Indian Journal of Chemical Technology

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VOLUME 15	NUMBER 3	MAY 2008
CODEN:ICHTEU ISSN:0971-457X

CONTENTS

Papers

Effect of substrate concentration on the transient dynamics of specific cell
growth during bioconversion of Cr^+6 to Cr^+3 using polyculture consortia	209
K Samanta, R Chowdhury & P Bhattacharya
Inhibition of mild steel corrosion in acid media by N- benzyl-N’- phenyl thiourea	216
S Divakara Shetty & Prakash Shetty
Study on corrosion control of N80 steel in acid medium using mixed organic
inhibitors	221
T Kumar, S Vishwanatham & Emranuzzaman
Some schiff bases as corrosion inhibitors for zinc in sulphuric acid	228
M N Desai, J D Talati, C V Vyas & N K Shah
Synthesis of monoesters and diesters using eco-friendly solid acid catalysts
M(IV) tungstates and phosphates	238
Rikesh Joshi, Heemanshu Patel & Uma Chudasama
Clean and efficient synthesis of coumarins over modified metal oxides via
Pechmann reaction	244
Joyce D’Souza & N Nagaraju
Effect of bath composition and operating parameters on deposit character and
corrosion behaviour of Zn-Ni alloy	252
K Venkatakrishna, V Tangaraj & A Chitharanjan Hegde
A study on brightening and corrosive resistance property of electrodeposited
zinc in non-cyanide alkaline bath	259
H B Muralidhara, Y Arthoba Naik, H P Sachin, Ganesha Achary &
T V Venkatesha
Recovery of acetic acid by supported liquid membrane using vegetable oils as
liquid membrane	266
Janani Narayanan & K Palanivelu
Identification and separation of cationic and non-ionic surfactants by reversed
phase thin layer chromatography	271
Ali Mohammad & Rubi Gupta

Hibiscus cannabinus and Hibiscus sabdariffa as an alternative pulp blend for
softwood: Optimization of soda pulping process	277
J S Upadhyaya, Dharm Dutt, Bahadur Singh & C H Tyagi
An extended salt-effect model for organic solubility of water in a 5-100% tri-n-
butyl phosphate/diluent/nitric acid/water biphasic system at 298.15 K	287
Shekhar Kumar, Rajnish Kumar & S B Koganti
Rapid extraction and separation of indium(III) with a high molecular weight amine	291
T N Shilmkar, S S Kolekar, P P Wadgaonkar & M A Anuse
Note
A comparative study of catalytic activity of tin phosphate and tin phenyl phosphonate	298
Chithra P G & Beena B
Trace level extraction and spectrophotometric determination of cyanide in
waste water and biological fluid	301
Anjum Ansari, Sulbha Amlathe & V K Gupta
A simple and sensitive method for determination of carbon disulphide in
environmental and biological samples	306
Urmila Tamrakar, V K Gupta, Sunitha B Mathew & Ajai K Pillai
Book review	310
Author Index	311
Keyword Index	312
Guidelines for Authors	313

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 209-215

Effect of substrate concentration on the transient dynamics of specific cell growth during bioconversion of Cr⁺⁶ to Cr⁺³ using polyculture consortia

K Samanta, R Chowdhury & P Bhattacharya*

The transient dynamics of specific cell growth rate during bioconversion of hexavalent chromium (Cr⁺⁶) to trivalent chromium (Cr⁺³) has been studied covering both Cr⁺⁶ uninhibited and Cr⁺⁶ inhibited conditions in a batch contacting system. Suitable polyculture consortia necessary for this bioconversion have been isolated and purified from tannery waste. It is observed that above the Cr⁺⁶ concentration of 33 mg/dm³, effect of Cr⁺⁶ inhibition on the specific cell growth rate is appreciably high. Detailed simulation and modeling work indicate that while Monod model equation is capable of describing the cell growth dynamics under Cr⁺⁶ uninhibited condition, the same can well be represented by Briggs-Haldane uncompetitive type model equation under Cr⁺⁶ inhibited condition. Since for the present system the difference in magnitudes of two intrinsic kinetic parameters, namely, Monod constant, K_S and the inhibition constant, K_i is not appreciably large, a unified transient specific cell growth dynamic equation has been presented.

Keywords: Transient growth dynamics, Cr⁺⁶ inhibition, Briggs-Haldane equation, Biological switch, Unified rate equation

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 216-220

Inhibition of mild steel corrosion in acid media by N-benzyl-N¢-phenyl thiourea

S Divakara Shetty & Prakash Shetty*

The inhibition effect of N-benzyl-N¢-phenyl thiourea (BPTU) on the corrosion of mild steel in 0.01 and 0.05 N HCl medium has been investigated by potentiostatic polarization technique. Results obtained reveal that BPTU is an efficient anodic inhibitor with greater than 94% of efficiency in the range of temperature studied. The adsorption of inhibitor on the mild steel surface obeys the Temkins’ adsorption isotherm and the inhibition is governed by chemisorption mechanism. The kinetic parameters of adsorption obtained reveal spontaneous adsorption and a strong interaction of the compound on the mild steel surface. The influences of the parameters like temperature, HCl concentration and inhibitor concentration on the corrosion of mild steel has also been investigated.

Keywords: Corrosion inhibition, Mild steel, Hydrochloric acid, Potentiostatic polarization technique, Adsorption, Activation energy

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 221-227

Study on corrosion control of N80 steel in acid medium using mixed
organic inhibitors

T Kumar, S Vishwanatham* & Emranuzzaman

Effects of inhibitor mixtures (TVE-3A, TVE-3B and TVE-3C) containing formaldehyde in combination with phenol or cresol on corrosion behaviour of N80 steel in 15% HCl solution were investigated using weight loss and potentiostatic polarization technique. The influence of temperature (30-115°C) and time interval (6-24 h) in the absence and presence of inhibitors on corrosion of the steel in the acid has been studied. TVE-3B has shown the maximum inhibition of 68.6% at ambient temperature whereas maximum inhibition shown by TVE-3A and TVE-3C was found to be 62.2% and 65.7% respectively. The inhibition efficiency was found to gradually decrease with increase in temperature in the case of TVE-3A while TVE-3B and TVE-3C showed a further increase in the protection at higher temperatures (about 81% at 115°C). The protective efficiency of TVE-3B and TVE-3C is comparable with Grade-III (about 88% at 115°C) commercial inhibitor. Inhibition of corrosion is due to adsorption of inhibitors on the metal surface. The adsorption is found to obey Frumkin isotherm. FTIR study of the metal surface products after the corrosion inhibition tests reveal presence of non-linear poly phenyl species, no free carbonyl group indicating formation of a cross linked and three dimensional networking resulting in novalac resin or bakelite by condensation polymerization (acid catalyzed). Oxygen atom, (of –OH group in phenol or substituted phenol) may coordinate to Fe²⁺ on the metal surface resulting in a protective inhibitor layer. Thermal stability of the inhibitor mixtures was determined by DSC, which has shown that the compounds present in TVE-3A vaporize with increase in temperature while the compounds present in the case of TVE-3B and TVE-3C are thermally stable up to 200°C.

Keywords: Corrosion inhibitor, N80 Steel, Phenol, Cresol

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 228-237

Some Schiff bases as corrosion inhibitors for zinc in sulphuric acid

M N Desai, J D Talati, C V Vyas & N K Shah*

The inhibition of corrosion of zinc in sulphuric acid by Schiff bases aniline-N-benzylidene(ANB), aniline-N-salicylidene(ANS), aniline-N-p-methoxybenzylidene(ANPMB), p-methoxybenzylidene-4,4¢-dimorpholine(p-MBDM) and salicylidene-4-4¢-dimorpholine(SDM) has been studied with respect to inhibitor concentration, exposure period, and temperature. More than 99% inhibition is achieved with 0.5% concentration of inhibitor except in case of ANB whose efficiency is found to decrease with time and rise in temperature. The activation energies in inhibited acid are higher than that in plain acid. For all the inhibitors, the heats of adsorption and free energies of adsorption are negative, while the entropies of adsorption are positive. The free energies are more negative in the case of inhibitors like ANS, SDM, ANPMB and p-MBDM. It appears that an efficient inhibitor is characterized by a relatively greater decrease in free energy of adsorption and less negative entropies of adsorption. Galvanostatic polarization data suggest that these are mixed type inhibitors with preferential action on local cathodes. Cathodic protection studies suggest that the protection is achieved at current densities much lower than that in plain acid. The conjoint effect of external cathodic current and the inhibitor is observed to be synergistic in most of the cases. The inhibitors appear to function through adsorption following Langmuir isotherm.

Keywords: Acid inhibition, Cathodic protection, Schiff bases, Zinc

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 238-243

Synthesis of monoesters and diesters using eco-friendly solid acid catalysts- M(IV) tungstates and phosphates

Rikesh Joshi, Heemanshu Patel & Uma Chudasama*

The present study involves synthesis and characterization of amorphous M(IV) phosphates and tungstates [M(IV) = Zr, Ti and Sn] which are inorganic ion exchangers of the class of tetravalent metal acid (tma) salts. The presence of protons contained in the structural hydroxyl groups indicates good potential for application in solid acid catalysis. The catalytic activity of the materials abbreviated as ZrP, TiP, SnP, ZrW, TiW and SnW has been explored by synthesizing some monoesters and diesters. Good yields are obtained in the case of monoesters as compared to diesters. The results reveal the promising use of tma salts as solid acid catalysts.

Keywords: Solid acid catalyst, Esterification, M(IV) phosphates and tungstates, Tetravalent metal acid salts, Inorganic ion exchangers

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 244-251

Clean and efficient synthesis of coumarins over modified metal oxides via Pechmann reaction

Joyce D’Souza & N Nagaraju*

The catalytic activity of solid acids such as zirconia, alumina and silica and their SO₄^2-, PO₄^3- and BO₃^3- modified forms has been studied in the Pechmann reaction between resorcinol and ethylacetoacetate under solvent-free liquid phase reflux conditions and autogenous pressure. A systematic study of this reaction has been made by varying the following parameters: catalyst, amount of catalyst, duration and temperature of reaction and molar ratio of reactants. Under refluxing conditions, in the presence of sulphated zirconia, the percentage yield of the product, 7-hydroxy 4-methyl coumarin was in the range of 30-75% which, however, contained many impurities. When the same reaction was conducted in an autoclave at 150°C, the clean product of yields upto 99% was obtained. Other phenols used in this work include catechol, hydroquinone, m-cresol, p-cresol, o-cresol, pyrogallol, phloroglucinol, orcinol, m-aminophenol and phenol. The sites of higher acid strength and perhaps super-acidic sites on the catalyst appear to be catalyzing the formation of coumarins via Pechmann reaction. Sulphated zirconia is found to be a promising catalyst for this reaction under autogenous conditions.

Keywords: Pechmann reaction, Coumarins, Solid acids, Metal oxides, Sulphate-, borate-, phosphate-modified zirconia, Alumina and silica

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 252-258

Effect of bath composition and operating parameters on deposit character and corrosion behaviour of Zn-Ni alloy

K Venkatakrishna, V Tangaraj & A Chitharanjan Hegde^*

Electrodeposited Zn-Ni alloys are extensively used as protective coatings for steel substrates and hence the studies on the factors which enhance corrosion resistance are of considerable significance. The present work details the optimization of acid chloride bath for bright Zn-Ni alloy over mild steel and study of the parameters which influence Ni content in the deposit. Use of sulphanilic acid and gelatin was found to show significant effect on brightness of the deposit. The effect of molar ratio of Ni⁺²/Zn^{+2 in the bath on limiting current density of nickel deposition was emphasized. Under no conditions of bath compositions and operating parameters studied, the change in codeposition behaviour from anomalous to normal type was observed. The wt. %Ni in the deposit was found to be the independent factor of its corrosion resistance. The photomicrograph of electroplates confirmed that superior corrosion resistance is due to good surface morphology. The effect of bath composition, current density (c.d.), pH and temperature on appearance, hardness and corrosion resistance of deposits were studied and discussed. Corrosion behaviour of electroplates has been studied by Tafel's extrapolation method. Electrochemical impedance spectroscopy analysis revealed that superior corrosion resistance of Zn-Ni alloy coatings at optimized current density is due to barrier resistance at the interface of deposit and medium. Formation of n-type semiconductor film at the interface was confirmed by Mott-Schottky plot. Addition of small amount of cadmium chloride did not increase corrosion resistance.}

Keywords: Zn-Ni alloy, Chloride bath, Corrosion resistance, Surface morphology, Electrochemical impedance

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 259-265

A study on brightening and corrosive resistance property of electrodeposited zinc in non-cyanide alkaline bath

H B Muralidhara, Y Arthoba Naik*, H P Sachin, Ganesha Achary & T V Venkatesha

Zinc was electrochemically deposited from non-cyanide alkaline bath solution containing condensation product formed between anthranillic acid (ANA) and furfural (FFL). The bath constituents and bath variables were optimized through standard Hull cell experiments. Current efficiency, throwing power, cathodic polarization and corrosion behaviour in 3.5% NaCl were studied under optimum concentration of additives and their effects were reported. Tafel polarization curves of the electrodeposited layers in 3.5% NaCl solution have been drawn. Weight loss and open circuit potentials were measured in order to study corrosion behaviour of zinc coated samples with and without additives. Structure of the deposits were characterized using scanning electron microscopic technique.

Keywords: Alkaline bath, Anthranillic acid, Electroplating of zinc, Hull cell studies, Furfural

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 266-270

Recovery of acetic acid by supported liquid membrane using vegetable oils as liquid membrane

Janani Narayanan & K Palanivelu*

An attempt has been made to recover acetic acid from aqueous solutions using supported liquid membrane (SLM) technique. A flat sheet polytetrafluoroethylene (PTFE) supported membrane impregnated with vegetable oils was tested for transport of acetic acid. The permeation of acetic acid was studied by varying the experimental conditions namely strength of stripping phase, stirring speed and selection of LM. The oils tested for acetic acid transport included sunflower oil, coconut oil, palm oil and peanut oil, among which, sunflower oil gave best results with permeability of 2.86 x 10^-2 m/s against a stripping solution of strength 0.1 N. After 4 h, 100% transport of acetic acid of initial concentration 0. 01 M was observed.

Keywords: Supported liquid membrane, Acetic acid recovery, Vegetable oils

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 271-276

Identification and separation of cationic and non-ionic surfactants by reversed phase thin layer chromatography

Ali Mohammad* & Rubi Gupta

Reversed phase thin layer chromatography (RPTLC) of non-ionic and cationic surfactants was performed on silica gel layers impregnated with 5% paraffin oil, silicone oil and tributyl phosphate as stationary phases using water and organic polar solvents as mobile phases. In all, four stationary phases and twelve mobile phases were used to examine the mobility pattern and to find out best TLC system for separation of surfactants from their mixtures. The TLC system comprising of 5% paraffin oil impregnated silica gel layers as stationary phase and pure methanol as mobile phase was found most favourable for achieving separation of non-ionic surfactants (Tx-100, Brij-35 and Tween-20) from cationic surfactants (CPC, CTAB and TTAB). The effects of loading amount of analyte and metal cations impurities in the sample have been examined on mutual separation of Tx-100 and TTAB. The results obtained with methanol were compared with those obtained with ethanol and butanol. The mobility of surfactants was found to increase with the increase of polarity of the alcohol used as mobile phase.

Keywords: Reversed phase TLC, Surfactants, Identification, Separation

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 277-286

Hibiscus cannabinus and Hibiscus sabdariffa as an alternative pulp blend for softwood: Optimization of soda pulping process

J S Upadhyaya, Dharm Dutt^*, Bahadur Singh & C H Tyagi

Due to dearth of forest based raw materials paper technocrats have explored the possibility of alternate cellulosic fibrous raw materials. H. cannabinus and H. sabdariffa—agro-based residues bear the characteristics of both, the softwood and hardwood fibers. The bast fibers of H. cannabinus and H. sabdariffa underneath the bark resemble with softwood and core fibers with hardwood. Morphological analysis and chemical composition of H. cannabinus and H. sabdariffa show their suitability for producing paper of various grades. This study provides optimized soda pulping conditions for better utilization of H. cannabinus and H. sabdariffa. Due to identical pulping conditions, H. cannabinus and H. sabdariffa can be delignified together. The optimum cooking conditions for H. cannabinus and H. sabdariffa were found to be as, active alkali 18% (as NaOH), temperature 165°C, time (at temperature) 180 min and wood to liquor ratio of 1:4.5. An AQ dose of 0.05% at an active alkali dose of 13% (as Na₂O) produces the screening rejects and kappa number similar to that obtained by using 15% active alkali (as Na₂O).

Keywords: Soda pulping, Lignin, Pulp yield, Kappa number, Activation energy, I^st order reaction constant, Non-wood plants, Agriculture residues

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 287-290

An extended salt-effect model for organic solubility of water in a 5-100% tri-n-butyl phosphate/diluent/nitric acid/water biphasic system at 298.15 K

Shekhar Kumar*, Rajnish Kumar & S B Koganti

The solubility of water in the organic solutions, containing hydrocarbons, has traditionally been modeled by using empirical correlations. In this communication, an extended Setschenow model is proposed for predicting the organic solubility of water in a 5-100% tri-n-butyl phosphate/diluent-nitric acid-water biphasic system at 298.2 K. The literature data on water solubility were correlated to aqueous acid concentration and diluent concentration in the solvents. The proposed model was extended for temperature dependency of the solubility.

Keywords: Solubility, PUREX process, TBP, Salt-effect, Setschenow models

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 291-297

Rapid extraction and separation of indium(III) with a high molecular weight amine

T N Shilmkar, S S Kolekar, P P Wadgaonkar & M A Anuse*

The liquid-liquid extraction of indium(III) from sodium succinate media using n-octylaniline in toluene as an extractant was studied. Quantitative extraction of indium(III) was observed in the range of 0.004-0.0075 M sodium succinate at pH 3.8-6.0 with 4% n-octylaniline in toluene. Indium(III) was completely stripped from the metal loaded organic phase of the extractant with water and determined complexometrically. The stoichiometry of the extracted species was determined on the basis of slope analysis. The extraction was found to proceed by a ion-pair mechanism with the extracted species being [RNH₃⁺In(succinate)₂‾]_org. Separation of indium(III) was carried out from some associated metals like Tl(I), Mg(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Pb(II), Ge(IV), Sb(III), Bi(III). The selectivity of the extraction of indium(III) can also be achieved by use of a suitable masking agent for estimation and determination from the synthetic mixture corresponding to alloy to show the practical utility of the extractant.

Keywords: Indium(III), n-Octylaniline, Solvent extraction, Separation, Succinate

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 298-300

A comparative study of catalytic activity of tin phosphate and tin phenyl phosphonate

Chithra P G* & Beena B

Amorphous ion exchangers tin(IV) phosphate and tin(IV) phenyl phosphonate have been prepared and characterized. Catalytic activity has been studied and compared by using esterification of ethylene glycol as a model reaction wherein glycol diacetate has been prepared. The materials indicate good potential for Bronsted acid catalysis for the above reaction.

Keywords: Tin phenyl phosphate, catalytic activity, Tin phosphate

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 301-305

Trace level extraction and spectrophotometric determination of cyanide in waste water and biological fluid

Anjum Ansari, Sulbha Amlathe* & V K Gupta

An extractive spectrophotometric method for the determination of cyanide in wastewater is developed. Cyanide is reacted with bromine to form cyanogen bromide, which subsequently reacts with pyridine. Glutaconic aldehyde is formed through the heterolytic cleavage of pyridine ring, which is then coupled with 4-amino salicylic acid. A yellow orange dye formed in alkaline medium is extractable in n-butanol in acidic medium. The extract shows absorbance maxima at 520 nm. The system obeys Beer’s law in the range of 0.03-0.20 mg/mL. Important analytical parameters such as time, temperature, reagent concentration, acidity etc. have been optimized for complete colour reaction. Sandell’s sensitivity and molar absorptivity for the system have been calculated. The method has been successfully applied for determination of cyanide in wastewater and biological fluid.

Keywords: Spectrophotometry, Cyanide, Pyridine, 4-Amino salicylic acid, n-Butanol, Sodium arsenite

Indian Journal of Chemical Technology

Vol. 15, May 2008, pp. 306-309

A simple and sensitive method for determination of carbon disulphide in environmental and biological samples

Urmila Tamrakar, V K Gupta, Sunitha B Mathew & Ajai K Pillai^*

An analytical method using potassium dichromate and diphenylcarbazide for determination of carbon disulphide has been proposed. In this method carbon disulphide reduces the Cr(VI) to Cr(III) and the unreduced Cr(VI) forms a pink-purple complex with diphenylcarbazide in acidic medium, which is measured spectrophotometrically at 530 nm. Beer’s law is obeyed over a concentration range of 0.01 to 0.1 µg mL^-1. Molar absorptivity and Sandell's sensitivity were found to be 5.5 × 10 ⁵ L mol^‑1 cm^‑1 and 0.00013 µg cm^‑2 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination of CS₂ was studied. The method has been successfully applied for the determination of CS₂ in grain samples, fungicides (ziram, thiram) and various environmental and biological samples.

Keywords: Spectrophotometric method, Carbon disulphide, Diphenylcarbazide, Potassium dichromate