Indian Journal of Chemical Technology

Research articles

Modification of layered double hydroxides by short chain organic surfactants via ion-exchange method	259
IPC Code: B01J39/04
R Anbarasan & S S Im

Fluoride adsorption studies of montmorillonite clay	263
IPC Code: B01D15/00
G Karthikeyan, Anitha Pius & G Alagumuthu

Determination of tinidazole by potentiometry, spectrophotometry and high performance liquid chromatography	273
IPC Code: G01J3/00; B01D15/00; A61K
K Basavaiah, P Nagegowda & U Chandrashekar

Adsorbent selection for anionic surfactant removal from water	281
IPC Code: C11D1/02; C02F1/28
Paritosh Das Purakayastha, Anjali Pal & Manas Bandyopadhyay

Utilization of a biosorbent based on Azadirachta indica (Neem) leaves for removal of water-soluble dyes	285
IPC Code: C09B61/00
Arunima Sharma & Krishna G Bhattacharyya

Adsorption equilibrium of 7-aminodeacetoxy cephalosporanic acid-cephalexin mixture onto activated carbon and polymeric resins	296
IPC Code: B01D15/08
N N Dutta & Monali Dutta Saikia

Some properties of sodium tungsten bronzes as a function of sodium concentration	304
IPC Code: C01B19/00; C21B13/00
A M El-Sayed & S M A Mousa

Correlation of mass transfer coefficient and solute permeate flux in pervaporation of benzene-cyclohexane mixtures using a composite PVA membrane on PAN support	309
IPC Code: B01D17/00
Debarati Mitra (nee: Sarkhel), Debashis Roy, Madhusree Bandyopadhyay & Pinaki Bhattacharya

Synthesis of p-tolyl stearate catalyzed by acid activated Indian bentonite	316
IPC Code: C01B3/16:33/38
B Vijayakumar, C Ravindra Reddy, Pushpa Iyengar, Gopalpur Nagendrappa & B S Jai Prakash
Batch kinetics and modeling of poly-β-hydroxy butyrate synthesis from Azotobacter vinelandii using different carbon sources	322
IPC Code: C08G61/00
R Dhanasekar & T Viruthagiri

Modeling of three phase inverse fluidized bed using artificial neural network	327
IPC Code: B01D3/26
Anant Dolas, S L Pandharipande & B S Chandak

Studies on effect of topology on pulp and paper characteristics of Eucalyptus camaldulenosis	332
IPC Code: D21C11/00: 9/00
Dharm Dutt, R S Malik, J S Upadhyaya, C H Tyagi & M K Upadhyaya

Synthesis and kinetics of ‘crumpled’ PMMA latex by non-conventionally initiated emulsion polymerization	341
IPC Code: C08F2/32
Roomky Mohapatra & Prafulla K Sahoo

Microstructural and corrosion studies of 9Cr-1Mo steel in acidic methanol solutions	347
IPC Code: C22C38/00
V B Singh & Archana Gupta

Corrosion inhibition of mild steel by ethanolic extracts of Ricinus communis leaves	356
IPC Code: C23F11/08
R Ananda Louise Sathiyanathan, S Maruthamuthu, M Selvanayagam, S Mohanan & N Palaniswamy

Notes

Indirect complexometric determination of mercury(II) using 2-mercaptopropionic acid (2-MPA) as a selective masking agent	361
IPC Code: C22B43/00; G01N
J Karthikeyan, P Parameshwara, A Nityananda Shetty & Prakash Shetty

Extractive spectrophotometric determination of bismuth(III) in alloy samples using 1-amino-4,4,6-trimethyl (1H, 4H) pyrimidine-2-thiol	365
IPC Code: G01J3/00; C01G29/00
S G Gaikwad, S V Mahamuni & M A Anuse

*Educator*

Matches-The manufacture of fire	369
Jaime Wisniak

*Chem-Tech Scan*	381

*Author Index*	385

*Keywords Index*	386

Modification of layered double hydroxides by short chain organic surfactants via ion-exchange method

The layered double hydroxides (LDH), hydrotalcite (HT) was modified through ion-exchange method with two different organic short chain anionic surfactants in the presence and absence of ultrasound (US). Hydroxy ethane sulphonic acid (HESA) modified HT prepared in the presence of US showed increase of peak intensity in XRD analysis. US assisted sulphoacetic acid (SAA) ion-exchanged HT exhibited completely delaminated/degraded amorphous HT structure. This was authenticated by XRD profiles. The presence of anionic surfactants in the LDH structure is evidenced by FTIR spectroscopy.

Keywords: Layered double hydroxides, organic surfactants, ion-exchange, XRD, FTIR

Fluoride adsorption studies of montmorillonite clay

Batch adsorption studies were conducted to determine the effects of contact time and temperature on fluoride removal by montmorillonite clay at neutral pH. The adsorption of fluoride was studied at four different temperatures, viz. 30, 40, 50 and 60°C. The kinetics of adsorption as well as adsorption isotherms at different temperatures were studied. Adsorption obeyed both Langmuir and Freundlich isotherm models. The percentage of fluoride removed increased with time and reached an optimum level at 50^th min. The material with particle size of 75 microns registered maximum percentage of fluoride adsorption, compared to the other particle sizes. Thermodynamic studies revealed that the adsorption of fluoride by montmorillonite is an endothermic process, showing increase in sorption at higher temperature. The negative values of ΔG° indicate the spontaneity of the sorption process. Adsorption takes place on the surface as well as through intraparticle diffusion pattern of the adsorbent material. SEM studies revealed the morphological characteristics of the untreated sorbents as well as the changes in the treated sorbents. X-ray diffraction studies also confirmed the deposition of fluoride on the surface of the clay material. FTIR studies showed the involvement of hydroxyl group present on the surface in the adsorption interaction.

Keywords: Adsorption, fluoride removal, montmorillonite clay, Langmuir isotherm, Freundlich isotherm

Determination of tinidazole by potentiometry, spectrophotometry and high performance liquid chromatography

Three assay procedures based on potentiometry, spectrophotometry and high performance liquid chromatography (HPLC) have been developed for the determination of tinidazole in tablets and injections. In the potentiometric titration method, the drug in glacial acetic acid is titrated with acetous perchloric acid with potentiometric end point detection. Spectrophotometry involves the addition of different amounts of tinidazole to a fixed amount of perchloric acid-malachite green mixture followed by measurement of absorbance at 615 nm. The HPLC determination was carried out on a reversed phase C₁₈column using a mobile phase consisting of acetonitrile-0.1 % phosphoric acid (70:30) at a flow rate of 1.0 mL min^-1 with UV-detection at 316 nm. Potentiometric tiration is applicable over 1-10 mg range of tinidazole and in spectrophotometry, the calibration graph is linear from 15-180 mg mL^-1 with a molar absorptivity of 9.02 ´ 10² L moL^-1 cm^-1 and a Sandell sensitivity of 385.2 ng cm^-2. The limits of detection and quantification are calculated to be 3.05 and 10.15 mg mL^-1, respectively. In HPLC method, a rectilinear relationship was observed between 6.25 and 250 mg mL^-1 tinidazole with a detection limit of 0.625 mg mL^-1 and a quantification limit of 1.875 mg mL^-1. The analysis time was less than 5 min. The statistical evaluation of the methods was examined by determining intra-day and inter-day precision. The methods when applied to the determination of tinidazole in tablets and injections gave satisfactory results. The accuracy and reliability of the proposed methods were further ascertained by parallel determination by the reference methods and by recovery studies using standard-addition technique.

Keywords: Tinidazole, potentiometry, spectrophotometry, HPLC, pharmaceuticals

Adsorbent selection for anionic surfactant removal from water

In the present study, an attempt was made to find out a low cost adsorbing material for the removal of anionic surfactant (AS) from water. Sodium dodecyl sulphate (SDS) has been selected as a representative member of AS. Adsorbents such as granular activated charcoal, waste tire rubber granules, wood charcoal, and silica gel were tried. Kinetic profiles of removal of SDS were generated for all materials to assess the equilibrium time. The percentage of SDS removal at 7h equilibrium time was 96% for granular activated charcoal, 96.5% for waste tire rubber granules, 88% for wood charcoal and 92% for silica gel. Equilibrium studies were carried out for all materials to assess the adsorption equilibrium model that they followed. The correlation coefficients were determined by linear regression analysis, and compared. Maximum adsorption capacities (Q_max) for granular activated charcoal, waste tire rubber granules, wood charcoal and silica gel, were found to be 3.750, 4.164, 5.170 and 5.181 mg/g, respectively. The removal efficiency, maximum adsorption capacity and cost were the guiding parameters for the selection of the adsorbent in the present study. Considering all factors waste tire rubber granule was chosen as the best adsorbent for AS removal. The physical or chemical characteristics of the rubber granules were reported.

Keywords: Anionic surfactant, sodium dodecyl sulphate, adsorbent selection, rubber granules

Utilization of a biosorbent based on Azadirachta indica (Neem) leaves for removal of water-soluble dyes

A biosorbent is developed from Azadirachta indica (Neem) leaves in the form of a finely ground dried powder (53–74 m). The powder was used to remove three water-soluble dyes, viz., brilliant green, congo red and methylene blue from aqueous medium. The adsorptive interactions were tested under varying conditions of concentration of the dyes, amount of adsorbent, pH, and temperature. It was found that 670, 1000 and 2000 mg respectively of the powder could remove almost 100 % of the dyes from 1 L of water containing 10, 20 and 25 mg of brilliant green, congo red and methylene blue dyes, respectively. The interactions followed pseudo first order kinetics. The Langmuir monolayer adsorption capacity had values of 133.69, 72.38 and 8.76 g kg^-1 for brilliant green, congo red and methylene blue. The adsorption of brilliant green and methylene blue on neem leaf powder (NLP) was endothermic with mean ΔH values of 12.12 and 9.40 kJ mol^-1 respectively while that of congo red was exothermic with mean ΔH value of –12.75 kJ mol^-1.

Keywords: Biosorbent, neem leaf powder (NLP), Water soluble dyes, brilliant green, congo red, methylene blue, Azadirachta indica

Adsorption equilibrium of 7-aminodeacetoxy cephalosporanic acid–cephalexin mixture onto activated carbon and polymeric resins

The adsorption of 7-aminodeacetoxy cephalosporanic acid (7-ADCA) – cephalexin binary mixture in aqueous solution has been studied using polymeric resins of two different types as well as activated carbon. The adsorption intensity was found to be strongly dependent on the aqueous phase pH and this dependence could be interpreted from a model for neutral species adsorption in all cases. Single-solute isotherms for 7-ADCA and cephalexin were correlated with the Langmuir, Freundlich and Redlich-Peterson isotherm models, the Langmuir model being found to provide the best fit of the experimental data. The differences in adsorption affinities of the solute obtained for different adsorbents were interpreted from sorbent surface chemistry and morphological structure. Experimental binary-solute adsorption isotherms were compared with four different types of binary-solute Langmuir models using single-solute parameters. The results showed that the difference in saturation capacities affected the adsorption equilibrium. Furthermore, three types of binary-solute Langmuir models were converted into the kinetic form and one of them was used to calculate the association rate constants of 7-ADCA and cephalexin from experimental data. The adsorption rate curves for 7-ADCA and cephalexin appear to be typical of the first order kinetics.

Keywords: Cephalosporinic acid, adsorption isotherm, activated carbon, polymeric resin

Some properties of sodium tungsten bronzes as a function of sodium concentration

Sodium tungsten bronzes, Na_XWO₃ have been prepared having x = 0.25-0.85 at temperatures between 700 and 850 °C in argon atmosphere. X-ray diffraction and IR absorption spectra were used to characterize the structure of the products. It was found to exist in two distinct phases tetragonal and cubic. The absorption spectra between 300 and 780 nm have been obtained by diffuse reflection method, and the characterized absorption peak wave length shows a slight shift to shorter wave lengths with increasing sodium content. The electrical conductivity (s) has been measured as a function of sodium concentration and temperature from 300 to 550 °K. The results indicate metallic conduction and the conductivity was found to increase with increasing sodium concentration.

Keywords: Sodium tungsten bronzes, X-ray, IR, electrical conductivity, optical reflectance

Correlation of mass transfer coefficient and solute permeate flux in pervaporation of benzene-cyclohexane mixtures using a composite PVA membrane on PAN support

Debarati Mitra (neé: Sarkhel), Debashis Roy, Madhusree Bandyopadhyay & Pinaki Bhattacharya*

Pervaporation of benzene-cyclohexane mixtures has been carried out in an agitated batch permeation cell (with vacuum maintained downstream) using a proprietary composite membrane of polyvinyl alcohol (PVA) on a porous polyacrylonitrile (PAN) support, at 298 K and 0.8 torr downstream pressure. Effect of operating parameters like feed solute concentration, C_L0 and agitator speed, n on the overall solute permeate flux has been elaborately studied. Based on the experimental data, an attempt has been made to predict mass transfer coefficient and pervaporative mass transfer flux, from semi-empirical approach. The predictive equations for the two above mentioned design parameters are presented.

Keywords: Benzene-cyclohexane mixture, pervaporation, PERVAP^® 2200 membrane, overall masstransfer coefficient, solute permeate flux

Synthesis of p-tolyl stearate catalyzed by acid activated Indian bentonite

B Vijayakumar, C Ravindra Reddy, Pushpa Iyengar, Gopalpur Nagendrappa& B S Jai Prakash*

Synthesis of p-tolyl stearate, catalyzed by acid activated Indian bentonite (AAIB) is reported. The esterification of stearic acid (SA) and p-cresol (p-C) gave p-tolyl stearate in high yield using acid activated Indian bentonite as the catalyst. White montmorillonite exchanged with Al³⁺ and treated with HCl gave 49 and 51% of the ester respectively after 12 h. Use of p-toluenesulphonic acid as catalyst gave 82% yield of the ester after 12 h in toluene. When the reaction was conducted in toluene and o-xylene with Indian bentonite treated with H₂SO₄ the yields were 89 and 97% (molar ratio, SA:p-C = 1:4) respectively after 12 h. Effects of molar ratio, amount of the catalyst, solvent, reaction time and catalyst activation temperature on the yield of p-tolyl stearate and reusability of the clay catalyst are investigated.

Keywords: Smectite, acid activated Indian bentonite, p-tolyl stearate, esterification, reusability

Batch kinetics and modeling of poly-b-hydroxy butyrate synthesis from Azotobacter vinelandii using different carbon sources

A mathematical model is presented for the batch production of poly-b-hydroxy butyrate, a well known biopolymer, from Azotobacter vinelandii utilizing different carbon sources, sucrose and cheese whey. The effect of substrate concentrations and inoculum concentrations on cell mass and P(3HB) production are studied in a batch experiment. Substrate utilization kinetics is also studied. Set of differential equations for cell mass rate, product formation rate, and substrate utilization rate as functions of initial cell concentration, cell concentration at any time and stationary cell concentrations, are used to predict the system behaviour. The kinetic pattern obtained from the batch experiments are used to simulate the models.

Keywords: P(3HB), Azotobacter vinelandii, sucrose, cheese whey, kinetic modeling

Modeling of three phase inverse fluidized bed using artificial neural network

Fluidization of a three-phase system can be achieved either with co-current up flow of gas and liquid or down flow of liquid and up flow of gas. Three Phase Inverse Fluidised Bed (TPIFB) falls in the second category. Because of high gas hold up and residence time, this type of fluidized bed has more mass transfer coefficient. In present work, experiments were conducted using polyethylene hollow spheres coated with benzoic acid and using water as solvent with air as the fluidizing medium. The data thus generated was used for developing models using Artificial Neural Networks (ANN). It has been observed that the ANN model developed has excellent accuracy level of more than 90%.

Studies on effect of topology on pulp and paper characteristics of Eucalyptus camaldulenosis

The seedlings of Eucalyptus camaldulenosis of same genotype were grown at different geographical locations having distinct pre- and post-monsoon ground water levels. It is observed that as the ground water level recedes, balloon like structures known as tyloses develop, which affect the plant anatomy, physico-chemical and pulp and paper making characteristics of E. camaldulenosis. The aging of E. camaldulenosis has marked adverse impact on morphological, physico-chemical composition, pulping and black liquor characteristics along with mechanical strength properties of paper.

Synthesis and kinetics of ‘crumpled’ PMMA latex by non-conventionally initiated emulsion polymerization

The aqueous emulsifier-free emulsion polymerization of methyl methacrylate (MMA) was studied under the catalytic effect of a prepared complex, [Cu(NH₃)₄]SO₄, with various initiators like potassium peroxodisulphate (KPS), potassium monopersulphate (KMPS) and ammonium persulphate (APS). The apparent activation energies E_a were found to be 36.52 (KMPS), 40.47 (KPS) and 31.9 kJ/mol (APS). The activation energies of initiator decomposition E_d were found to be, 31.04, 38.93 and 21.79 kJ/mol for KMPS, KPS and APS, respectively. The emulsion polymer (PMMA) latex was characterized through the determination of the size and morphology by scanning electron microscopy (SEM), FTIR spectroscopy, the average molecular weight by GPC and viscosity methods. The surface of the polymer latex was found to be somewhat ‘crumpled’. From the kinetic results, the rates of polymerization, R_p, at 50°C were determined.

Microstructural and corrosion studies of 9Cr-1Mo steel in acidic methanol solutions

The corrosion behaviour of 9Cr-1Mo ferritic steel has been studied in methanol containing different concentrations of sulphuric, hydrochloric acids and their mixtures using potentiostatic and potentiodynamic techniques at 30 °C. The influence of various heat treatments: furnace cooled (FC), air cooled (AC) and water quenched (WQ) on the electrochemical polarization behaviour has also been studied for a few selected compositions of these acids and their mixtures in methanolic solutions. The cathodic reaction is observed to be hydrogen evolution. The alloy showed active, passive and transpassive behaviour in different concentrations of sulphuric acid in methanol. The anodic polarization curves of the alloy revealed a characteristic ‘cathodic loop’ in methanol at higher concentrations of sulphuric acid (0.1 and 1.0 M). Stable passivity was also observed which became ustable at higher potential due to pitting. Well defined anodic Tafel region followed by a limiting current density region, in different concentrations of methanolic solution of hydrochloric acid, was observed. However, in the mixture of different concentrations of sulphuric acid and hydrochloric acids in methanol and at higher concentration of sulphuric acid (1.0 M) the alloy showed active, passive and transpassive behaviour. Such behaviour was not observed below 1.0 M concentration of either acid in methanol, rather a limiting nature was observed. It seems that in the acidic mixture, the SO^2-₄ ions act as inhibitor and decreases the adsorption of Cl^- ions and at sufficiently high concentration it effectively hinders the adsorption of the Cl^- ions on the surface. The anodic polarization curves for FC specimen shifted towards higher current density region and the curves for AC and WQ specimens shifted towards lower current density region in comparison to as-received one in methanolic solution of sulphuric acid. However, the anodic polarization curves for FC, AC and WQ specimen shifted towards higher current density region as compared to as-received specimen in methanolic solution of hydrochloric acid and in the mixture of hydrochloric and sulphuric acids in methanol. Examination of the sample surface was done using scanning electron microscopy (SEM).

Keywords: Corrosion, 9Cr-1Mo steel, potentiostatic technique , potentiodynamic technique

Corrosion inhibition of mild steel by ethanolic extracts of Ricinus communis leaves

R Ananda Louise Sathiyanathan^*, S Maruthamuthu, M Selvanayagam, S Mohanan & N Palaniswamy

Extracts of Ricinus communis leaves were tested for corrosion inhibitory effects towards mild steel in 100 ppm sodium chloride solution. The anticorrosion efficiency of plant extracts was studied by means of weight loss, electrochemical polarization and impedance measurements. It was found from weight loss measurements that the corrosion inhibition efficiency was about 84% in 300 ppm of the plant extract. Polarization measurements indicated that the plant extract acted as anodic inhibitor. Electrochemical impedance results also showed that the plant extract increased the corrosion resistance of mild steel and the formations of iron-organic complex reduced the corrosion of mild steel in neutral system.

Keywords: Ricinus communis, corrosion inhibitor, mild steel, electrochemical impedance

Indirect complexometric determination of mercury(II) using 2-mercaptopropionic acid (2-MPA) as a selective masking agent

A complexometric method for the determination of mercury(II) in presence of other metal ions is described based on the selective masking action of 2-mercaptopropionic acid towards mercury(II). Mercury(II) present in a given sample solution is first complexed with an excess of EDTA and the unreacted EDTA is titrated against zinc sulphate solution at pH 5-6 (hexamine buffer) using xylenol orange as the indicator. A 0.5% aqueous solution of 2-mercaptopropionic acid is then added to displace EDTA from the Hg(II)-EDTA complex. The released EDTA is estimated. Reproducible and accurate results are obtained for 4-88 mg of mercury(II) with relative error less than ± 0.46% and coefficient of variation not more than 0.34%. The effects of various ions were studied. The method is used for the analysis of mercury in its synthetic alloy mixtures and also in complexes.

Extractive spectrophotometric determination of bismuth(III) in alloy samples using 1-amino–4, 4, 6–trimethyl (1H, 4H) pyrimidine-2-thiol

Pyrimidine-2-thiols are reported to be good analytical reagents for the spectrophotometric determination of metal ions. In the present work 1-amino-4,4,6-trimethyl (1H,4H) pyrimidine-2-thiol(1-amino TPT) was used as an analytical reagent for the extractive spectrophotometric determination of bismuth(III). The optimum extraction conditions were evaluated by studying parameters like acidity, equilibration time, reagent concentration and stability of complex. 1-amino TPT in chloroform gives an orange coloured complex with bismuth(III) in 4.5 to 6.0 M perchloric acid medium. The absorption spectrum of bismuth(III) - 1-amino TPT complex shows maximum at 470 nm and obeys Beer’s law in the range of 7-24 ppm. The molar absorptivity and Sandell’s sensitivity were 6.501´10³ L mol^-1 cm^-1 and 32 ng cm^-1respectively. The composition of the bismuth(III) - 1-amino TPT complex was found to be 1:4 (metal:ligand). The effect of diverse ions has been studied and the method was found to be applicable in the determination of bismuth from alloy samples.

Matches-The manufacture of fire

The phosphorus match represents the culmination of the efforts to manufacture fire by friction at will, which started with the rubbing of two wood sticks. The modern cigarette lighter corresponds to the next evolutionary step in the process.

ISSN: 0971-457X		CODEN:ICHTEU 12(3) 253-386
Volume 12	Number 3	MAY 2005