Three organic inhibitors namely, 1- Vanillin thiosemicarbazone (VTS), 1- Salicylaldehyde thiosemicarbazone (STS), 1- Dimethyl aminobenzaldehyde thiosemicarbazone (DTS) were synthesized to investigate their inhibiting actions on corrosion of mild steel (MS) in aqueous solutions containing 20% formic acid and 20% acetic acid by weight loss and potentiodynamic polarization methods. All of these compounds have shown good inhibition efficiency (IE) in formic acid solutions. IE of these compounds has been found to vary with the concentration of the compounds, temperature and immersion time. The adsorption of these compounds on the steel surface from the acids has been found to obey Temkin’s adsorption isotherm. The values of activation energy (E_a) and free energy of adsorption (DG_ads) indicated physical adsorption of these compounds on the steel surface. The potentiodynamic polarization experiments revealed that all the compounds are mixed type inhibitors.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.484-486

Reaction kinetics of formation of Dibenz-[b,f]-1,4-oxazepine (CR) from potassium salt of Schiff’s base

Bidhan Chandra Bag* & M P Kaushik

The kinetics of formation of dibenz-[b,f]-1,4-oxazepine (CR) from potassium salt of schiff’s base (SB) has been studied at various temperatures. Integral method has been used for the analysis of the data and it has been observed that the reaction follows a unimolecular first order kinetics. The rate constant has been found to be 2.5×10^-3 min^-1, 2.99×10^-2min^-1 and 1.63×10^-1 min^-1 at 90°C, 120°C and 150°C respectively. The values of activation energy and the frequency factor have also been determined.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 487-490

Ionization constants of crown dyes

B R Pandya & Y K Agrawal*

The thermodynamic ionisation constants of the synthesised crown dyes are determined in aqueous and aqueous dioxane medium at 25±1°C by pH metric titration techniques. The thermodynamic ionisation constants were also determined in aqueous dioxane medium and in DMF by spectrophotometric method at 25±1°C.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 491-495

Bioremediation of anaerobically digested post-methanation distillery spent wash

V K Garg* & Renuka Gupta

Anaerobically treated post-methanation spent wash is highly coloured with exceptionally high chemical oxygen demand (COD). An efficient isolate of Pseudomonas sp., viz., RG-2 for decolourisation was isolated from soil collected from distillery premises by enrichment culture method. RG-2 isolate was having considerable decolourisation (34.6 per cent) of 12.5 per cent diluted post-methanation spent wash after 8 days incubation. Addition of glucose to medium was essential to have decolourisation by this isolate. The effect of pH, carbon source, carbon source dose, nitrogen source, incubation period and post-methanation spent wash concentration have also been studied.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 496-498

Albumin test strip for quick detection of albuminuria in human

Sandeep K Sharma^a, Madhu Bala^a, N B Tulsani^a, Neeta Sehgal^b & Ashok Kumar^a*

In this article, the dry-reagent test strip technique has been discussed for qualitative and semi-quantitative estimation of albumin in urine. The strip method developed in our laboratory is quick, simple, economical and based on indigenous technique. It is based on the principle of “Protein error” in which specific chromogen immobilized onto a pad reacts with albumin present in the urine and changes the colour of the strips from light yellow to blue-green. The change in colour is visible to the naked eyes and can be compared to the colour chart for the estimation of total albumin concentration present in the urine sample.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 499-503

Activated carbon from parthenium as adsorbent: Adsorption of Hg(II) from aqueous solution

K Kadirvelu^a, C Sivasankari^b, M Jambuligam^b & S Pattabhi^a*

Activated carbon (AC) prepared from parthenium was used to remove Hg(II) from aqueous solution by adsorption technique under varying conditions of agitation time, metal ion concentration, adsorbent dose and pH. Adsorption equilibrium reached within 165 min for all concentrations studied (10 to 50 mg/L). Adsorption is dependents on solution pH, Hg (II) concentration, carbon concentration and contact time. Adsorption followed both Langmuir and Freundlich isotherm models. The adsorption capacity was found to be 10 mg/g of AC at initial pH of 5.0 at 30+2°C for the particle size of 125-250µm. The percent removal increased with pH from 2 to 6 and remained constant up to pH 10.0.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 503-507

Enzymatic clarification of Bael juice by calcium alginate gel immobilized PME of Aspergillus oryzae

U Ghosh & H Gangopadhyay*

The production of pectin methyl esterase (PME) was investigated on solid substrate fermentation of Aspergillus oryzae. The optimum conditions of PME production were 30⁰C, incubation for 3 days and hydration of wheat bran 50% (w/v). The partially purified PME was then immobilized by 2% sodium alginate by crosslinking with 2% CaCl₂ solution, retaining 68% of the activity of free PME. Optimum pH for free and immobilized PME was 3.6 and 4.0 respectively. Optimum temperature was the same for free and immobilized PME. Michaelis constant for free and immobilized PME was 0.7% and 0.6% respectively. The immobilized PME retained about 72% of the initial activity after being used for 10 cycles for the clarification of Bael juice.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 508-512

Effect of transition metal cations and anions on the production of citric acid by Aspergillus niger

Ar Angumeenal^a, P Kamalakannan^a, H J Prabhu^b & D Venkappayya^a*

Interest in studying the effect of microelements on the metabolism of fungi during the bioconversion has led to this work. The present work reports the production of citric acid starting from glucose by Aspergillus niger. The microelements supplemented were cadmium, lead, chromium and molybdenum. The bioconversion path of Aspergillus niger was TCA cycle. The products of the microbial metabolism namely total titrable acidity, citric acid, succinic acid, malic acid, intracellular proteins, extracellular proteins, amylase activity, lipid and biomass contents were determined periodically. Among the nutritional supplements tried cadmium was found to drive the metabolism of Aspergillus niger to produce more amount of citric acid. Experimentally observed growth stages were used for mathematical modelling to explore kinetic parameters. The values calculated based on the model were found to agree well with the observed ones in the case of lead and cadmium as supplements, whereas in the case of molybdenum and chromium deviations occur between the calculated and observed values. This discrepancy in the values of metabolic products was ascribed to the pH, temperature and other inhibitory products formed during fermentation.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp. 513-518

Cobalt tungsten alloy-electrodeposition and characterisation

A Subramanian^a, G N Kousalya^a, V S Muralidharan^b* & T Vasudevan^a

Bright Co-W alloy on steel is obtained from the optimised bath with the operating conditions of cobalt sulphate 0.15 M sodium tungstate 24 gpl, ammonium chloride 0.2 M, sodium citrate 0.2 M, dimethyl sulphoxide 0.06 M, pH 8 at 4 Adm^-2. The hardness of the alloy deposit is two times that of cobalt deposit. The corrosion resistance in 1.0 M acidic solutions for Co-20% W alloy is in the order of HCl > H₂SO₄ > HClO₄. The deposition of cobalt on platinum takes place from cobalt citrate complex. This citrate complex undergoes successive electron transfer. During the Co-W alloy deposition on platinum, cobalt tungstate complex undergoes reduction to form an alloy. The dissolution of Co-W alloy film occurs from Co-W intermediate phase.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

An understanding of the dissolution and passivation of 70/30 cupronickel alloy

J Mathiyarasu, N Palaniswamy & V S Muralidharan*

Cyclic voltammetric studies carried out on copper, nickel and 70/30 cupronickel in 0.5 M NaCl solutions revealed that the passivation of copper is due to the formation of Cu₂O via CuCl₂^- and that of nickel is due to oxide formation. X-ray diffraction (XRD) and X-ray photoelectron spectral (XPS) studies on cupronickel revealed the presence of partially covered surface with a corrosion film containing essentially Cu₂O. Increase of anodic potential resulted in the formation of chloro hydroxy cupric compounds along with nickel oxide. At potential closer to oxygen evolution, divalent and trivalent oxides of nickel species were predominant. The surface film analysis by X-ray fluorescence (XRF) studies revealed the film to contain more copper than nickel at potential below + 200 mV (SCE). However, at higher anodic potentials the amount of nickel exceeded that of copper. The leaching of cupronickel alloy was found to be uniform and not a preferential one for a less noble metal, such as copper.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

Estimation of dielectric constants of some halogenated polymers by
group additive methods

Muneera Begum^a, A Varada Rajulu^b & Siddaramaiah^a*

The dielectric constants (e) of some halogenated polymers were estimated by employing four different equations based on the group additive principle. The estimated values were compared with the experimental values. The suitability of individual equations is discussed.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

Degumming of vegetable oil by membrane technology

N C Desai^a*, M H Mehta^b, A M Dave^c & J N Mehta^c

Conventional method of degumming of crude vegetable oil, which involves the treatment of oil with steam followed by acid, is associated with many drawbacks, such as loss of oil, generation of wash waters, poor quality of degummed oil, etc. These drawbacks can be eliminated by the use of membrane technology being energy efficient, ecofriendly, and simple in operation. In order to explore the possibilities of utilizing membrane based separation process for the degumming of crude vegetable oil, this study has been conducted. The findings of the study indicate that membranes can remove phospholipids approximately 90% and above from castor oil, salicorniaseed oil and cottonseed oil. The permeability of membrane depends on the pressure applied. Ultrafiltration membranes exhibit higher permeability comparative to nanofiltration membrane. In addition to removal of phospholipids, membranes can simultaneously remove colour approximately 80% from the oil.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

Comparative study of catalytic activity of immobilized invertase in sodium alginate gel on sucrose hydrolysis

C N Khobragade* & S G Chandel

Invertase is an intracellular hydrolytic enzyme widely used in the inversion of sucrose into glucose and fructose. Both glucose and fructose are the primary compounds used as sweeteners in the food processing industries. In the present investigation invertase was immobilized in sodium alginate gel by entrapment method and the catalytic activity of immobilized enzyme was compared with the activity of native enzyme at variable pH and temperatures. Experimental findings revealed that for native enzyme optimum activity was at pH 4.2 and at temperature 30°C, while for immobilized enzyme it was observed at pH 4.8 and at temperature 50°C. Kinetic parameters K_m and V_max as well as catalytic efficiency of invertase was also determined for both the native and immobilized enzyme.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

Removal of trace metals with mango seed powder

Dimple C Parekh^a, Jignesh B Patel^a, Padmaja Sudhakar^*a & V J Koshy^*b

Removal of heavy metals like Cu, Cd, Pb from aqueous solution was studied using mango seeds powder. Study was carried out in batch technique as a function of contact time, metal ion concentration and pH of the solution. The sorption process follows Freundlich sorption isotherm. Maximum sorption was observed at acidic pH itself. The method is applied to various synthetic solutions.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

The role of AlPO₄-11 in the synthesis of bisphenol-A and cinnamic acid

B V Suresh Kumar^a*, K Byrappa^a, K M Lokanatha Rai^b, S Anand^b & R V Rao^c

AlPO₄-11 was used as catalyst for the synthesis of bisphenol-A by Friedel-Crafts condensation of acetone with phenol in presence of carbon tetrachloride and synthesis of cinnamic acid by Knovenagel condensation of aromatic aldehydes with malonic acid in presence of ethyl alcohol.

Indian Journal of Chemical Technology

Vol. 9, November 2002, pp.

Heat Radiation Law—From Newton to Stefan

Jaime Wisniak

The understanding and quantification of the phenomenon of heat radiation has gone through many phases, parallel to the interpretation of the concept of heat.

CONTENTS

Research Articles

AR Angumeenal, P Kamalakannan, H J Prabhu & D Venkappayya

Notes

The role of AlPO4-11 in the synthesis of bisphenol-A and cinnamic acid 545

Educator

Heat Radiation Law-From Newton to Stefan 556

Vol. 9, November 2002, pp. 496-498

Enzymatic clarification of Bael juice by calcium alginate gel immobilized PME of Aspergillus oryzae

The role of AlPO₄-11 in the synthesis of bisphenol-A and cinnamic acid 545