ITALIC! N-Acetylcysteine (NAC) is the ITALIC! N-acetyl derivative of the amino acidl-cysteine and... more ITALIC! N-Acetylcysteine (NAC) is the ITALIC! N-acetyl derivative of the amino acidl-cysteine and is extensively used as a medicine to treat a variety of diseases. High-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method has been developed for the quantitative assessment of ITALIC! N-acetyl-l-cysteine. The method was further applied to study the distribution of the intraperitoneal injected drug into different tissues and plasma of Wistar rats, including liver, kidney, heart, lungs and spleen. The drug was having highest concentration in plasma and liver followed by kidney, lungs, heart and spleen. Method validation studies suggested being linear in the range of 1-15 µg mL(-1)for liver, kidney, heart, lungs and spleen and 1-120 µg mL(-1)for the plasma. The limit of detection and limit of quantitation were found to be 0.20 and 0.66 µg mL(-1), respectively. The recovery studies suggested that in all the cases, the obtained recovery was in the ra...
The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nic... more The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nickel [Ni(II)] from an aqueous solution, was investigated by both batch and column operations. The characterization studies showed the mesoporous nature of EAFS with dominance of acidic sites. The adsorption was found to be dependent on the adsorbent dosage, contact time, the pH, and initial metal ion concentration. Optimum Ni(II) uptake was 160.92 mg/g at 1000 mg/ L initial concentration with equilibration time 216 h. Adsorption follows the pseudo-second-order kinetics model. Linear and non-linear isotherm models revealed the applicability of the Langmuir model confirming monolayer adsorption. Both the column bed capacity and the exhaustion time increased with increase in bed height. The saturation time was found to increase from 42 to 46 h with a decrease in the flow rate from 15 to 5 mL/min. The bed depth saturation time and Thomas models were evaluated. The experimental breakthrough curves agreed well with the predicted model.
The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nic... more The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nickel [Ni(II)] from an aqueous solution, was investigated by both batch and column operations. The characterization studies showed the mesoporous nature of EAFS with dominance of acidic sites. The adsorption was found to be dependent on the adsorbent dosage, contact time, the pH, and initial metal ion concentration. Optimum Ni(II) uptake was 160.92 mg/g at 1000 mg/ L initial concentration with equilibration time 216 h. Adsorption follows the pseudo-second-order kinetics model. Linear and non-linear isotherm models revealed the applicability of the Langmuir model confirming monolayer adsorption. Both the column bed capacity and the exhaustion time increased with increase in bed height. The saturation time was found to increase from 42 to 46 h with a decrease in the flow rate from 15 to 5 mL/min. The bed depth saturation time and Thomas models were evaluated. The experimental breakthrough curves agreed well with the predicted model.
ABSTRACT Novel PMDA/TMSPEDA hybrid polymeric nano-composite (HPNC) was synthesized by ring openin... more ABSTRACT Novel PMDA/TMSPEDA hybrid polymeric nano-composite (HPNC) was synthesized by ring opening polymerization and sol–gel reaction. TGA analysis showed thermally stable polymeric material. FT-IR analysis revealed co-ordinate bonding between amine groups (present on HPNC) and bivalent metal ions as a possible adsorption mechanism. Adsorption studies showed maximum uptake of Pb(II) (49.72 mg/g) on HPNC followed by Cd(II) (45.22 mg/g), and Zn(II) (41.75 mg/g) at pH 7. Thermodynamically, the process was exothermic. Freundlich and pseudo-second-order kinetics model were the best fitted models to the experimental data. Kinetics studies showed better performance of HPNC for Cd(II) at lower concentration while Pb(II) adsorption was highly favorable at higher concentration. Rapid adsorption kinetics was observed for Pb(II) with equilibration time at various concentrations varied between 10 and 30 min. Desorption studies showed maximum metal elution [Pb(II) (94.13%) > Zn(II) (93.59%) > Cd(II) (84.15%)] with 0.1 M HCl. Regeneration studies showed 28.99% and 16.96% loss in Pb(II) adsorption and recovery after four consecutive cycles, respectively. The findings of present study showed potentiality of HPNC as an effective and economically feasible adsorbent for Pb(II).
Journal of Industrial and Engineering Chemistry, 2014
Surfactant modified carbon coated monolith was used as an adsorbent for methylene blue (MB) adsor... more Surfactant modified carbon coated monolith was used as an adsorbent for methylene blue (MB) adsorption. Effects of pH, salt, contact time, initial dye concentrations and temperature on dye adsorption were studied. Higher solution pH favoured MB adsorption. Furthermore, kinetics study showed that the adsorption could be better represented by the pseudo-second-order model. Linear and non-linear isotherm studies revealed better fitting of Langmuir model to adsorption data with maximum monolayer adsorption capacity 388 mg/g. The adsorption was found to be spontaneous and endothermic. Desorption studies indicate that 0.1 N HCl exhibits higher elution efficiency (82.1%) with appreciable quantitative MB recovery.
Journal of Industrial and Engineering Chemistry, 2014
Comparative sorption study of dissolved manganese and cobalt ions onto alginate beads (ABs) and t... more Comparative sorption study of dissolved manganese and cobalt ions onto alginate beads (ABs) and thermally activated nano-carbon beads (NCBs) was performed. Acidic functionalities dominate over sorbent surface. Elemental analysis confirmed that divalent calcium replacement with heavy metal ions might be a possible sorption mechanism. Optimum metal uptake was observed at pH 8. Most of the metal ions (80-92%) were sorbed within 4 h, followed by a slower sorption stage. Mn(II) and Co(II) recovery was greater than 99% with 0.1 N HCl, and NCB could be repeatedly utilized for Mn(II) and Co(II) sorption with negligible loss in sorption capacity.
Comparative removal of phenols and its chlorinated derivatives by carbon-coated monolith: equilib... more Comparative removal of phenols and its chlorinated derivatives by carbon-coated monolith: equilibrium, kinetics and regeneration studies, Desalination and Water Treatment, 54:2, 393-404,
Critical Reviews in Environmental Science and Technology, 2014
ABSTRACT Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical ... more ABSTRACT Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical composition and structure. Extremely high aspect ratios, molecularly smooth hydrophobic graphitic walls, and nanoscale inner diameters of CNTs give rise to the peculiar adsorption properties. This review provides an overview on CNTs functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems. A summary of recent information obtained using batch studies and deals with mechanisms involved during the adsorption have been reported. Adsorption capacity of CNTs has been observed by numerous investigators to increase substantially after functionalization/treatment with oxidizing agents such as NaOCl, HNO3, H2SO4, KMnO4, and other oxidizing agents. However, the selectivity of CNTs toward metal ions depends on both the route used for their synthesis and reagent employed for purification. The recovery of metal ions and the regeneration of CNTs have minimal impact on their performance. Desorption of metal ions from saturated adsorbent can be achieved using acid/base elution.
ABSTRACT We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric ammonia sen... more ABSTRACT We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric ammonia sensor operating at 9.06 μm for high-sensitivity, high temporal resolution, ground-based measurements. Atmospheric ammonia (NH3) is a gas-phase precursor to fine particulate matter, with implications for air quality and climate change. Currently, NH3 sensing challenges have led to a lack of widespread in situ measurements. Our open-path sensor configuration minimizes sampling artifacts associated with NH3 surface adsorption onto inlet tubing and reduced pressure sampling cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic wavelength modulation spectroscopy allows for selective and sensitive detection of atmospheric pressure-broadened absorption features. An in-line ethylene reference cell provides real-time calibration (±20% accuracy) and normalization for instrument drift under rapidly changing field conditions. The sensor has a sensitivity and noise-equivalent limit (1σ) of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and consumes ~ 50 W of electrical power. The total uncertainty in NH3 measurements is 0.20 ppbv NH3 ± 10%, based on a spectroscopic calibration method. Field performance of this open-path NH3 sensor is demonstrated, with 10 Hz time resolution and a large dynamic response for in situ NH3 measurements. This sensor provides the capabilities for improved in situ gas-phase NH3 sensing relevant for emission source characterization and flux measurements.
ITALIC! N-Acetylcysteine (NAC) is the ITALIC! N-acetyl derivative of the amino acidl-cysteine and... more ITALIC! N-Acetylcysteine (NAC) is the ITALIC! N-acetyl derivative of the amino acidl-cysteine and is extensively used as a medicine to treat a variety of diseases. High-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method has been developed for the quantitative assessment of ITALIC! N-acetyl-l-cysteine. The method was further applied to study the distribution of the intraperitoneal injected drug into different tissues and plasma of Wistar rats, including liver, kidney, heart, lungs and spleen. The drug was having highest concentration in plasma and liver followed by kidney, lungs, heart and spleen. Method validation studies suggested being linear in the range of 1-15 µg mL(-1)for liver, kidney, heart, lungs and spleen and 1-120 µg mL(-1)for the plasma. The limit of detection and limit of quantitation were found to be 0.20 and 0.66 µg mL(-1), respectively. The recovery studies suggested that in all the cases, the obtained recovery was in the ra...
The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nic... more The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nickel [Ni(II)] from an aqueous solution, was investigated by both batch and column operations. The characterization studies showed the mesoporous nature of EAFS with dominance of acidic sites. The adsorption was found to be dependent on the adsorbent dosage, contact time, the pH, and initial metal ion concentration. Optimum Ni(II) uptake was 160.92 mg/g at 1000 mg/ L initial concentration with equilibration time 216 h. Adsorption follows the pseudo-second-order kinetics model. Linear and non-linear isotherm models revealed the applicability of the Langmuir model confirming monolayer adsorption. Both the column bed capacity and the exhaustion time increased with increase in bed height. The saturation time was found to increase from 42 to 46 h with a decrease in the flow rate from 15 to 5 mL/min. The bed depth saturation time and Thomas models were evaluated. The experimental breakthrough curves agreed well with the predicted model.
The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nic... more The ability of electric arc furnace slag (EAFS), a by-product of the steel industry to adsorb nickel [Ni(II)] from an aqueous solution, was investigated by both batch and column operations. The characterization studies showed the mesoporous nature of EAFS with dominance of acidic sites. The adsorption was found to be dependent on the adsorbent dosage, contact time, the pH, and initial metal ion concentration. Optimum Ni(II) uptake was 160.92 mg/g at 1000 mg/ L initial concentration with equilibration time 216 h. Adsorption follows the pseudo-second-order kinetics model. Linear and non-linear isotherm models revealed the applicability of the Langmuir model confirming monolayer adsorption. Both the column bed capacity and the exhaustion time increased with increase in bed height. The saturation time was found to increase from 42 to 46 h with a decrease in the flow rate from 15 to 5 mL/min. The bed depth saturation time and Thomas models were evaluated. The experimental breakthrough curves agreed well with the predicted model.
ABSTRACT Novel PMDA/TMSPEDA hybrid polymeric nano-composite (HPNC) was synthesized by ring openin... more ABSTRACT Novel PMDA/TMSPEDA hybrid polymeric nano-composite (HPNC) was synthesized by ring opening polymerization and sol–gel reaction. TGA analysis showed thermally stable polymeric material. FT-IR analysis revealed co-ordinate bonding between amine groups (present on HPNC) and bivalent metal ions as a possible adsorption mechanism. Adsorption studies showed maximum uptake of Pb(II) (49.72 mg/g) on HPNC followed by Cd(II) (45.22 mg/g), and Zn(II) (41.75 mg/g) at pH 7. Thermodynamically, the process was exothermic. Freundlich and pseudo-second-order kinetics model were the best fitted models to the experimental data. Kinetics studies showed better performance of HPNC for Cd(II) at lower concentration while Pb(II) adsorption was highly favorable at higher concentration. Rapid adsorption kinetics was observed for Pb(II) with equilibration time at various concentrations varied between 10 and 30 min. Desorption studies showed maximum metal elution [Pb(II) (94.13%) > Zn(II) (93.59%) > Cd(II) (84.15%)] with 0.1 M HCl. Regeneration studies showed 28.99% and 16.96% loss in Pb(II) adsorption and recovery after four consecutive cycles, respectively. The findings of present study showed potentiality of HPNC as an effective and economically feasible adsorbent for Pb(II).
Journal of Industrial and Engineering Chemistry, 2014
Surfactant modified carbon coated monolith was used as an adsorbent for methylene blue (MB) adsor... more Surfactant modified carbon coated monolith was used as an adsorbent for methylene blue (MB) adsorption. Effects of pH, salt, contact time, initial dye concentrations and temperature on dye adsorption were studied. Higher solution pH favoured MB adsorption. Furthermore, kinetics study showed that the adsorption could be better represented by the pseudo-second-order model. Linear and non-linear isotherm studies revealed better fitting of Langmuir model to adsorption data with maximum monolayer adsorption capacity 388 mg/g. The adsorption was found to be spontaneous and endothermic. Desorption studies indicate that 0.1 N HCl exhibits higher elution efficiency (82.1%) with appreciable quantitative MB recovery.
Journal of Industrial and Engineering Chemistry, 2014
Comparative sorption study of dissolved manganese and cobalt ions onto alginate beads (ABs) and t... more Comparative sorption study of dissolved manganese and cobalt ions onto alginate beads (ABs) and thermally activated nano-carbon beads (NCBs) was performed. Acidic functionalities dominate over sorbent surface. Elemental analysis confirmed that divalent calcium replacement with heavy metal ions might be a possible sorption mechanism. Optimum metal uptake was observed at pH 8. Most of the metal ions (80-92%) were sorbed within 4 h, followed by a slower sorption stage. Mn(II) and Co(II) recovery was greater than 99% with 0.1 N HCl, and NCB could be repeatedly utilized for Mn(II) and Co(II) sorption with negligible loss in sorption capacity.
Comparative removal of phenols and its chlorinated derivatives by carbon-coated monolith: equilib... more Comparative removal of phenols and its chlorinated derivatives by carbon-coated monolith: equilibrium, kinetics and regeneration studies, Desalination and Water Treatment, 54:2, 393-404,
Critical Reviews in Environmental Science and Technology, 2014
ABSTRACT Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical ... more ABSTRACT Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical composition and structure. Extremely high aspect ratios, molecularly smooth hydrophobic graphitic walls, and nanoscale inner diameters of CNTs give rise to the peculiar adsorption properties. This review provides an overview on CNTs functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems. A summary of recent information obtained using batch studies and deals with mechanisms involved during the adsorption have been reported. Adsorption capacity of CNTs has been observed by numerous investigators to increase substantially after functionalization/treatment with oxidizing agents such as NaOCl, HNO3, H2SO4, KMnO4, and other oxidizing agents. However, the selectivity of CNTs toward metal ions depends on both the route used for their synthesis and reagent employed for purification. The recovery of metal ions and the regeneration of CNTs have minimal impact on their performance. Desorption of metal ions from saturated adsorbent can be achieved using acid/base elution.
ABSTRACT We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric ammonia sen... more ABSTRACT We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric ammonia sensor operating at 9.06 μm for high-sensitivity, high temporal resolution, ground-based measurements. Atmospheric ammonia (NH3) is a gas-phase precursor to fine particulate matter, with implications for air quality and climate change. Currently, NH3 sensing challenges have led to a lack of widespread in situ measurements. Our open-path sensor configuration minimizes sampling artifacts associated with NH3 surface adsorption onto inlet tubing and reduced pressure sampling cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic wavelength modulation spectroscopy allows for selective and sensitive detection of atmospheric pressure-broadened absorption features. An in-line ethylene reference cell provides real-time calibration (±20% accuracy) and normalization for instrument drift under rapidly changing field conditions. The sensor has a sensitivity and noise-equivalent limit (1σ) of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and consumes ~ 50 W of electrical power. The total uncertainty in NH3 measurements is 0.20 ppbv NH3 ± 10%, based on a spectroscopic calibration method. Field performance of this open-path NH3 sensor is demonstrated, with 10 Hz time resolution and a large dynamic response for in situ NH3 measurements. This sensor provides the capabilities for improved in situ gas-phase NH3 sensing relevant for emission source characterization and flux measurements.
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Papers by Moonis Khan