Journal of Purity Utility Reaction and Environment, Apr 1, 2013
ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyr... more ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyrolyzing of sawdust of the rubber wood (Heveabrasilensis). The experimental equilibrium data were analyzed using the isotherms of Langmuir, Freundlich, Tempkin. The Langmuir isotherm shows the maximum value of adsorption capacity was 333.33 mg/g and the correlation coefficient (R 2) was 0.999.Sawdust biochar is a fast and effective adsorbent for removing MB from aqueous solutions.
ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyr... more ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyrolyzing of sawdust of the rubber wood (Heveabrasilensis). The experimental equilibrium data were analyzed using the isotherms of Langmuir, Freundlich, Tempkin. The Langmuir isotherm shows the maximum value of adsorption capacity was 333.33 mg/g and the correlation coefficient (R 2) was 0.999.Sawdust biochar is a fast and effective adsorbent for removing MB from aqueous solutions.
Biochars have received increasing attention because of their potential environmental applications... more Biochars have received increasing attention because of their potential environmental applications such
as soil amending and atmospheric C sequestration. In this study, biochar was produced from waste
rubber-wood-sawdust. The produced biochars were characterized by Brunauer–Emmett–Teller (BET)
gas porosimetry, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis
(TGA), and Fourier transform infrared spectroscopy (FTIR). Pyrolysis temperature was shown to have
a strong influence on both thermal and chemical characteristic of biochar samples. The experimental data
shows that the biochar samples can absorb around 5% water by mass (hydrophilic) at lower temperatures
(<550 ◦C), and that lignin is not converted into a hydrophobic polycyclic aromatic hydrocarbon (PAH)
matrix. At higher temperatures (>650 ◦C), biochar samples were thermally stable and became hydrophobic
due to the presence of aromatic compounds. Carbon content (over 85%) increased with increasing
temperature, and showed an inverse effect to the elemental ratios of H/C and O/C. The very low H/C and
O/C ratios obtained for the biochar indicated that carbon in this material is predominantly unsaturated.
BET results showed that the sawdust derived biochars have surface areas between 10 and 200 m2 g−1
and FTIR indicated an aromatic functional group about 866 cm−1 in most of the samples. The rate of CO2
adsorption on sawdust derived biochar generally increased with increasing temperature from 450 to
650 ◦C but then decreased with increase in the production temperature. Derived biochar represents a
potential alternative adsorbent for C sequestration.
Journal of Dispersion Science and Technology, 2012
The changes in global temperatures as a result of carbon dioxide (CO2) emissions has suggested th... more The changes in global temperatures as a result of carbon dioxide (CO2) emissions has suggested that cumulative CO2 emissions will continue to increase over time. Many countries are looking for ways to reduce or alter the amount of CO2 harming our environment; therefore, this review is a compilation of CO2 adsorption on biomass-derived-biochar (BDB). This suggests that effective measures to mitigate the risk of dangerous climate change will need to limit cumulative emissions of CO2. Further, if cumulative CO2 emissions overshoot acceptable limits, it will become necessary to remove CO2 from the air, that is, the so-called “negative emissions.” In this review, we discuss the definitions and classes of technologies for capturing CO2 from the air and the application of biochar in the improvement of soil fertility. We also discuss the economic tradeoff between biochar and bio-oil, agricultural nutrient leaching, the novel magnetic property of biochar and its durability.
Journal of Dispersion Science and Technology, 2011
The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant so... more The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) on the rate of oxidation of D-penicillamine by alkaline hexacyanoferrate(III) has been studied by spectrophotometrically at different temperatures. The effect of CTAB and SDS on the rate of reaction has been observed at even below the critical micelle concentration (CMC) of the surfactants, indicating binding of the substrate with the surfactants. On the basis of the kinetic results, the mechanism of the reaction has been proposed. The kinetic data have been rationalized in terms of Manger and Portnoy's model for micellar inhibition and binding parameters (viz. binding constants, partition coefficient, free energy transfer from water to micelle, etc.); activation parameters have also been evaluated.
Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with Ca 2+ , Mg... more Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with Ca 2+ , Mg 2+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ in acidic medium showed the formation of 1:1 complex. The absorption spectrum of pure drug exhibits two prominent peaks at 270 and 345 nm. Its spectra scanned at several pH exhibited two isosbestic points (305 and 330 nm) indicating the presence of zwitterionic condition of drug in solution phase. The fluorescence emission spectra of CFP in presence of different concentrations of metal ions showed enhancement in fluorescence intensity which is ascribed to chelating enhancement fluorescence effect (CHEF). The stoichiometry of the complexes was determined by Job's and Benesi-Hildebrand method. The stability of the complexes follow the order Ca 2+ < Mg 2+ < Co 2+ < Ni 2+ < Zn 2+ < Mn 2+ < Cu 2+ < Fe 3+ .
The binding interaction of levofloxacin (LF) with toxic metal ions Cd +2 , Hg +2 and Pb +2 was in... more The binding interaction of levofloxacin (LF) with toxic metal ions Cd +2 , Hg +2 and Pb +2 was investigated in aqueous acidic medium by absorption and fluorescence spectrophotometry. The experimental results showed that the metal ions quench the fluorescence intensity of LF by forming LF 2 -metal complex. It was found that static quenching was the main reason of fluorescence quenching. Quenching of LF by toxic metal follows the order Hg>Cd>Pb. The stoichiometry and logK of formed chelate was determined by absorption and fluorescence spectrophotometry. The quenching constant Ksv and the binding sites "n" were determined together with their thermodynamic parameters at 25 ºC and 35 ºC. The positive entropy change indicated the gain in configurational entropy as a result of chelation. The process of interaction was spontaneous and mainly ∆S-driven.
Three simple and highly sensitive methods were designed for the determination of cephalosporins a... more Three simple and highly sensitive methods were designed for the determination of cephalosporins antibiotics (CFs) such as cefpodoxime proxetil (CFPD), cefdinir (CFDN), and cefuroxime axetil (CFRX) by means of the enhancement effect on resonance Rayleigh scattering (RRS) ...
The determination of the stoichiometry of complex formation and the mechanism of fluorescence que... more The determination of the stoichiometry of complex formation and the mechanism of fluorescence quenching of telmisartan (TMST) with Y(III) and Nd(III) was carried out in great detail by a fluorometric method. The quenching was interpreted in terms of chelation-enhanced quenching. The experimental results showed that both Y(III) and Nd(III) quench the intrinsic fluorescence of TMST without inducing any conformational change in it. The quenching of fluorescence was found to be static and due to the formation of a nonfluorescent complex in the ground state. Linear Stern-Volmer plots were obtained for both complexes. The pH of the solution was found to have a profound effect on quenching, and effective quenching was obtained at pH 7. The stoichiometry of metal-TMST complexes was found to be 1:2 through the Benesi-Hildebrand method. The quenching constant K sv and association constant were determined together with their thermodynamic parameters at (25, 35, and 45)°C. The negative ∆G values indicate that the complexation process is spontaneous. A decrease in log K with an increase in temperature and the negative values of ∆H for the complexation show that all the complexation reactions are exothermic and the metal-ligand binding process is enthalpy driven.
The interaction of clofazimine (CFZ) with divalent metal cations was studied by measuring fluores... more The interaction of clofazimine (CFZ) with divalent metal cations was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultraviolet spectra. The fluorescence quenching spectra of CFZ in the presence of metal ions showed that ...
A simple, sensitive, and rapid method based on ion association, for the determination of FLD has ... more A simple, sensitive, and rapid method based on ion association, for the determination of FLD has been developed. Flutamide (FLD) can react with Cu(II) to form 1:1 cationic chelate at pH 2.2-7.0 Mclivaine buffer medium, which can further react with anionic surfactants (AS) such as sodium dodecyl sulfate (SDS), sodium lauryl sulfonate (SLS) and sodium dodecylbenzene sulfonate (SDBS) to form 1:1 ion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced to the highest degree. The maximum RRS, SOS and FDS wavelengths of three ion-association complexes were located at 345/345 nm, 610/305 nm and 430/860 nm, respectively. The increments of scattering intensity (ΔI) were directly proportional to the concentration of FLD in certain ranges. The detection limits (3σ) of FLD for SDS, SLS and SDBS systems were 1.9 ng ml(-1), 2.1 ng ml(-1) and 2.2 ng ml(-1)(RRS method), 2.4 ng ml(-1), 2.7 ng ml(-1) and 2.6 ng ml(-1) (SOS method) and 2.3 ng ml(-1), 2.4 ng ml(-1) and 2.5 ng ml(-1) (FDS method), separately. The sensitivity of RRS method was higher than those of FDS and SOS methods. The optimum conditions of RRS method and the influence factors, the composition and the reaction mechanism have been discussed. Since the method is highly selective, it does not interference concomitant substances. These methods were applied successfully for the determination of FLD in pharmaceutical formulation and urine samples.
The development of UV and fluorescence spectrophotometric methods for the quantitative determinat... more The development of UV and fluorescence spectrophotometric methods for the quantitative determination of alprazolam in dosage forms using As(III)−SDS system. The two simple and sensitive, spectrophotometric and spectrofluorimetric methods were developed for the determination of alprazolam (ALP) in tablets. These methods are based on formation of ALP−As(III) complex in the presence of SDS. The UV-spectrum of 30% methanolic solution of
Journal of Purity Utility Reaction and Environment, Apr 1, 2013
ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyr... more ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyrolyzing of sawdust of the rubber wood (Heveabrasilensis). The experimental equilibrium data were analyzed using the isotherms of Langmuir, Freundlich, Tempkin. The Langmuir isotherm shows the maximum value of adsorption capacity was 333.33 mg/g and the correlation coefficient (R 2) was 0.999.Sawdust biochar is a fast and effective adsorbent for removing MB from aqueous solutions.
ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyr... more ABSTRACT The adsorption of methylene blue (MB) onto sawdust biochar and biochar was formed by pyrolyzing of sawdust of the rubber wood (Heveabrasilensis). The experimental equilibrium data were analyzed using the isotherms of Langmuir, Freundlich, Tempkin. The Langmuir isotherm shows the maximum value of adsorption capacity was 333.33 mg/g and the correlation coefficient (R 2) was 0.999.Sawdust biochar is a fast and effective adsorbent for removing MB from aqueous solutions.
Biochars have received increasing attention because of their potential environmental applications... more Biochars have received increasing attention because of their potential environmental applications such
as soil amending and atmospheric C sequestration. In this study, biochar was produced from waste
rubber-wood-sawdust. The produced biochars were characterized by Brunauer–Emmett–Teller (BET)
gas porosimetry, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis
(TGA), and Fourier transform infrared spectroscopy (FTIR). Pyrolysis temperature was shown to have
a strong influence on both thermal and chemical characteristic of biochar samples. The experimental data
shows that the biochar samples can absorb around 5% water by mass (hydrophilic) at lower temperatures
(<550 ◦C), and that lignin is not converted into a hydrophobic polycyclic aromatic hydrocarbon (PAH)
matrix. At higher temperatures (>650 ◦C), biochar samples were thermally stable and became hydrophobic
due to the presence of aromatic compounds. Carbon content (over 85%) increased with increasing
temperature, and showed an inverse effect to the elemental ratios of H/C and O/C. The very low H/C and
O/C ratios obtained for the biochar indicated that carbon in this material is predominantly unsaturated.
BET results showed that the sawdust derived biochars have surface areas between 10 and 200 m2 g−1
and FTIR indicated an aromatic functional group about 866 cm−1 in most of the samples. The rate of CO2
adsorption on sawdust derived biochar generally increased with increasing temperature from 450 to
650 ◦C but then decreased with increase in the production temperature. Derived biochar represents a
potential alternative adsorbent for C sequestration.
Journal of Dispersion Science and Technology, 2012
The changes in global temperatures as a result of carbon dioxide (CO2) emissions has suggested th... more The changes in global temperatures as a result of carbon dioxide (CO2) emissions has suggested that cumulative CO2 emissions will continue to increase over time. Many countries are looking for ways to reduce or alter the amount of CO2 harming our environment; therefore, this review is a compilation of CO2 adsorption on biomass-derived-biochar (BDB). This suggests that effective measures to mitigate the risk of dangerous climate change will need to limit cumulative emissions of CO2. Further, if cumulative CO2 emissions overshoot acceptable limits, it will become necessary to remove CO2 from the air, that is, the so-called “negative emissions.” In this review, we discuss the definitions and classes of technologies for capturing CO2 from the air and the application of biochar in the improvement of soil fertility. We also discuss the economic tradeoff between biochar and bio-oil, agricultural nutrient leaching, the novel magnetic property of biochar and its durability.
Journal of Dispersion Science and Technology, 2011
The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant so... more The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) on the rate of oxidation of D-penicillamine by alkaline hexacyanoferrate(III) has been studied by spectrophotometrically at different temperatures. The effect of CTAB and SDS on the rate of reaction has been observed at even below the critical micelle concentration (CMC) of the surfactants, indicating binding of the substrate with the surfactants. On the basis of the kinetic results, the mechanism of the reaction has been proposed. The kinetic data have been rationalized in terms of Manger and Portnoy's model for micellar inhibition and binding parameters (viz. binding constants, partition coefficient, free energy transfer from water to micelle, etc.); activation parameters have also been evaluated.
Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with Ca 2+ , Mg... more Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with Ca 2+ , Mg 2+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ in acidic medium showed the formation of 1:1 complex. The absorption spectrum of pure drug exhibits two prominent peaks at 270 and 345 nm. Its spectra scanned at several pH exhibited two isosbestic points (305 and 330 nm) indicating the presence of zwitterionic condition of drug in solution phase. The fluorescence emission spectra of CFP in presence of different concentrations of metal ions showed enhancement in fluorescence intensity which is ascribed to chelating enhancement fluorescence effect (CHEF). The stoichiometry of the complexes was determined by Job's and Benesi-Hildebrand method. The stability of the complexes follow the order Ca 2+ < Mg 2+ < Co 2+ < Ni 2+ < Zn 2+ < Mn 2+ < Cu 2+ < Fe 3+ .
The binding interaction of levofloxacin (LF) with toxic metal ions Cd +2 , Hg +2 and Pb +2 was in... more The binding interaction of levofloxacin (LF) with toxic metal ions Cd +2 , Hg +2 and Pb +2 was investigated in aqueous acidic medium by absorption and fluorescence spectrophotometry. The experimental results showed that the metal ions quench the fluorescence intensity of LF by forming LF 2 -metal complex. It was found that static quenching was the main reason of fluorescence quenching. Quenching of LF by toxic metal follows the order Hg>Cd>Pb. The stoichiometry and logK of formed chelate was determined by absorption and fluorescence spectrophotometry. The quenching constant Ksv and the binding sites "n" were determined together with their thermodynamic parameters at 25 ºC and 35 ºC. The positive entropy change indicated the gain in configurational entropy as a result of chelation. The process of interaction was spontaneous and mainly ∆S-driven.
Three simple and highly sensitive methods were designed for the determination of cephalosporins a... more Three simple and highly sensitive methods were designed for the determination of cephalosporins antibiotics (CFs) such as cefpodoxime proxetil (CFPD), cefdinir (CFDN), and cefuroxime axetil (CFRX) by means of the enhancement effect on resonance Rayleigh scattering (RRS) ...
The determination of the stoichiometry of complex formation and the mechanism of fluorescence que... more The determination of the stoichiometry of complex formation and the mechanism of fluorescence quenching of telmisartan (TMST) with Y(III) and Nd(III) was carried out in great detail by a fluorometric method. The quenching was interpreted in terms of chelation-enhanced quenching. The experimental results showed that both Y(III) and Nd(III) quench the intrinsic fluorescence of TMST without inducing any conformational change in it. The quenching of fluorescence was found to be static and due to the formation of a nonfluorescent complex in the ground state. Linear Stern-Volmer plots were obtained for both complexes. The pH of the solution was found to have a profound effect on quenching, and effective quenching was obtained at pH 7. The stoichiometry of metal-TMST complexes was found to be 1:2 through the Benesi-Hildebrand method. The quenching constant K sv and association constant were determined together with their thermodynamic parameters at (25, 35, and 45)°C. The negative ∆G values indicate that the complexation process is spontaneous. A decrease in log K with an increase in temperature and the negative values of ∆H for the complexation show that all the complexation reactions are exothermic and the metal-ligand binding process is enthalpy driven.
The interaction of clofazimine (CFZ) with divalent metal cations was studied by measuring fluores... more The interaction of clofazimine (CFZ) with divalent metal cations was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultraviolet spectra. The fluorescence quenching spectra of CFZ in the presence of metal ions showed that ...
A simple, sensitive, and rapid method based on ion association, for the determination of FLD has ... more A simple, sensitive, and rapid method based on ion association, for the determination of FLD has been developed. Flutamide (FLD) can react with Cu(II) to form 1:1 cationic chelate at pH 2.2-7.0 Mclivaine buffer medium, which can further react with anionic surfactants (AS) such as sodium dodecyl sulfate (SDS), sodium lauryl sulfonate (SLS) and sodium dodecylbenzene sulfonate (SDBS) to form 1:1 ion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced to the highest degree. The maximum RRS, SOS and FDS wavelengths of three ion-association complexes were located at 345/345 nm, 610/305 nm and 430/860 nm, respectively. The increments of scattering intensity (ΔI) were directly proportional to the concentration of FLD in certain ranges. The detection limits (3σ) of FLD for SDS, SLS and SDBS systems were 1.9 ng ml(-1), 2.1 ng ml(-1) and 2.2 ng ml(-1)(RRS method), 2.4 ng ml(-1), 2.7 ng ml(-1) and 2.6 ng ml(-1) (SOS method) and 2.3 ng ml(-1), 2.4 ng ml(-1) and 2.5 ng ml(-1) (FDS method), separately. The sensitivity of RRS method was higher than those of FDS and SOS methods. The optimum conditions of RRS method and the influence factors, the composition and the reaction mechanism have been discussed. Since the method is highly selective, it does not interference concomitant substances. These methods were applied successfully for the determination of FLD in pharmaceutical formulation and urine samples.
The development of UV and fluorescence spectrophotometric methods for the quantitative determinat... more The development of UV and fluorescence spectrophotometric methods for the quantitative determination of alprazolam in dosage forms using As(III)−SDS system. The two simple and sensitive, spectrophotometric and spectrofluorimetric methods were developed for the determination of alprazolam (ALP) in tablets. These methods are based on formation of ALP−As(III) complex in the presence of SDS. The UV-spectrum of 30% methanolic solution of
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Papers by Dr. Ayaz Mohd
as soil amending and atmospheric C sequestration. In this study, biochar was produced from waste
rubber-wood-sawdust. The produced biochars were characterized by Brunauer–Emmett–Teller (BET)
gas porosimetry, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis
(TGA), and Fourier transform infrared spectroscopy (FTIR). Pyrolysis temperature was shown to have
a strong influence on both thermal and chemical characteristic of biochar samples. The experimental data
shows that the biochar samples can absorb around 5% water by mass (hydrophilic) at lower temperatures
(<550 ◦C), and that lignin is not converted into a hydrophobic polycyclic aromatic hydrocarbon (PAH)
matrix. At higher temperatures (>650 ◦C), biochar samples were thermally stable and became hydrophobic
due to the presence of aromatic compounds. Carbon content (over 85%) increased with increasing
temperature, and showed an inverse effect to the elemental ratios of H/C and O/C. The very low H/C and
O/C ratios obtained for the biochar indicated that carbon in this material is predominantly unsaturated.
BET results showed that the sawdust derived biochars have surface areas between 10 and 200 m2 g−1
and FTIR indicated an aromatic functional group about 866 cm−1 in most of the samples. The rate of CO2
adsorption on sawdust derived biochar generally increased with increasing temperature from 450 to
650 ◦C but then decreased with increase in the production temperature. Derived biochar represents a
potential alternative adsorbent for C sequestration.
as soil amending and atmospheric C sequestration. In this study, biochar was produced from waste
rubber-wood-sawdust. The produced biochars were characterized by Brunauer–Emmett–Teller (BET)
gas porosimetry, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis
(TGA), and Fourier transform infrared spectroscopy (FTIR). Pyrolysis temperature was shown to have
a strong influence on both thermal and chemical characteristic of biochar samples. The experimental data
shows that the biochar samples can absorb around 5% water by mass (hydrophilic) at lower temperatures
(<550 ◦C), and that lignin is not converted into a hydrophobic polycyclic aromatic hydrocarbon (PAH)
matrix. At higher temperatures (>650 ◦C), biochar samples were thermally stable and became hydrophobic
due to the presence of aromatic compounds. Carbon content (over 85%) increased with increasing
temperature, and showed an inverse effect to the elemental ratios of H/C and O/C. The very low H/C and
O/C ratios obtained for the biochar indicated that carbon in this material is predominantly unsaturated.
BET results showed that the sawdust derived biochars have surface areas between 10 and 200 m2 g−1
and FTIR indicated an aromatic functional group about 866 cm−1 in most of the samples. The rate of CO2
adsorption on sawdust derived biochar generally increased with increasing temperature from 450 to
650 ◦C but then decreased with increase in the production temperature. Derived biochar represents a
potential alternative adsorbent for C sequestration.