Manas Bandyopadhyay - Academia.edu (original) (raw)

Papers by Manas Bandyopadhyay

Bioprocess Engineering, 1996

Biosorption technique was used for removal of cadmium under different conditions from water envir... more Biosorption technique was used for removal of cadmium under different conditions from water environment using a biosorbent, Volveriella volvaceas, locally growing fruit bodies of mushroom. Effects of different parameters like pH, sorbent concentration, ionic strength on the removal efficiency of cadmium by V. volvacea were carried out in continuation with adsorption kinetics and equilibrium isotherm experiments. From the kinetics studies

Indian Journal of Chemical Technology, 1997

A simple and rapid method for the determination of trichloroacetic acid (TCA) at the parts per mi... more A simple and rapid method for the determination of trichloroacetic acid (TCA) at the parts per million (ppm) level is developed. This is based on the photoreaction ofTCA with diphenylamine (DPA) to give a fluorescent product (Aem: 380 nm. ~c: 335 nm). The method has excellent reproducibility. The linear dy­ namic range for TCA is 20-200 ppm. Effects of reagent concentration, irradiation time and solvent are studied. The method is applicable to water analysis. A selective technique for the quantitative determi­ nation of trichloroacetic acid (TCA) is getting in­ creasing attention because it has been found in measurable amounts in drinking water1 along with other chloroorganics such as chloroform (CHCI3), carbon tetrachloride (CC4), dichloroacetic acid (DCA), monochloro acetic acid (MCA), etc. It is believed that, in drinking water TCA originates as a residual of sodium trichloroacetate associated with atrazine in weed killers, or from the reaction of cer­ tain organic compounds with...

Indian Journal of Chemical Technology, 2001

A new fluorimetric method based on the photochemical reaction of CHBr3 with diphenylamine (DP A) ... more A new fluorimetric method based on the photochemical reaction of CHBr3 with diphenylamine (DP A) in aqueous Triton X-lOO (TX-lOO) medium is described for the determination of bromoform (CHBr3)' The fluorescence intensity of the product at 480nm (A.ex: 400 nm) is a direct measure of CHBr3 concentration. The calibration graph is linear in the range of 0-21.8 ppm of CHBr3' The limit of detection (LOD) is 0. 1 ppm of CHBr3' The effect of reagent concentration, TX-lOO concentration, time of irradiation, interfering substances, and statistical parameters are discussed. Chlorination is the most widely used technique for disinfection of drinking water, which leads to the formation of trihalomethanes (THMs) 1.2 . The THMs include chloroform (CHCh), dichlorobromomethane (CHBrCh), chlorodibromomethane (CHBr 2 CI) and bromoform (CHBr 3 ) all of which have been enlisted as priority pollutants due to their carcinogenic behaviour, by the US Environmental Protection Agency. The formation of THMs takes place due to the reactions of chlorine with naturally occurring organic materials such as humic and fulvic acids. Several studies have shown that the formation of THMs and their ratio depends on a number of parameters such as the concentration of precursor materials, bromide ions, water, temperature, pH and chlorine dose. 2 It has been observed that due to the presence of bromide, the yield of THMs is increased for a particular chlorine dose 3 , 4 and also it influences the composition of by-product mixture. Bromoform, thus, among all THMs could be dominant (even to 71 % of total THMs) species formed during chlorination in the case of high bromide contained water 5 ; the remaining THMs formed being CHBr2Cl and very little CHBrCh and CHCI 3 .

International Journal of Environment and Pollution, 2003

... Paritosh Das Purakayastha, Anjali Pal* and Manas Bandyopadhyay ... h /mg cm 6360 1 ln 1 3 B 0... more ... Paritosh Das Purakayastha, Anjali Pal* and Manas Bandyopadhyay ... h /mg cm 6360 1 ln 1 3 B 0 0 - C C bC K = │ │ ⌋ ... 8 Darmstadt, H., Roy, C. and Kaliaguine, S. (1995) ”Fractal analysis of commercial and pyrolytic carbon blacks using nitrogen adsorption data', Rubber Chem. ...

Separation and Purification Technology, 2005

... Then the alumina, now can be designated as SMA, was dried at 60 °C for 24 h. 3.2. Kinetic stu... more ... Then the alumina, now can be designated as SMA, was dried at 60 °C for 24 h. 3.2. Kinetic study on the removal of CV. Kinetic studies were conducted to find out the equilibrium time for CV-uptake by SMA. ... View Within Article. 3.3. Effect of adsorbent dose on the removal of CV. ...

Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, 2005

In the present investigation, an attempt was made to develop a treatment system for the managemen... more In the present investigation, an attempt was made to develop a treatment system for the management of atrazine bearing wastewater. The system consists of an upflow anaerobic sludge blanket ͑UASB͒ reactor followed by an adsorption column using waste activated carbon as the adsorbent. The UASB reactor could remove more than 80% of organic matter and 40-50% of atrazine, irrespective of the concentration of organic matter and atrazine tried. Though low concentration of atrazine did not affect the anaerobic system, higher atrazine concentration in the range of 10-15 mg/ L had a little effect on the treatment system. The adsorption column could remove atrazine from the UASB effluent effectively. Methanol could desorb the atrazine from the adsorbent. The regenerated adsorbent retained 80% of its original capacity. The regenerant can be utilized as a pesticide.

Journal of Hazardous Materials, 2007

Synthetically prepared arsenic-laden CalSiCo-sludge was converted to pulverized cement concrete (... more Synthetically prepared arsenic-laden CalSiCo-sludge was converted to pulverized cement concrete (PCC) using solidification/stabilization technology with cement. Batch leaching experiments were conducted to estimate the leaching of As(III) and As(V) from the CalSiCo-sludge as well as from the PCC. The leaching of As(III) and As(V) was found to be the function of time, pH and concentration of anions such as Cl − , NO 3 − , and SO 4 2− present in the extraction fluid. It is observed that from the CalSiCo-sludge the leaching of As(III) is >0.05 mg/l (which is above the permissible limit for arsenic in drinking water) at any pH. But in case of As(V) the leaching is >0.05 mg/l only at pH > 8 and at pH < 4. It is noted that maximum leaching occurs when the extraction liquid contains Cl −. In contrary, NO 3 − and SO 4 2− have negligible effect on arsenic leaching from the CalSiCo-sludge. Extraction tests were carried out to determine the maximum leachable concentration under the chosen conditions of leaching medium and leaching time. Leaching of As(III) and As(V) from exhausted arsenic-laden CalSiCo-sludge and from PCC was carried out in both tap water and rain water. It was noticed that tap water has no effect in leaching of arsenic from CalSiCo-sludge but rain water causes significant amount of leaching, which is mostly due to pH effect. However, in all cases the leaching of As(III) was more than that of As(V). When compared with CalSiCo-sludge PCC showed negligible leaching of arsenic. It was noticed further that the variation of 28 days compressive strength was within 15% of the original strength after replacing 35% cement with exhausted CalSiCo-sludge.

Journal of Environmental Systems, 2002

The first part of this article presented a general-purpose linear programming model and applied i... more The first part of this article presented a general-purpose linear programming model and applied it to an existing petroleum refinery in India to evaluate the impact of imposed maximum SO 2 emission limits on operations and profitability. The present study presents two-step solution methodology designed to minimize SO 2 emission rates while preserving refinery profit. The proposed two-step procedure identifies an alternate solution of the LP model leading to an operating plan with maximized profit and minimized SO 2 emission rates. The study also shows that the alternative of increasing low-sulfur crude processing for lowering the total SO 2 emission rate may be effective only up to a certain proportion of the low-sulfur crude.

Journal of Environmental Science and Health, Part A, 2003

In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfat... more In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfate (SDS, an anionic surfactant) removal capacity. Waste activated carbon (WAC) from the aqua purifier has shown high efficiency for SDS removal. The performance evaluation in the presence of various ions (Ca2+, SO4(2-), NO3-, and Cl-) and at various pH was studied. Desorption studies were conducted using simple sonication and pH variation technique. Column adsorption studies were performed. SEM and EDS studies were done on the adsorbing material before adsorption, after adsorption and after desorption of SDS.

Journal of Environmental Science and Health, Part A, 2002

This study was undertaken to evaluate the efficiency of rubber granule, a low-cost adsorbent for ... more This study was undertaken to evaluate the efficiency of rubber granule, a low-cost adsorbent for the removal of sodium dodecyl sulfate (SDS) that is a representative member of anionic surfactant (AS). In the batch experiments conducted at an initial concentration range of 2-6 mg/l, it was found that the rubber granules selected could remove SDS from water up to 90%. Kinetic profiles were developed for various conditions. Effects of adsorbent size, initial adsorbate concentration and adsorbent dose, pH, Ca2+ ion concentration, Fe2+ ion concentration, Cl- ion concentration, and ionic strength on the adsorption of SDS on rubber granules were studied. The adsorption isotherm studies were also conducted.

Journal of Dispersion Science and Technology, 2007

For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-... more For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-6-isopropylamino-s-traiazine) from water environment, batch studies were performed to study the kinetics of 2,4-D and atrazine sorption by rubber granules. Experiments were conducted at various initial concentrations of 7.5 mg/L, 4 mg/L, and 0.5 mg/L of 2,4-D and atrazine with 18 g/L sorbent dose. The equilibrium time was found to be 120 minutes for both 2,4-D and atrazine. The regression analysis for the experimental data showed that the rapid stage zone of kinetics profiles followed a first order reversible kinetics for all initial concentrations of sorbate. The various thermodynamic properties such as enthalpy and entropy activation values (DH and DS) also show that the sorption is spontaneous. This article will provide information toward understanding the sorption phenomena of 2, 4-D and atrazine on waste tyre rubber granules. It also is valuable to us in finding out the rate constant of sorption of 2,4-D and atrazine.

International Journal of Water, 2001

The Homogeneous Charge Compression Ignition Engine, HCCI has the potential to combine the best of... more The Homogeneous Charge Compression Ignition Engine, HCCI has the potential to combine the best of the Spark Ignition and Compression Ignition Engines. With high octane number fuel, the engine operates with high compression ratio and lean mixtures giving CI engine equivalent fuel consumption or better. Owing to pre-mixed charge without rich or stoichiometric zones, the production of soot and NO x can be avoided. This paper presents some results from advanced laser diagnostics showing the fundamental behaviour of the process from a close to homogeneous combustion onset towards a very stratified process at around 20-50% heat released. The need for active combustion control is shown and possible means of control are discussed. Results with multi-cylinder engines using negative valve overlap, variable compression ratio, fast inlet temperature control as well as dual fuel are given.

Interdisciplinary Environmental Review, 2003

Dyes and Pigments, 2006

The fixed bed column study was undertaken for the removal of crystal violet (CV), also known as B... more The fixed bed column study was undertaken for the removal of crystal violet (CV), also known as Basic Violet 3, a well-known cationic dye from wastewater using surfactant-modified alumina (SMA) as an adsorbing media. The SMA was found to be a very efficient media for the removal of dye from wastewater. The column with 2 cm diameter, different bed heights such as 10, 20 and 30 cm could treat 3.58 l, 7.94 l and 12.51 l, respectively, of CV bearing wastewater with CV concentration 200 mg/l and flow rate 8.5 ml/min. The adsorption bed was exhausted within a very short time (w1.5 h) after the breakthrough occurred. This indicated that the adsorption zone was almost saturated at the time of exhaustion. Different column design parameters like depth of exchange zone, time required for exchange zone to move its own height, adsorption rate, adsorption capacity etc. were calculated. Effect of flow rate and initial concentration was studied. Theoretical breakthrough curve was drawn from the batch isotherm data and was compared with experimental breakthrough curve. Desorption of CV from the SMA surface was possible using 1 M sodium hydroxide solution, rectified spirit and acetone.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2005

The adsorption characteristics of sodium dodecyl sulfate (SDS) on neutral alumina were studied in... more The adsorption characteristics of sodium dodecyl sulfate (SDS) on neutral alumina were studied in detail. Alumina was found to be an efficient adsorbent for SDS and could be used for the removal of anionic surfactant (AS) from wastewater when it is present in high concentration (several thousand ppm). In the present work the actual laundry wastewater was treated by both batch and continuous mode. The initial AS concentration in wastewater was 8068 ppm. The optimum adsorbent dose and equilibrium time found were 120 g/l and 1 h, respectively. Under optimised conditions the removal efficiency was found to be 94%. The removal of SDS by alumina follows the pseudo-second order reaction kinetics. In column study the flow rate was maintained at 1.63 m 3 /m 2 /h. The breakthrough and exhaust time were found to be 48 and 86 min, respectively, using 10 cm column depth. Height of adsorption zone was found to be 5.5 cm and the rate at which the adsorption zone was moving through the bed was 9.42 cm/h. The percentage of the total column saturated at breakthrough was found 75.5%. The value of adsorption rate coefficient (K) and adsorption capacity coefficient (N) were obtained as 0.000824 l/(mg h) and 143460 mg/l, respectively. After exhaustion, aqueous NaOH could efficiently regenerate alumina.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006

... The engineering aspect of these processes, however, still remains unexplored. In a very recen... more ... The engineering aspect of these processes, however, still remains unexplored. In a very recent study, we have showed how the surfactant-modified alumina could be used efficiently for the removal of crystal violet (CV), a cationic dye from wastewater [30]. ...

Separation and Purification Technology, 2005

The efficiency of a locally available very low cost waste tire rubber granule in removing anionic... more The efficiency of a locally available very low cost waste tire rubber granule in removing anionic surfactant (AS) by adsorption process was evaluated. As a representative member of AS sodium dodecyl sulfate (abbreviated as SDS) was used. It was found that in the batch experiment conducted at 2.0 mg/l initial concentration of SDS, rubber granules could remove up to 92% of SDS from wastewater. Kinetic profiles under various conditions were developed. The equilibrium time was found to be 6 h. Reaction rate constants (forward, reverse and overall) were determined for different initial concentrations of SDS by approximating the kinetic data to the first-order reversible kinetic model. Pore and film diffusion coefficients were determined from the half-time equations and film diffusion appeared to be rate limiting. This was further supported by multiple interruption tests.

Bioprocess Engineering, 1996

Biosorption technique was used for removal of cadmium under different conditions from water envir... more Biosorption technique was used for removal of cadmium under different conditions from water environment using a biosorbent, Volveriella volvaceas, locally growing fruit bodies of mushroom. Effects of different parameters like pH, sorbent concentration, ionic strength on the removal efficiency of cadmium by V. volvacea were carried out in continuation with adsorption kinetics and equilibrium isotherm experiments. From the kinetics studies

Indian Journal of Chemical Technology, 1997

A simple and rapid method for the determination of trichloroacetic acid (TCA) at the parts per mi... more A simple and rapid method for the determination of trichloroacetic acid (TCA) at the parts per million (ppm) level is developed. This is based on the photoreaction ofTCA with diphenylamine (DPA) to give a fluorescent product (Aem: 380 nm. ~c: 335 nm). The method has excellent reproducibility. The linear dy­ namic range for TCA is 20-200 ppm. Effects of reagent concentration, irradiation time and solvent are studied. The method is applicable to water analysis. A selective technique for the quantitative determi­ nation of trichloroacetic acid (TCA) is getting in­ creasing attention because it has been found in measurable amounts in drinking water1 along with other chloroorganics such as chloroform (CHCI3), carbon tetrachloride (CC4), dichloroacetic acid (DCA), monochloro acetic acid (MCA), etc. It is believed that, in drinking water TCA originates as a residual of sodium trichloroacetate associated with atrazine in weed killers, or from the reaction of cer­ tain organic compounds with...

Indian Journal of Chemical Technology, 2001

A new fluorimetric method based on the photochemical reaction of CHBr3 with diphenylamine (DP A) ... more A new fluorimetric method based on the photochemical reaction of CHBr3 with diphenylamine (DP A) in aqueous Triton X-lOO (TX-lOO) medium is described for the determination of bromoform (CHBr3)' The fluorescence intensity of the product at 480nm (A.ex: 400 nm) is a direct measure of CHBr3 concentration. The calibration graph is linear in the range of 0-21.8 ppm of CHBr3' The limit of detection (LOD) is 0. 1 ppm of CHBr3' The effect of reagent concentration, TX-lOO concentration, time of irradiation, interfering substances, and statistical parameters are discussed. Chlorination is the most widely used technique for disinfection of drinking water, which leads to the formation of trihalomethanes (THMs) 1.2 . The THMs include chloroform (CHCh), dichlorobromomethane (CHBrCh), chlorodibromomethane (CHBr 2 CI) and bromoform (CHBr 3 ) all of which have been enlisted as priority pollutants due to their carcinogenic behaviour, by the US Environmental Protection Agency. The formation of THMs takes place due to the reactions of chlorine with naturally occurring organic materials such as humic and fulvic acids. Several studies have shown that the formation of THMs and their ratio depends on a number of parameters such as the concentration of precursor materials, bromide ions, water, temperature, pH and chlorine dose. 2 It has been observed that due to the presence of bromide, the yield of THMs is increased for a particular chlorine dose 3 , 4 and also it influences the composition of by-product mixture. Bromoform, thus, among all THMs could be dominant (even to 71 % of total THMs) species formed during chlorination in the case of high bromide contained water 5 ; the remaining THMs formed being CHBr2Cl and very little CHBrCh and CHCI 3 .

International Journal of Environment and Pollution, 2003

... Paritosh Das Purakayastha, Anjali Pal* and Manas Bandyopadhyay ... h /mg cm 6360 1 ln 1 3 B 0... more ... Paritosh Das Purakayastha, Anjali Pal* and Manas Bandyopadhyay ... h /mg cm 6360 1 ln 1 3 B 0 0 - C C bC K = │ │ ⌋ ... 8 Darmstadt, H., Roy, C. and Kaliaguine, S. (1995) ”Fractal analysis of commercial and pyrolytic carbon blacks using nitrogen adsorption data', Rubber Chem. ...

Separation and Purification Technology, 2005

... Then the alumina, now can be designated as SMA, was dried at 60 °C for 24 h. 3.2. Kinetic stu... more ... Then the alumina, now can be designated as SMA, was dried at 60 °C for 24 h. 3.2. Kinetic study on the removal of CV. Kinetic studies were conducted to find out the equilibrium time for CV-uptake by SMA. ... View Within Article. 3.3. Effect of adsorbent dose on the removal of CV. ...

Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, 2005

In the present investigation, an attempt was made to develop a treatment system for the managemen... more In the present investigation, an attempt was made to develop a treatment system for the management of atrazine bearing wastewater. The system consists of an upflow anaerobic sludge blanket ͑UASB͒ reactor followed by an adsorption column using waste activated carbon as the adsorbent. The UASB reactor could remove more than 80% of organic matter and 40-50% of atrazine, irrespective of the concentration of organic matter and atrazine tried. Though low concentration of atrazine did not affect the anaerobic system, higher atrazine concentration in the range of 10-15 mg/ L had a little effect on the treatment system. The adsorption column could remove atrazine from the UASB effluent effectively. Methanol could desorb the atrazine from the adsorbent. The regenerated adsorbent retained 80% of its original capacity. The regenerant can be utilized as a pesticide.

Journal of Hazardous Materials, 2007

Synthetically prepared arsenic-laden CalSiCo-sludge was converted to pulverized cement concrete (... more Synthetically prepared arsenic-laden CalSiCo-sludge was converted to pulverized cement concrete (PCC) using solidification/stabilization technology with cement. Batch leaching experiments were conducted to estimate the leaching of As(III) and As(V) from the CalSiCo-sludge as well as from the PCC. The leaching of As(III) and As(V) was found to be the function of time, pH and concentration of anions such as Cl − , NO 3 − , and SO 4 2− present in the extraction fluid. It is observed that from the CalSiCo-sludge the leaching of As(III) is >0.05 mg/l (which is above the permissible limit for arsenic in drinking water) at any pH. But in case of As(V) the leaching is >0.05 mg/l only at pH > 8 and at pH < 4. It is noted that maximum leaching occurs when the extraction liquid contains Cl −. In contrary, NO 3 − and SO 4 2− have negligible effect on arsenic leaching from the CalSiCo-sludge. Extraction tests were carried out to determine the maximum leachable concentration under the chosen conditions of leaching medium and leaching time. Leaching of As(III) and As(V) from exhausted arsenic-laden CalSiCo-sludge and from PCC was carried out in both tap water and rain water. It was noticed that tap water has no effect in leaching of arsenic from CalSiCo-sludge but rain water causes significant amount of leaching, which is mostly due to pH effect. However, in all cases the leaching of As(III) was more than that of As(V). When compared with CalSiCo-sludge PCC showed negligible leaching of arsenic. It was noticed further that the variation of 28 days compressive strength was within 15% of the original strength after replacing 35% cement with exhausted CalSiCo-sludge.

Journal of Environmental Systems, 2002

The first part of this article presented a general-purpose linear programming model and applied i... more The first part of this article presented a general-purpose linear programming model and applied it to an existing petroleum refinery in India to evaluate the impact of imposed maximum SO 2 emission limits on operations and profitability. The present study presents two-step solution methodology designed to minimize SO 2 emission rates while preserving refinery profit. The proposed two-step procedure identifies an alternate solution of the LP model leading to an operating plan with maximized profit and minimized SO 2 emission rates. The study also shows that the alternative of increasing low-sulfur crude processing for lowering the total SO 2 emission rate may be effective only up to a certain proportion of the low-sulfur crude.

Journal of Environmental Science and Health, Part A, 2003

In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfat... more In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfate (SDS, an anionic surfactant) removal capacity. Waste activated carbon (WAC) from the aqua purifier has shown high efficiency for SDS removal. The performance evaluation in the presence of various ions (Ca2+, SO4(2-), NO3-, and Cl-) and at various pH was studied. Desorption studies were conducted using simple sonication and pH variation technique. Column adsorption studies were performed. SEM and EDS studies were done on the adsorbing material before adsorption, after adsorption and after desorption of SDS.

Journal of Environmental Science and Health, Part A, 2002

This study was undertaken to evaluate the efficiency of rubber granule, a low-cost adsorbent for ... more This study was undertaken to evaluate the efficiency of rubber granule, a low-cost adsorbent for the removal of sodium dodecyl sulfate (SDS) that is a representative member of anionic surfactant (AS). In the batch experiments conducted at an initial concentration range of 2-6 mg/l, it was found that the rubber granules selected could remove SDS from water up to 90%. Kinetic profiles were developed for various conditions. Effects of adsorbent size, initial adsorbate concentration and adsorbent dose, pH, Ca2+ ion concentration, Fe2+ ion concentration, Cl- ion concentration, and ionic strength on the adsorption of SDS on rubber granules were studied. The adsorption isotherm studies were also conducted.

Journal of Dispersion Science and Technology, 2007

For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-... more For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-6-isopropylamino-s-traiazine) from water environment, batch studies were performed to study the kinetics of 2,4-D and atrazine sorption by rubber granules. Experiments were conducted at various initial concentrations of 7.5 mg/L, 4 mg/L, and 0.5 mg/L of 2,4-D and atrazine with 18 g/L sorbent dose. The equilibrium time was found to be 120 minutes for both 2,4-D and atrazine. The regression analysis for the experimental data showed that the rapid stage zone of kinetics profiles followed a first order reversible kinetics for all initial concentrations of sorbate. The various thermodynamic properties such as enthalpy and entropy activation values (DH and DS) also show that the sorption is spontaneous. This article will provide information toward understanding the sorption phenomena of 2, 4-D and atrazine on waste tyre rubber granules. It also is valuable to us in finding out the rate constant of sorption of 2,4-D and atrazine.

International Journal of Water, 2001

The Homogeneous Charge Compression Ignition Engine, HCCI has the potential to combine the best of... more The Homogeneous Charge Compression Ignition Engine, HCCI has the potential to combine the best of the Spark Ignition and Compression Ignition Engines. With high octane number fuel, the engine operates with high compression ratio and lean mixtures giving CI engine equivalent fuel consumption or better. Owing to pre-mixed charge without rich or stoichiometric zones, the production of soot and NO x can be avoided. This paper presents some results from advanced laser diagnostics showing the fundamental behaviour of the process from a close to homogeneous combustion onset towards a very stratified process at around 20-50% heat released. The need for active combustion control is shown and possible means of control are discussed. Results with multi-cylinder engines using negative valve overlap, variable compression ratio, fast inlet temperature control as well as dual fuel are given.

Interdisciplinary Environmental Review, 2003

Dyes and Pigments, 2006

The fixed bed column study was undertaken for the removal of crystal violet (CV), also known as B... more The fixed bed column study was undertaken for the removal of crystal violet (CV), also known as Basic Violet 3, a well-known cationic dye from wastewater using surfactant-modified alumina (SMA) as an adsorbing media. The SMA was found to be a very efficient media for the removal of dye from wastewater. The column with 2 cm diameter, different bed heights such as 10, 20 and 30 cm could treat 3.58 l, 7.94 l and 12.51 l, respectively, of CV bearing wastewater with CV concentration 200 mg/l and flow rate 8.5 ml/min. The adsorption bed was exhausted within a very short time (w1.5 h) after the breakthrough occurred. This indicated that the adsorption zone was almost saturated at the time of exhaustion. Different column design parameters like depth of exchange zone, time required for exchange zone to move its own height, adsorption rate, adsorption capacity etc. were calculated. Effect of flow rate and initial concentration was studied. Theoretical breakthrough curve was drawn from the batch isotherm data and was compared with experimental breakthrough curve. Desorption of CV from the SMA surface was possible using 1 M sodium hydroxide solution, rectified spirit and acetone.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2005

The adsorption characteristics of sodium dodecyl sulfate (SDS) on neutral alumina were studied in... more The adsorption characteristics of sodium dodecyl sulfate (SDS) on neutral alumina were studied in detail. Alumina was found to be an efficient adsorbent for SDS and could be used for the removal of anionic surfactant (AS) from wastewater when it is present in high concentration (several thousand ppm). In the present work the actual laundry wastewater was treated by both batch and continuous mode. The initial AS concentration in wastewater was 8068 ppm. The optimum adsorbent dose and equilibrium time found were 120 g/l and 1 h, respectively. Under optimised conditions the removal efficiency was found to be 94%. The removal of SDS by alumina follows the pseudo-second order reaction kinetics. In column study the flow rate was maintained at 1.63 m 3 /m 2 /h. The breakthrough and exhaust time were found to be 48 and 86 min, respectively, using 10 cm column depth. Height of adsorption zone was found to be 5.5 cm and the rate at which the adsorption zone was moving through the bed was 9.42 cm/h. The percentage of the total column saturated at breakthrough was found 75.5%. The value of adsorption rate coefficient (K) and adsorption capacity coefficient (N) were obtained as 0.000824 l/(mg h) and 143460 mg/l, respectively. After exhaustion, aqueous NaOH could efficiently regenerate alumina.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006

... The engineering aspect of these processes, however, still remains unexplored. In a very recen... more ... The engineering aspect of these processes, however, still remains unexplored. In a very recent study, we have showed how the surfactant-modified alumina could be used efficiently for the removal of crystal violet (CV), a cationic dye from wastewater [30]. ...

Separation and Purification Technology, 2005

The efficiency of a locally available very low cost waste tire rubber granule in removing anionic... more The efficiency of a locally available very low cost waste tire rubber granule in removing anionic surfactant (AS) by adsorption process was evaluated. As a representative member of AS sodium dodecyl sulfate (abbreviated as SDS) was used. It was found that in the batch experiment conducted at 2.0 mg/l initial concentration of SDS, rubber granules could remove up to 92% of SDS from wastewater. Kinetic profiles under various conditions were developed. The equilibrium time was found to be 6 h. Reaction rate constants (forward, reverse and overall) were determined for different initial concentrations of SDS by approximating the kinetic data to the first-order reversible kinetic model. Pore and film diffusion coefficients were determined from the half-time equations and film diffusion appeared to be rate limiting. This was further supported by multiple interruption tests.