The Experts below are selected from a list of 4413 Experts worldwide ranked by ideXlab platform
S Swarnalatha - One of the best experts on this subject based on the ideXlab platform.
-
efficient and safe disposal of chrome shavings discharged from leather industry using Thermal combustion
Journal of Chemical Technology & Biotechnology, 2009Co-Authors: Arumugam Ganesh Kumar, S Swarnalatha, Srinivasulu Tandaiah, G. SekaranAbstract:BACKGROUND: The high concentration of trivalent chromium along with organic/inorganic compounds in shavings (ChS) discharged from leather industries causes severe groundwater contamination in land disposal and chronic air pollution during Thermal Incineration. In the present investigation, ChS were subjected to Incineration at 800 °C in a Thermal incinerator under different volumes of oxygen to optimize the flow rate of oxygen to prevent the conversion of Cr3+ to Cr6+ (starved air combustion) followed by solidification and stabilization of calcined shavings. RESULTS: Net energy changes resulting from the combustion of shavings showed that the energy of the organic fractions is utilized to the maximum extent at an O2 flow rate of 3.0 g min−1. The ChS were effectively solidified/stabilized using Portland cement and fine aggregate. The unconfined compressive strength of the blocks was in the region of 160 kg cm−2. Leachability studies using a toxicity characterization of leachate procedure test (TCLP) on a solidified block were carried out to determine the percentage metal fixation and dissolved organic (as chemical oxygen demand) concentration in the leachate. CONCLUSION: The stabilization of chromium(III) in the cement gel matrix was confirmed using different instrumental techniques. The leaching characteristics through TCLP confirmed the effective stabilization of chromium; i.e., the metal fixing capacity was 99.95%. Copyright © 2009 Society of Chemical Industry
-
safe disposal of toxic chrome buffing dust generated from leather industries
Journal of Hazardous Materials, 2008Co-Authors: S Swarnalatha, T Srinivasulu, M Srimurali, G. SekaranAbstract:The high concentration of trivalent chromium along with organic/inorganic compounds in chrome buffing dust (CBD), the solid waste discharged from leather industries, causes severe groundwater contamination on land co-disposal and chronic air pollution during Thermal Incineration. In the present investigation, CBD was subjected to starved air Incineration (SAI) at 800 degrees C in a Thermal incinerator under different flow rates of oxygen to optimize the oxygen required to incinerate the organic compounds and simultaneously preventing the conversion of Cr(3+) to Cr(6+). The energy audit of SAI of buffing dust under the external supply of oxygen was carried out under different Incineration conditions. The bottom ash from SAI was effectively solidified/stabilized using Portland cement and fine aggregate. The solidified blocks were tested for unconfined compressive strength and heavy metal leaching. Unconfined compressive strength of the blocks was in the range of 120-180 kg/cm(2). The stabilization of chromium(III) in the cement gel matrix was confirmed using Scanning Electron Microscopy SEM, Electron Paramagnetic Resonance spectroscopy (EPR) and X-ray diffraction spectroscopy (XRD). Leachability studies through TCLP on solidified blocks were carried out to determine the degree of leaching of chromium and organic compounds (expressed as COD) under standard conditions.
G. Sekaran - One of the best experts on this subject based on the ideXlab platform.
-
efficient and safe disposal of chrome shavings discharged from leather industry using Thermal combustion
Journal of Chemical Technology & Biotechnology, 2009Co-Authors: Arumugam Ganesh Kumar, S Swarnalatha, Srinivasulu Tandaiah, G. SekaranAbstract:BACKGROUND: The high concentration of trivalent chromium along with organic/inorganic compounds in shavings (ChS) discharged from leather industries causes severe groundwater contamination in land disposal and chronic air pollution during Thermal Incineration. In the present investigation, ChS were subjected to Incineration at 800 °C in a Thermal incinerator under different volumes of oxygen to optimize the flow rate of oxygen to prevent the conversion of Cr3+ to Cr6+ (starved air combustion) followed by solidification and stabilization of calcined shavings. RESULTS: Net energy changes resulting from the combustion of shavings showed that the energy of the organic fractions is utilized to the maximum extent at an O2 flow rate of 3.0 g min−1. The ChS were effectively solidified/stabilized using Portland cement and fine aggregate. The unconfined compressive strength of the blocks was in the region of 160 kg cm−2. Leachability studies using a toxicity characterization of leachate procedure test (TCLP) on a solidified block were carried out to determine the percentage metal fixation and dissolved organic (as chemical oxygen demand) concentration in the leachate. CONCLUSION: The stabilization of chromium(III) in the cement gel matrix was confirmed using different instrumental techniques. The leaching characteristics through TCLP confirmed the effective stabilization of chromium; i.e., the metal fixing capacity was 99.95%. Copyright © 2009 Society of Chemical Industry
-
safe disposal of toxic chrome buffing dust generated from leather industries
Journal of Hazardous Materials, 2008Co-Authors: S Swarnalatha, T Srinivasulu, M Srimurali, G. SekaranAbstract:The high concentration of trivalent chromium along with organic/inorganic compounds in chrome buffing dust (CBD), the solid waste discharged from leather industries, causes severe groundwater contamination on land co-disposal and chronic air pollution during Thermal Incineration. In the present investigation, CBD was subjected to starved air Incineration (SAI) at 800 degrees C in a Thermal incinerator under different flow rates of oxygen to optimize the oxygen required to incinerate the organic compounds and simultaneously preventing the conversion of Cr(3+) to Cr(6+). The energy audit of SAI of buffing dust under the external supply of oxygen was carried out under different Incineration conditions. The bottom ash from SAI was effectively solidified/stabilized using Portland cement and fine aggregate. The solidified blocks were tested for unconfined compressive strength and heavy metal leaching. Unconfined compressive strength of the blocks was in the range of 120-180 kg/cm(2). The stabilization of chromium(III) in the cement gel matrix was confirmed using Scanning Electron Microscopy SEM, Electron Paramagnetic Resonance spectroscopy (EPR) and X-ray diffraction spectroscopy (XRD). Leachability studies through TCLP on solidified blocks were carried out to determine the degree of leaching of chromium and organic compounds (expressed as COD) under standard conditions.
Jan Baeyens - One of the best experts on this subject based on the ideXlab platform.
-
catalytic combustion of volatile organic compounds
Journal of Hazardous Materials, 2004Co-Authors: K Everaert, Jan BaeyensAbstract:Despite the success of adsorption and Thermal Incineration of (C)VOC emissions, there is still a need for research on techniques which are both economically more favorable and actually destroy the pollutants rather than merely remove them for recycling elsewhere in the biosphere. The catalytic destruction of (C)VOC to CO2, H2O and HCl/Cl2 appears very promising in this context and is the subject of the present paper. The experiments mainly investigate the catalytic combustion of eight target compounds, all of which are commonly encountered in (C)VOC emissions and/or act as precursors for the formation of PCDD/F. Available literature on the different catalysts active in the oxidation of (C)VOC is reviewed and the transition metal oxide complex V2O5-WO3/TiO2 appears most suitable for the current application. Different reactor geometries (e.g. fixed pellet beds, honeycombs, etc.) are also described. In this research a novel catalyst type is introduced, consisting of a V2O5-WO3/TiO2 coated metal fiber fleece. The conversion of (C)VOC by thermo-catalytic reactions is governed by both reaction kinetics and reaction equilibrium. Full conversion of all investigated VOC to CO2, Cl2, HCl and H2O is thermodynamically feasible within the range of experimental conditions used in this work (260-340 degrees C, feed concentrations 30-60 ppm). A first-order rate equation is proposed for the (C)VOC oxidation reactions. The apparent rate constant is a combination of reaction kinetics and mass transfer effects. The oxidation efficiencies were measured with various (C)VOC in the temperature range of 260-340 degrees C. Literature data for oxidation reactions in fixed beds and honeycomb reactors are included in the assessment. Mass transfer resistances are calculated and are generally negligible for fleece reactors and fixed pellet beds, but can be of importance for honeycomb monoliths. The experimental investigations demonstrate: (i) that the conversion of the hydrocarbons is independent of the oxygen concentration, corresponding to a zero-order dependency of the reaction rate; (ii) that the conversion of the hydrocarbons is a first-order reaction in the (C)VOC; (iii) that the oxidation of the (C)VOC proceeds to a higher extent with increasing temperature, with multiple chlorine substitution enhancing the reactivity; (iv) that the reaction rate constant follows an Arrhenius dependency. The reaction rate constant kr (s(-1)) and the activation energy E (kJ/mol) are determined from the experimental results. The activation energy is related to the characteristics of the (C)VOC under scrutiny and correlated in terms of the molecular weight. The kr-values are system-dependent and hence limited in design application to the specific VOC-catalyst combination being studied. To achieve system-independency, kr-values are transformed into an alternative kinetic constant K (m3/(m2u)) expressed per unit of catalyst surface and thus independent of the amount of catalyst present in the reactor. Largely different experimental data can be fitted in terms of this approach. Results are thereafter used to define the Arrhenius pre-exponential factor A*, itself expressed in terms of the activation entropy. Destruction efficiencies for any given reactor set-up can be predicted from E- and A*-correlations. The excellent comparison of predicted and measured destruction efficiencies for a group of chlorinated aromatics stresses the validity of the design approach. Since laboratory-scale experiments using PCDD/F are impossible, pilot and full-scale tests of PCDD/F oxidation undertaken in Flemish MSWIs and obtained from literature are reported. From the data it is clear that: (i) destruction efficiencies are normally excellent; (ii) the efficiencies increase with increasing operating temperature; (iii) the higher degree of chlorination does not markedly affect the destruction efficiency. Finally, all experimental findings are used in design recommendations for the catalytic oxidation of (C)VOC and PCDD/F. Predicted values of the a)VOC and PCDD/F. Predicted values of the acceptable space velocity correspond with the cited industrial values, thus stressing the validity of the design strategy and equations developed in the present paper.
Arumugam Ganesh Kumar - One of the best experts on this subject based on the ideXlab platform.
-
efficient and safe disposal of chrome shavings discharged from leather industry using Thermal combustion
Journal of Chemical Technology & Biotechnology, 2009Co-Authors: Arumugam Ganesh Kumar, S Swarnalatha, Srinivasulu Tandaiah, G. SekaranAbstract:BACKGROUND: The high concentration of trivalent chromium along with organic/inorganic compounds in shavings (ChS) discharged from leather industries causes severe groundwater contamination in land disposal and chronic air pollution during Thermal Incineration. In the present investigation, ChS were subjected to Incineration at 800 °C in a Thermal incinerator under different volumes of oxygen to optimize the flow rate of oxygen to prevent the conversion of Cr3+ to Cr6+ (starved air combustion) followed by solidification and stabilization of calcined shavings. RESULTS: Net energy changes resulting from the combustion of shavings showed that the energy of the organic fractions is utilized to the maximum extent at an O2 flow rate of 3.0 g min−1. The ChS were effectively solidified/stabilized using Portland cement and fine aggregate. The unconfined compressive strength of the blocks was in the region of 160 kg cm−2. Leachability studies using a toxicity characterization of leachate procedure test (TCLP) on a solidified block were carried out to determine the percentage metal fixation and dissolved organic (as chemical oxygen demand) concentration in the leachate. CONCLUSION: The stabilization of chromium(III) in the cement gel matrix was confirmed using different instrumental techniques. The leaching characteristics through TCLP confirmed the effective stabilization of chromium; i.e., the metal fixing capacity was 99.95%. Copyright © 2009 Society of Chemical Industry
K Everaert - One of the best experts on this subject based on the ideXlab platform.
-
catalytic combustion of volatile organic compounds
Journal of Hazardous Materials, 2004Co-Authors: K Everaert, Jan BaeyensAbstract:Despite the success of adsorption and Thermal Incineration of (C)VOC emissions, there is still a need for research on techniques which are both economically more favorable and actually destroy the pollutants rather than merely remove them for recycling elsewhere in the biosphere. The catalytic destruction of (C)VOC to CO2, H2O and HCl/Cl2 appears very promising in this context and is the subject of the present paper. The experiments mainly investigate the catalytic combustion of eight target compounds, all of which are commonly encountered in (C)VOC emissions and/or act as precursors for the formation of PCDD/F. Available literature on the different catalysts active in the oxidation of (C)VOC is reviewed and the transition metal oxide complex V2O5-WO3/TiO2 appears most suitable for the current application. Different reactor geometries (e.g. fixed pellet beds, honeycombs, etc.) are also described. In this research a novel catalyst type is introduced, consisting of a V2O5-WO3/TiO2 coated metal fiber fleece. The conversion of (C)VOC by thermo-catalytic reactions is governed by both reaction kinetics and reaction equilibrium. Full conversion of all investigated VOC to CO2, Cl2, HCl and H2O is thermodynamically feasible within the range of experimental conditions used in this work (260-340 degrees C, feed concentrations 30-60 ppm). A first-order rate equation is proposed for the (C)VOC oxidation reactions. The apparent rate constant is a combination of reaction kinetics and mass transfer effects. The oxidation efficiencies were measured with various (C)VOC in the temperature range of 260-340 degrees C. Literature data for oxidation reactions in fixed beds and honeycomb reactors are included in the assessment. Mass transfer resistances are calculated and are generally negligible for fleece reactors and fixed pellet beds, but can be of importance for honeycomb monoliths. The experimental investigations demonstrate: (i) that the conversion of the hydrocarbons is independent of the oxygen concentration, corresponding to a zero-order dependency of the reaction rate; (ii) that the conversion of the hydrocarbons is a first-order reaction in the (C)VOC; (iii) that the oxidation of the (C)VOC proceeds to a higher extent with increasing temperature, with multiple chlorine substitution enhancing the reactivity; (iv) that the reaction rate constant follows an Arrhenius dependency. The reaction rate constant kr (s(-1)) and the activation energy E (kJ/mol) are determined from the experimental results. The activation energy is related to the characteristics of the (C)VOC under scrutiny and correlated in terms of the molecular weight. The kr-values are system-dependent and hence limited in design application to the specific VOC-catalyst combination being studied. To achieve system-independency, kr-values are transformed into an alternative kinetic constant K (m3/(m2u)) expressed per unit of catalyst surface and thus independent of the amount of catalyst present in the reactor. Largely different experimental data can be fitted in terms of this approach. Results are thereafter used to define the Arrhenius pre-exponential factor A*, itself expressed in terms of the activation entropy. Destruction efficiencies for any given reactor set-up can be predicted from E- and A*-correlations. The excellent comparison of predicted and measured destruction efficiencies for a group of chlorinated aromatics stresses the validity of the design approach. Since laboratory-scale experiments using PCDD/F are impossible, pilot and full-scale tests of PCDD/F oxidation undertaken in Flemish MSWIs and obtained from literature are reported. From the data it is clear that: (i) destruction efficiencies are normally excellent; (ii) the efficiencies increase with increasing operating temperature; (iii) the higher degree of chlorination does not markedly affect the destruction efficiency. Finally, all experimental findings are used in design recommendations for the catalytic oxidation of (C)VOC and PCDD/F. Predicted values of the a)VOC and PCDD/F. Predicted values of the acceptable space velocity correspond with the cited industrial values, thus stressing the validity of the design strategy and equations developed in the present paper.