Indian Journal of Chemical Technology

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VOLUME 15	NUMBER 4		JULY 2008
CODEN:ICHTEU		ISSN:0971-457X

CONTENTS

Papers
Electrochemical behaviour of pyridostigmine bromide-an anticolinergic drug at polyaniline/polypyrrole composite polymer electrode	319
D C Tiwari, Rajeev Jain & Shraddha Sharma
Jute-fibre glass-plywood/particle board composite	325
D N Goswami, M F Ansari, A Day, N Prasad & B Baboo
Mathematical modelling of the washing zone of an industrial rotary vacuum washer	332
Shelly Arora, S S Dhaliwal & V K Kukreja
Sorption of Pb(II) and Cd(II) ions onto chemically unmodified and modified oil palm fruit fibre adsorbent: Analysis of pseudo second order kinetic models	341
A A Abia & E D Asuquo
Adsorption of comb-type superplasticizers on calcium carbonate in alkaline medium in presence of electrolytes and rheological properties	349
Sarita Rai & N S Gajbhiye
Blends of polyvinyl pyrrolidone and polyacrylamide as corrosion inhibitors for aluminium in acidic medium	355
S A Umoren & E E Ebenso
Some triphosphates as corrosion inhibitors for mild steel in 3% NaCl solution	364
Suman Lata & R S Chaudhary
Enhanced corrosion resistance of rebar embedded in fly ash added concrete: Role of “k” factor	375
R Vedalakshmi, K Rajagopal & N Palanisamy
Selective flocculation of celestite from celestite-calcite fines	383
A Ozkan & H Ucbeyiay
Identification of various chemical phenomena in concrete using thermal analysis	388
R Vedalakshmi, A Sundara Raj & N Palaniswamy
Recovery of chromium(VI) from electroplating effluent by solvent extraction with tri-n-butyl phosphate	397
S K Sahu, Vijay K Verma, D Bagchi, Vinay Kumar & B D Pandey
Extraction chromatographic studies of Gallium (III), Indium (III) and Thallium (III) with n-octylaniline		403
Haribhau R Aher & Shashikant R Kuchekar
Interaction studies in binary liquid mixtures of methyl formate with o-, m- and p-xylenes using viscosity data at 303.15K		409
M V Rathnam, Sudhir Mohite & M S S Kumar
Notes
Arsenic removal from water using activated carbon obtained from chemical activation of jute stick		413
M Israt Jahan, M Abdul Motin, M Moniuzzaman & M Asadullah
Investigation on pH dependent uptake of Cr(III) and Cr(VI) by Baker’s yeast		417
Susanta Lahiri & Kamalika Roy
Pressure casting of composite propellant		420
Ganesh Dombe, M Jain, P P Singh, K K Radhakrishnan & B Bhattacharya
Author Index		425
Keyword Index		426
Guidelines for Authors		427

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 319-324

Electrochemical behaviour of pyridostigmine bromide-an anticolinergic drug at polyaniline/polypyrrole composite polymer electrode

D C Tiwari¹, Rajeev Jain^2* & Shraddha Sharma²

¹School of Studies in Physics, ²School of Studies in Chemistry, Jiwaji University, Gwalior, 474011, India

Email: rajeevjain54@yahoo.co.in

A composite polymer surface coated on a tin oxide offers dramatic improvement in the stability and sensitivity of voltammetric measurement of pyridostigmine bromide as compared to individual tin oxide, polyaniline or polypyrrole coated electrode. A linear current response was achieved with a detection limit of 1x10^-6 M. The stability and morphology of the polymer surfaces were determined by thermogravimetry and scanning electron microscopy respectively. The results suggest that composite polymer electrode is the best detector for pyridostigmine bromide (PB) at lower concentration.

Keywords: Composite polymer, Pyridostigmine bromide, Polyaniline, Polypyrrole, Cyclic voltammetry, Scanning Electron Microscopy, Thermogravimetry

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 325-331

Jute-fibre glass-plywood/particle board composite

D N Goswami, M F Ansari*, A Day¹, N Prasad & B Baboo

Division of Lac Processing and Product Development, Indian Lac Research Institute, Namkum, Ranchi 834 010, India

¹National Institute of Research for Jute and Allied Fibre Technology, 12 Regent Park, Kolkata 700 040, India

Email: mfansari@rediffmail.com

Jute-fibre glass reinforced sheets were prepared with shellac-containing sheet moulding compound. Highest tensile strength and tensile modulus values of jute-fibre glass composites were obtained in the range of 49.76-51.71 MPa and 1.84–1.85 Gpa repectively. Flexural strength and flexural modulus were found to be 72.97-95.98 Mpa and 2.7-4.2 GPa respectively. Flexural strength values were found to be in the range of those of the reinforced sheets prepared using fiberglass alone, when the thickness of the sheets was increased up to 7-7.5 mm. Flame retardance of the sheets could be improved with the use of flame retardant. Thermal resistance of the sheets was found to be upto 220^oC. Lamination of plywood and particleboard was also tried with jute-fibre glass, which yielded improved mechanical properties.

Keywords: Jute-fibre glass plywood, Particle board composite, Fibre reinforced composite

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 332-340

Mathematical modelling of the washing zone of an industrial rotary
vacuum washer

Shelly Arora¹, S S Dhaliwal & V K Kukreja*

Department of Mathematics, Sant Longowal Institute of Engineering and Technology, Longowal 148106, India

¹Department of Mathematics, Punjabi University, Patiala, India

Email: vkkukreja@lycos.com

The flow of miscible fluids through the beds of finite length to investigate the mechanism of displacement washing is presented through a diffusion-dispersion model. The model is based on phenomenon of diffusion-dispersion in porous cylindrical particles, e.g., fibers. The data of 4^th stage industrial brown stock washer is used for simulation. Empirical relations have been found between key parameters such as cake thickness, fiber porosity, bed porosity and fiber consistency. Concentration of black liquor solids in discharge pulp and efficiency parameters have been correlated using least square principle.

Keywords: Washing process, Displacement ratio, Percentage efficiency, Wash yield, Distribution ratio, Peclet number

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 341-348

Sorption of Pb(II) and Cd(II) ions onto chemically unmodified and modified oil palm fruit fibre adsorbent: Analysis of pseudo second order kinetic models

A A Abia* & E D Asuquo

Department of Pure and Industrial Chemistry, University of Port Harcourt, P. M. B. 5323, Choba, Port Harcourt, Rivers State, Nigeria

Email: abiauniport2005@yahoo.com

This study examines the sorption kinetics of Pb (II) and Cd (II) ions from aqueous solutions using unmodified and chemically modified oil palm fruit fibre. Four different models of the pseudo-second order equation were used to characterize the metal ion sorption kinetics. The results indicate that different kinetic parameters were obtained from the four forms of the pseudo-second order equations. The chemical modification of the adsorbent increased the equilibrium sorption capacity with maximum values of 5.579 mg/g for Pb(II) and 7.980 mg/g for Cd(II) for the 1.0 MOPF adsorbents. The coefficient of determination (r²) was used to analyse the different pseudo second order equations with the best fit for each of the different metal ions.

Keywords: Sorption, Kinetics, Pseudo-second order, Oil palm fibre, Cadmium, Lead

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 349-354

Adsorption of comb –type superplasticizers on calcium carbonate in alkaline medium in presence of electrolytes and rheological properties

Sarita Rai & N S Gajbhiye*

Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India

Email: nsg@iitk.ac.in

Adsorption behaviour of polycarboxylate type superplasticizers (PC) on CaCO₃ suspension in a basic medium has been studied in the presence of NaCl, Na₂SO₄ and CaCl₂ having same ionic strength. The amount of PC adsorbed was found out by determining the amount of PC present in supernatant solution with the help of total organic analyzer. It is found that the adsorption decreased when the POE chain length decreased. The adsorption was increased in presence of CaCl₂ while NaCl and Na₂SO₄ decreased the adsorption. The adsorption is not a competitive process but depends on ionic strength. Rheological measurements of suspensions have also shown that lower the POE chain length, higher the viscosity of the CaCO₃ suspension.

Keywords: Polycarboxylate, Superplasticizer, Adsorption, Cement

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 355-363

Blends of polyvinyl pyrrolidone and polyacrylamide as corrosion inhibitors for aluminium in acidic medium

S A Umoren^a* & E E Ebenso^b

^aDepartment of Chemistry, Faculty of Science, University of Uyo, Uyo, Nigeria

^bDepartment of Chemistry and Chemical Technology, National University of Lesotho, P. O. Roma 180,

Lesotho, Southern Africa

Email: saviourumoren@yahoo.com

The corrosion and inhibition behaviour of aluminium in hydrochloric acid (HCl) in the absence and presence of polyvinyl pyrrolidone (PVP), Polyacrylamide (PA) and their blends was studied in the temperature range of 30 – 60^oC using weight loss, hydrogen evolution and thermometric techniques. The inhibition efficiency (%I) increased with increase in inhibitors concentration. Increased in temperature led to increase in corrosion rate but decreased the inhibition efficiency PVP was found to have the higher inhibition efficiency than PA which may suggest that the differences in their molecular structures play a significant role in the adsorption and hence inhibition process. Inhibition efficiency was enhanced on blending the two polymers; the optimum inhibition efficiency was obtained at 3:1 blending ratio for PVP: PA. The inhibitors (PVP and PA) obey Freundlich, Temkin and Flory-Huggins adsorption isotherms at all the temperatures. Results obtained from the kinetic and thermodynamic parameters indicate spontaneous adsorption of the inhibitors unto aluminium surface following physical adsorption mechanism.

Keywords: Polyacrylamide, Polyvinyl pyrrolidone, Polymer blends, Adsorption isotherms, Aluminium, Corrosion inhibition

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 364-374

Some triphosphates as corrosion inhibitors for mild steel in

3% NaCl solution

Suman Lata* & R S Chaudhary

Department of Chemistry, M D University, Rohtak 124 001, India

Email: jakhar.suman@rediffmail.com

Inhibition of mild steel corrosion in 3% sodium chloride solution by sodium triployphosphate (STPP), sodium hexametaphosphate (SHMP) and adenosine triphosphate (ATP) in presence of 200 ppm zinc acetate has been investigated using weight loss, electrochemical polarisation and scanning electron microscopy techniques. Various corrosion parameters such as Tafel slopes, corrosion current density, heat of adsorption and activation energy value have been calculated to understand the inhibition mechanism. Inhibition efficiency increased with increase in concentration for STPP and SHMP whereas it decreased for ATP. However, inhibition efficiency decreased for all the three phosphates with increase in temperature. All the three phosphates acted as mixed inhibitors though anodic reactions are suppressed more in comparison to the cathodic reactions. STPP acted through chemisorption whereas SHMP and ATP are physically adsorbed over the surface of mild steel.

Keywords: Mild steel, Sodium chloride, Corrosion inhibitor, Phosphates

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 375-382

Enhanced corrosion resistance of rebar embedded in fly ash added concrete: Role of “k” factor

R Vedalakshmi^a, K Rajagopal^b & N Palanisamy^a

^aCorrosion Protection Division, Central Electrochemical Research Institute, Karaikudi, 630 006, India

^bDepartment of Civil Engineering, A C College of Engineering and Technology, Karaikudi, 630 007, India

Email: corrveda @yahoo.co.in

In India, the abundant availability of fly ash necessitates the increase in the addition of fly ash in pozzolana cement from 25 to 35%. Higher replacement level of fly ash reduced the development of early age strength of concrete. By adopting the cement efficiency factor (k) when designing the fly ash added concrete, either equal or more compressive strength has been attained. In the present study, by adopting this factor, the concretes having strength of 20 and 35 MPa were designed at 40% replacement of fly ash. The enhanced corrosion resistance of rebar was evaluated by conducting chloride migration test, potential-time studies and 90 days chloride ponding test. Results were compared with Ordinary Portland cement (OPC) and Fly ash added concrete (FAC) without k factor. The studies reveal that the diffusion co-efficient of chloride is less in FAC- with k than that of OPC and FAC without k concretes. In 1% chloride contaminated concrete, the rebar in FAC- with k shows more passive potential than the other two concretes. Under 90 days chloride ponding test, the corrosion resistance of rebar in FAC is 3-7 times more than that of the rebar in OPC concrete. The reduced chloride ion penetration increased the corrosion resistance of rebar. The 40% replacement of fly ash reduced the alkalinity of FAC-without k whereas the OH ^– ions concentration increases in FAC-with-k and maintained the passivity of rebar in presence of chloride. Hence in addition to early strength development, the enhanced corrosion resistance of rebar in FAC- with k is mainly because of reduced chloride ions penetration and increased OH^- ions concentration.

Keywords: Fly ash, Pozzolana cement, Efficiency factor, Chloride diffusion, Corrosion rate

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 383-387

Selective flocculation of celestite from celestite-calcite fines

A Ozkan* & H Ucbeyiay

Department of Mining Engineering, Selcuk University, 42075 Konya, Turkey

Email: alpozkan@selcuk.edu.tr

In this study, selective hydrophobic flocculation of celestite with sodium dodecyl sulphate (SDS) from the mixtures of celestite and calcite was investigated using sodium silicate as inorganic dispersant. Prior to the selective flocculation process, the critical surface tension of wetting (g_c) values of these minerals were determined as a function of SDS concentration. A significant difference between the g_c values of celestite and calcite was found at concentrations around 20 mg/dm³, indicating that celestite particles can be selectively flocculated from the mixtures at these concentrations. Then, the effects of pH, dispersant concentration, flocculation and settling times on the selective flocculation of celestite mineral were studied. Experiments carried out with sodium silicate at optimum conditions yielded a concentrate, which is flocculated material, assaying 85% SrSO₄ with a recovery 90% and separation index of 0.90 from a mixture containing 50% SrSO₄.

Keywords: Celestite, Calcite, Selective flocculation, Sodium dodecyl sulphate, Sodium silicate

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 388-396

Identification of various chemical phenomena in concrete using thermal analysis

R Vedalakshmi^a, A Sundara Raj^b & N Palaniswamy^a

^aCorrosion Protection Division, ^bCharacterization and Measurement Division,

Central Electrochemical Research Institute, Karaikudi 630 006, India

Email: corrveda@yahoo.co.in

Chemical changes that occur in concrete at the microstructure level due to environmental effects are normally identified by SEM, XRD, thermal analysis and by chemical analysis. In the present investigation, the chemical compounds formed in various chemical reactions are quantified using thermal analysis. The concrete having characteristic compressive strength of 20 MPa was subjected to undergo various chemical reactions for a specified period. Three types of cements were used for casting the concrete specimens. The thermal analyses (DTA and TG) were carried out on powdered concrete samples passing through 75 μm sieve drawn from the concrete specimens which were subjected to various chemical phenomenon. Chemical compounds such as Ca(OH)₂, gypsum, ettringite, calcium chloroaluminate are estimated quantitatively. The type of fly ash blended with cement and complex amine salt in Migrating Corrosion Inhibitor (MCI) treated concrete are also identified. Each chemical compound is identified by a distinct endotherm present in the DTA (Differential Thermal Analysis) plot and quantitative estimation has been done using the TG (Thermo-gravimetric) curve.

Keywords: Chemical changes, Thermal analysis, Pozzolanic reaction, Sulphate attack, Friedel’s salt, Migrating corrosion inhibitor

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 397-402

Recovery of chromium(VI) from electroplating effluent by solvent extraction with tri-n-butyl phosphate

S K Sahu*, Vijay K Verma, D Bagchi, Vinay Kumar & B D Pandey

Metal Extraction & Forming Division, National Metallurgical Laboratory, Jamshedpur 831 007, India

Email: sushanta_sk@yahoo.com

Recovery of hexavalent chromium from a model and real electroplating effluent by solvent extraction with tri-n-butyl phosphate (TBP) was studied. In different acid media chromium(VI) extraction with TBP followed the order HCl > H₂SO₄ ~ HNO₃. In acidic chloride medium chromium(VI) was extracted as HCrO₃Cl.2TBP. The loading capacity of TBP for chromium(VI) was found to be 5.35 g/L. Stripping of chromium(VI) from loaded TBP was also studied. With 0.1 N NaOH solution chromium(VI) was stripped quantitatively from loaded organic. TBP was also used to recover chromium(VI) and zinc from electroplating effluent collected from an electroplating industry. By simultaneous extraction with TBP, and stripping with 10% H₂SO₄ and 1 N NaOH zinc and chromium(VI) were recovered, quantitatively.

Keywords: Chromium(VI), Electroplating effluent, Solvent extraction, TBP

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 403-408

Extraction chromatographic studies of Gallium (III), Indium (III) and Thallium (III) with n-octylaniline

Haribhau R Aher & Shashikant R Kuchekar*

P. G. Department of Analytical Chemistry, P. V. P. College, Pravaranagar,

At/Po – Loni (Kd), Tal. Rahata, Dist. Ahmednagar 413 713, India

Email: shashi17@gmail.com

A selective method has been developed for extraction chromatographic separation of gallium (III), indium (III), thallium (III) with n-octylaniline (a liquid anion exchanger) as a stationary phase on silica gel. Quantitative extraction of gallium (III), indium (III) and thallium (III) has been achieved in 6.0, 0.7 and 0.7 M hydrochloric acid media respectively from 0.0135 M (0.3 %) n-octylaniline. The extracted metals has been stripped with distilled water and estimated spectrophotometrically. The effects of acid concentrations, reagent concentration and diverse ions have been studied. The optimum conditions for extraction have been investigated. Gallium (III), indium (III) and thallium (III) have been separated from its associated elements and synthetic mixtures. Scheme for separation of gallium from indium or thallium has been developed. The probable extracted species was ascertained from log C - log D plots.

Keywords: Extraction chromatography, Gallium (III), Indium (III), Thallium (III)

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 409-412

Interaction studies in binary liquid mixtures of methyl formate with o-, m- and p-xylenes using viscosity data at 303.15K

M V Rathnam*, Sudhir Mohite & MSS Kumar¹

B N Bandodkar College of Science, Thane 400 601, India

¹Zulal Bhilajirao Patil College, Deopur, Dhule 424 002, India

Email: mvrathnam58@yahoo.co.in

Densities, viscosities, refractive indices of binary liquid mixtures composed of methyl formate and

o-, m- and p-xylenes were determined at 303.15K and atmospheric pressure for the whole range of composition. From the experimental results the deviation in viscosity (∆h), excess Gibbs free energy of activation of flow (∆G*^E), and the deviation in molar refraction (∆R) were deduced. The deviation in viscosities were correlated with Redlich-Kister polynomial equation. The ∆h values are negative while the values of ∆G*^E are positive and the ∆R values are both positive and negative over the entire range of composition for all the studied systems. The ability of different one parameter and two parameter empirical models to predict mixing viscosities was also studied.

Keywords: Methyl formate, Viscosity, Molar refraction, Xylenes, Binary mixture

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 413-416

Arsenic removal from water using activated carbon obtained from chemical activation of jute stick

M Israt Jahan, M Abdul Motin, M Moniuzzaman & M Asadullah*

Department of Applied Chemistry and Chemical Technology, University of Rajshahi, Rajshahi 6205, Bangladesh

Email: asad@ru.ac.bd; asadullah8666@yahoo.com

Arsenic removal from water in the form of As(III) and As(IV) was investigated using activated carbon obtained from jute stick using H₃PO₄. Arsenic contaminated water was treated in two ways: (1) batch feeding system and (2) continuous flow system through a column filter. Removal of arsenic in continuous system was much better than that of batch feeding system. In the continuous system, where 0.15 ppm arsenic contaminated water was passed through a column packed with activated carbon, the maximum separation of As(III) was as high as 80%. In case of As(V) contaminated solution, almost complete separation of arsenic was achieved with activated carbon column filter. As(III) was converted to As(V) in the solution using very small amount of KMnO₄.

Keywords: Activated carbon, Adsorbent, Arsenic contamination, Water pollution

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 417-419

Investigation on pH dependent uptake of Cr(III) and Cr(VI) by Baker’s yeast

Susanta Lahiri^* & Kamalika Roy

Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India

Email: susanta.lahiri@saha.ac.in

Yeast cells of Saccharomyces cerevisiae were found to accumulate ⁵¹Cr(III) radioisotope at basic pH in trace level. There was no uptake of Cr(VI) at the same pH (~10.5). An assay of the products of cell lysis reveals that Cr(III) first gets adsorbed at the cell wall and then slowly enters the cytoplasm. On the other hand Cr(VI) has a faster penetration into the cytoplasm which increases with time, attains a maximum value and then release the metal ion from cytoplasm. The behavior and uptake kinetics of ⁵¹Cr(III) or ⁵¹Cr(VI) were studied using g-spectrometry.

Keywords: Saccharomyces cervisiae, Baker’s yeast, Cr (III) and Cr(VI) uptake

Indian Journal of Chemical Technology

Vol. 15, July 2008, pp. 420-423

Pressure casting of composite propellant

Ganesh Dombe, M Jain, P P Singh, K K Radhakrishnan & B Bhattacharya*

High Energy Materials Research Laboratory, Sutarwadi, Pune 411 021, India
Email: ganeshdombe@rediffmail.com

Conventional vacuum casting technique is suitable only to propellant slurry with low viscosity (<16 KP), grains with simple geometry and sufficiently large annular space between mandrel and motor case (web thickness). To overcome these limitations, pressure casting technique is adopted. The present paper gives details of pressure casting technique and its advantages over the other casting techniques. The rheological behaviour of propellant slurry and the methodology for calculation of pressure drop during pressure casting is described. This procedure is illustrated for pressure drop calculation during pressure casting for a typical rocket motor. The pressure drop in the rocket motor is also calculated using CFD software Fluent.

Keywords: Composite propellant, Pressure casting, Vacuum casting, Pseudo plastic, Web thickness