Kshitij Tewari - Academia.edu (original) (raw)
Papers by Kshitij Tewari
Chemical Engineering & Technology, 2022
Microbial Electrochemical Technologies, 2020
Journal of Environmental Chemical Engineering, 2019
Ce-CNFs are synthesized using CVD technique. The average diameter of synthesized Ce-CNFs rang... more Ce-CNFs are synthesized using CVD technique. The average diameter of synthesized Ce-CNFs ranges from 20 nm to 40 nm. The linear range and LOD of Cu (II) ions are 0.6-1.8 ppb and 0.3 ppb respectively. The linear range and LOD of Pb (II) ions are 0.9-2.1 ppb and 0.6 ppb respectively.
Journal of Environmental Chemical Engineering, 2018
In this study, an easy and facile route is followed to synthesize carbon dots (CDs) from candle s... more In this study, an easy and facile route is followed to synthesize carbon dots (CDs) from candle soot (CS) for efficient and selective detection of mercury (Hg (II)) and iron (Fe (III)) toxic metals ions. These CDs were obtained via oxidation process are furthermore doped with nitrogen (N) to make them more competent towards the target applications. N-doped CDs (N-CDs) are synthesized by ethylene diamine (N source) and sodium lauryl sulphate (favorable for synthesis of smaller N-CDs). The average size of synthesized N-CDs is found in between 2.0 nm to 5.0 nm and they efficaciously have emitted blue FL under UV lamp exposure (∼290-365 nm). Zeta potential shows the net surface charge of N-CDs is negative (−10.4 mV) and plays an important role for the sensitivity of sensor and its binding efficiency towards metal ions. Functional groups (amine, hydroxyl, carbonyl, nitryl and alkenes) present on N-CDs are favorable for quenching and binding probability. Optimum pH was found 4-5 for getting better FL intensity of N-CDs. This FL is disappeared during quenching of certain concentrations of Hg(II) and Fe(III) ions due to the selective quenching of N-CDs with these metal ions. The linear range and optical detection limit of Hg (II) ions are 20-50 μM and 50 nM respectively, while for Fe (III) ions these values are 20-50 μM and 10.0 nM respectively. The fabricated N-CDs are inexpensive colorimetriC-Optical detector, selective and sensitive towards the detection of Hg (II) and Fe (III) ions contaminations and could be used as FL sensor probe for the detection of toxic metals sensing applications.
Reviews in Chemical Engineering, 2017
In this review, the state of the art on the removal of malachite green dye from aqueous solution ... more In this review, the state of the art on the removal of malachite green dye from aqueous solution using adsorption technique is presented. The objective is to critically analyze different adsorbents available for malachite green dye removal. Hence, the available recent literature in the area is categorized according to the cost, feasibility, and availability of adsorbents. An extensive survey of the adsorbents, derived from various sources such as low cost biological materials, waste material from industry, agricultural waste, polymers, clays, nanomaterials, and magnetic materials, has been carried out. The review studies on different adsorption factors, such as pH, concentration, adsorbent dose, and temperature. The fitting of the adsorption data to various models, isotherms, and kinetic regimes is also reported.
Progress in Organic Coatings, 2017
This review paper deals the history and development of various theories to predict the diffusion ... more This review paper deals the history and development of various theories to predict the diffusion in polymeric systems. The basis and application of various theories with the prediction capabilities are discussed. The most commonly used theory is Vrentas and Duda free volume theory with excellent agreement with experimental data report so far. This theory predicts the data very accurately in rubbery region. However, few modifications have come up in this theory to predict the diffusion above the glass transition with a little success. Relation between Fujita −Kishimoto theory [15] and Vrentas and Duda Theory [11,12] is
In industrial processes, there are many streams in which some streams need heating and other need... more In industrial processes, there are many streams in which some streams need heating and other need cooling, usually achieved by using hot and cold utilities respectively. Pinch technology is a very well-established methodology which is mostly used in process industries for determining the pinch temperatures and minimum utility requirements i.e. minimum heating load and minimum cooling load. This technology is based on 'Process integration concept'. Pinch analysis is a thermodynamically oriented method for the synthesis of minimum utility requirements. It is based on first law and second law of thermodynamics. According to Linnhoff and flower, pinch principle states that do not transfer the heat across the pinch. If heat is transferred across the pinch in any process will need much more energy than minimum energy/utility requirements which increases the cost of the process that is not feasible. A pinch point follows (i) Don't transfer the heat across the pinch, (ii) Don...
Chemical Engineering & Technology, 2015
ABSTRACT In pinch analysis, the calculations needed for determining pinch temperatures and minimu... more ABSTRACT In pinch analysis, the calculations needed for determining pinch temperatures and minimum utility requirements are simple and can be done manually in case of a small number of streams. However, in real-scale industrial problems, the calculation can become tedious and very much time-consuming. A generalized low-cost and user-friendly scheme for pinch design using MATLAB is proposed. This scheme is tested for several problems for accuracy and robustness to determine hot pinch temperature, cold pinch temperature, minimum cooling load, and minimum heating load using the temperature interval method. The solutions developed by the proposed scheme are mirror images of solutions found by applying a rigorous procedure.
Progress in Organic Coatings, 2016
Concentration profiles in two binary polymeric coatings of poly (styrene)-p-xylene and poly (meth... more Concentration profiles in two binary polymeric coatings of poly (styrene)-p-xylene and poly (methyl methacrylate)-ethylbenzene system have been measured using confocal laser Raman spectroscopy. Measured profiles are very different from as shown earlier for rubbery coatings. Sigmoidal profiles are observed in these polymeric coatings because they went through the glass transition temperature during the course of drying. These coating have reasonably very high concentration of polymer in the top as compared to the concentration in the deep of the coating near the substrate. The results follow the case-II diffusion trend in glassy coatings.
Chemical Engineering & Technology, 2022
Microbial Electrochemical Technologies, 2020
Journal of Environmental Chemical Engineering, 2019
Ce-CNFs are synthesized using CVD technique. The average diameter of synthesized Ce-CNFs rang... more Ce-CNFs are synthesized using CVD technique. The average diameter of synthesized Ce-CNFs ranges from 20 nm to 40 nm. The linear range and LOD of Cu (II) ions are 0.6-1.8 ppb and 0.3 ppb respectively. The linear range and LOD of Pb (II) ions are 0.9-2.1 ppb and 0.6 ppb respectively.
Journal of Environmental Chemical Engineering, 2018
In this study, an easy and facile route is followed to synthesize carbon dots (CDs) from candle s... more In this study, an easy and facile route is followed to synthesize carbon dots (CDs) from candle soot (CS) for efficient and selective detection of mercury (Hg (II)) and iron (Fe (III)) toxic metals ions. These CDs were obtained via oxidation process are furthermore doped with nitrogen (N) to make them more competent towards the target applications. N-doped CDs (N-CDs) are synthesized by ethylene diamine (N source) and sodium lauryl sulphate (favorable for synthesis of smaller N-CDs). The average size of synthesized N-CDs is found in between 2.0 nm to 5.0 nm and they efficaciously have emitted blue FL under UV lamp exposure (∼290-365 nm). Zeta potential shows the net surface charge of N-CDs is negative (−10.4 mV) and plays an important role for the sensitivity of sensor and its binding efficiency towards metal ions. Functional groups (amine, hydroxyl, carbonyl, nitryl and alkenes) present on N-CDs are favorable for quenching and binding probability. Optimum pH was found 4-5 for getting better FL intensity of N-CDs. This FL is disappeared during quenching of certain concentrations of Hg(II) and Fe(III) ions due to the selective quenching of N-CDs with these metal ions. The linear range and optical detection limit of Hg (II) ions are 20-50 μM and 50 nM respectively, while for Fe (III) ions these values are 20-50 μM and 10.0 nM respectively. The fabricated N-CDs are inexpensive colorimetriC-Optical detector, selective and sensitive towards the detection of Hg (II) and Fe (III) ions contaminations and could be used as FL sensor probe for the detection of toxic metals sensing applications.
Reviews in Chemical Engineering, 2017
In this review, the state of the art on the removal of malachite green dye from aqueous solution ... more In this review, the state of the art on the removal of malachite green dye from aqueous solution using adsorption technique is presented. The objective is to critically analyze different adsorbents available for malachite green dye removal. Hence, the available recent literature in the area is categorized according to the cost, feasibility, and availability of adsorbents. An extensive survey of the adsorbents, derived from various sources such as low cost biological materials, waste material from industry, agricultural waste, polymers, clays, nanomaterials, and magnetic materials, has been carried out. The review studies on different adsorption factors, such as pH, concentration, adsorbent dose, and temperature. The fitting of the adsorption data to various models, isotherms, and kinetic regimes is also reported.
Progress in Organic Coatings, 2017
This review paper deals the history and development of various theories to predict the diffusion ... more This review paper deals the history and development of various theories to predict the diffusion in polymeric systems. The basis and application of various theories with the prediction capabilities are discussed. The most commonly used theory is Vrentas and Duda free volume theory with excellent agreement with experimental data report so far. This theory predicts the data very accurately in rubbery region. However, few modifications have come up in this theory to predict the diffusion above the glass transition with a little success. Relation between Fujita −Kishimoto theory [15] and Vrentas and Duda Theory [11,12] is
In industrial processes, there are many streams in which some streams need heating and other need... more In industrial processes, there are many streams in which some streams need heating and other need cooling, usually achieved by using hot and cold utilities respectively. Pinch technology is a very well-established methodology which is mostly used in process industries for determining the pinch temperatures and minimum utility requirements i.e. minimum heating load and minimum cooling load. This technology is based on 'Process integration concept'. Pinch analysis is a thermodynamically oriented method for the synthesis of minimum utility requirements. It is based on first law and second law of thermodynamics. According to Linnhoff and flower, pinch principle states that do not transfer the heat across the pinch. If heat is transferred across the pinch in any process will need much more energy than minimum energy/utility requirements which increases the cost of the process that is not feasible. A pinch point follows (i) Don't transfer the heat across the pinch, (ii) Don...
Chemical Engineering & Technology, 2015
ABSTRACT In pinch analysis, the calculations needed for determining pinch temperatures and minimu... more ABSTRACT In pinch analysis, the calculations needed for determining pinch temperatures and minimum utility requirements are simple and can be done manually in case of a small number of streams. However, in real-scale industrial problems, the calculation can become tedious and very much time-consuming. A generalized low-cost and user-friendly scheme for pinch design using MATLAB is proposed. This scheme is tested for several problems for accuracy and robustness to determine hot pinch temperature, cold pinch temperature, minimum cooling load, and minimum heating load using the temperature interval method. The solutions developed by the proposed scheme are mirror images of solutions found by applying a rigorous procedure.
Progress in Organic Coatings, 2016
Concentration profiles in two binary polymeric coatings of poly (styrene)-p-xylene and poly (meth... more Concentration profiles in two binary polymeric coatings of poly (styrene)-p-xylene and poly (methyl methacrylate)-ethylbenzene system have been measured using confocal laser Raman spectroscopy. Measured profiles are very different from as shown earlier for rubbery coatings. Sigmoidal profiles are observed in these polymeric coatings because they went through the glass transition temperature during the course of drying. These coating have reasonably very high concentration of polymer in the top as compared to the concentration in the deep of the coating near the substrate. The results follow the case-II diffusion trend in glassy coatings.