Papers by Alessandro Galia
Cathodic reduction of hexavalent chromium coupled with electricity generation achieved by reverse-electrodialysis processes using salinity gradients
Electrochimica Acta, Aug 1, 2014
ABSTRACT A new approach for the simultaneous generation of electric energy and the treatment of w... more ABSTRACT A new approach for the simultaneous generation of electric energy and the treatment of waters contaminated by recalcitrant pollutants using salinity gradients was proposed. Reverse electrodialysis allows for the generation of electric energy from salinity gradients. Indeed, the utilization of different salt concentrations gives a potential difference between the electrodes which allows the generation of electric energy by using suitable electrolytes and an external circuit. The simultaneous generation of electric energy and the treatment of waters contaminated by Cr(VI) was successfully achieved for the first time by reverse electrodialysis processes using salinity gradients and proper redox processes. The effect on the process of many operative parameters, such as the extent of the salinity gradient, the number of membrane pairs in the stack, the initial concentration of Cr(VI), the concentration of the supporting electrolyte and the flow rates of the solutions fed in the stack, was also investigated.
Selection of Redox Systems for Reverse Electrodialysis Processes
In reverse electrodialysis (RED) processes, electrical energy is directly extracted from chemical... more In reverse electrodialysis (RED) processes, electrical energy is directly extracted from chemical potential gradients arising from salinity differences, especially from sea and river water. In RED there are at least four complementary elements: (1) electrodes, where electron transfer reactions occur to allow the transformation of the charge carrier from ion to electron; (2) ion selective exchange membranes, which allow the selective transport of ions; (3) solvents, which make a continuum for ion transport; (4) electrolytes, i.e. the current carriers between cathode and anode. Studies on RED processes were mainly focused on membranes but also on several other aspects including electrolyte compositions and concentration, modeling and fluidodynamics. Less attention has been given to the selection of the electrodic material-redox couple system (for the purpose of this work defined electrode system) with very few exceptions , the most relevant being a very recent paper of Veerman and co-authors that carried out a very detailed comparative assessment of the suitability for RED of selected electrode systems described in literature [1]. On the other hand, the behavior of these systems was rarely experimentally investigated under operative conditions of interest for RED or electrodialysis (ED) applications. Electrode systems can be grouped in two categories: with or without opposite electrode reactions [1]. In the first case, when recirculation of electrode rinse solution is adopted, no net modification of the chemical composition occurs and the electrodic thermodynamic voltage is null. The opposite electrode reactions can involve reactive electrodes such as in the systems Cu-CuSO4 , Ag-AgCl, Zn-ZnCl2 or homogeneous redox couples with inert electrodes [1]. This work was devoted to the study of the utilization of iron based redox couples FeCl3/FeCl2, Hexacyanoferrate(III)/Hexacyanoferrate(II) and Fe(III)EDTA/Fe(II)EDTA on graphite and DSA electrodes for RED processes. To evaluate the advantages and disadvantages of these processes, numerous experiments were carried out in undivided and divided cells and in stack for the generation of energy. The Hexacyanoferrate(III)/Hexacyanoferrate(II) system was stable for long times in the absence of light and oxygen at high redox couple concentrations and low current densities both at compact graphite and DSA electrodes. Perfluorinated Nafion cationic membranes were found to be impermeable to the components of the redox couple. Fe(II)EDTA exhibited a limited electrochemical stability in long term electrolyses at all adopted operative conditions, that discourages the use of the Fe(III)EDTA/Fe(II)EDTA for RED applications. The system FeCl3/FeCl2 was, on the other hand, stable for long times at acidic pH at compact graphite electrodes. Selemion anionic membranes allowed to confine the redox couple in the electrode compartments with very slow passage of protons to the side compartment
Modeling Heterogeneous copolymerization of fluorinated monomers in scCO2
In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and reactio... more In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and reaction has emerged as a \u201cgreen\u201d alternative to replace both environmentally hazardous organic solvents and water, whose utilization involves the production of large amount of waste streams. Moreover, scCO2 is non-toxic, inexpensive, and often exhibits intense plasticizing effect on polymers. In this work, the copolymerization of fluorinated monomers in scCO2 is explored. Batch free-radical copolymerization reactions of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) have been carried out at temperature of 50 C and pressure of 400 bar using DEPDC as initiator and different amounts of stabilizer (FLK-7004A). Conversion, composition, molecular weight and particle size have been measured by gravimetry, 19F-NMR, gel permeation chromatography and electron microscopy, thus providing a comprehensive characterization of the product. In the case of VDF precipitation homopolymerization in scCO2, bimodal MWDs have been reported. Two different hypotheses regarding the phase behavior of the system have been proposed to explain such eterogeneity, the first invokes chain-transfer to polymer in an homogeneous reaction system, the second mass transport limitations of the radicals between supercritical and polymer phase in an heterogeneous reaction system. The experimental data here presented support the second scenario; namely, monomodal high-MWDs are obtained carrying out the reaction under stable dispersion conditions, thus favoring the radical transport from the continuous to the dispersed phase by increasing the interfacial area. Accordingly, a mathematical model accounting for two reaction loci (continuous and dispersed phases) as well as the interphase transport of radicals, has been developed and validated by comparison with the experimental results. Even though some parameter fitting was required, the final model prediction ability is satisfactory, especially in terms of copolymer composition and molecular weight distribution. Such agreement is believed to represent an effective confirmation of the presumed two loci reaction mechanism
Modeling Heterogeneous copolymerization in scCO2
Reduction of Carbon Dioxide to Formic Acid in Various Kinds of Electrochemical Devices
Polymer Synthesis in Supercritical Carbon Dioxide
Springer eBooks, 2003
... carbocation and the counterion alone or associated to a suitable Lewis base to increase ... T... more ... carbocation and the counterion alone or associated to a suitable Lewis base to increase ... This effort must be coupled with a more thorough understanding of the phase behaviour ... these considerations it seems reasonable to foresee that the sector of polymerisation in supercritical ...
Electrochemistry Communications, 2013
The electro-generation of H 2 O 2 and the abatement of the model organic pollutant Acid Orange 7 ... more The electro-generation of H 2 O 2 and the abatement of the model organic pollutant Acid Orange 7 (AO7) in water by an electro-Fenton process were performed both in a conventional undivided macro cell and, for the first time, in a microfluidic reactor. Under optimized operative conditions, the reduction of oxygen in the microdevice gave rise, using graphite cathode, to a concentration of H 2 O 2 of about 6 mM, one order of magnitude higher than that achieved in conventional cells. Similarly, when electro-Fenton was performed in the microfluidic reactor a dramatic increase of the abatement of COD was achieved with respect to that obtained in a conventional cell.
Electrochemical remediation of phenol contaminated kaolin under low-strength electric fields
Environmental Technology and Innovation, Nov 1, 2023
Cathodic reduction of hexavalent chromium coupled with electricity generation achieved by reverse-electrodialysis processes using salinity gradients
Electrochimica Acta, Aug 1, 2014
ABSTRACT A new approach for the simultaneous generation of electric energy and the treatment of w... more ABSTRACT A new approach for the simultaneous generation of electric energy and the treatment of waters contaminated by recalcitrant pollutants using salinity gradients was proposed. Reverse electrodialysis allows for the generation of electric energy from salinity gradients. Indeed, the utilization of different salt concentrations gives a potential difference between the electrodes which allows the generation of electric energy by using suitable electrolytes and an external circuit. The simultaneous generation of electric energy and the treatment of waters contaminated by Cr(VI) was successfully achieved for the first time by reverse electrodialysis processes using salinity gradients and proper redox processes. The effect on the process of many operative parameters, such as the extent of the salinity gradient, the number of membrane pairs in the stack, the initial concentration of Cr(VI), the concentration of the supporting electrolyte and the flow rates of the solutions fed in the stack, was also investigated.
Selection of Redox Systems for Reverse Electrodialysis Processes
In reverse electrodialysis (RED) processes, electrical energy is directly extracted from chemical... more In reverse electrodialysis (RED) processes, electrical energy is directly extracted from chemical potential gradients arising from salinity differences, especially from sea and river water. In RED there are at least four complementary elements: (1) electrodes, where electron transfer reactions occur to allow the transformation of the charge carrier from ion to electron; (2) ion selective exchange membranes, which allow the selective transport of ions; (3) solvents, which make a continuum for ion transport; (4) electrolytes, i.e. the current carriers between cathode and anode. Studies on RED processes were mainly focused on membranes but also on several other aspects including electrolyte compositions and concentration, modeling and fluidodynamics. Less attention has been given to the selection of the electrodic material-redox couple system (for the purpose of this work defined electrode system) with very few exceptions , the most relevant being a very recent paper of Veerman and co-authors that carried out a very detailed comparative assessment of the suitability for RED of selected electrode systems described in literature [1]. On the other hand, the behavior of these systems was rarely experimentally investigated under operative conditions of interest for RED or electrodialysis (ED) applications. Electrode systems can be grouped in two categories: with or without opposite electrode reactions [1]. In the first case, when recirculation of electrode rinse solution is adopted, no net modification of the chemical composition occurs and the electrodic thermodynamic voltage is null. The opposite electrode reactions can involve reactive electrodes such as in the systems Cu-CuSO4 , Ag-AgCl, Zn-ZnCl2 or homogeneous redox couples with inert electrodes [1]. This work was devoted to the study of the utilization of iron based redox couples FeCl3/FeCl2, Hexacyanoferrate(III)/Hexacyanoferrate(II) and Fe(III)EDTA/Fe(II)EDTA on graphite and DSA electrodes for RED processes. To evaluate the advantages and disadvantages of these processes, numerous experiments were carried out in undivided and divided cells and in stack for the generation of energy. The Hexacyanoferrate(III)/Hexacyanoferrate(II) system was stable for long times in the absence of light and oxygen at high redox couple concentrations and low current densities both at compact graphite and DSA electrodes. Perfluorinated Nafion cationic membranes were found to be impermeable to the components of the redox couple. Fe(II)EDTA exhibited a limited electrochemical stability in long term electrolyses at all adopted operative conditions, that discourages the use of the Fe(III)EDTA/Fe(II)EDTA for RED applications. The system FeCl3/FeCl2 was, on the other hand, stable for long times at acidic pH at compact graphite electrodes. Selemion anionic membranes allowed to confine the redox couple in the electrode compartments with very slow passage of protons to the side compartment
Modeling Heterogeneous copolymerization of fluorinated monomers in scCO2
In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and reactio... more In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and reaction has emerged as a \u201cgreen\u201d alternative to replace both environmentally hazardous organic solvents and water, whose utilization involves the production of large amount of waste streams. Moreover, scCO2 is non-toxic, inexpensive, and often exhibits intense plasticizing effect on polymers. In this work, the copolymerization of fluorinated monomers in scCO2 is explored. Batch free-radical copolymerization reactions of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) have been carried out at temperature of 50 C and pressure of 400 bar using DEPDC as initiator and different amounts of stabilizer (FLK-7004A). Conversion, composition, molecular weight and particle size have been measured by gravimetry, 19F-NMR, gel permeation chromatography and electron microscopy, thus providing a comprehensive characterization of the product. In the case of VDF precipitation homopolymerization in scCO2, bimodal MWDs have been reported. Two different hypotheses regarding the phase behavior of the system have been proposed to explain such eterogeneity, the first invokes chain-transfer to polymer in an homogeneous reaction system, the second mass transport limitations of the radicals between supercritical and polymer phase in an heterogeneous reaction system. The experimental data here presented support the second scenario; namely, monomodal high-MWDs are obtained carrying out the reaction under stable dispersion conditions, thus favoring the radical transport from the continuous to the dispersed phase by increasing the interfacial area. Accordingly, a mathematical model accounting for two reaction loci (continuous and dispersed phases) as well as the interphase transport of radicals, has been developed and validated by comparison with the experimental results. Even though some parameter fitting was required, the final model prediction ability is satisfactory, especially in terms of copolymer composition and molecular weight distribution. Such agreement is believed to represent an effective confirmation of the presumed two loci reaction mechanism
Electrocarboxylation of Benzyl Halides through Redox Catalysis on the Preparative Scale
Chemistry: A European Journal, Sep 25, 2006
The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogene... more The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid dimethyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/[CO2]bulk and [RX]bulk/[catalyst] ratios.
Modeling Heterogeneous copolymerization in scCO2
Reduction of Carbon Dioxide to Formic Acid in Various Kinds of Electrochemical Devices
Polymer Synthesis in Supercritical Carbon Dioxide
Springer eBooks, 2003
... carbocation and the counterion alone or associated to a suitable Lewis base to increase ... T... more ... carbocation and the counterion alone or associated to a suitable Lewis base to increase ... This effort must be coupled with a more thorough understanding of the phase behaviour ... these considerations it seems reasonable to foresee that the sector of polymerisation in supercritical ...
Electrochemistry Communications, 2013
The electro-generation of H 2 O 2 and the abatement of the model organic pollutant Acid Orange 7 ... more The electro-generation of H 2 O 2 and the abatement of the model organic pollutant Acid Orange 7 (AO7) in water by an electro-Fenton process were performed both in a conventional undivided macro cell and, for the first time, in a microfluidic reactor. Under optimized operative conditions, the reduction of oxygen in the microdevice gave rise, using graphite cathode, to a concentration of H 2 O 2 of about 6 mM, one order of magnitude higher than that achieved in conventional cells. Similarly, when electro-Fenton was performed in the microfluidic reactor a dramatic increase of the abatement of COD was achieved with respect to that obtained in a conventional cell.
Electroactivation of Transition Metal Redox Couples for the Carbonylation of Alcohols to Dialkylcarbonates
ABSTRACT
Electrochemical remediation of phenol contaminated kaolin under low-strength electric fields
Environmental Technology and Innovation, Nov 1, 2023
Electrocarboxylation of Benzyl Halides through Redox Catalysis on the Preparative Scale
Chemistry: A European Journal, Sep 25, 2006
The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogene... more The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid dimethyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/[CO2]bulk and [RX]bulk/[catalyst] ratios.
Electroactivation of Transition Metal Redox Couples for the Carbonylation of Alcohols to Dialkylcarbonates
ABSTRACT
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Papers by Alessandro Galia