Indian Journal of Chemistry

Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical

http://www.niscair.res.in; http://nopr.niscair.res.in

Total visitors: 954 since 15-9-2016

CODEN: ICACEC; ISSN: 0376-4710 (Print), 0975-0975 (Online)

 

 

 

VOLUME 55A

NUMBER 9

SEPTEMBER 2016

 

CONTENTS

 

 

1045

 

Influence of sulphonic acid groups on enhanced anchoring of Pt to carbon black support and hence enhanced methanol oxidation activity

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

S Chandravathanam & B Viswanathan*

 

 

 

Grafting of alkyl sulphonic acid groups on Pt/CDX975 catalyst shows redistribution of Pt nanoparticles on the carbon black support, along with enhanced activity for methanol electrooxidation. Sulphonation with sodium sulphite and formaldehyde shows better performance and stability than that by diazotization with 2-aminoethanesulfonic acid and sodium nitrite in the presence of mineral acid

 

 

 

 

1052

 

Investigation on the role of hydrous ruthenium oxide in PtRu/C catalyst for methanol electrooxidation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jingjing Yang, Yuan-Yuan Chu*, Zhen-Bo Wang,
Yu Qian, Yongxiang Jin, Xiaoyao Tan*

 

 

 

PtRu/Vulcan XC-72 catalyst with high catalytic performance has been synthesized by microwave-assisted polyol process. The effect of annealing on performance of the PtRu/C catalyst has been investigated. Prior to the annealing treatment, the as-prepared PtRu/C catalyst has a small particle size and a relatively high amount of Pt and Ru in their metallic state, along with some amount of hydrous ruthenium oxides, all of which contribute to the higher activity of catalyst. On the other hand, after annealing at 300 °C for 1 h, the anhydrous ruthenium oxide is found to be less active for methanol electrooxidation.

 

 

 

 

1059

 

Oxidative degradation of norfloxacin by water soluble colloidal MnO2 in the presence of cationic surfactant

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ajaya Kumar Singh*, Neelam Sen &
Som Kumar Chatterjee

 

 

 

The oxidative degradation of norfloxacin by water soluble colloidal MnO2 in alkaline medium is studied spectrophotometrically at
298 K,
in the absence and presence of the cationic surfactant, cetyltrimethylammonium bromide. Under pseudo-first order condition with respect to [MnO2], positive fractional order and negative fractional order are observed with respect to [NOR] and [NaOH] respectively in both aqueous and micellar media. The rate constant increases with decreasing dielectric constant of the medium in both the systems.

 

 

 

 

Notes

 

1068

 

Kinetics and mechanism of oxidation of thiourea by Waugh-type enneamolybdomanganate(IV) in aqueous perchloric acid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Shekhar S More & Gavisiddappa S Gokavi*

 

 

The Waugh-type polyoxometalate, enneamolybdomanganate(IV), oxidizes thiourea in aqueous perchloric acid to give formamidine disulphide. The proposed mechanism involves formation of a precursor complex which decomposes in a slow step.

 

 

 

1074

 

Kinetics and mechanism of electron transfer reaction: Oxidation of sulfanilic acid by hexachloroiridate(IV) in acid medium

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Riya Sailani, Deepmala Pareek, Anita Meena,
Kritika Jangid & Chandra L Khandelwal
*

 

 

 

Kinetics of oxidation of sulfanilic acid by [IrCl6]2- in acid medium is studied. The reaction is overall second order, being first order with respect to each reactant. However, the rate is retarded by hydrogen ion concentration. The activation parameters such as energy and entropy of activation calculated by Eyring equation are found to be 59.99±0.93 kJ mol-1 and –106.44±2.2 J K-1 mol-1 respectively. The oxidation product, 2-keto-azoxy- benzene-4,4′-disulfonic acid has been confirmed spectrally.

 

Graphical abstract_Corr.tif

 

 

 

 

1080

 

Intermolecular interactions in sulfuric acid-water system

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Renu Loshali* & Narain D Kandpal

 

 

Viscosity and density of aqueous concentrated sulfuric acid
(1.0–9.0) mol dm−3 have been measured at 297.65 K and the values of A and B coefficients of Jones-Dole equation have been calculated from the viscosity data. The interaction parameters obtained from Jones-Dole equation confirm the presence of three concentration regions of sulfuric acid in water with the following order of B coefficient: 1.0–4.0 mol dm−3 < 4.0–7.0 mol dm−3 < 7.0–9.0 mol dm−3. In the concentration range of 1.0–4.0 mol dm−3, the existence of HSO53− has been proposed. In the concentration range of 4.0–7.0 mol dm−3, intermolecular association is more effective due to the large number of bond formation between
the solute and solvent molecules. In the concentration range of 7.0–9.0 mol dm−3, the solute-solvent interaction attains the higher value and intermolecular forces are strong due to the formation of hydrated species like H2SO4.H2O.

 

 

 

 

1084

 

Sodium polystyrene sulfonate template assisted hydrothermal synthesis of hydroxyapatite nanorods

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pakvipar Chaopanicha & Punnama Siriphannon

 

 

 

Hydroxyapatite nanoparticles (nHAp) have been synthesized by benign hydrothermal reaction from the aqueous mixture of Ca(NO3)2·4H2O and (NH4)2HPO4 solutions in the presence of
non-toxic sodium polystyrene sulfonate (PSS) template.
. The PSS template generates the largely negative surface of dicalcium phosphate dihydrate precursor, resulting in minimization of precursor agglomeration and promoting the hydrothermal growth of nHAp along the preferential c-axis as rod-shaped crystals. The crystallite sizes along 002-plane of nHAp synthesized with and without PSS template are 47.1 and 29.5 nm, respectively. With longer hydrothermal treatment time, larger crystallite size of nHAp is obtained.

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

 


Online Submission for IJCA Articles

 

Articles submitted for consideration of publication in the Indian J Chem, Sec A, should be uploaded through our Online Submission portal, http://op.niscair.res.in. Articles submitted by email or postal services shall not be processed.

Authors are requested to register at http://op.niscair.res.in. The articles (in MS Word) appended with the certificate of originality, illustrations (jpeg/tiff) and supplementary data,
if any, may be uploaded through the User Home page. Further information is available
at http://www.niscair.res.in/jinfo/author_guidelines_online_submission.pdf.

For technical support and assistance for online submission, Shri Sanjay Burde may be contacted (sanjayburde@niscair.res.in); Tel.: 91-11-25846301.

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1045-1051

 

 

Influence of sulphonic acid groups on enhanced anchoring of Pt to carbon black support and hence enhanced methanol oxidation activity

S Chandravathanama & B Viswanathanb,*

aDepartment of Chemistry, SRM University, Kattankulathur 603 203, Tamil Nadu, India

bNational Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras,
Chennai 600 036, Tamil Nadu, India

Email: bvnathan@iitm.ac.in

Received 12 July 2016; revised and accepted 31 August 2016

Sulphonic acid groups have been introduced on Pt supported carbon black catalyst by two different methods, i. e., (i) alkyl sulfonic acid group incorporated on the carbon black support through diazotization step by the reaction of 2-aminoethanesulfonic acid and sodium nitrite in the presence of mineral acid and (ii) methylsulfonic acid group incorporated using sodium sulphite and formaldehyde. The prepared catalysts have been characterized by FT-IR, XRD, TGA, SEM, TEM and electrochemical methods. The catalysts prepared by both the methods have shown the redistribution of Pt nanoparticles on the carbon black support upon introduction of the sulphonic acid groups, along with enhanced activity for methanol oxidation. Among these two methods of sulphonation, the latter with sodium sulphite and formaldehyde has shown better performance and stability.

Keyword: Catalysts, Platinum catalysts, Sulphonation, Oxidation, Methanol oxidation

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1052-1058

 

 

Investigation on the role of hydrous ruthenium oxide in PtRu/C catalyst
for methanol electrooxidation

Jingjing Yanga, Yuan-Yuan Chua, *, Zhen-Bo Wangb, Yu Qiana, Yongxiang Jina & Xiaoyao Tana, *

aState Key Laboratory of Separation Membranes and Membrane Processes,
Tianjin Polytechnic University, No.399 Binshui West Road, Tianjin 300387, China

bSchool of Chemical Engineering and Technology, Harbin Institute of Technology,
No. 92 West-Da Zhi Street, Harbin 150001, China

Email: chuyuanyuan1982@163.com (Y-Y Chu)

Received 25 March 2016; revised and accepted 26 August 2016

PtRu/Vulcan XC-72 catalyst with high catalytic performance has been synthesized by microwave-assisted polyol process, heat-treated, and characterized by X-ray diffraction, X-ray photoelectron spectra, transmission electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Their electrochemical performance has been tested by cyclic voltammetry, chronoamperometry curves, and CO-stripping techniques. The effect of annealing treatment on performance of the PtRu/C catalyst has been investigated. The results show that prior to the annealing treatment the as-prepared PtRu/C catalyst has a small particle size and has a relatively high amount of Pt and Ru in their metallic state, along with some amount of hydrous ruthenium oxides (RuOxHy), all of which contribute to the higher activity of catalyst. On the other hand, the anhydrous ruthenium oxide, which exist after the catalyst is annealed at 300 °C for 1 h, is found to be less active for methanol electrooxidation.

Keywords: Catalysts, Direct methanol fuel cell PtRu/C electrocatalysts, Annealing treatment, Anode catalyst, Electrooxidation, Methanol electrooxidation

 

 

 

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1059-1067

 

 

Oxidative degradation of norfloxacin by water soluble colloidal MnO2
in the presence of cationic surfactant

Ajaya Kumar Singha,*, Neelam Sena & Som Kumar Chatterjeeb

aDepartment of Chemistry, Government Vishwanath Yadav Tamaskar Post Graduate Autonomous
College Durg, Chhattisgarh, 491 001, India

Email: ajayaksingh_au@yahoo.co.in

bDepartment of Chemistry, Government Narayan Rao Meghawale Girls College,
Dhamtari
Chhattisgarh 493 773, India

Received 7 October 2015; revised and accepted 31 August 2016

The oxidative degradation of norfloxacin (NOR) by water soluble colloidal MnO2 in alkaline medium has been studied spectrophotometrically in the absence and presence of cationic surfactant, cetyltrimethylammonium bromide (CTAB) at 298 K. The rate of reaction has been followed under pseudo-first order condition with respect to [MnO2]. Positive fractional order and negative fractional order are observed with respect to [NOR] and [NaOH] respectively in both aqueous and micellar media. The rate constant increases with decreasing dielectric constant of the medium in both the systems. The retardation effect observed by CTAB is discussed by well known Berezin’s model and from this model micelle binding constant has been computed. Using the Arrhenius equation, thermodynamic activation parameters have also been evaluated in both the media. On the basis of experimental results suitable mechanism and rate law are proposed.

Keywords: Kinetics, Reaction mechanisms, Degradation, Oxidative degradation, Surfactants,
Cationic surfactants, Colloidal MnO2, Norfloxacin, Cetyltrimethylammonium bromide

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1068-1073

 

 

Kinetics and mechanism of oxidation of thiourea by Waugh-type enneamolybdomanganate(IV) in aqueous perchloric acid

Shekhar S More & Gavisiddappa S Gokavi*

Department of Chemistry, Shivaji University, Kolhapur 416 004, Maharashtra, India

Email: gsgokavi52@gmail.com

Received 20 April 2016; revised and accepted 21 August 2016

The Waugh-type polyoxometalate, enneamolybdomanganate (IV), oxidizes thiourea in aqueous perchloric acid, to give formamidine disulphide as confirmed by HRMS spectra. The rate of reaction increases linearly as hydrogen ion and thiourea concentrations increase, while it remains constant as the concentration of oxidant, enneamolybdomanganate(IV), is varied. The protonated form of the oxidant and the unprotonated form of thiourea were found to be active species of the reaction. The protonation and the interaction of thiourea with the oxidant have been supported by UV-vis spectral studies. The reaction is found to be initiated by nucleophilic attack of unprotonated thiourea on the protons attached to the oxygen atoms directly bound to the Mn(IV) centre. The interaction between the thiourea and the oxidant to form a precursor complex has been verified spectrophotometrically. The proposed mechanism, in accordance with the kinetic results obtained, involves formation of a precursor complex between thiourea and oxidant which decomposes in a slow step. The corresponding sulfenic acid is the intermediate formed due to the decomposition of the complex which reacts with another thiourea molecule giving the final product. The rate law derived as per the proposed mechanism is also verified kinetically. The results of effects of ionic strength, solvent polarity and the temperature also support the proposed mechanism.

 Keywords: Kinetics, Oxidation, Polyoxometalate oxidation, Reaction mechanism, Enneamolybdomanganate, Thiourea

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1074-1079

 

 

Kinetics and mechanism of electron transfer reaction: Oxidation of sulfanilic acid by hexachloroiridate(IV) in acid medium

Riya Sailani, Deepmala Pareek, Anita Meena, Kritika Jangid & Chandra L Khandelwal*

Department of Chemistry, University of Rajasthan, Jaipur 302 055, India

Email: clkhandelwal@ymail.com

Received 8 December 2015; revised and accepted 21 August 2016

The kinetics of oxidation of sulfanilic acid by [IrCl6]2- in acid medium has been studied. The reaction is overall second order being first order with respect to each reactant. However, rate is retarded by hydrogen ion concentration. Various proposals have been suggested on the basis of reactivity of Ir(IV) species. The activation parameters such as energy and entropy of activation calculated by Eyring equation are found to be 59.99±0.93 kJ mol-1 and -106.44±2.2 J K-1 mol-1 respectively. The oxidation product, 2-keto-azoxy- benzene-4,4′-disulfonic acid has been confirmed spectrally.

Keywords: Kinetics, Reaction mechanisms, Oxidation, Electron transfer reactions, Sulfanilic acid, Hexachloroiridate(IV)

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1080-1083

 

 

Intermolecular interactions in sulfuric acid-water system

Renu Loshali* & Narain D Kandpal

Physical Chemistry Laboratory, Department of Chemistry, Kumaun University, SSJ Campus,
Almora 26301, Uttarakhand, India

Email: renu.loshali@gmail.com

Received 3 May 2016; revised and accepted 30 August 2016

Viscosity (ƞ) and density (ρ) of aqueous concentrated sulfuric acid (1.0–9.0) mol dm−3 have been measured at 297.65 K and the values of A and B- coefficients of Jones-Dole equation have been calculated from the viscosity data. The value of B-coefficient is positive which suggests a strong ion-solvent interaction in aqueous sulfuric acid. It is assumed that in concentrated aqueous sulfuric acid, HSO53- acts as structure maker. Three concentration regions of sulfuric acid having value of B-coefficient (measure of ion-solvent interaction or structure making capacity) in the order 1.0–4.0 mol dm−3 < 4.0–7.0 mol dm−3 < 7.0–9.0 mol dm−3 have been proposed.

Keywords: Intermolecular interactions, Viscosity, Jones-Dole equation, Parabisulfate anion

 

Indian Journal of Chemistry

Vol. 55A, September 2016, pp. 1084-1089

 

 

Sodium polystyrene sulfonate template assisted hydrothermal synthesis of hydroxyapatite nanorods

Pakvipar Chaopanicha & Punnama Siriphannon a, b, *

aDepartment of Chemistry, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang,
Chalongkrung Road, Ladkrabang, Bangkok 10520, Thailand

bFunctional Nanostructured Materials Laboratory, College of KMITL Nanotechnology, King Mongkut's Institute of
Technology Ladkrabang, Chalongkrung Road, Ladkrabang, Bangkok 10520, Thailand

Email: punnama.si@kmitl.ac.th

Received 8 February 2016; revised and accepted 31 August 2016

Hydroxyapatite nanoparticles (nHAp) have been synthesized by benign hydrothermal reaction from the aqueous mixture of Ca(NO3)2·4H2O and (NH4)2HPO4 solutions in the presence of non-toxic sodium polystyrene sulfonate (PSS) template. The pH of starting precursors has been adjusted to 10.5 before hydrothermal treatment at 100°C for 1, 2 and 3 h. The added PSS template generates the largely negative surface of dicalcium phosphate dihydrate (DCPD) precursor, resulting in minimization of precursor agglomeration and promoting the hydrothermal growth of nHAp along preferential c-axis as rod-shaped crystals. The crystallite sizes along 002-plane of nHAp synthesized with and without PSS template are 47.1 and 29.5 nm, respectively. With longer hydrothermal treatment time, larger crystallite size of nHAp is obtained. In vitro cytotoxicity of the synthesized nHAp has been evaluated by MTT assay using African green monkey kidney fibroblast cells, in which the nHAp exhibits low cytotoxicity. Antibacterial activities of the synthesized nHAp against S.aureus and E.coli have been tested. Due to the presence of largely negative surface, the nHAp could inhibit only the gram-positive S.aureus, creating a clear zone of about 9.5 mm.

Keywords: Hydroxyapatite nanoparticles, Hydrothermal synthesis, Polyelectrolytes, Nanorods