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Papers by sunil bajpai

Environmental Engineering and Management Journal, 2012

In this study, chitin (CT) has been used as a potential sorbent for the removal of antibiotic dru... more In this study, chitin (CT) has been used as a potential sorbent for the removal of antibiotic drug Gatifloxacin (GF) from aqueous solutions using batch experiments. The equilibrium drug uptake was studied as a function of sorbent dose, pH of sorbate solution and temperature. The experimental data was analyzed using Langmuir, Freundlich and Temkin isotherm models. It was found that to some extent, all the models showed their suitability. The equilibrium sorption capacity obtained at 18, 28 and 37 o C was 97.108 ± 2.35, 100.0 ± 3.23 and 181.818 ± 5.58 mg g-1 respectively. The optimum uptake was found to be in the drug solution with pH value of nearly 6.0. The thermodynamic parameters, free energy change (G o sorp), change in enthalpy (H o) and change in entropy (S o) of sorption, were evaluated using equilibrium uptake data obtained at three temperatures. G o sorp was calculated from Langmuir, Frumkin and modified Frumkin models. The negative value of G o sorp and positive H o indicated that drug uptake process was spontaneous and endothermic in nature respectively. The mean sorption energy E, as determined using Dubinin-Radushkevich (D-R) isotherm model, was found to be 7.424 ± 0.03 kJ mol-1 thus, indicating physical sorption process. Finally, the sorption of drug was also confirmed by antimicrobial test.

Pakistan Journal of Chemistry, 2014

This work describes moisture sorption behavior and water vapor permeability of gluteraldehyde-cro... more This work describes moisture sorption behavior and water vapor permeability of gluteraldehyde-crosslinked Carrageenen/polyvinyl alcohol (Carr/PVA) films. The moisture uptake has been studied under various relative humidity (RH) and the data obtained has been interpreted in the terms of various isotherm models such as GAB, Oswin and Halsey models. The moisture permeability through the films has been characterized in the terms of various parameters like water vapor transmission rate (WVTR), permeance (P) and Water vapor permeability (WVP). It was found that these parameters are greatly affected by the degree of crosslinking of the films. Finally, the model drug Gentamycin Sulphate was loaded in to the films and its release was monitored kinetically in the physiological buffer (PF) at 37 0 C. The films exhibited diffusion controlled release mechanism.

Journal of Engineered Fibers and Fabrics, 2009

The present work describes synthesis of copper alginate-cotton cellulose (CACC) composite fibers ... more The present work describes synthesis of copper alginate-cotton cellulose (CACC) composite fibers and detailed investigation of antimicrobial action against the model bacteria E.coli. The CACC fibers were prepared by immersing cotton fibers in aqueous solution of sodium alginate, followed by ionic crosslinking of alginate chains within the cotton cellulose fibers with Cu(II) ions to yield CACC composite fibers. The resulting CACC fibers were investigated for their biocidal action against E.coli, by using zone inhibition and colonies counting method. Finally, CACC fibers were reduced with sodium borohydride to yield copper nanoparticles-loaded composite fibers and investigated for biocidal action. It was found that CACC fibers possessed both, the fair mechanical strength and antibacterial action. The extent of biocidal action was found to depend upon the amount of Cu(II) loaded and concentration of alginate into cotton- cellulose fibers. The fibers showed higher Cu(II) release in phys...

Journal of Applied Chemistry, 2014

Regenerated cellulose/poly(acrylic acid) composite films have been synthesized for wound dressing... more Regenerated cellulose/poly(acrylic acid) composite films have been synthesized for wound dressing applications. The water absorbency of these films was studied as a function of amount of cross-linker N,N′-methylenebisacrylamide and cellulose contents in the feed mixture. The samples, having different compositions, showed tensile strength and percent elongation in the range of 9.98×105 to 13.40×105 N/m2 and 110 to 265, respectively. The water vapor transmission rate (WVTR) for various films was found to be in the range of 2.03 to 7.18 mg/cm2/h. These films were loaded with antibacterial drug miconazole nitrate and their release was studied in the physiological pH at 37°C. The release data was found to fit well the diffusion controlled Higuchi model. Finally the films demonstrated fair antibacterial and antifungal action, thus establishing their strong candidature as wound dressing materials.

Water Science and Engineering, 2021

In this work spent tea leaves were used as a non-conventional, cost-effective sorbent for removal... more In this work spent tea leaves were used as a non-conventional, cost-effective sorbent for removal of Cu(II) from aqueous solutions in batch systems. The sorbent was characterised with respect to surface area, pore volume, density, etc. The equilibrium sorption data were applied to various sorption isotherm models, and the order of fitness was: Langmuir > Temkin > Freundlich. The maximum sorption capacity Q o was found to be almost 90.9 and 68.4, as evaluated using Langmuir isotherms at 27ºC and 37ºC respectively. The observed decrease in sorption capacity with temperature indicated the exothermic nature of the uptake process. The kinetic uptake data were best interpreted by a pseudo second-order kinetic model with values of rate constants of adsorption of 1.47 x 10-2 and 3.01 x 10-2 g/mg•min, respectively, for the initial sorbate concentrations of 10 and 20 mg•ℓ-1 at 27ºC. The sorption mean free energy was determined from the Dubinin Radushkevich (DR) isotherm model and was found to be 9.91 kJ•mol-1 , indicating ion exchange/chemisorption nature of uptake process. The Cu(II) uptake was found to increase with the pH of the sorbate solution and maximum sorption was observed in the pH range of 1.0 to 4.8. Finally, thermodynamic parameters like ∆G o , ∆H o , ∆S o were also evaluated.

International Food Research Journal, 2013

This study describes investigation of moisture sorption behavior of Carrageenan at 10, 20 and 30 ... more This study describes investigation of moisture sorption behavior of Carrageenan at 10, 20 and 30 o C under different relative humidity, in the range of 23 to 96 percent using gravimetric method. The equilibrium moisture uptake data, thus obtained, were fitted to three well known three sorption isotherm models, namely GAB, Halsey and Oswin models using non-linear least square method. The well-known GAB model best interpreted the equilibrium data in a satisfactory manner. The monolayer moisture content X m , as determined from GAB model, was found to be 31.72 x 10-3 , 43.60 x 10-3 and 17.41 x 10-3 kg kg-1 , db at 10, 20, and 30 o C. The isosteric heat of sorption (q st) was determined using Clausius-Clapeyron type equation. The uptake data was also used to determine isokinetic temperature T β (301.7 K) and harmonic mean temperature T hm (292.82 K). The enthalpy-entropy compensation theory indicated that moisture sorption process was enthalpy driven.

Water SA, 2014

This study describes adsorptive removal of the antibiotic drug ciprofloxacin hydrochloride from s... more This study describes adsorptive removal of the antibiotic drug ciprofloxacin hydrochloride from simulated water using poly(methacrylic acid) (PMAA) as adsorbent. The adsorbent was characterised by various instrumental techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The adsorption equilibrium data, as studied at 3 temperatures, namely, 15, 25 and 37°C, were best interpreted by the Langmuir adsorption isotherm model. Moreover, an increase in temperature reduces drug uptake. A pH of the adsorption system in the range of 5.0 to 8.0 causes maximum adsorption of the drug. The presence of drug molecules in the adsorbent particles was shown by various techniques: X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Antibacterial studies also reveal the adsorption of the drug from solution.

Acta chimica Slovenica, 2010

The low cost adsorbent, spent tea leaves (STL) has been tested for the effectiveness in decoloriz... more The low cost adsorbent, spent tea leaves (STL) has been tested for the effectiveness in decolorization of wastewater containing crystal violet dye in batch experiments. Effect of various parameters such as agitation time, pH, temperature and adsorbent dose has been investigated. The dye uptake has been found to increase with pH and temperature. The kinetic uptake data, obtained at different sorbate concentrations, is best interpreted by pseudo second order model and rate constants for adsorption are found to be 8.5 × 10-3, 22.2 × 10-3 and 42.0 × 10-3 g mg-1 min-1 for initial dye concentrations of 10, 20 and 30 mg L-1 respectively. The dye uptake was found to increase with temperature and the activation energy for adsorption process was found to be 10.45 ± 0.89 kJ mol-1.

Acta Pharmaceutica Sinica B, 2014

A series of novel indole-2-carboxylate derivatives were synthesized and assayed to determine thei... more A series of novel indole-2-carboxylate derivatives were synthesized and assayed to determine their in vitro broad-spectrum antiviral activities. The biological results showed that some of the synthesized compounds exhibited potent broad-spectrum antiviral activity. Notably, compound 8f showed the highest SI value (17.1) to Cox B3 virus. Compound 14f showed both potent inhibitory activity against influenza A (IC 50 ¼7.53 μmol/L) and the highest SI value (12.1). SAR results showed that the alkyloxy at the 4-position of indole ring was not crucial to the antiviral activities. Incorporation of an acetyl substituent at the amino group disfavored antiviral activity towards RNA viruses.

Water SA, 2012

The present work describes dynamic uptake of the antibiotic drug ciprofloxacin hydrochloride (CH)... more The present work describes dynamic uptake of the antibiotic drug ciprofloxacin hydrochloride (CH), by using a costeffective agricultural by-product-sawdust (SD). The sawdust was characterised by FTIR and SEM analysis. The sorbent particles were highly porous with average pore diameter of nearly 10 μm. The optimum pH and solid/liquid ratio for sorption of CH were found to be 5.8 and 2.0, respectively. The dynamic drug uptake data was applied to various kinetic models and their order of fitness was found to be pseudo second order > Elovich equation > power function model, as indicated by their regression values. The experimental equilibrium uptake values (q e) were in close agreement with those evaluated from the pseudo second order equation for initial sorbate concentrations of 10 and 20 mg•ℓ-1 at 33°C. The drug uptake mechanism was found to be attractive non-electrostatic interactions, involving H-bonding interactions between H atoms and other electro negative species such as F, O and N of the drug molecule. The mechanism is discussed on the basis of pH pzc of sawdust and zwitterionic nature of drug CH. Mass transfer analysis was carried out using the drug uptake data obtained with sorbate concentrations of 10 and 20 mg•ℓ-1. The used sorbent could be regenerated using 1.0 mol•ℓ-1 HCl solution with a regeneration efficiency of nearly 85%.

Polymer Bulletin, 2007

Summary Carboxymethylcellulose (CMC, DSCM = 1) was partially hydrophobized in order to prepare p... more Summary Carboxymethylcellulose (CMC, DSCM = 1) was partially hydrophobized in order to prepare polymeric surfactants by the transesterification reaction using the methyl ester of the fatty acid complex of rapeseed oil (MERO). The chemical modification was performed in different reaction media (i) DMF/TSA and (ii) H2O/DMF with and without K2CO3 as catalyst, at various reaction conditions and using microwave radiation with

Journal of Macromolecular Science, Part A, 2010

... V. Chaurasia a , Navin Chand b & SK Bajpai a pages 309-317. ... Singh, M., Singh, S.,... more ... V. Chaurasia a , Navin Chand b & SK Bajpai a pages 309-317. ... Singh, M., Singh, S., Prasad, S. and Gambhir, IS 2008. Digest J. Nanometer Biostructures , 3(3): 115–120. [Web of Science ®] View all references) has become a serious problem in public health. ...

Journal of Macromolecular Science, Part A, 2010

This study involves comparative study of equilibrium and kinetic sorption studies to remove antib... more This study involves comparative study of equilibrium and kinetic sorption studies to remove antibiotic drug Ciprofloxacin (CF) from aqueous solutions using poly (acrylamide-coitaconic acid)/charcoal composite i.e. [poly(AAm-co-IA)/Chl] and chitosan-charcoal composite i.e. Cht/Chl as polymeric cation exchanger sorbent materials. The composites prepared were characterized by FTIR spectroscopy and TGA analysis. In addition their physicochemical parameters were also determined. The various isotherm models, when applied to equilibrium sorption data at 25 o C, followed the order of fitness as Temkin > Langmuir≈ Freundlich and Temkin>Freundlich>Langmuir, respectively for [poly (AAm-co-IA)/Chl] and Cht/Chl. The kinetic uptake data, obtained for [poly (AAm-co-IA)/Chl] and Cht/Chl sorbents exhibited the order of fitness as: pseudo first order > Pore diffusion> simple Elovich model> pseudo second order and Pseudo second order > pseudo first order > pore diffusion > simple Elovich respectively. The sorption mean free energy from the Dubinin-Raduschkevich (DR) isotherm was found to be nearly 12.91 kJ mol-1 and 5.59 kJ mol-1 indicating an ion-exchange mechanism for drug uptake for only [poly (AAm-co-IA)/Chl. The optimum pH value of sorbate solution for drug uptake was found to be around 6.0. Finally, the antibacterial action of drug was investigated and it was found that after adsorption there was a decrease in bacterial growth inhibition efficiency of drug solution.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008

Higher environmental standards have made for the removal of arsenic from water, an important prob... more Higher environmental standards have made for the removal of arsenic from water, an important problem for environmental engineering. Iron oxide is a particularly interesting sorbent to consider for this application. Its magnetic properties allow relatively routine dispersal and recovery of the adsorbent into and from groundwater or industrial processing facilities; in addition, iron oxide has strong and specific interactions with both As (III) and As(V). Finally, this material can be produced with nanoscale dimensions, which enhance both its capacity and removal. The present study focuses on iron-oxide based complexes that were found to adsorb arsenic from water. Their composition, morphology, magnetic behaviour and potential were studied by Fourier Transform Infra-Red (FTIR) Spectroscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Zeta potential and Vibrating Sampling Magnetometer (VSM). Arsenic concentrations were recorded by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Finally, the particles were also investigated for their antimicrobial properties that can be used against gram positive and gram-negative bacteria. The study suggests that among various iron oxide sorbents magnetite chitosan beads provides a low cost, fast and effective method for removal of arsenic from potable water, and thus making it suitable for drinking purpose.

Chinese Science Bulletin, 2003

A large quantity of SARS-CoV virus was proliferated in Vero cells, inactivated with-propiolactone... more A large quantity of SARS-CoV virus was proliferated in Vero cells, inactivated with-propiolactone, then purified by Sepharose 4FF column chromatography to prepare inactivated vaccine. The vaccine was identified by Western blot, mass spectrographic analysis, ELISA and electron microscopy. The vaccine with or without aluminum hydroxide adjuvant was inoculated into female BALB/c mice at different dosages. The result showed that the antibodies to SARS-CoV were induced in the mice. The antibody levels induced by the vaccine with aluminum hydroxide were higher than those without aluminum hydroxide.

Carbohydrate Polymers, 2006

A novel chitosan–Ca3V10O28 complex membrane with sustained antimicrobial capability was prepared ... more A novel chitosan–Ca3V10O28 complex membrane with sustained antimicrobial capability was prepared by the self-assembly of V10O286- and chitosan, using Ca2+ as the linker. The complex membrane was characterized by means of FT-IR, TG-DSC, X-ray diffraction, SEM and elemental analysis. It is shown that Ca3V10O28 is evenly present on the surface of chitosan–Ca3V10O28 complex membrane in the form of amorphous crystal.

Acta chimica slovenica, 2009

This research focuses on removal of Cu(II) from aqueous solution using magnetite loaded cationic ... more This research focuses on removal of Cu(II) from aqueous solution using magnetite loaded cationic resin (MLCR) at three different temperatures 15, 30 and 40 °C. The uptake of Cu(II) follows Freundlich sorption isotherm and is endothermic in nature. Out of various kinetic models proposed, the šsecond order' seems to fit in the experimental data in the best way. The sorption appears to be governed by chemical forces rather than physical electrostatic interactions. The Dubinin-Radushkevich isotherm with mean sorption energy value of 9.45 kJ mol-1 also supports chemical nature of sorption process. The sorption capacity of MLCR particles for Cu(II) was found to increase with pH of the sorbate solution, thus reaching maximum at pH 6.0. The positive value of ΔH o indicates endothermic nature of uptake process and positive ΔS° indicates increased randomness due to sorption.

Reactive and Functional Polymers, 2004

Spherical beads have been prepared by ionotropic gelation of sodium alginate in the presence of C... more Spherical beads have been prepared by ionotropic gelation of sodium alginate in the presence of CaCl 2 and BaCl 2 solutions and their swelling behavior has been studied. The barium ion-crosslinked beads exhibit almost minimum swelling of 40 AE 3% in PBS at pH 7.4 but possess greater stability while calcium alginate beads exhibit nearly 160% of water uptake and subsequently dissolve. The beads appear to swell through ion-exchange process which was confirmed by monitoring the Ca 2þ release from the calcium alginate beads. The release was found to be diffusion controlled. On treatment with 0.1 M HCl, the calcium alginate beads demonstrated a decrease in water uptake in PBS at pH 7.4 with faster degradation while for acid treated barium alginate beads, the water uptake was found to increase on treatment with HCl. When the two beads samples were put in media of continuous varying pH (to mimic the passage of beads from mouth to colon), barium alginate beads possessed greater stability, thus showing potential to be used for colontargeted oral delivery.

Reactive and Functional Polymers, 2006

An investigation of water uptake behavior of a novel pH-sensitive poly(methacrylamide-co-methacry... more An investigation of water uptake behavior of a novel pH-sensitive poly(methacrylamide-co-methacrylic acid) hydrogel system was carried out with two major objectives. First was to study the effect of various synthesis conditions like reaction temperature, initiator content and degree of dilution of feed mixture on the water absorbency of resulting hydrogels and the second was to interpret the water uptake data by various kinetic models. The 2.25 times dilution of the reaction mixture resulted in the formation of hydrogels with highest water uptake of 1423 ± 21% in the simulating intestinal fluid of pH 7.4 at 37°C. Likewise, the optimum synthesis temperature and initiator concentration were found to be 80°C and 11.04 • 10 À2 mM, respectively. The kinetic models proposed by Peppas and Hopfenberg were applied on the water uptake data to obtain the best fit. The enthalpy of mixing DH mix was also evaluated for hydrogels with varying concentrations of monomer acid in the feed mixture. Finally, the gels demonstrated sharp change in their water absorbency and mesh size of networks with pH of the swelling media, thus suggesting their strong candidature for being used as oral drug-delivery systems along the gastrointestinal tract.

Environmental Engineering and Management Journal, 2012

In this study, chitin (CT) has been used as a potential sorbent for the removal of antibiotic dru... more In this study, chitin (CT) has been used as a potential sorbent for the removal of antibiotic drug Gatifloxacin (GF) from aqueous solutions using batch experiments. The equilibrium drug uptake was studied as a function of sorbent dose, pH of sorbate solution and temperature. The experimental data was analyzed using Langmuir, Freundlich and Temkin isotherm models. It was found that to some extent, all the models showed their suitability. The equilibrium sorption capacity obtained at 18, 28 and 37 o C was 97.108 ± 2.35, 100.0 ± 3.23 and 181.818 ± 5.58 mg g-1 respectively. The optimum uptake was found to be in the drug solution with pH value of nearly 6.0. The thermodynamic parameters, free energy change (G o sorp), change in enthalpy (H o) and change in entropy (S o) of sorption, were evaluated using equilibrium uptake data obtained at three temperatures. G o sorp was calculated from Langmuir, Frumkin and modified Frumkin models. The negative value of G o sorp and positive H o indicated that drug uptake process was spontaneous and endothermic in nature respectively. The mean sorption energy E, as determined using Dubinin-Radushkevich (D-R) isotherm model, was found to be 7.424 ± 0.03 kJ mol-1 thus, indicating physical sorption process. Finally, the sorption of drug was also confirmed by antimicrobial test.

Pakistan Journal of Chemistry, 2014

This work describes moisture sorption behavior and water vapor permeability of gluteraldehyde-cro... more This work describes moisture sorption behavior and water vapor permeability of gluteraldehyde-crosslinked Carrageenen/polyvinyl alcohol (Carr/PVA) films. The moisture uptake has been studied under various relative humidity (RH) and the data obtained has been interpreted in the terms of various isotherm models such as GAB, Oswin and Halsey models. The moisture permeability through the films has been characterized in the terms of various parameters like water vapor transmission rate (WVTR), permeance (P) and Water vapor permeability (WVP). It was found that these parameters are greatly affected by the degree of crosslinking of the films. Finally, the model drug Gentamycin Sulphate was loaded in to the films and its release was monitored kinetically in the physiological buffer (PF) at 37 0 C. The films exhibited diffusion controlled release mechanism.

Journal of Engineered Fibers and Fabrics, 2009

The present work describes synthesis of copper alginate-cotton cellulose (CACC) composite fibers ... more The present work describes synthesis of copper alginate-cotton cellulose (CACC) composite fibers and detailed investigation of antimicrobial action against the model bacteria E.coli. The CACC fibers were prepared by immersing cotton fibers in aqueous solution of sodium alginate, followed by ionic crosslinking of alginate chains within the cotton cellulose fibers with Cu(II) ions to yield CACC composite fibers. The resulting CACC fibers were investigated for their biocidal action against E.coli, by using zone inhibition and colonies counting method. Finally, CACC fibers were reduced with sodium borohydride to yield copper nanoparticles-loaded composite fibers and investigated for biocidal action. It was found that CACC fibers possessed both, the fair mechanical strength and antibacterial action. The extent of biocidal action was found to depend upon the amount of Cu(II) loaded and concentration of alginate into cotton- cellulose fibers. The fibers showed higher Cu(II) release in phys...

Journal of Applied Chemistry, 2014

Regenerated cellulose/poly(acrylic acid) composite films have been synthesized for wound dressing... more Regenerated cellulose/poly(acrylic acid) composite films have been synthesized for wound dressing applications. The water absorbency of these films was studied as a function of amount of cross-linker N,N′-methylenebisacrylamide and cellulose contents in the feed mixture. The samples, having different compositions, showed tensile strength and percent elongation in the range of 9.98×105 to 13.40×105 N/m2 and 110 to 265, respectively. The water vapor transmission rate (WVTR) for various films was found to be in the range of 2.03 to 7.18 mg/cm2/h. These films were loaded with antibacterial drug miconazole nitrate and their release was studied in the physiological pH at 37°C. The release data was found to fit well the diffusion controlled Higuchi model. Finally the films demonstrated fair antibacterial and antifungal action, thus establishing their strong candidature as wound dressing materials.

Water Science and Engineering, 2021

In this work spent tea leaves were used as a non-conventional, cost-effective sorbent for removal... more In this work spent tea leaves were used as a non-conventional, cost-effective sorbent for removal of Cu(II) from aqueous solutions in batch systems. The sorbent was characterised with respect to surface area, pore volume, density, etc. The equilibrium sorption data were applied to various sorption isotherm models, and the order of fitness was: Langmuir > Temkin > Freundlich. The maximum sorption capacity Q o was found to be almost 90.9 and 68.4, as evaluated using Langmuir isotherms at 27ºC and 37ºC respectively. The observed decrease in sorption capacity with temperature indicated the exothermic nature of the uptake process. The kinetic uptake data were best interpreted by a pseudo second-order kinetic model with values of rate constants of adsorption of 1.47 x 10-2 and 3.01 x 10-2 g/mg•min, respectively, for the initial sorbate concentrations of 10 and 20 mg•ℓ-1 at 27ºC. The sorption mean free energy was determined from the Dubinin Radushkevich (DR) isotherm model and was found to be 9.91 kJ•mol-1 , indicating ion exchange/chemisorption nature of uptake process. The Cu(II) uptake was found to increase with the pH of the sorbate solution and maximum sorption was observed in the pH range of 1.0 to 4.8. Finally, thermodynamic parameters like ∆G o , ∆H o , ∆S o were also evaluated.

International Food Research Journal, 2013

This study describes investigation of moisture sorption behavior of Carrageenan at 10, 20 and 30 ... more This study describes investigation of moisture sorption behavior of Carrageenan at 10, 20 and 30 o C under different relative humidity, in the range of 23 to 96 percent using gravimetric method. The equilibrium moisture uptake data, thus obtained, were fitted to three well known three sorption isotherm models, namely GAB, Halsey and Oswin models using non-linear least square method. The well-known GAB model best interpreted the equilibrium data in a satisfactory manner. The monolayer moisture content X m , as determined from GAB model, was found to be 31.72 x 10-3 , 43.60 x 10-3 and 17.41 x 10-3 kg kg-1 , db at 10, 20, and 30 o C. The isosteric heat of sorption (q st) was determined using Clausius-Clapeyron type equation. The uptake data was also used to determine isokinetic temperature T β (301.7 K) and harmonic mean temperature T hm (292.82 K). The enthalpy-entropy compensation theory indicated that moisture sorption process was enthalpy driven.

Water SA, 2014

This study describes adsorptive removal of the antibiotic drug ciprofloxacin hydrochloride from s... more This study describes adsorptive removal of the antibiotic drug ciprofloxacin hydrochloride from simulated water using poly(methacrylic acid) (PMAA) as adsorbent. The adsorbent was characterised by various instrumental techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The adsorption equilibrium data, as studied at 3 temperatures, namely, 15, 25 and 37°C, were best interpreted by the Langmuir adsorption isotherm model. Moreover, an increase in temperature reduces drug uptake. A pH of the adsorption system in the range of 5.0 to 8.0 causes maximum adsorption of the drug. The presence of drug molecules in the adsorbent particles was shown by various techniques: X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Antibacterial studies also reveal the adsorption of the drug from solution.

Acta chimica Slovenica, 2010

The low cost adsorbent, spent tea leaves (STL) has been tested for the effectiveness in decoloriz... more The low cost adsorbent, spent tea leaves (STL) has been tested for the effectiveness in decolorization of wastewater containing crystal violet dye in batch experiments. Effect of various parameters such as agitation time, pH, temperature and adsorbent dose has been investigated. The dye uptake has been found to increase with pH and temperature. The kinetic uptake data, obtained at different sorbate concentrations, is best interpreted by pseudo second order model and rate constants for adsorption are found to be 8.5 × 10-3, 22.2 × 10-3 and 42.0 × 10-3 g mg-1 min-1 for initial dye concentrations of 10, 20 and 30 mg L-1 respectively. The dye uptake was found to increase with temperature and the activation energy for adsorption process was found to be 10.45 ± 0.89 kJ mol-1.

Acta Pharmaceutica Sinica B, 2014

A series of novel indole-2-carboxylate derivatives were synthesized and assayed to determine thei... more A series of novel indole-2-carboxylate derivatives were synthesized and assayed to determine their in vitro broad-spectrum antiviral activities. The biological results showed that some of the synthesized compounds exhibited potent broad-spectrum antiviral activity. Notably, compound 8f showed the highest SI value (17.1) to Cox B3 virus. Compound 14f showed both potent inhibitory activity against influenza A (IC 50 ¼7.53 μmol/L) and the highest SI value (12.1). SAR results showed that the alkyloxy at the 4-position of indole ring was not crucial to the antiviral activities. Incorporation of an acetyl substituent at the amino group disfavored antiviral activity towards RNA viruses.

Water SA, 2012

The present work describes dynamic uptake of the antibiotic drug ciprofloxacin hydrochloride (CH)... more The present work describes dynamic uptake of the antibiotic drug ciprofloxacin hydrochloride (CH), by using a costeffective agricultural by-product-sawdust (SD). The sawdust was characterised by FTIR and SEM analysis. The sorbent particles were highly porous with average pore diameter of nearly 10 μm. The optimum pH and solid/liquid ratio for sorption of CH were found to be 5.8 and 2.0, respectively. The dynamic drug uptake data was applied to various kinetic models and their order of fitness was found to be pseudo second order > Elovich equation > power function model, as indicated by their regression values. The experimental equilibrium uptake values (q e) were in close agreement with those evaluated from the pseudo second order equation for initial sorbate concentrations of 10 and 20 mg•ℓ-1 at 33°C. The drug uptake mechanism was found to be attractive non-electrostatic interactions, involving H-bonding interactions between H atoms and other electro negative species such as F, O and N of the drug molecule. The mechanism is discussed on the basis of pH pzc of sawdust and zwitterionic nature of drug CH. Mass transfer analysis was carried out using the drug uptake data obtained with sorbate concentrations of 10 and 20 mg•ℓ-1. The used sorbent could be regenerated using 1.0 mol•ℓ-1 HCl solution with a regeneration efficiency of nearly 85%.

Polymer Bulletin, 2007

Summary Carboxymethylcellulose (CMC, DSCM = 1) was partially hydrophobized in order to prepare p... more Summary Carboxymethylcellulose (CMC, DSCM = 1) was partially hydrophobized in order to prepare polymeric surfactants by the transesterification reaction using the methyl ester of the fatty acid complex of rapeseed oil (MERO). The chemical modification was performed in different reaction media (i) DMF/TSA and (ii) H2O/DMF with and without K2CO3 as catalyst, at various reaction conditions and using microwave radiation with

Journal of Macromolecular Science, Part A, 2010

... V. Chaurasia a , Navin Chand b & SK Bajpai a pages 309-317. ... Singh, M., Singh, S.,... more ... V. Chaurasia a , Navin Chand b & SK Bajpai a pages 309-317. ... Singh, M., Singh, S., Prasad, S. and Gambhir, IS 2008. Digest J. Nanometer Biostructures , 3(3): 115–120. [Web of Science ®] View all references) has become a serious problem in public health. ...

Journal of Macromolecular Science, Part A, 2010

This study involves comparative study of equilibrium and kinetic sorption studies to remove antib... more This study involves comparative study of equilibrium and kinetic sorption studies to remove antibiotic drug Ciprofloxacin (CF) from aqueous solutions using poly (acrylamide-coitaconic acid)/charcoal composite i.e. [poly(AAm-co-IA)/Chl] and chitosan-charcoal composite i.e. Cht/Chl as polymeric cation exchanger sorbent materials. The composites prepared were characterized by FTIR spectroscopy and TGA analysis. In addition their physicochemical parameters were also determined. The various isotherm models, when applied to equilibrium sorption data at 25 o C, followed the order of fitness as Temkin > Langmuir≈ Freundlich and Temkin>Freundlich>Langmuir, respectively for [poly (AAm-co-IA)/Chl] and Cht/Chl. The kinetic uptake data, obtained for [poly (AAm-co-IA)/Chl] and Cht/Chl sorbents exhibited the order of fitness as: pseudo first order > Pore diffusion> simple Elovich model> pseudo second order and Pseudo second order > pseudo first order > pore diffusion > simple Elovich respectively. The sorption mean free energy from the Dubinin-Raduschkevich (DR) isotherm was found to be nearly 12.91 kJ mol-1 and 5.59 kJ mol-1 indicating an ion-exchange mechanism for drug uptake for only [poly (AAm-co-IA)/Chl. The optimum pH value of sorbate solution for drug uptake was found to be around 6.0. Finally, the antibacterial action of drug was investigated and it was found that after adsorption there was a decrease in bacterial growth inhibition efficiency of drug solution.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008

Higher environmental standards have made for the removal of arsenic from water, an important prob... more Higher environmental standards have made for the removal of arsenic from water, an important problem for environmental engineering. Iron oxide is a particularly interesting sorbent to consider for this application. Its magnetic properties allow relatively routine dispersal and recovery of the adsorbent into and from groundwater or industrial processing facilities; in addition, iron oxide has strong and specific interactions with both As (III) and As(V). Finally, this material can be produced with nanoscale dimensions, which enhance both its capacity and removal. The present study focuses on iron-oxide based complexes that were found to adsorb arsenic from water. Their composition, morphology, magnetic behaviour and potential were studied by Fourier Transform Infra-Red (FTIR) Spectroscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Zeta potential and Vibrating Sampling Magnetometer (VSM). Arsenic concentrations were recorded by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Finally, the particles were also investigated for their antimicrobial properties that can be used against gram positive and gram-negative bacteria. The study suggests that among various iron oxide sorbents magnetite chitosan beads provides a low cost, fast and effective method for removal of arsenic from potable water, and thus making it suitable for drinking purpose.

Chinese Science Bulletin, 2003

A large quantity of SARS-CoV virus was proliferated in Vero cells, inactivated with-propiolactone... more A large quantity of SARS-CoV virus was proliferated in Vero cells, inactivated with-propiolactone, then purified by Sepharose 4FF column chromatography to prepare inactivated vaccine. The vaccine was identified by Western blot, mass spectrographic analysis, ELISA and electron microscopy. The vaccine with or without aluminum hydroxide adjuvant was inoculated into female BALB/c mice at different dosages. The result showed that the antibodies to SARS-CoV were induced in the mice. The antibody levels induced by the vaccine with aluminum hydroxide were higher than those without aluminum hydroxide.

Carbohydrate Polymers, 2006

A novel chitosan–Ca3V10O28 complex membrane with sustained antimicrobial capability was prepared ... more A novel chitosan–Ca3V10O28 complex membrane with sustained antimicrobial capability was prepared by the self-assembly of V10O286- and chitosan, using Ca2+ as the linker. The complex membrane was characterized by means of FT-IR, TG-DSC, X-ray diffraction, SEM and elemental analysis. It is shown that Ca3V10O28 is evenly present on the surface of chitosan–Ca3V10O28 complex membrane in the form of amorphous crystal.

Acta chimica slovenica, 2009

This research focuses on removal of Cu(II) from aqueous solution using magnetite loaded cationic ... more This research focuses on removal of Cu(II) from aqueous solution using magnetite loaded cationic resin (MLCR) at three different temperatures 15, 30 and 40 °C. The uptake of Cu(II) follows Freundlich sorption isotherm and is endothermic in nature. Out of various kinetic models proposed, the šsecond order' seems to fit in the experimental data in the best way. The sorption appears to be governed by chemical forces rather than physical electrostatic interactions. The Dubinin-Radushkevich isotherm with mean sorption energy value of 9.45 kJ mol-1 also supports chemical nature of sorption process. The sorption capacity of MLCR particles for Cu(II) was found to increase with pH of the sorbate solution, thus reaching maximum at pH 6.0. The positive value of ΔH o indicates endothermic nature of uptake process and positive ΔS° indicates increased randomness due to sorption.

Reactive and Functional Polymers, 2004

Spherical beads have been prepared by ionotropic gelation of sodium alginate in the presence of C... more Spherical beads have been prepared by ionotropic gelation of sodium alginate in the presence of CaCl 2 and BaCl 2 solutions and their swelling behavior has been studied. The barium ion-crosslinked beads exhibit almost minimum swelling of 40 AE 3% in PBS at pH 7.4 but possess greater stability while calcium alginate beads exhibit nearly 160% of water uptake and subsequently dissolve. The beads appear to swell through ion-exchange process which was confirmed by monitoring the Ca 2þ release from the calcium alginate beads. The release was found to be diffusion controlled. On treatment with 0.1 M HCl, the calcium alginate beads demonstrated a decrease in water uptake in PBS at pH 7.4 with faster degradation while for acid treated barium alginate beads, the water uptake was found to increase on treatment with HCl. When the two beads samples were put in media of continuous varying pH (to mimic the passage of beads from mouth to colon), barium alginate beads possessed greater stability, thus showing potential to be used for colontargeted oral delivery.

Reactive and Functional Polymers, 2006

An investigation of water uptake behavior of a novel pH-sensitive poly(methacrylamide-co-methacry... more An investigation of water uptake behavior of a novel pH-sensitive poly(methacrylamide-co-methacrylic acid) hydrogel system was carried out with two major objectives. First was to study the effect of various synthesis conditions like reaction temperature, initiator content and degree of dilution of feed mixture on the water absorbency of resulting hydrogels and the second was to interpret the water uptake data by various kinetic models. The 2.25 times dilution of the reaction mixture resulted in the formation of hydrogels with highest water uptake of 1423 ± 21% in the simulating intestinal fluid of pH 7.4 at 37°C. Likewise, the optimum synthesis temperature and initiator concentration were found to be 80°C and 11.04 • 10 À2 mM, respectively. The kinetic models proposed by Peppas and Hopfenberg were applied on the water uptake data to obtain the best fit. The enthalpy of mixing DH mix was also evaluated for hydrogels with varying concentrations of monomer acid in the feed mixture. Finally, the gels demonstrated sharp change in their water absorbency and mesh size of networks with pH of the swelling media, thus suggesting their strong candidature for being used as oral drug-delivery systems along the gastrointestinal tract.