007916   Upadhyayula S (Chemical Engineering Dep, Indian Institute of Technology Delhi, Delhi-110 016, Email: sreedevi@chemical.iitd.ac.in) : Alkylation of benzene and toluene with alcohols over modified 13 x zeolite. Int J chem Sci 2007, 5(4), 1775-84.

Commercially available 13X were modified using rare earth and AICl₃ impregnations and ion exchange with rare earth cerium ions to enhance their catalytic activity in the Alkylation reaction of benzene and toluene with C₁-C₄ alcohols. All the modified catalysts were tested for structure stability using XRD and were found to be crystalline pure phases. These catalysts were tested in the alkylation reactions in a fixed packed bed reactor. The process parameters like temperature and pressure varied in the ranges of 350°C-500°C and 2.4-24.7 kg/cm² absolute respectively.

6 tables, 15 ref

007915   Tripathy H K;Murthy B V R;Swamy Y V;Mohanty J N;Tripathy A K (NO, Institute of Minerals and Materials Technology, Formerly Regional Rese, Bhubaneswar-751 013, Email: hktripathy@yahoo.com) : Briquetting of steel plant wastes suitable for charging in blast furnace. J Mines Metals Fuels 2008, 56(1-2), 28-32.

Steel plants generate huge amount of wastes like iron ore fines, flue dust, granulated slag, mill-scale, coke breeze etc. These wastes are briquetted using organic, inorganic binders and also combination of both. Various organic binders are tried in combination with lime. The briquettes obtained with organic binder have sufficient green strength (+ 5 drops) but have poor reduction disintegration index (RDI). Whereas the briquettes obtained with a combination of organic and inorganic binders have improved green strength (10 drops) with high cold crushing strength (CCS) but with insufficient RDI Activated inorganic binder along with refractory grade binder improves the briquette characteristics in terms of green strength, CCS and RDI. The briquettes obtained using this combination of binders have sufficient green strength (3 drops), CCS (above 200 kg/ briquette) and RDI (10-20%) which are found to be suitable for charging into blast furnace.

9 tables, 6 ref

007914   Swati D;Rao V S R;Pickhardt R;Chidambaram M (NO, National Institute of Technology, Tiruchirappalli-620 015, Email: chidam@iitm.ac.in) : Nonlinear PI controller for time delayed pH system. Indian chem Engr 2008, 50(2), 93-105.

The Wiener model is a suitable mathematical description of the highly nonlinear pH process with time delays. A nonlinear controller based on this model is designed to control the pH of a time delayed pH system. The performance improvement of a Wiener model based nonlinear PI controller over that of the linear PI controller is evaluated via numerical simulations. Also, the robustness of the controller is studied for mild deviations in the titration curve. Experimental results at the highly sensitive operating point of pH 9 are also presented.

14 illus, 5 tables, 15 ref

007913   Sivakumar V;Senthilkumar K;Kannan K (Chemical Engng Dep, Kongu Engg College, Perundurai, Erode-638 052, Email: drvsivakumar@yahoo.com) : Prediction of phase holdups in three-phase fluidized bed reactor using Newtonian fluids. Int J chem Sci 2007, 5(4), 1723-31.

Simultaneous contact of gas and liquid phases in three- phase contactors is commonly encountered in many of the petroleum, petrochemical, chemical and biochemical industries. Multiphase catalytic reactors have received wide recognition and are widely used in commercial chemical and biochemical industries. Though, multiphase reactors with varying configurations are used in industry, three-phase fluidized bed reactor has found extensive application in waste-water treatment and other biochemical processes. For the design and development of three-phase fluidized bed reactors, knowledge of the hydrodynamic parameters viz., Gas holdup and Liquid holdup is essential and hence in this paper an attempt has been made to study the effect of fundamental and operating variables on these phase holdups using various Newtonian fluids and also on the basis of the experimental results, generalized correlations are developed to predict liquid and gas holdup in three-phase fluidized beds. The experimental results showed good conformity with those predicted according to the developed equations for both liquid and gas holdup.

7 illus, 2 tables, 16 ref

007912   Sirkar A;Ghosh S;Laha S;Banerjee M (Chemical Engineering Dep, Haldia Institute of Technology, Hatiberia Haldia, East Midnapore-721 657, Email: Sirkar_a@hotmail.com) : Design of a novel pre-heater-cum-reactor for hydrogenation of coal. Indian chem Engr 2008, 50(1), 17-26.

A short residence time pre-heater-cum-reactor has been designed for hydrogenation of coal. Inlet velocity and inlet temperature of hydrogen have been varied and their effects on the volume of pre-heater have been predicted. Design considerations for the reactor following the pre-heater have been discussed. A modification of the preªheater design has also been proposed and an alternative design presented.

6 illus, 2 tables, 9 ref

007911   Singh S K;Singh J K;Deo G (Chemical Engineering Dep, Indian Institute of Technology Kanpur, Kanpur-208 016, Email: jayantks@iitk.ac.in) : Effect of surface characteristics and pore size of nano confinements on the thermophysical properties of nano confinements on the thermophysical properties of natural gas components. Int J chem Sci 2007, 5(4), 1745-54.

Molecular simulation reveals that the various thermophysical properties such as saturation properties, adsorption properties, critical properties, and vapor-liquid interfacial properties of the natural gas components (methane and ethane), changes a great extent under the confinement. These properties are sensitive to the nature of the surface as well as to the extent of confinement. Simulation investigations indicate that the physical phenomenon that occur in porous systems depend primarily on the pore size and its surface characteristics. In the graphitic slit-pore, both critical temperature and critical density is lower than that of bulk fluid. But in the case of mica slit pore critical temperature follow the similar trend as in the case of graphite slit pore but critical density with 30 Angstrom pore width is more than the bulk critical density and then it decreases with further decrease in slit width. This increase in critical density in 30 Angstrom pore width is attributed to the shift of vapor-like density region towards higher values. Finite size scaling analysis along with grand-canonical Monte Carlo simulations is utilized to obtain the vapor-liquid surface tension of ethane and methane under different pore size and characteristic. Vapor-liquid interfacial tension under confinement is found to be 5 to 16 times lower than its bulk vapor-liquid interfacial tension value.

4 illus, 3 tables, 19 ref

007910   Singh R K;Prakash S;Singh S K;Prakash D (Chemistry Dep, Patna Univ, Patna-800 005) : Inhibition of stainless steel by use of thiourea derivative as inhibitors in 20% HCl. J Indian Chem Soc 2008, 85(6), 643-6.

The stainless steel is very important material for petroleum industry and it is used in several processing units like oil recovery, refining of crude oil, transportation, storage and petroleum products. The corrosion inhibitors are used to reduce corrosion damage in sub-surface equipments in both oil and gas well. For this work inhibition activity is studied by use of inhibitors, N,N'-di-o-tolythiourea, N,N'-diphenylthiourea and A'-phenylthiourea and experimental work can be done by gravimetric method and potentiostatic polarization at different temperature in 20% HCl solution.

1 illus, 4 tables, 9 ref

007909   Siddiqui M;Swaminathan T;Jayanti S (Chemical Engineering Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: sjayanti@iitm.ac.in) : Modeling approaches for the propagation of dense gas. Int J chem Sci 2007, 5(4), 1797-1808.

The spreading and dispersion of denser-than-air gases can be very different from that of a neutrally-buoyant gas due to gravity driven flow and stable stratification. The use of one dimensional or quasi-two-dimensional Gaussian or box models for predicting the spreading and dispersion pattern of these dense gases can result in an entirely incorrect and non-conservative approach. Computational Fluid Dynamics (CFD) has rigorously been employed for predicting the slumping, propagation and dispersion of the two dense gases in an open channel with different specific gravity ratios. Two modeling approaches within the framework of multiphase modeling, viz, the Volume of Fluid (VOF) method and the species transport method that were employed are presented. The results show the formation of a hump-like gravity head which is confirmed from the experimental results obtained from literature. Results obtained from the two approaches are also compared with the experimental results for the comparison of the two approaches. Concluded that the diffusion controlled spreading of the dense gas is better modeled by the species method while convection dominated flows is represented better by the VOF method.

7 illus, 12 ref

007908   Sharma D K (Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016, Email: sharmadk@ces.iitd.ernet.in) : Cleaner coal technologies: concept of coal refineries for added value and efficient use of coal. Indian chem Engr 2008, 50(2), 155-68.

Coal reserves in the world are much larger and more abundant. These may last for more than 250 yrs. Direct use of coal leads to environmental pollution. Unlike oil, coal is not refined, but is just washed and cleaned. Thus, there is a need to develop cleaner coal technologies where coal could be refined in coal refineries to obtain different fractionated products having different quality-grade-class (QGC) of fuels, beyond pre-, during- and post-combustion clean coal technologies. Physical coal cleaning involving oil agglomeration, homogenisation, blending etc., may not be sufficient. Chemical coal cleaning involving alkali-acid leaching or hydrodesulfurisation may also not sufficiently produce cleaner coal fragments for cleaner power generation. Co-combustion of coal with plastics, biomass, oil, water, natural gas etc., may again involve combustion of coal to generate heat inefficiently. Integrated gasification combined cycle (IGCC) power generation through hydrogen generation may be practised for zero emission power generation. Carbonisation of coal may have to be developed further to get more refined products from coal by adding plastic or vacuum residue to coal. Liquefaction of coal may afford liquid fuels from coal for further refining. Organo-refining of coal may be carried out to obtain different QGC products. The use of ultra super clean coal in gas turbines directly may enhance the efficiency of power generation to 52-55% from the existing efficiency of pulverised coal power generation of 33-38%. In fact, there is a need to develop clean coal technologies that may be adapted in future coal refineries to obtain different QGC products. Brute force high pressure coal conversion processes may have to be replaced by the convenient and cost effective low to atmospheric pressure processes through further research and development work.

3 illus, 41 ref

007907   Selvanathan S;Tangirala A K (Chemical Engineering Dep, IIT Madras, Chennai-600 036) : Time delay estimation in closed loop siso systems using Hilbert transform relations. Int J chem Sci 2007, 5(4), 1821-9.

Estimation of delay under closed-loop conditions is crucial to the performance assessment of controllers. It has an important role to play in identification and control. While delay estimation in open-loop conditions has relatively been well-addressed using sophisticated techniques, delay estimation under closed-loop conditions remains a challenge. Hilbert Transform (HT) relations have been used elsewhere to estimate time delays in neurological setups, which are open-loop systems. Work deals with the application of HT relations to time-delay estimation in closed-loop systems. The key advantages of this method are (i) it does not require information on the directionality of dependence (causality) (ii) its simplicity since it can be applied to routine operating data without the need for interruption and (iii) it is robust in the presence of measurement noise (iv) since it is a frequency domain technique, it naturally allows the user to choose the frequency range where signal to noise ratio is relatively high with the need for a filter. Simulation results using nonlinear process models demonstrate the effectiveness and potential of the method.

2 illus, 12 ref

007906   Saxena A K;Sharma U L;Rao V G (Research Reactor Services Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, Email: aksaxena@barc.gov.in) : Code RAMM for rewetting velocity on vertical nuclear fuel clad. Indian chem Engr 2008, 50(3), 205-13.

Computer code RAMM was developed for studying the rewetting behaviour of the vertical clad of nuclear fuel under bottom flooding conditions and was validated using experimental results. The code was applied to predict the rate of rise of temperature of clad after LOCA for a typical nuclear research reactor. The predicted value is in close agreement with the value available in literature. Since the code is general it has wide range of applications.

3 illus, 1 table, 6 ref

007905   Sarkar B;Pal S;Banerjee U;Dasgupta S (Chemical Engineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: sunando@che.iitkgp.ernet.in) : Evaluation of surface charge by electrokinetic method of ultrafiltration membranes. Int J chem Sci 2007, 5(4), 1902-12.

Surface charge properties of commercially available ultrafiltration membranes have been investigated by streaming potential measurement. Zeta potential is a measure of surface charge as it is directly measurable. In the study, zeta potential of 30 kDa molecular weight cut-off (MWCO) high flow ultrafiltration Poly (1, 4 phenylene ether sulfone) and 20 kDa molecular weight cut-off Polyethersulfone membrane are determined as a function of pH and ionic strength. For both the membranes, values of zeta potential are found to be negative in the pH range 3.5-10. Surface charge properties of membrane have a significant influence on the separation of biological macromolecules like protein, polysaccharide etc. The effect of solute-solute and solute-membrane interaction on permeate flux has been studied during separation of protein, bovine serum albumin from aqueous solution using 30 kDa molecular weight cut-off membrane. From experimental results, it is observed that, increase in solution pH from 5.5 to 9.0 has made an increase in permeate flux of about 20%.

5 illus, 1 table, 11 ref

007904   Saravanan V;Rajamohan N (Chemical Engineering Dep, Annamalai University, Annamalai Nagar-608 002, Email: sarav_30@yahoo.co.uk) : Removal of xylene vapor using press mud as a packing material in vapor phase biofilter. Int J chem Sci 2007, 5(4), 1634-42.

Biofiltration of xylene vapors has been investigated on a laboratory scale, biofilter packed with a press mud as filter material composed with activated sludge from pharmaceutical industry initial inoculated with a microbial consortium. Four various gas flow rates, i.e. 0.03, 0.06, 0.09 and 1.2 m³/h, were tested for xylene inlet concentration ranging from 0.2 to 1.2 g/m³. The biofilter prove, to be highly efficient in the removal of xylene at a gas flow rate of 0.03 m³/h corresponding to a gas residence time of 2.8 min. For all the tested inlet concentrations, the removal efficiency decreased for high gas flow rates. For all the tested gas flow rates, a decrease in the removal efficiency was notice for high xylene inlet concentration. The follow-up of carbon dioxide concentration profile through the biofilter revealed that the mass ratio of carbon dioxide produced to the xylene removed, which confirm complete degradation of xylene if one considers the fraction of the consumed organic carbon used for the microbial growth.

4 illus, 21 ref

007903   Sahu B;Pugazhenthi G (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: pugal@iitg.ernet.in) : Synthesis of polystyrene (PS)/ novel layered double hydroxide (LDH) nanocomposites by solvent blending method. Int J chem Sci 2007, 5(4), 1755-63.

Polystyrene (PS)/ novel layered double hydroxide (LDH) nanocomposites were synthesized by solvent blending method using xylene as a solvent. Cu-AI, Ni-AI, Co-AI LDHs were synthesized by co-precipitation method using their nitrate salts. Then, PS nanocomposites with the above synthesized LDHs content of 5 wt.% were prepared by solvent blending method. The structures, properties of LDHs and corresponding nanocomposites were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), FTIR spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD analysis revealed that the crystal sizes of the LDHs were found to be in the ranges of 14 to 20 nm. All these nanocomposites showed significantly enhancement of crystallization temperatures compared to pristine PS, as identified in DSC analysis. The TGA results showed that the LDHs catalyze degradation of PS and decreases the thermal stability of PS/LDH nanocomposites. The presence ofN03 and OH' groups in the LDHs were confirmed by FTIR spectroscopy.

5 illus, 1 table, 9 ref

007902   Sachdeva S;Anil Kumar (Chemical Engineering Dep, Indian Institute of Technology Kanpur, Kanpur-208 016) : Synthesis and characterization of carbon membrane to study the influence of organic solvents on its performance. Int J chem Sci 2007, 5(4), 1873-81.

Resol type composite carbon membranes has been prepared by first casting a graphite layer on the clay support followed by two coats of phenoIªformaldehyde prepolymer solution. This is then cross-linked and carbonized to obtain a porous carbon membrane. The membrane has been characterized using SEM, FTIR and solvent stability. Solvent flux has been obtained for solvents of four homologous families namely paraffins, alcohols, acetates and aromatics. Solute rejection of various molecular weights from ethanol has also been obtained. Carbon membranes prepared in this work demonstrate high solvent stability and shows a promising future application in non-aqueous based separations.

8 illus, 16 ref

007901   Roy A;Manigandan S;Ganguly S;Kargupta K (Chemical Engineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: kajari.kargupta@rediffmail.com) : Ordered pattern formation in conducting polymer. Int J chem Sci 2007, 5(4), 1958-64.

Dewetting and ordered pattern formation of Polyaniline (PANI) on Silicon wafer, are studied experimentally. Polyaniline is deposited on Silicon wafer using drop casting as well as spin casting techniques. Dewetting of relatively thicker films (~ 100 nm) produces novel PANI fiber like morphology of submicron diameter. Ordered submicron droplets are formed during the dewetting of thinner film (50 nm). Better ordering is observed in case of dewetting of drop casted PANI. The results are of significance in development of chemical vapor sensor and conducting polymer based controlled drug release system for the lower diffusional resistance and greater surface to volume ratio offered by such submicron patterns.

3 illus, 22 ref

007900   Ravikumar C;Ethayaraja M;Bandyopadhyaya R (Chemical Engineering Dep, Indian Institute of Technology Bombay, Powai, Mumbai-400 076) : Discrete-continuous hybrid simulation of monodisperse nanoparticle formation. Int J chem Sci 2007, 5(4), 1764-74.

A new mechanism for monodisperse nanoparticle formation, which includes Smoluchowski coagulation and simultaneous diffusion-controlled growth of particles. Coagulation rates favour coagulation of bigger particles with smaller ones, than between similar sized particles. The growth rate is inversely proportional to the particle size, so smaller particles grow faster than the bigger particles. Such a combination of coagulation and diffusional growth leads to a slow sharpening of particle size distribution (PSD). We develop a discrete-continuous Monte Carlo simulation scheme to solve this problem as there is no known analytical solution. In this method, the random events are carried out by simulation at the end of a quiescence interval, while the differential equations corresponding to the continuous events are solved within each of the quiescence intervals. Thus this mechanism opens up a new route to monodisperse nanoparticle formation, and the discrete-continuous hybrid simulation provides an alternative to numerical techniques to track evolution of particulate processes.

3 illus, 1 table, 13 ref

007899   Panwar C;Kumar A;Paliwal M;Punjabi P B;Ameta S C (Chemistry Dep, College of Science Univ, Mohanlal Sukhadia Univ, Udaipur-313 001, Email: ameta_sc@yahoo.com) : Sonochemical degradation of brilliant cresyl blue - an ecofriendly approach. J Indian Chem Soc 2008, 85(6), 654-7.

Dyestuffs which are often present in industrial waste water may have a serious impact on the environment as well as on the health of human beings. Report describes an ecofriendly method which has been developed for the degradation of brilliant cresyl blue. Ultrasonic frequency of 4 MHz was used for all experiments in order to find the best conditions for degradation. The effect of operating variables like pH, concentration of dye, solvent composition, temperature, nature and concentration of surfactant etc. on the reaction rate has been observed. The progress of the sonochemical degradation was monitored spectrophotometrically. The value of energy of activation was also computed for this sonochemical degradation. A suitable tentative mechanism for sonochemical degradation of brilliant cresyl blue has also been proposed.

3 illus, 1 table, 7 ref

007898   Mukhopadhyay M;Karamta H (Chemical Engineering Dep, Indian Institute of Technology Bombay, Powai, Mumbai-400 076, Email: mm@che.iitb.ac.in) : Novel process for supercritical fluid extraction of nutraceuticals enriched with carotenoids. Indian chem Engr 2008, 50(2), 106-21.

An innovative process has been developed for the recovery of carotenoids from natural sources such as lycopene from tomato, β-carotene from carrot, and lutein from marigold flowers. The conventional supercritical fluid extraction (SCFE) of these active ingredients (AI) from natural sources requires supercritical carbon dioxide (SC CO₂) at very high (400-700 bar) pressures, in addition to an elaborate process for feed preparation. This necessitates long time for removal of a large quantity of moisture and elaborate feed pretreatment to release AI from the bound state in the cellular matrix. In order to obviate these difficulties, an improved feed pretreatment protocol has been evolved for selective SC CO₂ fractionation at relatively moderate condition of pressure and for lessening the time of extraction, facilitating enrichment of AI in the extracted nutraceuticals with high recovery efficiency (92-97%) even at lower pressures (< 350 bar). SC CO₂ at 300 bar and 60°C yields highest purity of 21 % lycopene in one fraction whereas 13.6% lycopene as average purity of the extract with 81 % recovery in 3 h. The process of SCFE is useful for enrichment of any AI, including all carotenoids, e.g. β-carotene and lutein, and facilitates higher recovery efficiency of nutraceuticals with much higher concentrations of carotenoids at relatively lower pressures compared to the existing processes.

6 illus, 5 tables, 14 ref

007897   Mukhopadhyay M;Chowdhury R;Bhattacharya P (Chemical Engineering Dep, Jadavpur University, Kolkata-700 032, Email: ftbe_bon@yahoo.com) : Mathematical simulation of transient behaviour of a biotrickling reactor for the desulfurization of diesel. Int J chem Sci 2007, 5(4), 1785-96.

Biodesulfurization of hydrodesulfurized diesel has been carried out in a 600mm high and 66mm diameter trickle bed reactor using Rhodococcus Sp. in immobilized form. The initial concentration of organo-sulfur compounds of diesel has been varied in the range of 200 to 540 ppm. Liquid hourly space velocity (LHSV) and recycle ratio have been varied in the range of 0.125 to 0.25h^-1 and 0.25 to 1.25 respectively. A deterministic mathematical model has been developed using all kinetic and hydrodynamic parameters including μ_max, maximum specific growth rate of Monod type, K_s, saturation constant, Y, yield coefficient, LHSV, bed porosity, pressure drop and recycle ratio. Experimental trends have been observed to be well explained by the model predictions.

7 illus, 2 tables, 13 ref

007896   Monash P;Majhi A;Pugazhenthi G (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati, Email: pugal@iitg.ernet.in) : Characterization of low cost clays for preparation of porous ceramic membrane supports. Int J chem Sci 2007, 5(4), 1862-72.

A uniaxial compaction route was employed for preparation of porous ceramic membrane supports using locally available low cost clays. Study the effect of sintering temperature on structural properties of the membrane supports, the above prepared green supports were sintered at different temperature starting from 850°C to l000°C. The clays and membrane supports were characterized by thermo gravimetric analysis (TGA), particle size distribution (PSD) and X-ray diffraction (XRD). From the thermo gravimetric analysis, it is found that the supports have to be sintered at a minimum temperature of 850°C. It is observed from the XRD results that the phase transformation of the clay mixture occurs during sintering of the supports and quartz is found to be the major phase. The shrinkage of the sintered supports (~6%) is very less compared to that of the commercially available supports (alumina ~12% and zirconia ~8%). From these results, the clay support sintered at 900øC is found to be the optimized support for the membrane applications.

7 illus, 3 tables, 18 ref

007895   Mishra S;Singh G;Jha U;Ganguly S (Centre of Mining Environment, Indian School of Mines, Dhanbad-826 004, Email: sumit_ism@yahoo.com) : Long term leaching studies on coal combustion residues from Balco Captive Power Plant, Korba. J Indian Chem Soc 2008, 85(4), 429-33.

The study was conducted to assess the leaching of coal combustion residues (CCRs) from Balco Captive Power Plant, Korba, India through five different standard techniques. The leaching procedures included acid digestion, short term (24-hour shake test, TCLP) and long term leaching (Open column percolation experiments, ASTM column experiments) studies for a period of more than three years. The physico-chemical characteristics (pH, conductivity and TDS) were observed within the permissible limits. The leachates were analysed for twenty-three elements like Na, K, Mg, Ca, Fe, Ni, Cu, Zn, Pb, Mn, Cr, Co, Cd, Se, Al, Ag, As, B, Ba, V, Sb, Mo, W and compared with their compositional analysis. Among these elements, only Na, K, Mg and Ca were found to be leaching throughout the study period and were within permissible limits of the prescribed standards (IS : 2490). However, Fe, Pb, Ni, Cu and Mn were observed at significant concentration levels on a few occasions. Overall, this study establishes the CCRs of Balco Captive Power Plant as environmentally benign material and encourages its large-scale utilisation.

1 illus, 4 tables, 13 ref

007894   Manivannan R;Ramanathan S (Particle Science Laboratory, Chemical Engineering Dep, Indian institute of Technology Madras, Chennai-600 036, Email: srinivar@iitm.ac.in) : Effect of aditives in chemical mechanical planarization for shallow trench isolation. Int J chem Sci 2007, 5(4), 1643-51.

Chemical Mechanical Planarization (CMP) of Silicon dioxide and Silicon nitride with various additives in Ceria slurries was investigated. The thickness of the film was measured using Interferometer. Experiments were conducted for various additives as a function of pH. Among those additives used in the polishing experiments, only L-Arginine was found to inhibit the oxide and nitride polish rate moderately, while Catechol was strongly inhibiting both the polish rates. Many additives which are believed to increase the glass polish rates were found to decrease the silicon dioxide removal rate instead. Thus it was found that the correlation between glass polishing and silicon di oxide thin film polishing is poor.

6 illus, 1 table, 12 ref

007893   Mandal T K;Jana A K;Patra R;Das G (Chemical Engineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: tapasmn@gmail.com) : Hydrodynamics of intermittent flow through small diameter vertical pipe during liquid-liquid two-phase flow. Int J chem Sci 2007, 5(4), 1701-11.

Intermittent flow pattern is frequently observed during vertical air-water flow through small diameter pipes and several researchers have studied the hydrodynamics of this flow pattern. Past literature shows that there is no work regarding such flow during liquid-liquid two-phase flows. Therefore an attention has been made to study the hydrodynamics of intermittent flow pattern in 0.0 12 m ID pipe. The holdup and pressure drop of the intermittent flow pattern has also been estimated experimentally and predicted theoretically. Drift flux and homogeneous model are used to predict the holdup and pressure drop of the intermittent flow pattern.

6 illus, 1 table, 13 ref

007892   Mandal B;Winston Ho W S (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: bpmandal@iitg.ernet.in) : Synthesis gas purification by polymeric membranes containing fixed and mobile carriers. Int J chem Sci 2007, 5(4), 1938-46.

The synthesis and characterization of CO₂-selective crosslinked poly(vinyl alcohol) membranes containing poly(allylamine) as fixed carrier and 2-aminoisobutyric acid potassium salt and potassium hydroxide as mobile carriers. Thin-film polymeric membranes were prepared by casting aqueous solution onto glass plates. The effects' of feed pressure and temperature on the flux and permeability of CO₂ and H₂ as well as the selectivity of CO₂/H₂ have been investigated. As expected, the CO₂ flux increased with increasing feed pressure and temperature. The selectivity of CO₂ over H₂ decreased with increasing feed pressure and temperature.

5 illus, 11 ref

007891   Majumdar R;Sinha N;Majumdar S;Mandal P K (Chemical Technology Dep, Calcutta Univ, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, Email: rabin.majumdar@gmail.com) : Sorption of aqueous fluoride by active silica-carbon from rice husk. J Indian Chem Soc 2008, 85(6), 638-42.

Fluoride in drinking water in excess of desirable levels has been a serious threat to public health in many places in India. Distilled water containing 5 ppm fluoride (dissolved as NaF) passed through a glass column (2.5 cm id) packed with 10 g of iron-impregnated active silica-carbon composite char derived from rice husk, yielded treated water with fluoride concentrations between 1 and 2.5 ppm, that are desirable as per drinking water standards in India and elsewhere.

5 illus, 1 table, 18 ref

007890   Madhu G M;Lourdu M A;Raj A;Vasantha Kumar Pai K (Chemical Engineering Dep, R V College of Engineering, Bangalore-560 059, Email: madhugm_2000@yahoo.com) : Photodegradation of congo red dye using UV/TiO₂, UV/H₂O₂ and UV/H₂O₂/TiO₂ oxidation processes. Int J chem Sci 2007, 5(4), 1652-64.

The aqueous solution containing congo red has been subjected to Photocatalytic degradation using UV source in presence of TiOv>2 photo catalyst combined with different concentrations of H₂O₂. The experiments conducted at different catalyst loading, pH and H₂O₂ dosage (l-8mL/L), revealed that the degradation rate is strongly dependent on respective experimental parameters. The influence of catalyst alone is not predominant in degradation. The decolorization of dye exhibited near completeness when H₂O₂ is used in presence of UV source. The best degradation results were observed at 1gm/L of catalyst loading at pH 4 for TiO₂/UV system. It has been found that the optimum dosage of H₂O₂ for 20 ppm concentration of dye was 3ml/L for UV/H₂O₂ system. The experimental kinetic data for the degradation of the dye followed the first order pseudo rate and Langmuir Hinshelwood kinetic model for heterogeneous system. The degradation test on the dye using TiO₂/UV/H₂O₂ system, provided enhancement in the degradation rate as compared with UV/H₂O₂ system, i,e. without photo catalyst.

11 illus, 2 tables, 21 ref

007889   Kumar S;Chattopadhyaya M C (Electrochemical Sensor Laboratory, Chemistry Dep, Allahabad Univ, Allahabad-211 002, Email: mcc46@rediffmail.com) : Studies of natrolite and its cation-exchanged and adsorbed derivatives with Co<. J Indian Chem Soc 2008, 85(4), 462-6.

These studies are based on the investigation carried out on the cation exchange and adsorption behaviour of a natrolite which is natural zeolite collected from Sinner, Nasik (Maharashtra) as a geological specimen. Co^II-natrolite was prepared hy treating a saturated aqueous Co^II-nitrate solution with natrolite by continuous shaking at 60 °C for maximum interaction. A portion of this exchanged derivative was then heated over a maker burner for several days in a platinum crucible. Both, the original and the preheated Co^II-natrolite samples were also interacted with gaseous H₂S and liqueor NH₃ to study their sorption capacity and preheating affects. All the derivatives and the original natrolite before and after heating were analyzed by XRD and FTIR.

1 illus, 4 tables, 12 ref

007888   Kumar K V;Porkodi K (Chemical and Biological Engineering Dep, Faculdade de Engenharia U, Universidade de Porto, Porto, Portugal, Email: vasanth_vit@yahoo.com) : Pseudo second order kinetics for the sorption of auramine O onto activated carbon. Indian chem Engr 2008, 50(3), 227-38.

Kinetic experiments were carried out for the sorption of Auramine O onto activated carbon particles. The experimental kinetic data were fitted to the pseudo second order kinetic expressions of Ho; Sobkowsk and Czerwinski; Ritchie; and Blanchard et al. by both linear and non-linear methods. Non-linear method was found to be a better method of obtaining the kinetic parameters. The linear and non-linear methods suggest the kinetic expressions of Sobkowsk and Czerwinski and the Ritchie kinetic expression are the same. Non-linear method suggests both Blanchard et al. and Ho have similar ideas on the pseudo second order kinetics. The best-fit of experimental kinetic data in Ho's pseudo second order expression by linear and non-linear methods suggests that pseudo second order model is a better kinetic expression to represent the Aurarnine a sorption onto activated carbon when compared to the other pseudo second order kinetic expressions. The dye uptake process was found to be controlled by diffusion. The average diffusion coefficient for the sorption of Auramine O by activated carbon was estimated to be 7.52 x 10^-3 cm²/s.

4 illus, 3 tables, 14 ref

007887   Krishna B S V S R;Krishnaiah K (NO, Nagarjuna Fertilizers and Chemicals Limited, R & D, Nagarjuna Hills, Punjagutta, Hyderabad-500 086, Email: krishnabandaru@nagarjunagroup.com) : Minimum and uniform fluidization velocity of inverse fluidized bed. Int J chem Sci 2007, 5(4), 1733-44.

Hydrodynamic characteristics of three-phase inverse fluidized bed are studied experimentally using low density particles for different gas velocities with batch liquid (zero liquid velocity). The hydrodynamic studies included axial pressure, pressure drop, minimum, uniform gas fluidization velocities and local phase holdups. The minimum and uniform gas fluidization velocity determined using conductivity method. The uniform gas fluidization velocity depends strongly on slip velocity and density of the particle. The axial profiles of phase holdups shows that, the liquid hold up increases along the bed height, where as the solid holdup decreases down the bed. However, the gas holdup is almost uniform in the bed.

8 illus, 1 table, 12 ref

007886   Komati S;Madadapu R R;Suresh A K (Chemical Engineering Dep, Indian Institute of Technology, Mumbai-400 076) : Synthesis, characterization and testing for ferrofluids for mass transfer intensification. Int J chem Sci 2007, 5(4), 1913-28.

Ferrofluids are interesting materials and recent reports indicate that they may have considerable potential in chemical engineering processes involving interphase mass transfer. Clearly, stability of the ferrofluid with respect to agglomeration of the particulates is of central importance in such applications, and the materials and synthesis conditions have to be selected. This work, presents some results on the preparation and characterization of a stable, surfactant coated, water-based magnetic fluid for mass transfer applications, and demonstrate its efficacy for the absorption of carbon dioxide with amine solutions in a bubble column. The fluids have been characterized in detail, for particle size, shape, charge and phase of iron oxide precipitated. The magnetization behaviour of the fluids has also been studied and their super-paramagnetic nature has been established. The particle size, when these fluids are added to amine and other solutions of interest in carbon-dioxide capture, has been studied as a function of concentration and time. The fluid has been shown to enhance mass transfer rates by upto 43%, in the instantaneous regime of absorption of carbon dioxide in methyl diethanolamine solutions.

11 illus, 2 tables, 22 ref

007885   Jena H M;Roy G K;Meikap B C (Chemical Engineering Dep, NIT, Rourkela-769 008, Email: hara.jena@gmail.com) : Gas holdup in a three-phase fluidized bed with cylindrical particles. Int J chem Sci 2007, 5(4), 1712-22.

The gas holdup characteristics in a cocurrent three-phase fluidized bed with liquid as continuous phase and gas as the discontinuous phase have been studied. Air, water and ceramic raschig rings are used as the gas, liquid and solid phases respectively. The experiments were carried out in a 0.1 m internal diameter, 1.88 m height vertical Plexiglas column. Results indicate that gas holdup increases with increasing gas velocity and decreasing liquid velocity. From the correlation developed for gas holdup it is found that gas holdup is a strong function of modified gas Reynolds number and a weak function of the liquid Reynolds number. The experimental values have been compared with those calculated from the developed correlation and have been found to agree well.

6 illus, 1 table, 17 ref

007884   Hua Q I A N;Chunxu L V;Zhiwen Y E (Fine Chemicals Dep, School of Chemical Engineering, Nanjing Univ of Science and Technology, Nanjing 210094, P.R. China, Email: jyqianhua@yahoo.com.cn) : Synthesis of CL-20 by clean nitrating agent dinitrogen pentoxide. J Indian Chem Soc 2008, 85(4), 434-9.

CL-20 is a high energy material. It is usually prepared via nitration with concentrated nitric and sulfuric acid, but this technique pollutes the environment. CL-20 was synthesized with 2,6,8,12-tetraacetylhexaazatetracyclo[5,5,0,0^3,11,0^5,9]dod ecane (TAIW) and clean nitrating agent dinitrogen pentoxide. By the use of new nitrating agent, the reaction eliminated the use of concentrated sulfuric acid and was environmental friendly with high atom economy. The structure of the compound was characterized by elemental analysis, IR, ¹H NMR and MS. Meanwhile, the effects of reaction temperature, time and other factors on yield were analyzed. Through the separation of intermediate, the nitration course and mechanism were also discussed.

4 illus, 4 tables, 13 ref

007883   Gupta R K;Bhattacharya S N (Rheology and Materials Processing Centre, School of Civil, Environment, RMIT University, Melbourne, Email: sati.bhattacharya@rmit.edu.au) : Polymer-clay nanocomposites: current status and challenges. Indian chem Engr 2008, 50(3), 242-67.

The key to the performance of polymer nanocomposites is the quality of dispersion of the nano-reinforcement particles and the interfacial interaction between the matrix and the reinforcement phase. Optimisation of these properties requires various special and complicated treatments, which are not always easy to determine. Often property enhancement is not as significant as expected by the industry for the use of these nanocomposites. Aims to provide an overview of the current status of these materials in terms of their development and production. Examples have been provided for the production of thermoplastic, thermoset and biodegradable polymer nanocomposites by different means, such as melt blending and in-situ polymerisation. It also focusses on properties enhancement reported by different researchers and future challenges for these emerging materials in engineering applications.

13 illus, 2 tables, 79 ref

007882   Gupta N;Singh R P;Gupta V;Gupta S;Upadhyay S K;Sharma G (Faculty of Engineering & Technology, R. B. S. College (Bichpuri Campus), Agra-283 105, Email: ngp28@yahoo.com) : Adsorbing micellar interface for enhanced removal of lead from aqueous solution. J Indian Chem Soc 2008, 85(4), 425-8.

An enhanced removal of lead with polymerized saw dust (PSD) in the presence of micellar solutions of sodium dodecylsulfate (SDS), cetyl trimethylammonium bromide (CTAB) and Criton X-100 has been investigated. The PSD with micellar solution was found to be an effective sorbent for removal of lead from wastewaters in laboratory-scale experiments. Batch studies of PSD with and without micellar systems indicate that Pb removal is greater with micellar systems. The percentage removal of Pb on PSD with micelles increased on decreasing lead concentration and increasing sorbent dose, micellar concentration and electrolyte addition. The single and binary micellar systems also showed marked variations in percentage removal. In single systems of SDS, CTAB and Criton X-100 percentage removal enhancements of lead were 68.5, 65.0 and 3.2 respectively. The binary mixtures of Criton X-100 with SDS and with CTAB enhanced removal upto 74.0 and 69.3 respectively. The combination of SDS and CTAB had no significance effect. The adsorption equilibrium followed Freundlich and Langmuir isotherms. The enhancement in removal was possibly due to interaction between Pb and micellar media and then adsorption on PSD. So, PSD is a good sorbent for both Pb and micelles.

2 tables, 18 ref

007881   Goyal G K;Alam T;Preeti Singh;Shrivastava S (Food Packaging Lab, Dairy Technology Div, National Dairy Research Institute, Karnal-132 001, Email: gkg5878@yahoo.com) : Lacquered tin cans for food industry. Indian Dairyman 2008, 60(9), 59-65.

Tinplate has been universally adopted for the manufacture of containers and closures for foods and beverages, largely due to its important qualities These include their mechanical strength and resistance to working, low toxicity, superior barrier properties to gases, moisture and light, their ability to withstand wide extremes of temperature and provide ideal surfaces for decoration and lacquering. Modern metal cans have internal lacquer coatings, which act as 'barriers' between the metal surfaces and the food or beverage These 'barrier' coatings play an important role in maintaining the quality of the food or beverage.

3 ref

007880   Goud V V;Patwardhan A V;Pradhan N C (Chemical Engineering Group, , BITS-Pilani, Goa Campus, GOA-403 726, Email: vaibhav.goud@gmail.com) : Kinetic studies on degradation of the oxirane ring of epoxidised karanja oil. Int J chem Sci 2007, 5(4), 1533-40.

Degradation of epoxidised karanja oil by hydrogen peroxide attack, using sulfuric acid and acidic ion exchange resin as catalysts was studied. The degradation of the epoxidised karanja oil with aqueous hydrogen peroxide in acid media was quite fast, proceeding under a kinetic regime (E_a = 19.9 kcal/mol), and in the absence of any observable induction time. The degradation of the oxirane ring with aqueous hydrogen peroxide using acidic ion exchange resin as catalyst was found to be reduced by several orders of magnitude - under otherwise similar process conditions.

3 illus, 1 table, 9 ref

007879   Goswami D;Patil A D;Patwardhan A V;Basu J K; De S (ChemicalEngineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: sde@che.iikgp.ernet.in) : Hydrolysis of castor oil using lipase with oil as dispersion medium. Int J chem Sci 2007, 5(4), 1487-96.

Ricinoleic acid, a hydroxy monounsaturated fatty acid, is the main fatty acid of castor oil. It has different commercial applications and can be obtained by hydrolysis of castor oil. In comparison with conventional hydrolysis processes, lipase catalyzed hydrolysis is better as process conditions are mild and products do not have disadvantages like odour and colour as in conventional processes. Castor oil is hydrolyzed using various lipases e.g., candida rugosa lipase and porcine pancreas lipase. In order to consume low amount of water soluble enzyme, weight ratio of oil to buffer is kept more than 1: 1. Optimum oil to buffer weight ratio is found to be 3: 1. Optimum stirrer speed is found to be 900 rpm. Besides, it is observed that candida rugosa lipase acts better than porcine pancreas lipase. It is also found that on increasing lipase concentration from 1 to 3 mg/gm oil, percentage hydrolysis increases from 32% to 44% in 6 hours under optimum operating conditions. It is also observed that initial rate of hydrolysis remains fast but decreases rapidly after a few hours. For example, in case of I mg lipase/gm oil, percentage hydrolysis becomes 32% in 6 hours and it increases by 19% only in next 66 hours. Actually, after 46 hours, this becomes nearly constant. After first recycle, candida rugosa lipase retains 50% of its activity.

6 illus, 14 ref

007878   Gogoi S B (Petroleum Technology Dep, Dibrugarh University, Dibrugarh-786 004) : Evaluation of lignin based surfactants for enhanced oil recovery of naharkotyiya porous media. Indian chem Engr 2008, 50(1), 47-55.

The study examines the effect of using Black liquor, spent sulfite liquors which emanate as effluent from Nowgong Paper Mill, Jagiroad, Assam, in enhanced crude oil recovery from Naharkotiya porous media. The Naharkotiya crude oil reservoir has been producing since 1952 and it is at the depleting stage after water flooding. Studies the effect of interfacial tension of Black liquor and how it affects the recovery of crude oil from the porous rock of Naharkotiya reservoir of Oil India Limited, Duliajan, Assam. The main constituent of Black liquor is Na-lignosulfonate, an anionic water soluble surfactant. Addition of Na-lignosulfonate to crude oil emulsions gives rise to ultra-low interfacial tensions (10^-6-10^-7N/m) between the oil and the aqueous phase, which are very much in demand in enhanced oil recovery projects. Reduction of interfacial tension leads to the release of residual oil droplets from the capillaries in the porous media, thereby increasing substantially the amount of petroleum obtainable from a given porous media.

6 illus, 1 table, 15 ref

007877   Giriraj Kumar S M;Jain R;Anantharaman N; Dharmalingam V;Sheriffa Begum K M M (Electronics and Instrumentation Engineering Dep, SASTRA University, Thanjavur-613 402, Email: smgirirajkumar@gmail.com) : Genetic algorithm based PID controller tuning for a model bioreactor. Indian chem Engr 2008, 50(3), 214-26.

Proportional-integral-derivative (PID) control schemes continue to provide the simplest and yet effective solutions to most of the control engineering applications today. A number of processes in the chemical industries are controlled using PID controllers. However, most of the processes are complex and nonlinear in nature resulting into their poor performance when controlled by traditional tuned PID controllers. The need for improved performance of the process has led to the development of optimal controllers. Genetic algorithm (GA) is an evolutionary algorithm that is widely used in this respect. Determination or tuning of the PID parameters continues to be important as these parameters have a great influence on the stability and performance of the control system. GA is proposed to improve the performance of a bioreactor. The methodology and efficiency of the proposed method are compared with that of traditional methods. The results obtained reflect that use of GA based controllers improves the performance of the process in terms of time domain specifications, setpoint tracking, regulatory changes and also provides an optimum stability.

10 illus, 2 tables, 18 ref

007876   Gill B S;Saha P (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: p.saha@iitg.ac.in) : Model based control of continuous bioreactor. Int J chem Sci 0000, 5(4), 1809-20.

Model Based Controllers hold a strong position when it comes to merits of industrial implementations. Two types of model based controllers, viz. Model Predictive Control (MPC) and Internal Model Control (IMC), are focused in this work. An MPC is a prediction based optimal controller where the minimization (optimization) of objective function is a crucial issue. Markov Chain Monte Carlo (MCMC) technique has been applied for solving this minimization issue. Monte Carlo methods based on sampling using Markov chains provide a rich array of techniques that can be applied to problems in optimization. IMC is also another efficient model based control technique which uses the process model as an integral component for design of controller. A comparative study of their control performance has been carried out through a case study on a continuous bioreactor process.

3 illus, 2 tables, 10 ref

007875   Garg G;Saraf S;Saraf S (NO, Pharmacy Institute, Pt. Ravishankar Shukla Univ, Raipur-492 010, Email: swarnlata_saraf@rediffmail.com) : New spectrophotometric methods for the simultaneous determination of amlodipine and ramipril. J Indian Chem Soc 2008, 85(7), 769-72.

Three new analytical methods were developed based on the simultaneous estimation of drugs in a binary mixture without prior separation of amlodipine and ramipril. Quantitative estimation of these drugs in marketed brands of the tablets was carried out using first order derivative, simultaneous equations and multi wavelength methods. Amlodipine and ramipril have absorbance maxima at 360 nm and 206.5 nm respectively in methanol. Both the drugs obey Beer's law in the concentration range employed for these methods. The results of analysis have been validated statistically and also by recovery studies.

1 illus, 3 tables, 11 ref

007874   Ganguly U P (NO, , Flat No. B 17/257, Kendriya Vihar, V.I.P. Road, Kolkata-700 052, Email: upiitganguly@gmail.com) : Prediction of critical concentration in the phenomenon of elutriation of solid from a gas-solid fluidised bed system. Indian chem Engr 2008, 50(2), 141-8.

Like other physical rate governed processes, e.g. drying, adsorption etc., the entrainment of solid from a mixture of solids in the gas-solid fluidised bed system is characterised by the existence of a constant rate, which is followed by a falling rate period. The point of transition between these two rates is known as the critical state, which, with reference to the concentration of solids, is characterised by the term critical concentration C_c of the elutriable solids (finer/lighter) in the fluidised bed. Considering the practical importance to predict such system property of a fluidised bed process, a dimensionless correlation has been developed with reference to the relevant system parameters. Taking into account air as the fluid and solids like coke, coal, (NH₄)₂SO₄' NaCl, graphite, sand and magnetite, the proposed correlation is given by C_c = 3.1554( G/G_me)^-0.879(d₂/d₁)^-0.145(p₂/p₁)^-0.389(H/H_s)^-0.283(w/w)1.145 which has got a standard deviationof ± 4.3%.

9 illus, 6 ref

007873   Dubey A;Vamsikrishna K;Archana;Ghoshal A K (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-721 302, Email: aloke@iitg.ernet.in) : Effect of pH and carrier on separation of chromium (VI) from aqueous solution using bulk liquid membrane. Int J chem Sci 2007, 5(4), 1840-50.

The transport of Chromium (VI) ions from an aqueous feed solution through a bulk liquid membrane containing Tri-n-octylamine (TOA) and tri-n -butyl amine (TBA) as carrier is studied. The influence of pH on feed phase and effect of carriers on Cr(VI) transport are studied. The result indicates that the aqueous feed phase has high permeability at more acidic condition but there comes a point where increasing the acidity of feed phase leads to decrease in permeability. The kinetic of the transport are analyzed in the formalism of two consecutive irreversible first-order reactions and kinetic parameters are also calculated.

3 illus, 3 tables, 9 ref

007872   Das R;Ghosh S;Bhatterjee C (Chemical Technology Dep, University of Calcutta, 92 APC Road, Kolkata-700 009, Email: cbhattacharyya@chemical.jdvu.ac.in) : Comparative performance study during ultrafiltration of sesame protein hydrolysate in rotating disk module and cross flow module. Int J chem Sci 2007, 5(4), 1851-61.

Ultrafiltration is a potential device to be used in the protein fractionation process. Apart from various advantages, this process suffer from two major drawbacks, the permeate flux and fouling of the membrane. We are using two different membrane modules, Cross flow module (CFM), Rotating disk module (RDM) with 5kDa PES membrane to study the performance and optimize the process parameters with the focus of minimizing the fouling during the fractionation of sesame -protein hydrolysate. Apparently the flux value in CFM is higher but the extent of flux decline is more for CFM. The flux value in RDM with membrane rotation is very close to that in CFM. During the processing of highly concentrated feed solution the percent flux decline is less in RDM (with membrane rotation) compared to CFM. In RDM at neutral pH maximum flux can be achieved along with maximum permeate concentration, which is not observed for CFM. Extent of fouling of the, membrane is also less in RDM module with membrane rotation compared to CFM. Membrane cleaning procedure is much easier compared to that in CFM. So, during the processing of the concentrated feed solution, RDM with suitable membrane rotation can compete the classical cross flow filtration technique.

6 illus, 18 ref

007871   Das C;Maity P;Deb R;De S (Chemical Engineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: sde@che.iitkgp.ernet.in) : Optimization of composition of foam controlling agent for process industries. Int J chem Sci 2007, 5(4), 1947-57.

Optimum composition of a foam controlling agent in context of chemical synthesis is attempted in this work. The main reagents used were two surfactants, namely, di-octyl sodium sulphosuccinate (DOSS) and linear alkyl benzene sulphonic acid (LABS). Two more surfactants, NP 9 (9 moles of ethylene oxide in the molecule) and NP 40 (40 moles of ethylene oxide in the molecule) were also used as performance enhancer. Methanol, butanol and water were used as solvents. Linseed oil was used as an additive. The optimum composition of the foam controlling agent was established experimentally by observing its performance during the reaction of rock phosphate and nitric acid in a laboratory scale set up. The optimization was carried out with respect to maximum height of the foam. foam killing time, weight of foam controlling agent and its cost.

2 illus, 9 tables, 12 ref

007870   Chavan A;Mukherji S (Centre for Environmental Science and Engineering, Indian Institute of Technology Bombay, Mumbai, Email: mitras@iitb.ac.in) : Effect of non-aqueous phase liquids on oxygen transfer in rotating biological contactor. Int J chem Sci 2007, 5(4), 1893-1901.

Oxygen mass transfer in non-aqueous phase liquid (NAPL)-water system is important for the treatment of wastewater containing hydrocarbons. The research work focuses on impact of a complex NAPL, diesel oil on oxygen transfer in rotating biological contactor (RBC). Based on reaeration profile generated in RBCs, the apparent saturation concentration of oxygen (C_s) in neat diesel was 1.84 times higher than that in clean water system. In the three RBCs, C_s in NAPL-water system was significantly different and the oxygen transfer coefficient (K_La) was found to increase' with increase in diesel concentration (C_D), reach a maximum value at C_D,max and subsequently decrease. C_D,max was found to vary with the size of the reactor, such that 2.3,2.9 and 4.5 fold increase in K_La was observed at C_D.max in RBCs with working volume 18,4 and 0.85 L, respectively.

4 illus, 2 tables, 19 ref

007869   Chatterjee S G (Paper and Bioprocess Engineering Dep, S.U.N.Y. College of Environment Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, USA, Email: schatterjee@esf.edu) : Simple description of transient moisture diffusion in paper. Indian chem Engr 2008, 50(1), 34-46.

Simple and holistic model based on a linear driving force approximation for describing the unsteady-state transport of moisture in the thickness direction of paper is formulated that accounts for the parallel diffusion of moisture in the pore and fibre phases, as well as external mass-transfer resistance. The transport model is able to correlate measurements of the transient weight change and average relative humidity (RH) of stacks of bleached kraft paperboard sheets subjected to ramp changes of the external RH with an average error of 9.3%.

2 illus, 3 tables, 25 ref

007868   Chakrabarty B;Ghoshal A K;Purkait M K (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati, Email: mihir@iitg.ernet.in) : Structural and transport property enhancement of polysulfone membrane due to peg as additive. Int J chem Sci 2007, 5(4), 1882-92.

Flat sheet asymmetric polymeric membranes were prepared from homogeneous solution of Polysulfone (PSf) by phase inversion method. N-methyl-2-pyrrolidone (NMP) and Dimethyl Acetamide (DMAc) were used as solvents separately. Poly(ethylene glycol) (PEG) of molecular weight 20000 Da were used as the polymeric additives in the casting solution. The morphology and structure of the resulting membranes were observed by scanning electron microscope (SEM). The pore number, their distribution and average pore size of the membranes were determined by the liquid displacement method. The permeation performances of the membranes were evaluated in terms of pure water flux (PWF), equilibrium water content (EWC) and hydraulic resistance. Results show that addition of PEG has a significant effect on the morphology as well as performance of the prepared membranes.

3 illus, 2 tables, 13 ref

007867   Banerjee T;Khanna A (Chemical Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: tamalb@iitg.ac.in) : Ionic conductivity prediction of a phosphonium ionic liquid using molecular dynamics. Int J chem Sci 2007, 5(4), 1965-71.

Molecular dynamic studies was done to determine the ionic conductivity of the phosphonium ionic liquid: trihexyl tetradecyl phosphonium chloride [ThTd-Ph][Cl]. Initially the molar volume was compared with the existing literature value; thereafter ionic conductivity was predicted using the Nernst Einstein relation. Along with the Ionic conductivity the volume expansivity and isothermal compressibility have also been predicted. The center of mass radial distribution function between the cation-anion pair was also obtained. The predictions were further been compared with two imidazolium based ionic liquids namely: l-octyl-3-methylimidazolium hexafluorosphosphate [Omim][PF₆] and: l-octyl-3-methylimidazolium tetrafluoroborate. [Omim][BF ₄].

2 illus, 3 tables, 16 ref