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Indian Journal of Chemical Technology

 

ISSN: 0971-457X   CODEN:ICHTEU 10(6) 579-724 
VOLUME 10  

 NUMBER 6

 NOVEMBER  2003

                                                                                                                                                                                                         

CONTENTS

Research Articles

 

Preservation of bagasse through biotech approach for pulp and paper industry

     587

K  R  Yadav,  Rajesh K  Sharma &  R M Kothari

 

 

 

Fabrication of a laboratory scale flotation cell device for bio-deinking of waste papers

     593

Santosh Vyas, S R Sainkar & Anil Lachke

 

 

 

Lipase immobilized on walls of plastic beaker: Kinetic properties and

 

application in washing of oil stained cloth

     598

S Arya, V Kalia, P Chandran & C S Pundir

 

 

 

Determination of acetylsalicylic acid and related substances in pharmaceutical preparations and bulk drugs by capillary electrophoresis

 

 

R Sekar, P Ravi Prasad & M  Vairamani

603 

 

 

Microorganism based biosensor for monitoring of microbiologically influenced corrosion caused by fungal species

 

    607

R S Dubey & S N Upadhyay

 

 

 

Effect of thermal and mechanical treatments on corrosion of API X-52 grade line pipe steel in flowing 3.5% NaCl solution

 

    611

Amarnath, S N Upadhyay & T K G Namboodhiri 

 

 

 

Conversion of ethane to ethylene in presence of limited O2 over supported SrO promoted Sm2O3 catalyst

 

    615

S A R Mulla & V R Choudhary

 

 

 

Carboxymethylation of wood residues: Effect of etherification process variables

     619

T O Egbuchunam &  F E Okieimen

 

  

 

Phenol-formaldehyde cationic matrices substituted by sulphonated

Acacia nilotica charcoal

 

    623

N Kannan, R K Seenivasan  & R Mayilmurugan

 

 

 

Catalytic hydrogenation of p-nitroaniline and 2-methoxy-5-nitroaniline

 

Sunil P Bawane & Sudhirprakash B Sawant

627

 

Application of solar photocatalysis for colour removal from dye-bath wastewater

 632

Vibha Chaturvedi, R S Dhodapkar, N N Rao & S N Kaul

 

 

Performance studies on novel solar photocatalytic reactors for decolourisation of textile dyeing wastewaters

 

 

S  Kanmani, K Thanasekaran & Dieter Beck 

638

 

 

Ideas for process improvement emanating from audit of a bromine plant in the Greater Rann of Kutch

 

    644

A S Mehta, P K Ghosh, H N Shah & R J Sanghavi

 

 

 

Performance of different oils in oil agglomeration of Zonguldak coal

 

Yakup Cebeci 

654

 

 

Flame atomic absorption spectrometric determination of trace amounts of copper after solid-liquid extraction and preconcentration with use of 1, 10-phenanthroline onto benzophenone

 

Mohammad Ali Taher 

661

 

 

Solvent extraction and separation studies of antimony(III) and  bismuth(III) by using cyanex-925

 

J N Iyer & P M Dhadke 

665

 

 

Treatment of wastewater from dyes manufacture using adsorption

 

A K A Rathi & S A Puranik 

670

 

 

Modelling of sterilization and air exchange rates for indoor environment:

An application to effect of ozone concentration on room bacteria

 

 

J J Gaware, P V Joshi & V Abrol

680

 

 

Kinetic and mechanistic studies of saponification of industrially important esters viz. diesters  in alcohol-water and dioxane-water moieties - A  novel mathematical approach for evaluation of concentrations of half-ester and end-products

 

 B M Rao, K Gajanan &  T Raghunath Rao

684

 

 

Studies   on   ionic   mass   transfer   with   insert   helical tape   promoters   in   batch  fluidized   beds

 

V Sujatha,  P Rajendra Prasad,  C Bhaskara Sarma &  G J V Jagannadha Raju

694

   
Notes

 

Reduction of bitter component of pomelo juice by chemical treatment and immobilized enzyme

 

U Ghosh & H Gangopadhyay

701

 

 

Educator

 

The chemical balance-From stones to electronics

 

Jaime Wisniak

705

 

 

Chem-Tech Scan

713

 

 

 

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 587-592

 

Preservation of bagasse through biotech approach for pulp
and paper industry

 K R Yadav, Rajesh K Sharma & R M Kothari*

 

Bagasse, a by-product of sugarcane industry, has potential to serve as a source of cellulosic fibre for paper making. For its consumption throughout the year, bagasse needs to be preserved for at least 6-8 months. The use of chemicals for preservation of bagasse has been found unsafe in practice, hazardous for health and polluter of eco-system. An attempt has been made to preserve bagasse through biotechnological approaches. For this purpose, bagasse was exposed to three plant-derived, anti-microbial powders, individually and cumulatively, with and without organic acid producing bacteria. The exposed bagasse was preserved for 6 months, under ambient conditions mimicking the storage in paper mills. Subsequently, it was subjected to physical, chemical and microbiological examination to evaluate the effect of each preservative. It was observed that neem leaf powder exposure in conjunction with acid producing bacteria afforded maximum preservative effect on bagasse, as it retained necessary characteristics desired for good quality pulp making.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 593-597

 

Fabrication of a laboratory scale flotation cell device
for bio-deinking of waste papers

Santosh Vyas, S R Sainkar & Anil Lachke*

 

Fabrication of a cost effective, laboratory scale flotation device that can be used for deinking of various grades of wastepaper has been described. The unit consists of aeration device, sparger, baffles for high air to stock ratios and high shear mixing. The sparger is designed in such a way, that, it gives micro turbulent airflow necessary for removal of smaller ink particles. The deinking experiments using alkaline active cellulases from an alkalotolerant Fusarium sp have been reported. The enzyme preparation showed different cellulolytic and xylanolytic activities. Successful application of cellulases in enzymatic deinking of mixed office waste paper has been described.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 598-602

 

Lipase immobilized on walls of plastic beaker: Kinetic properties and
application in washing of oil stained cloth

 S Arya, V Kalia, P Chandran & C S Pundir*

 

Commercial porcine pancreas lipase was immobilized covalently onto alkylamine glass-beads affixed on the inner wall of a plastic beaker by an adhesive. The immobilized en­zyme retained 10.8% of the initial activity of free enzyme with a conjugation yield of 52 mg/g support. The optimum pH and incubation temperature were decreased, while time for linearity and Km for triolein of enzyme were increased after immobilization. The utility of immobilized enzymes in removal of oil stain from cotton cloth by various detergents was tested by chemical method. All the detergents gave better washing in presence of immobilized lipase than that by detergent alone. Further, the washing by cheaper (non-enzymic) detergents in presence of immobilized lipase was almost similar to that by expensive (enzymic) detergents. The immobilized enzyme was used about 100 times without any considerable loss of activity.

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 603-606

 

Determination of acetylsalicylic acid and related substances in pharmaceutical preparations and bulk drugs by capillary electrophoresis

R Sekar*, P Ravi Prasad & M Vairamani

 

Micellar electrokinetic chromatography (MEKC) using sodium dodecyl sulphate (SDS) in separation buffer has been employed for the separation and determination of acetylsalicylic acid and related compounds in tablets and bulk drugs. Base line separation was achieved by using 12.5 mM sodiumtetraborate decahydrate, 15 mM boric acid (pH 9.0) and 50 mM SDS. Analytical characteristics such as migration time, relative migration time and relative response factor were determined. Acetaminophen was used as internal standard to correct and compensate errors due to injection and evaporation losses. Drug content in formulations and bulk drugs was determined and the recovery was between 98.6 and 101.5%. All the preparations and bulk drugs examined were found to contain the hydrolyzed and starting material of salicylic acid, in varying amounts.

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 607-610

 

Microorganism based biosensor for monitoring of microbiologically
influenced corrosion caused by fungal species

R S Dubey* & S N Upadhyay

 

The microfungi are a group microorganisms, which obtain their energy either by aerobic oxidation or by anerobic fermentation of organic materials and release organic acid metabolite as an end-product, which is corrosive in nature. The metabolites could be detected online by microbial biosensor. An amperometric microbial biosensor for the direct measurement of metabolites was developed on a modified oxygen electrode with immobilized Acetobacter sp. on acetylcellulose membrane. The sensor signal and response time were optimized with respect to pH, temperature, concentration and weight of the immobilized microbial cells. The best sensitivity and response time by microbial biosensor were obtained with 1.2 mg of microbial cells at 4.3 pH of the corrosive environment at room temperature (29°C). The reproducibility of current and response time difference were examined, using, the same corrosive environment.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 611-614

 

Effect of thermal and mechanical treatments on corrosion of API X-52 grade line pipe steel in flowing 3.5% NaCl solution

Amarnatha*, S N Upadhyay & T K G Namboodhiri

 

Commercial API X-52 grade line pipe steel was studied for its corrosion resistance in 3.5% NaCl solution under static and dynamic conditions. Heat treatments and cold rolling resulted in considerable variations in mechanical properties and microstructure of the steel. These treatments resulted in insignificant changes in static corrosion rate, whereas considerable variations in corrosion rate were observed under dynamic conditions. Quenched and tempered steel showed the maximum corrosion resistance and annealed steel showed the minimum resistance under dynamic conditions.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 615-618

 

Conversion of ethane to ethylene in presence of
limited O2 over supported SrO promoted Sm2O3 catalyst

S A R Mulla* & V R Choudhary

 

Oxidative dehydrogenation of ethane to ethylene in presence of steam (steam/C2H6 mole ratio = 1.0) and limited O2 (C­2H6/O2 mole ratio ³ 4.0) over a SrO-promoted Sm2O3, supported on low surface area macroporous silica-alumina commercial catalyst carrier (SA5205, obtained from Norton Co. USA) has been thoroughly investigated. Effect of different process parameters such as temperature (700-850oC), C2H6/O2 feed ratio (4.0-8.0) and gas hourly space velocity (5´104- 20´104 cm3g-1h-1) on the conversion of ethane and product selectivity in the process has been studied. High selectivity (³80%) of C2+ olefins at 50-70% conversion of ethane could be obtained at very low contact time without coke deposition on the catalyst at 800–850oC.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 619-622

 

Carboxymethylation of wood residues: Effect of
etherification process variables

 T O Egbuchunam* & F E Okieimen

 

A study of carboxymethylation of wood residues from Terminalia superba (ash content 0.018; organic extractives, 2.14; holocellulose, 76.45; a-cellulose, 55.87%; DP 331.86) was carried out using various alkali/cellulose ratios in various organic solvent mediums (benzene, methylene chloride) and organic solvent mixtures (benzene/isopropanol, and acetonitrile/ acetone). The extent of etherification was found to be dependent on the strength of the aqueous alkali solution and was the highest (DS, 0.431) for cellulosic materials impregnated with CuSO4 prior to alkali treatment. It was found that an increase in the time of alkali-treatment from 0.5-24 h was accompanied by marked changes, of up to 44%, in the degree of substitution. The lowest DS (0.315) was obtained for carboxymethylation in methylene chloride and in acetonitrile/acetone (1:1) mixture and the highest (0.438) in benzene/isopropanol (1:1) mixture. The viscosity of dilute aqueous solutions of carboxymethyl cellulose prepared, was measured at low shear rate (200 s-1) at various temperatures, in the presence of mono-, di-, and trivalent cations; in order to determine the reduction in viscosity with time.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 623-626

 

Phenol-formaldehyde cationic matrices substituted by
sulphonated Acacia nilotica charcoal

 N Kannan*, R K Seenivasan & R Mayilmurugan

 

Sulphonated Acacia nilotica charcoal (SANC) could be used as a substituent for cation exchanger viz., sulphonated phenol-formaldehyde resin(SPFR). SANC was used to partly replace the polymeric matrix of sulphonated phenol-formaldehyde cation exchanger, by varying the substituent content of SANC. All the important physico-chemical, thermal and spectral characteristic properties of the composites have been determined. The cation exchange capacity (CEC) of the composite was found to decrease with the increase in the substitution by SANC(%w/w) in the SPFR. It was observed that SANC retains all the properties, as compared to that of the unsubstituted phenol-formaldehyde cationic resin(PFCR). It is concluded that SANC could partly replace PFCR, upto 20% (w/w) substitution without affecting the properties of the PFCR.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 627-631

 

Catalytic hydrogenation of p-nitroaniline and 2-methoxy-5-nitroaniline

 Sunil P Bawane & Sudhirprakash B Sawant*

 

Catalytic hydrogenation of p-nitroaniline (PNA) to p-phenylenediamine (PPD) was carried out in methanol using 5% Pd/C as a catalyst at hydrogen pressures in the range of 200-1000 kPa, reaction temperatures 313-333 K, catalyst loadings 200-500 mg dm-3 and PNA concentrations 0.3-1.02 mol dm-3. Catalytic hydrogenation of 2-methoxy-5-nitroaniline (MNA) to 4-methoxy-1,3, benzenediamine (MBD) was carried out in dimethylformamide as a solvent using 5% Pd/C as catalyst at hydrogen pressures 1000-2000 kPa, reaction temperatures 413-433 K, catalyst loadings 200-600 mg dm-3 and MNA concentrations 0.22-1.7 mol dm-3. Speed of agitation beyond 17 rps had no effect on the progress of the reaction. The study shows that PNA and MNA can be selectively hydrogenated to PPD and MBD, respectively and the initial rate of hydrogenations showed first order dependence on the reactant concentration, hydrogen partial pressure, and the catalyst loading for both the reactions. The activation energies for the catalytic hydrogenation of PNA and MNA were found to be 37.26 and 93.73 kJ mol-1, respectively.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 632-637

 

Application of solar photocatalysis for colour removal
from dye-bath wastewater

 Vibha Chaturvedi, R S Dhodapkar, N N Rao* & S N Kaul

 

The photocatalytic colour removal from water containing two commercial dyes was examined under sunlight. Three types of reactors, continuously stirred batch reactor (CSBR), solar slurry reactor (SSR) and an open-trough reactor (OTR) were used. Titanium oxide (TiO2) was used for making slurry as well as for immobilization on polyester fabric (PE). The dyes were reactive orange M2R (RO4) and reactive black B (RB5) which were treated in continuously stirred batch reactor (CSBR). About 99% colour removal and 84% reduction in COD was observed during 3 h of exposure to sunlight, at an initial concentration of 50 mg/L of RO4 and 0.2g TiO2/L in suspensions. About 92% colour removal and 65% reduction in COD was observed during 4 h exposure to sunlight at an initial concentration of RB5 of 50 mg/L and 0.2 g TiO2/L in suspensions. In SSR, about 98% reduction in colour of dye-bath wastewater (DBWW) was observed while COD removal was 8%. In the experiments using immobilized TiO2 (TiO2/PE) and open trough reactor, 99% and 97% colour removal was observed for RO4 and RB5 respectively in 5 h. However, the COD removal was low, 19 and 7.2% respectively with RO4 and RB5. Dye bath wastewater was also treated in OTR; 97% reduction in colour and 8% reduction in COD were achieved in 5 h. Increase in biodegradability of wastewater was also observed after solar photocatalytic treatment.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 638-643

 

Performance studies on novel solar photocatalytic reactors
for decolourisation of textile dyeing wastewaters

S Kanmani*, K Thanasekaran & Dieter Beck

 

Two ‘Water Fountain Solar Photocatalytic Reactors’ of trapezoidal and circular configurations without any ultraviolet (UV) transparent walls were developed and the practical applicability of the reactors for solar photocatalytic decolourisation of textile dyeing wastewaters was proved for the first time. The photocatalytic reactors were operated in batch mode for 3 h so as to study the influence of operating variables viz., liquid volume, constant liquid depth and solar ultraviolet light intensity. The studies were carried out using simulated rinse wastewaters prepared with red dye having concentration of 40 mg/L. A catalyst dosage of 1.0 g/L was adopted and the [S1] samples were collected at 15 min interval for analysis of colour. For each study on photocatalytic decolourisation, the kinetic rate equation was arrived, from which the reaction time (i.e. the time taken for 90% decolourisation) was derived and it was used to compare the influence of operating variables. The reaction time was less than 3h for liquid volumes upto 16 L and thereafter, it increased up to 7 h. The performance of the reactors was not uniform with similar liquid depths. The influence of solar UV light intensity on the performance of the reactor was found to be significant. The scale-up of the water fountain solar photoreactors is simple and also economical as expensive and fragile UV transparent walls are not necessary.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 644-653

  

Ideas for process improvement emanating from audit
of a bromine plant in the Greater Rann of Kutch

 A S Mehta*, P K Ghosh, H N Shah & R J Sanghavi

 

 The main effluent in the ‘Steaming Out Process’ for recovery of elemental bromine from salt bittern is hot acidified debrominated bittern. An exercise was undertaken recently in collaboration with a manufacturer in Greater Rann of Kutch to audit the performance of the plant, evaluate the composition of effluent discharged from the bromine plant, and explore the possibility of value addition of the effluent or, preferably, minimise effluent at source. Important recommendations made at the end of the study are: (i) controlled neutralization of acidified debrominated bittern by lime can produce fine granules of calcium sulphate of ca. 95 % purity, (ii) there is need to enhance the debromination efficiency as, otherwise, bromate formation is inevitable in the course of neutralization, (iii) evaporation of dilute brine is essential for recovery of marine chemicals and (iv) debrominated bittern could be utilised in solar ponds which would be a suitable source of non-conventional energy in the highly remote and arid region.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 654-660

 

Performance of different oils in oil agglomeration of Zonguldak coal

 Yakup Cebeci

 

In this study, comparison of performance of different oils, in the cleaning of Zonguldak coal, by oil agglomeration was investigated. The feed coal was agglomerated with both classic oils (kerosene, diesel and fuel) used for the coal agglomeration and lubricating oils (spindle, heavy neutral and bright stock) over a wide range of oil concentrations. The performance of the agglomeration process was evaluated by the combustible recovery, ash rejection and efficiency index. It was found that the combustible recovery and ash rejection changed, depending on the type and concentration of oil. The oils were tested for combustible recovery and maximum combustible recovery was obtained on using kerosene. It was found that kerosene, diesel-oil, spindle oil and heavy neutral were suitable for the agglomeration of Zonguldak coal. On considering the efficiency index values, the best results were obtained with heavy neutral. Consequently, it was shown that heavy neutral and spindle oil can be used as alternative oils instead of classic oils for the cleaning of Zonguldak coal by the oil agglomeration.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 661-664

 

Flame atomic absorption spectrometric determination of trace amounts
of copper after solid-liquid extraction and preconcentration with
use of 1,10-phenanthroline onto benzophenone

 Mohammad Ali Taher

 

Copper is quantitatively retained by 1,10-phenanthroline and tetraphenylborate onto benzophenone in the pH range 1.6-10.4 from a large volume of aqueous solutions of various samples. After filtration, the solid mass consisting of copper complex and benzophenone was dissolved in 5 mL of dimethylformamide and the metal was determined by flame atomic absorption spectrometric. About 0.2 mg of copper can be concentrated from 500 mL of aqueous sample, where its concentration is as low as 0.4 ng/mL. Eight replicate determinations of 3.0 mg/mL of copper in final dimethylformamide solution gave a mean absorbance of 0.180 with a relative standard deviation of 1.8%. The sensitivity for 1% absorption was 73 ng/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of copper in various alloys and biological samples.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 665-669

 

Solvent extraction and separation studies of antimony(III) and
bismuth(III) by using cyanex-925

J N Iyer* & P M Dhadke

 

Cyanex-925 in xylene was used for extraction and separation of antimony(III) and bismuth(III) from aqueous solution. It was found that Sb(III) gets quantitatively extracted in the range 0.1-0.8 M HCl and 0.01-1.0 M H2SO4, while Bi(III) in the range 0.01-0.4 M HCl and 0.1-1.0 M HNO3. From organic phase, Sb(III) was stripped back with 8.0 M H2SO4 and Bi(III) with 2.0-3.0 M HNO3. The extraction behaviour of both the metal ions was studied separately as a function of acid concentration, temperature, equilibrium time and stripping ability using various acids and bases. Based on these results, sequential methods for their separation from multicomponent mixtures were developed.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 670-679

 

Treatment of wastewater from dyes manufacture using adsorption

A K A Rathi* & S A Puranik

 

In a typical wastewater treatment flow sheet used by several industrial units in India, various stages of treatment include the primary treatment-oil/grease removal and neutralization, followed by the secondary treatment-chemical/biological oxidation and clarification, and the tertiary treatment-adsorption onto activated carbon. The neutralization of the wastewater with acid/milk of lime increases the concentration of total dissolved solids, which adversely affects the activity of microorganisms during biological oxidation process. To overcome this limitation, adsorption is proposed in the first stage of treatment and other stages could follow depending on the quality of the wastewater. Experiments were carried out on wastewater samples from different plants manufacturing dyes using adsorbents-activated carbon, fly ash, bentonite and lignite. The effectiveness of adsorbents in reducing chemical oxygen demand (COD) and colour was evaluated. The results of COD reduction are fitted into different models available in the literature. A model for predicting COD equilibrium values is proposed. Sorption kinetics and rate of reduction of COD over time are also discussed.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 680-683

 

Modelling of sterilization and air exchange rates for indoor environment: An application to effect of ozone concentration on room bacteria

J J Gaware, P V Joshi & V Abrol*

 

Under the assumption of well mixed indoor air, the effect of ozone generated from an ozonizer on the room bacteria is mathematically modelled. The model computations give the effective air exchange rate, sterilization rate, ozone destruction rate and the release rate of ozone for ozonizer.

 

 

Indian Journal of Chemical Technology V

ol. 10, November 2003, pp. 684-693

 

Kinetic and mechanistic studies of saponification of industrially
important esters viz. diesters in alcohol-water and dioxane-water moieties
—A novel mathematical approach for evaluation of concentrations of
half-ester and end-products

B M Rao*, K Gajanan & T Raghunath Rao

 

Kinetic and mechanistic studies of saponification of seven structurally related and industrially important diesters have been investigated. These saponification processes were followed as series first order reactions and a novel mathematical approach of determinantal method of evaluation of concentrations of half-ester and other end-products was applied. Time ratio method and Swain's standard data for series first order reactions have been utilized for the evaluation of rate data and thermodynamic parameters viz. DE¹, -DH¹, DG¹, DS¹ and logA for both the steps which involve the competitive and consecutive saponification reactions. Further, these reactions indicate that the first step of saponification process is much faster than the second step and the laurates are more saponifiable than stearates and oleostearates. The concentrations of half-ester and end-products could not be monitored experimentally, however, they are evaluated through the application of the above said mathematical approach. The advantage of this novel mathematical approach is that the concentrations of half-ester and end-products thus evaluated are with in the mathematical accuracy of ±0.005%.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 694-700

 

Studies on ionic mass transfer with insert helical tape promoters
in batch fluidized beds

V Sujatha*, P Rajendra Prasad, C Bhaskara Sarma & G J V Jagannadha Raju

 

Augmentation of mass transfer coefficients, due to the presence of helical tape promoters in batch fluidized beds has been presented. Mass transfer coefficients have been evaluated from the measured limiting current densities and the concentrations of the reacting ions. The variables studied are the geometric parameters of the promoter-tape width, pitch and diameter of the promoter rod, the flow rate of the electrolyte, void fraction and particle diameter. It is found that kL increased with increased flow rate and particle diameter. The increase in tape width and diameter of the promoter rod resulted in slightly increased mass transfer coefficients. Pitch of the promoter showed negligible effect on kL.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 701-704

 

Reduction of bitter component of pomelo juice by
chemical treatment and immobilized enzyme

U Ghosh & H Gangopadhyay*

 

Effect of pH, total soluble solids (TSS), b-cyclodextrin, immobilized enzyme on removal of naringin and on quality of pomelo juice was studied. The maximum reduction in naringin content (0.34 mg/mL) was observed in juice, treated with immobilized naringinase compared to control (1.1 mg/mL). Change of pH from 3.5 to 4.5 reduced naringin content from 31.8% (pH 3.5) to 40.9% (pH 4.5). However, lowering of bitter principle was 49% for 30°B and 43.6% for juice of pH 4.5 & TSS 30°B. Minimum changes in physico-chemical parameters were observed with immobilized enzyme treated juice. Effect of these treatments on the activity of enzymes were also studied. Minimum amylase activity was observed with immobilized enzyme treated sample 18.9 U to that of control 32 U. Change in pectin methyl esterase (PME) activity was not so significant with an increase of pH. Maximum reduction of PME activity was observed with sample of 30°B TSS. However, retention of peroxidase activity was maximum for b-cyclodextrin treated sample 2.1 K1´103/mL compared to control 2.7 K1´103/mL. Treatment with immobilized enzyme gave an acceptable debittered pomelo juice.

 

 

 

Indian Journal of Chemical Technology

Vol. 10, November 2003, pp. 705-712

 

The Chemical Balance¾From stones to electronics

 Jaime Wisniak

 

A chemical balance is standard equipment in any chemistry or physics laboratory, but in this electronic age a balance using weights is as odd as a slide rule. Weighing devices made their appearance at the time when human societies started to take root; the early devices were mechanical and developed very slowly until the seventeenth or eighteenth century when science started to set its principles. The next two centuries saw the mechanical balance achieve its final shape until its replacement by electronic devices in the second part of the twentieth century. Here, the history of the development of the balance since the dawn of history until its final mechanical form in the second half of the nineteenth century is being traced.