Showing papers in "Indian Journal of Chemical Technology in 2000"

Synthesis and characterization of maleilated chitosan for dye house effluent

Abstract: Efficient procedure for the preparation of maleilated chitosan derivative has been established on the basis of the chemical modifications. Selective and quantitative maleilation of chitosan proceeds smoothly by the reaction of chitosan with maleic anhydride in dimethyl acetamide at 120°C for 4 h and resulted in the formation of amide product. Thereafter imidization by curing was done. The structure of the derivative is well confirmed by titration of carboxylic groups, elemental analysis and IR spectroscopy. The resulting maleilated chitosan exhibits much improved swelling in water. It is expected that multifunctional polar group in chitosan should have good dye adsorption capacity than pure chitosan.

Studies on chemical constituents and antifungal activity of leaf essential oil of Lippia alba (Mill)

Abstract: The leaf volatile oil of Lippia alba (Mill) has been analysed by GC and GC-MS. Fifty components have been identified accounting for about 90% of the total oil. The major constituent is geranial (15.57%) followed by a unresolvable mixture of myrthenol and myrthenal (9.89%), neral (9.44%), geraniol (7.36%), 2,6-octadien-1-ol, 3,7-dimethyl acetate (6.87%), 1-octene-3-ol (4.66%),6-methyl-5-hepten-2-one (4.60%), caryophyllene oxide (4.52%), β-caryophyllene (3.09%), citronellol (2.63%), linalool (2.20%), 3-pinene-2-ol (2.19%), β-myrcene (1.49%), farnesol (1.35%) and spathulenol. It was also found that oil vapours possessed strong antifungal activity against sugarcane pathogens. The oil was highly effective in controlling teleutospore germination of Ustilago scitaminea and conidial germination of Colletotrichum falcatum and Curvularia lunata at 3×10 3 μl/L concentration. The oil also proved superior in comparison to commercial fungicides in controlling plant pathogenic fungi.

Treatment of distillery waste after bio-gas generation: Wet oxidation

Abstract: A process scheme has been presented for treating the waste stream originating from bio-gas generation unit of distillery waste by wet oxidation after thermal pretreatment for membrane process. The objective was not only to make the stream suitable to meet futuristic standards but also to produce acetic acid . The pretreatment can achieve a 40% reduction in COD with 30% color reduction. The wet oxidation of pretreated waste was studied in the range of 180-225°C and oxygen partial pressure 0.69-1.38 MPa. Kinetic studies were performed with and without catalyst. The overall kinetics of distillery waste obeyed a two step mechanism namely, the fast oxidation of organic substrate followed by slower oxidation of low molecular weight compounds formed such as acetic acid . Homogeneous ferrous sulfate is found to be a suitable catalyst to treat the waste effectively , which increases the performance of wet oxidation. While noncatalytic wet oxidation at 220°C achieved a 60% reduction in COD during 120 mins with 95 % color destruction, catalytic wet oxidation achieved this at 21 0°C. Catalytic .wet oxidation with FeS04 increases acetic acid formation . Also, addition of trace amount of hydroquinone significantly increased the acid formation alongwith enhanced rates of COD destruction. Sugarcane molasses based alcohol industry represents one of the largest segments in the Indian chemical industry. The aqueous waste stream left after the recovery of alcohol from the fermented molasses is known in different ways such as spent wash, slope, vinasses, stillage etc., depending upon the. distillery unit. The aqueous waste stream is one of the most complex effluents having high biological oxygen demand (BOD) and high chemical oxygen demand (COD). The fermentation of molasses to produce alcohol results in a waste stream having a COD of the order of I ,50,000 - I ,90,000 mg!L. Typically, production of I T of 95 % alcohol requires about 5.5 T of molasses and produces around 16 m 3 of effluent. The waste stream thus produced is difficult to treat. Various primary treatment processes like anaerobic lagooning, incineration, bio-methanation, electro­ chemical oxidation etc. are available to treat the waste

Immobilization of porcine pancreas lipase on zirconia coated alkylamine glass using glutaraldehyde

Abstract: Commercially available lipase from porcine-pancreas has been immobilized onto zirconia coated alkylamine glass-beads through the process of glutaraldehyde coupling with 100% retention of its initial activity . The enzyme showed changes in its physical properties after immobilization. The utility of immobilized enzyme in removal of oil stain from cotton cloth is demonstrated. Lipases have attracted more attention compared to other classes of enzyme because of their commercial use in the food industr/ as well as in the high tech. production (If fine chemicals and pharmaceuticals 2

Adsorption kinetics of o-cresol on activated carbon from palm seed coat

Abstract: The activated carbon prepared from palm seed coat by dolomite process showed more than 95% removal of o-cresol from aqueous solution under optimum conditions. The adsorption capacity calculated by Freundlich adsorption isotherm gave 19.58 mg/g of o-cresol removal. The kinetic studies revealed the overall rate constant decrease with increasing concentration of o-cresol. The activated carbon showed reversible uptake of o-cresol and thus have a good application potential for the removal/recovery of o-cresol from aqueous solution. Film diffusion was found to be the rate limiting step. Recovery of used carbon was studied by in situ chemical regeneration technique and showed good result.

Liquid-liquid extraction of Palladium (II) with Cyanex 302 i.e.bis (2,4,4-trimethylpentyl) monothiophosphinic acid

Abstract: A method is proposed for the extraction of Pd(II) from 1.0 M HCl medium using Cyanex 302 in toluene. Palladium(II) is determined in the organic phase by direct spectrophotometry at 336 nm. Various parameters such as acid concentration, reagent concentration, time and effect of foreign ions were studied. The probable extracted species is determined by the log(D)-log(C) plot. The method is simple, rapid and permits separation of Pd(II) from closely associated metals like Pt(IV), Rh(III), Ru(III), Fe(III) and Ni(II). It has been applied for analysis of Pd(II) in commercial samples. The proposed method is reproducible with a relative standard deviation of ±1.0%.

Treatment of wood with thermosetting resins: Effect on dimensional stability, strength and termite resistance

Abstract: The effect of thermosetting resins viz. phenol formaldehyde (PF) and melamine formaldehyde (MF) on dimensional stability, strength property and termite (Odontotermis spp) resistant capacity of a soft wood, bombax ceiba were assessed. The wood was treated with 30% resin concentration in 110°C at 75 psi air pressure and then dimensional stability in terms of anti-shrink efficiency (ASE) of 70.59% and 68.23% were achieved at 32.1 and 33.0 levels of weight percent gain (WPG) for PF and MF resins respectively. Maximum bulking co-efficient (BC) of 15.39% and 13,28%, and moisture excluding efficiency (MEE) of 45.31% and 41.39% were achieved for PF and MF treated samples at the above two WPG levels. Three cycles of repeated wetting and drying did not cause any further change in BC and ASE. The treatment also increased modulus of rupture (MOR) by 21.6% and 19.48% and modulus of elasticity (MOE) by 12.86% and 11.10% over the untreated samples without any remarkable change in specific gravity. Furthermore, the treated wood showed resistance to termite.

A rapid estimation of urea in adulterated milk using dry reagent strip

Abstract: +his-articl describes development and optimization of a visually evalua Ie dry reagent strip technique for semiquantitative estimation of urea in adulterated milk. It is based on (i) urease reacting with urea to liberate ammonia and carbon dioxide and (ii ) liberated ammonia reacting with a specific chromogen to change color of the strip from light yellow to magenta, which is visible with naked eyes. The technique is versatile as (i) it is used single step-working reagent to complete the reaction within 30 s at room temperature, (i i) gives different shades of color from yellow to magenta, depending upon concentration of urea present in the milk, (iii) this strip can measure urea concentration as low as 0.1 giL and (iv) thi s dry reagent strip is stable up to one year at room tempera~ur~

Reactions of nitrotoluenes with sodimn sulphide :Phase transfer catalysis and role of Ω phase

Abstract: The reactions of nitrotoluenes (o-, m- and p-) with sodium sulphide were carried out both in the liquid-liquid and solid-liquid modes with phase transfer catalyst, tetrabutylammonium bromide (TBAB). In the liquid-liquid mode, the reactions of all three nitrotoluenes were found to be kinetically controlled with activation energy values of 47100, 52500 and 39200 kJ/mol with o-, m- and p-nitrotoluenes respectively as the organic substrates. In solid-liquid mode, the reactions of o- and p-nitrotoluenes were kinetically controlled whereas that of m-nitrotoluene was found to be mass transfer controlled with an activation energy of 11600 kJ/mol. The effect of Ω phase on the rate of solid-liquid reaction was also studied and a maximum six-fold enhancement in rate was observed with m-nitrotoluene as the organic substrate.

Kinetic studies on the photo decolourisation of textile dyes (reactive) using ZnO catalyst

Abstract: Photo decolourisation of various reactive textile dyes such as Procion Brilliant Yellow M-4G (PBY), Procion Brilliant Magenta M-B (PBM) and Procion Brilliant Orange M-2R (PBO) have been studied using ZnO as photocatalyst. Complete decolourisation (100%) of dyes by sunlight was obtained when ZnO was used as a catalyst. Decolourisation of dyes by sunlight was found to be more effective as compared to UV light. This paper also discusses the effect of pH, H 2 O 2 concentration, dye concentration and catalyst weight on the decolourisation of dyes. The decolourisation was not affected by changes in pH. The degradation kinetics involving Langmuir-Hinshelwood model for PBY has been studied in detail.

Pyridine-2-acetaldehyde salicyloylhydrazone as reagent for extractive and spec­ trophotometric determination of cobalt(II) at trace level

Abstract: ­tion. Cobalt(! I) is extracted quantitati ve ly in th e pH ran ge 1.0- 4.0. Th e ye ll ow coloured I :2 metal:li ga nd co mpl ex in chl o­ roform is determined spec troph otometri ca ll y at 4 15 nm. Beer's law was obeyed over the concentrati on range of 0.5-7.0 J.l g mL- 1 of cobal t(II ). The molar absorptivit y and Sandell sensiti vit y were found to be 1.04 x 10 4 L mo1' 1 cm· 1 an d 5.63 ng cnf~ re spec tiv ely. The meth od is prec ise and simpl e. It was applied for the an alys is of hi gh speed stee ls and pharmace uti ca l sa m­ ples for th e es timati on of coba lt (II ). Cobalt is industrially ve ry important metal , also it has become increasingly important as constituent of high temperature, hi gh duty steel alloys and super alloys. Th ough it ha s little importance as magnetic material when it is alloyed with iron and nickel it shows exceptional magnetic properties. Biologically it is a significant element playing micronutritive and toxic rol es and env ironmentally pollutant capable of causing health risks even at tra ce levels. Considering versatile applications of cobalt, good and sensitive methods are often required for it s separation and es timation. Various methods have already been reported for determination of cobalt(II) in vario us sa mples by applying so lvent extraction followed by spectrophotometric measurement s. However these methods are time-consuming as they require heating at hi gh temperature

Behaviour of non-ionic Inicroe1nulsion containing Tween-80, iso-amyl alcohol, hexane and water

Abstract: Ph ase diagrams of pseu doternary mixtures of emulsifier (tll'een-80 and iso-amyl alco hol), he xane and water ha ve been constructed with va rying surfac tant cosurfactant ratio. Tran sparent and translucent domains ha ve been identifi ed in th e phase diagra m by vis ual titration method. Th e viscomet ry and electrical conductance studies of the microemulsion demarca te th e oil in water, bicontinuou s and water in oil phases. A microemulsion is a thermodynamically stable di spers ion of two immisc ible liquids (oil and water) consisting of microdomains of one or both liquids stabilized by th e interfacial films of surface active molecules (s urfactants). The physical properties of the microemul sion systems in a w id e range of va ri ed compositi ons make it difficult to decide whether those are oi l in water (o/w) o r water in oil (w/o). Tt has been necessary to invoke a bicontinuous structure in order to explain some of these properties.' This bicontinuous structure can be vis uali sed a s a rapidly c hangi ng three dimensional network of inte r­ con nected volumes of eac h phase which are completel y interwin ed. The constituting surfactants make up th e s hape of microemulsion determining interfacial la yers . An attempt ha s been made by Talman and Prager 2 to re present thi s theoretica ll y us in g stati stical mechanics. In order to explain the unexpectedly high electrical conductance of some hi g h oi l contammg microemulsion of ionic s urfactants, a percolation mechani s m has been proposed. 3 - 5 According to this mechanis m, conductin g path occurs as a result of colli sions between inverted micelles. There is a finite probability of continuous path through the organic medium occurring instantaneously thus allow:ng the passage of current through the medium. Bostok and McDonald 6 have measured the electrical

Solvent extraction-spectrofluorometric determination of anionic surfactants using acridine orange

Abstract: A simple and rapid extraction-fluorometric method for the determination of anionic surfactant (AS) at the parts-perbillion (ppb) level is developed. Sodium dodecyl sulfate (SDS), an anionic surfactant after the formation of an ion-associate with acridine orange (ACO), a fluorescent cationic dye was extracted in toluene. The fluorescence intensity (λ em : 530 nm, λ exc : 480 nm) of the complex is a direct measure of the SDS concentration. The calibration graph is linear in the range of 0-1040 ppb of SDS (in toluene). The relative standard deviation is <±7%. The method is applicable to river water, pond water and tap water. It is free from interference from sodium chloride upto 0.5M concentration level, and also from many cations and anions upto a large concentration.

Removal kinetics of arsenic from aqueous media on modified alumina

Abstract: Thi s paper examin es arse ni c removal kinetics by applying modified alumina, so as to attain, max imum co nt amin ation leve l (MCL) at faster rat e. !-alumina has been widely used, as an ads orbent to poli sh off residu al arsenic in water foll owing coagul ant (Fe'•) trea tment. Ferric sys tem mounted over porous Y '-a lumina shows better efficiency. Adsorption iso th erm of the adso rbent s, !-alumina and it s mod ified version indicate that adso rpti on obeys Freundlich equ ation . The in te nsity factor, n of th e modi fied alumin a being clo se r to unity than alumina alone, th e rat e of adso rpti on becomes distin ctl y fas ter. The ad­ so rptio n capac ity , k 1 which is a measure of heat of adsorpti on, remai ns more or less th e sa me, indi ca tin g marginal difference onl y. Th e su peri ority of thi s protocol is es tablish ed further, as, th ere shall be no arseni c bearin g sludge with its att endin g di sposal problem. In th e wake of incidence of arsenic in ground water, a:; evidenced in some di stricts of West Bengal, Lnd ia, assuming health probl ems of episodi c dimension , thi s inves tigation was initiat ed as refl ex re ponse to gen­ erate so me data ba se to lean on. The exact reason for such contamination is ye t to emerge. It may however emperically be suggested th at arsenic contamjnation 1

Use of some hydrazine derivatives for the separation of mercury(II) from aqueous solutions by flotation technique

Abstract: Some hydrazine derivatives viz, pyridinium chloride acetylhydrazine (PAH), 1-acetylpyridinium chloride-4-phenylthiosemicarbazide (APPT), 1-acetylpyridinium chloride-o-hydroxyacetophenone hydrazone (APHH), trimethylammonium chloride acetylhydrazine (TAH), 1-acetyltrimethylammonium chloride-o-hydroxyacetophenone hydrazone (ATHH) and 1-acetyltrimethylammonium chloride diacetylmonoxime hydrazone (ATDH) are investigated as floating agents for the separation of mercury(II) using oleic acid surfactant. Of these, APPT is the most suitable for giving maximum flotation efficiency (∼100 %). Surfactant, metal ion and ligand concentrations, ionic strength, foreign ions, pH and temperature are examined as important parameters affecting the floatability of Hg(II). The procedure is successfully applied to recover Hg(II) from some natural water samples with a relative standard deviation of 1.6%. Moreover, the mechanism of flotation is suggested based on some physical and chemical studies on the solid complexes isolated from aqueous and scum layers.

Low pressure equilibrium between H2S and CO2 over aqueous alkanolamine solution

Abstract: The simultaneous absorption of H 2 S and CO 2 in aqueous alkanolamine solution is of considerable commercial importance. The reversible nature of reactions always results in equilibrium partial pressure of CO 2 and H 2 S over amine solution. A simple method is presented to determine the equilibrium partial pressure having very low loading of H 2 S and CO 2 with the select-ion electrode. The entire equilibrium is divided into two parts, namely first equilibrium and the final equilibrium. A (H 2 S+CO 2 )-aqueous alkanolamine system is highly non-ideal. Therefore, an attempt has been made to correlate data by using final equilibrium expression based on ideal behaviour and then introducing a lumped correction factor (β) to predict observed data between H 2 S-CO 2 and diethanolamine solution. This methodology being process engineering friendly can be extended to other systems also.

Process technology development for LOVA gun propellant

Abstract: LOVA gun propellants are formulated with the use of a suitable inert binder and a cyclic nitramine as the energetic ingredient. For the technology development of LOVA gun propellant a suitable manufacturing method was required to be developed. Manufacture of propellant formulation using cellulose acetate and RDX was tried by conventional solvent process by two different methods. In the first method the fine RDX was first desensitised by the plasticiser coating and the desensitised fine RDX was incorporated with the inert binder. In the second method a two stage process technology was adopted. In the first stage, the basic composition is prepared by wet mixing process and in the second stage the dry basic mix is solvent incorporated for extrusion into the required size and shape. The first method was termed as dry process and the second method as wet process. The comparative analysis of the ballistic aspects as determined by closed vessel firing indicated that the propellant batches made by the wet mix process gave consistent and reliable results, and has been adopted for the manufacture of'LOVA' gun propellants.

Synthesis and studies of coloured polyesters derived from bis-azo diols

Abstract: A series of coloured polyesters have been synthesized by interfacial polycondensation reaction of terephthaloyl chloride and various bis-azo diols. The bis-azo diols have been prepared from two different heterocyclic diols, 7,7'-dihydroxy-4,4,4',4'-tetramethyl-2,2'-spirobis [chroman] and 2,9-di(2-dimethyl-p-hydroxy benzyl)-5a,10b-dihydro benzofuro [2,3-b] benzofuran by coupling with various diazotized fast bases. These bis-azo diols (dyes) were characterized by their m.p., % yield, elemental analysis and uv-visible spectroscopy and applied on nylon and polyester fibres and their dying performance were assessed. These dyes showed fair to fairly good fastness to light and very good to excellent fastness to washing, rubbing, perspiration and sublimation. All the coloured polyesters were characterized by their elemental analysis, ir and uv-visible spectroscopy. Their viscosity, solubility, bleeding test and thermogravimetric analysis were also studied.

Flocculation studies on hematite-silica system using polymeric flocculants

Abstract: The dispersion-flocculation behaviour of synthetic mineral mixture using polymeric flocculants was investigated. Results reveal that flocculation of the separate minerals with 50 ppm causticised cassava starch occurred within the acidic pH region (pH 3-6) with maximum flocculation occurring at pH 5 and the optimum flocculation occurring within a narrow causticised starch concentration range of 20-40 ppm (hematite suspension), while the flocculation of silica suspension was found to be independent of starch concentration above 25 ppm. For the effective flocculation of the separate minerals, 75 ppm of polyacrylamide was found to be needed. It was established that for the hematite/silica mixture suspension, 50 ppm causticised starch concentration in the acidic pH region (pH 3-6) gave the best result. Electrokinetic studies conducted to study the mechanisms involved provided indication for the shift of shear plane. Based on the data gathered in the study, it is concluded that causticised cassava starch is a better flocculant for the selective flocculation of hematite/silica mixture suspension than polyacrylamide.

Tin-Zinc alloy electrodeposit- Physicochemical characterisation

Abstract: Efforts are being made globally to replace the cadmium plating, which is being outlawed due to its toxic and carcinogenic nature. Tin - zinc alloy plating is one such approach to combine the good properties of the parent metals such as solderability and ductility with sacrificial corrosion resistance and hardness. A gluconate bath, identified in this work offers many advantages. Some additional information on their solderability, hardness, porosity, crystallography and surface topography are discussed in this paper.

Studies on fouling and gel polarisation aspects of polyvinyl butyral blended cellulose acetate ultrafiltration membrane by resistance model approach

Abstract: Ultrafiltration (UF) process is gaining increasing attention for processing a variety of chemical effluent streams. A large number of polymeric candidates have been identified as potentially useful UF membrane candidates. A series of UF membranes from polyvinyl butyral blended cellulose acetate were synthesized and their fouling characteristics were investigated with respect to changing polarity of the polymer candidate. The results are analysed using resistance model approach using polyethylene glycol and polyethyleneimine solutes. Membrane fouling and gel polarisation aspects are studied from the observed changes in water permeation rates when polar and nonpolar macromolecular solutes are employed. The effect of operating pressure, time and concentration were studied and the various resistances are quantified. Attempts were made to predict gel polarisation resistance using a simplified model.

Conversion of anilines to their oligomers by copper hexacyanoferrate(II)

Abstract: Aniline, p-toluidine and p-chloroaniline have been oxidized by copper hexacyanoferrate(II). The reaction was appreciable in basic medium. The resultant oxidation products deposited on copper hexacyanoferrate (II) surface are reddish brown in colour. The oxidation products have been characterized by GC-MS and IR spectroscopy. From the spectral studies, the oxidation product of aniline has been identified as tetramer, while that of p-toluidine and p-chloroaniline are trimer and dimer, respectively.

Photochemical formation of gold nanoparticles in aqueous Triton X-I 00 and its application for cyanide determination

Abstract: Pink coloured stable gold sol (λ max : 523 nm) has been prepared photochemically in aqueous Triton X-100 (TX-100) medium and used for spectrophotometric determination of cyanide. The colour of the sol decreases on cyanide addition and becomes colourless at the end point. Linear calibration is obtained in the range of 0-26 ppm of cyanide concentration. The relative standard deviation for 8.65 ppm of cyanide is found to be ±2.03%. The method is simple, rapid and applied for real sample analysis.

Solvent extraction separation of bismuth(III) with hexaacetato calix(6)arene

Abstract: Bismuth(III) was quantitatively extracted from 0.1M HCl with 0.0001 M of hexaacetato calix(6)arene in toluene. It was stripped with 2 M nitric acid and determined from the aqueous phase spectrophotometrically at 470 nm as its complex with thiourea. The various parameters such as pH, reagent concentration, kind of diluents, stripping agents, effect of diverse ions were studied to ascertain optimum conditions for the quantitative extraction of bismuth. Bismuth was separated from thorium(IV), iron(III), manganese(II), chromium(III), lead(II), palladium(II) and thallium(III) in multicomponent mixtures. The method was extended for the analysis of bismuth in real samples (pharmaceutical preparation).

Biomass conversion : Synergistic use of immobilized α-amylase and amyloglucosidase for rapid and maximum conversion of starch into glucose

Abstract: Enzyme technology is developed for the conversion of starch into glucose syrup, containing 99% (w/w) glucose using synergistic action of α-amylase and amyloglucosidase For repeated and efficient use of these enzymes, they were covalently immobilized on agaropectin, which proved to be an ideal support for immobilization of these enzymes Parameters for immobilized enzymes were determined and compared with free enzymes Optimum enzyme starch ratio was determined for rapid and maximum conversion of starch into glucose Attempts were made to improve quality of glucose by minimizing the reversion product formation

Synthesis of polyacrylonitrile (PAN) catalyzed by Ni(II)/glycine chelate complex through emulsion polymerization initiated by monopersulphate

Abstract: A radical polymer of acrylonitrile (AN) was prepared usi ng a non-conventional complex initiating system Ni(II)/Giycine/KHS05 in the absence of an added emulsifier. The polymerization reaction was also carried out in the pres­ ence of various divalent transition metal salts, certain amino acids and their chelate complexes in atmospheric oxygen. The metal salts and amino acids with free amino and carboxyl groups have a retarding effect on the polymerization reaction .while their chelate complexes have catalytic effect. From among the data, NiCiiglycine chelate complex was chosen for detailed kinetic st udy of acrylonitrile polymerization. The stirring of solution produces dispersion of the in soluble monomer in the continuous phase. The rate of polymerization (Rp) was studied for varying concentration of monomer, initiator, gly­ cine, NiCI 2 and solvents over a temperature range of 40-70°C. The polymers were characterized by molecular weight deter­ mination by GPC and viscosity methods. The overall act iv ation energy was computed to be 5.35 kcal mol' 1 • From kinetic and spectrophotometric study, the mechanism of KHS05 decomposition by Ni(ll)/glycine complex and initiation of poly­ merization was suggested. Emulsifier-free emulsion polymerization of vinyl and acrylic monomers have received much attention be­ cause of both practical and academic interests 1 10 , and also with a view to synthesize commercial polymers for biomedical , coating and adhesive applications. Several studies were carried out in the field of emul­ sion polymerization of various monomers using dif­ ferent redox pairs 11 14 and metal ions but most of these are performed at high temperature over 70°C under oxygen-free (inert) atmosphere. In previous

Physico-chemical and compositional studies on vacuum gas oils from North Gujarat crudes

Abstract: ~a lytica l data has been ge nerated on vacuum gas oil s from North Gujarat crude oils usin g se paration te chn iqu es and average structural parameters were es timated on compound typ e concentrate s by'T! ~d DC nmr. The co mbinati on of analytic al data wit h ave rage stru ctural parameters accounted for cert ain di stin cti ve features of the compositi on of va cuum gas oils from hea vy and li ght crud eS) Q r- ",r r" ~ "'J -' 1

Electroless deposition of Fe-P, Fe-P-Pt alloys

Abstract: Fe-P and Fe-P-Pt alloys have been developed by electroless plating technique using suitable acidic bath solution and plating conditions. The alloys are characterised to be used as cathode materials for hydrogen evolution reaction in alkaline solution. The alloys exhibited an overpotential of 332 (Fe-P- Pt) and 412 mYs (Fe- P) for about 70 h of continuous electroly­ sis in 30% KOH at a current density of I 00 mA/cm 2 and temperature 323 K. The electrocatalytic acti vity depends on th e al­ loying elements and the composition of the alloy. Electrokinetic parameters for hydrogen evolution reaction are evaluated. Electrolytic production of H2 for Hr02 fuel cell is a reaction frequently encountered in industrial operations. In recent years electrolytically prepared alloys are being used as cathode materials in alkaline water electrolysis 1 · 3 • Despite many developments in fuel cell technolog/ the rational approach to the problem is still in its infancy. The catalytic activity of the cathode is reduced considerably because of the surface contamination from solution components 5

Hydrocarbon class type distribution of crude oils by high performance liquid chromatography

Abstract: High performance liquid chromatography (HPLC) provides a rapid analytical technique for chemical group type separation for evaluating crude oils. Seven crude oils of different origins and a technical blend of these crudes were taken up for this study. Crude oils were separated into total saturates and total aromatics on amino bonded silica column through HPLC system using UV and RI detectors. The quantitation of all class types were carried out by applying the response factors of separated concentrates from the technical blend of crude oils and calculating their response factors. The precision and the accuracy of the method was demonstrated by determining the standard deviation for the peak areas using pure compounds and comparison of HPLC procedure with their gravimetric data obtained by open column chromatography on technical blend of crude oils. The method is simple, accurate and provides compound class type analysis with microgram sample and is suitable for quick compositional surveys of crude oils. It uses a single solvent elution, requires minimum sample preparation and the time required for single analysis is less then an hour. Therefore, the method can be adapted for routine analysis of crude oils and streams from various processes.

Modelling of distribution coefficients of nitrous acid in 15-30 vol.% TBP/n-dodecane-nitric acid system

Abstract: During partitioning of uranium and plutonium, nitrous acid re-oxidises Pu(III) to Pu(IV). Therefore a large excess of U(IV) is required. Since the scavenger reagent hydrazine is not extracted into the organic phase, even a small amount of extracted nitrous acid will cause cyclic reactions in the organic phase. In this scenario, study of the distribution behaviour of nitrous acid is important. In this paper, a model, based on extraction mechanism, is reported and compared with the model reported in the literature. The model reported in this paper is considered more reliable than the model available in the literature.