - 2011 . - pp. 9280-9285. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9280-9285 Mots-clés : Aqueous  solution  Uptake  Calcination Résumé : Layered double hydroxides of Mg and Al (Mg-Al LDH) were synthesized with OH-, Cl-, or CO32- as charge compensating anions. The materials were calcined at 500 °C in air. The bromate uptakes of calcined and uncalcined LDH materials were investigated from 0.78 μmol/dm3 bromate solution. Results show that uncalcined LDH exhibited no bromate uptake, although calcined LDH exhibited bromate uptake: the initial bromate concentration of 0.78 μmol/dm3 decreased to less than 0.078 μmol/dm3, the maximum contaminant level established for bromate in drinking water. The rate of bromate uptake of calcined LDH was slow to attain equilibrium in 48 h. The bromate uptake data of calcined LDH agreed well with the Freundlich model. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395872

A new method for synthesis of Mg−Al, Mg−Fe, and Zn−Al layered double hydroxides and their uptake properties of bromide ion / Ramesh Chitrakar in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4905–4908 Titre : A new method for synthesis of Mg−Al, Mg−Fe, and Zn−Al layered double hydroxides and their uptake properties of bromide ion Type de document : texte imprimé Auteurs : Ramesh Chitrakar, Auteur ; Satoko Tezuka, Auteur ; Akinari Sonoda, Auteur ; Kohji Sakane, Auteur Année de publication : 2008 Article en page(s) : p. 4905–4908 Langues : Anglais (eng) Mots-clés : Layered  double  hydroxides;  Bromide  ion Résumé : We report a very simple and efficient method to prepare LDHs of Mg−Al, Mg−Fe, and Zn−Al by simply mixing solid divalent metal oxide with trivalent metal chloride solution at 30 °C. Calcined Mg−Al and Mg−Fe are effective in removing low concentration of Br− from a mixed solution (Br− = 0.1 mmol/dm3, Cl− = 1.0 mmol/dm3) at a material dose of 1 g/dm3. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716417 [article] A new method for synthesis of Mg−Al, Mg−Fe, and Zn−Al layered double hydroxides and their uptake properties of bromide ion [texte imprimé] / Ramesh Chitrakar, Auteur ; Satoko Tezuka, Auteur ; Akinari Sonoda, Auteur ; Kohji Sakane, Auteur . - 2008 . - p. 4905–4908. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4905–4908 Mots-clés : Layered  double  hydroxides;  Bromide  ion Résumé : We report a very simple and efficient method to prepare LDHs of Mg−Al, Mg−Fe, and Zn−Al by simply mixing solid divalent metal oxide with trivalent metal chloride solution at 30 °C. Calcined Mg−Al and Mg−Fe are effective in removing low concentration of Br− from a mixed solution (Br− = 0.1 mmol/dm3, Cl− = 1.0 mmol/dm3) at a material dose of 1 g/dm3. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0716417

Selective uptake by akaganeite (B - FeOOH) of phosphite from hypophosphite and phosphite solutions / Ramesh Chitrakar in Industrial & engineering chemistry research, Vol. 51 N° 2 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 972-977 Titre : Selective uptake by akaganeite (B - FeOOH) of phosphite from hypophosphite and phosphite solutions Type de document : texte imprimé Auteurs : Ramesh Chitrakar, Auteur ; Yoji Makita, Auteur ; Takahiro Hirotsu, Auteur Année de publication : 2012 Article en page(s) : pp. 972-977 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Uptake Résumé : The anion-exchange properties of akaganeite (β-FeOOH) with phosphite (H2PO3― and HPO32― ) are reported herein. Uptake of phosphite by akaganeite followed the Freundlich isotherm model with exchange capacity of 1.0 mmol/g, and high distribution coefficients in multianion solution of 2.0 mmol/dm3 concentration (7.0 x 103 cm3/g at pH 3.9). Akaganeite displayed nearly constant uptake of phosphite (0.9 mmol/g) at pH 2.5―6.0. The kinetics on uptake of phosphite rapidly reached an equilibrium in 4 h. Akaganeite was also found to be feasible for high uptake of phosphite (1.2 mmol/g) and low uptake of hypophosphite (<0.10 mmol/g) at pH 6.3 from a highly concentrated binary solution containing 0.70 mol/dm3 phosphite, and 0.20 mol/dm3 hypophosphite. Akaganeite can be regenerated and reused for uptake of phosphite with an exchange capacity equivalent to that of the original akaganeite. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476430 [article] Selective uptake by akaganeite (B - FeOOH) of phosphite from hypophosphite and phosphite solutions [texte imprimé] / Ramesh Chitrakar, Auteur ; Yoji Makita, Auteur ; Takahiro Hirotsu, Auteur . - 2012 . - pp. 972-977. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 972-977 Mots-clés : Uptake Résumé : The anion-exchange properties of akaganeite (β-FeOOH) with phosphite (H2PO3― and HPO32― ) are reported herein. Uptake of phosphite by akaganeite followed the Freundlich isotherm model with exchange capacity of 1.0 mmol/g, and high distribution coefficients in multianion solution of 2.0 mmol/dm3 concentration (7.0 x 103 cm3/g at pH 3.9). Akaganeite displayed nearly constant uptake of phosphite (0.9 mmol/g) at pH 2.5―6.0. The kinetics on uptake of phosphite rapidly reached an equilibrium in 4 h. Akaganeite was also found to be feasible for high uptake of phosphite (1.2 mmol/g) and low uptake of hypophosphite (<0.10 mmol/g) at pH 6.3 from a highly concentrated binary solution containing 0.70 mol/dm3 phosphite, and 0.20 mol/dm3 hypophosphite. Akaganeite can be regenerated and reused for uptake of phosphite with an exchange capacity equivalent to that of the original akaganeite. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476430

Uptake of bromate ion on amorphous aluminum hydroxide / Ramesh Chitrakar in Industrial & engineering chemistry research, Vol. 49 N° 18 (Septembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8726–8732 Titre : Uptake of bromate ion on amorphous aluminum hydroxide Type de document : texte imprimé Auteurs : Ramesh Chitrakar, Auteur ; Keisuke Mizobuchi, Auteur ; Akinari Sonoda, Auteur Année de publication : 2010 Article en page(s) : pp. 8726–8732 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Uptake  aqueous  solutions  Hydroxide Résumé : Batch experiments were performed to examine the BrO3− uptake from dilute aqueous solutions on amorphous aluminum hydroxide (Cl− type), which was synthesized by addition of a 3 mol/dm3 NaOH solution to a 0.1 mol/dm3 AlCl3 solution until the pH reached 5.8. The uptake from a 0.78 μmol/dm3 BrO3− solution (100 μg of BrO3/dm3) was rapid: equilibrium was attained within 3 min. The BrO3− uptake was found to decrease slowly at pH 4−8 and rapidly at pH >8. The isotherm for BrO3− uptake was well fitted with the Freundlich isotherm model. From distribution coefficient (Kd) values determined from mixed solutions containing 0.10, 1.0, and 2.0 mmol/dm3 NaCl, NaBrO3, NaNO3, Na2SO4, and Na2CO3, the selectivity order was reported as NO3− < BrO3− < SO42− at a pH range 4.8−7.9. These results suggest that the BrO3− uptake on the amorphous aluminum hydroxide occurs through an outer-sphere complex reaction. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901705n [article] Uptake of bromate ion on amorphous aluminum hydroxide [texte imprimé] / Ramesh Chitrakar, Auteur ; Keisuke Mizobuchi, Auteur ; Akinari Sonoda, Auteur . - 2010 . - pp. 8726–8732. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8726–8732 Mots-clés : Uptake  aqueous  solutions  Hydroxide Résumé : Batch experiments were performed to examine the BrO3− uptake from dilute aqueous solutions on amorphous aluminum hydroxide (Cl− type), which was synthesized by addition of a 3 mol/dm3 NaOH solution to a 0.1 mol/dm3 AlCl3 solution until the pH reached 5.8. The uptake from a 0.78 μmol/dm3 BrO3− solution (100 μg of BrO3/dm3) was rapid: equilibrium was attained within 3 min. The BrO3− uptake was found to decrease slowly at pH 4−8 and rapidly at pH >8. The isotherm for BrO3− uptake was well fitted with the Freundlich isotherm model. From distribution coefficient (Kd) values determined from mixed solutions containing 0.10, 1.0, and 2.0 mmol/dm3 NaCl, NaBrO3, NaNO3, Na2SO4, and Na2CO3, the selectivity order was reported as NO3− < BrO3− < SO42− at a pH range 4.8−7.9. These results suggest that the BrO3− uptake on the amorphous aluminum hydroxide occurs through an outer-sphere complex reaction. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901705n