Documents disponibles écrits par cet auteur

Electrokinetic delivery and activation of persulfate for oxidation of PCBs in clayey soils / Yeliz Yukselen-Aksoy in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 175-184 Titre : Electrokinetic delivery and activation of persulfate for oxidation of PCBs in clayey soils Type de document : texte imprimé Auteurs : Yeliz Yukselen-Aksoy, Auteur ; Krishna R. Reddy, Auteur Année de publication : 2013 Article en page(s) : pp. 175-184 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : electrokinetic  remediation;  soil  remediation;  persulfate  oxidation;  advanced  oxidation  process;  polychlorobiphenyls Résumé : Contamination of soils by polychlorobiphenyls (PCBs) is of environmental concern because of their toxicity, persistence, hydrophobic nature, and slow biodegradation potential. Among the PCB remedial technologies, direct oxidation by persulfate is considered to have great potential to be both simple and rapid. However, to produce faster reaction rates, persulfate is often activated using heat, metal chelates, hydrogen peroxide, or high pH. Furthermore, delivery of persulfate in low permeability clayey soils is difficult. Integrating electrokinetic remediation with persulfate has the potential to overcome such difficulties because the applied electric potential can facilitate the delivery of persulfate in low permeability soils as well as activate oxidizing radicals and simultaneously induce oxidative/reductive reactions directly in the soil. This study investigates the potential for in situ oxidation of PCBs in low permeability soils using persulfate as an oxidant and also evaluates the benefits of integrating oxidation with electrokinetic remediation. Several series of laboratory batch and bench-scale electrokinetic experiments were conducted using kaolin, a representative clayey soil, spiked with 50 mg/kg of 2,2′,3,5′ tetrachlorobiphenyl (PCB 44), a representative PCB. Persulfate oxidation activators [elevated temperature (45°C) and high pH (at the cathode)] were investigated to maximize the PCB degradation. In addition, the effect of oxidant dosage on PCB degradation was investigated. The electrokinetically enhanced temperature-only activated persulfate oxidation test resulted in better PCB 44 remediation (77.9%) than the temperature and high-pH activated persulfate oxidation (76.2%) in a 7-day period. The optimal dosage for effective remediation was 30% Na-persulfate (76.2%) because a 20% concentration of the oxidant yielded a lower rate of degradation (55.2%) of PCB 44. The results are encouraging for the use of electrokinetically enhanced persulfate oxidation for the effective remediation of PCBs in soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000744 [article] Electrokinetic delivery and activation of persulfate for oxidation of PCBs in clayey soils [texte imprimé] / Yeliz Yukselen-Aksoy, Auteur ; Krishna R. Reddy, Auteur . - 2013 . - pp. 175-184. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 175-184 Mots-clés : electrokinetic  remediation;  soil  remediation;  persulfate  oxidation;  advanced  oxidation  process;  polychlorobiphenyls Résumé : Contamination of soils by polychlorobiphenyls (PCBs) is of environmental concern because of their toxicity, persistence, hydrophobic nature, and slow biodegradation potential. Among the PCB remedial technologies, direct oxidation by persulfate is considered to have great potential to be both simple and rapid. However, to produce faster reaction rates, persulfate is often activated using heat, metal chelates, hydrogen peroxide, or high pH. Furthermore, delivery of persulfate in low permeability clayey soils is difficult. Integrating electrokinetic remediation with persulfate has the potential to overcome such difficulties because the applied electric potential can facilitate the delivery of persulfate in low permeability soils as well as activate oxidizing radicals and simultaneously induce oxidative/reductive reactions directly in the soil. This study investigates the potential for in situ oxidation of PCBs in low permeability soils using persulfate as an oxidant and also evaluates the benefits of integrating oxidation with electrokinetic remediation. Several series of laboratory batch and bench-scale electrokinetic experiments were conducted using kaolin, a representative clayey soil, spiked with 50 mg/kg of 2,2′,3,5′ tetrachlorobiphenyl (PCB 44), a representative PCB. Persulfate oxidation activators [elevated temperature (45°C) and high pH (at the cathode)] were investigated to maximize the PCB degradation. In addition, the effect of oxidant dosage on PCB degradation was investigated. The electrokinetically enhanced temperature-only activated persulfate oxidation test resulted in better PCB 44 remediation (77.9%) than the temperature and high-pH activated persulfate oxidation (76.2%) in a 7-day period. The optimal dosage for effective remediation was 30% Na-persulfate (76.2%) because a 20% concentration of the oxidant yielded a lower rate of degradation (55.2%) of PCB 44. The results are encouraging for the use of electrokinetically enhanced persulfate oxidation for the effective remediation of PCBs in soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000744

Electrokinetic remediation modeling incorporating geochemical effects / Ashraf Z. Al-Hamdan in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°1 (Janvier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°1 (Janvier 2008) . - pp. 91–105 Titre : Electrokinetic remediation modeling incorporating geochemical effects Type de document : texte imprimé Auteurs : Ashraf Z. Al-Hamdan, Auteur ; Krishna R. Reddy, Auteur Année de publication : 2008 Article en page(s) : pp. 91–105 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Electrokinetics  PH  Heavy  metals  Kaolin  Adsorption  Remedial  action Résumé : Electrokinetic remediation technology is one of the developing technologies that offers great promise for the cleanup of soils contaminated with heavy metals. However, the performance of an electrokinetic remediation system depends on the interaction of a complex set of interrelated system variables and parameters. Many of these interactions were addressed in this study by incorporating geochemical reactions into electrokinetic remediation modeling. A one-dimensional transport model was developed to predict the transport and speciation of heavy metals (chromium, nickel, and cadmium) in soil during electrokinetic remediation as a function of time and space. The model incorporates: (1) pH-dependent adsorption of contaminants to the soil surface; (2) sensitivity of soil surface potential and electroosmotic flow to the pore water properties; and (3) synergistic effects of multiple chemical species on electrokinetic remediation. The model considers that: (1) Electrical potential in the soil is constant with time; (2) surface complexation reactions are applicable in the highly concentrated clay suspensions; (3) the effect of temperature is negligible; and (4) dissolution of soil constituents is negligible. The predicted pH profiles, electroosmotic flow, and transport of chromium, nickel, and cadmium in kaolin soil during electrokinetic remediation were found to reasonably agree with the bench-scale electrokinetic experimental results. The predicted contaminant speciation and distribution (aqueous, adsorbed, and precipitated) allow for an understanding of the transport processes and chemical reactions that control electrokinetic remediation. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A1%2891 [...] [article] Electrokinetic remediation modeling incorporating geochemical effects [texte imprimé] / Ashraf Z. Al-Hamdan, Auteur ; Krishna R. Reddy, Auteur . - 2008 . - pp. 91–105. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°1 (Janvier 2008) . - pp. 91–105 Mots-clés : Electrokinetics  PH  Heavy  metals  Kaolin  Adsorption  Remedial  action Résumé : Electrokinetic remediation technology is one of the developing technologies that offers great promise for the cleanup of soils contaminated with heavy metals. However, the performance of an electrokinetic remediation system depends on the interaction of a complex set of interrelated system variables and parameters. Many of these interactions were addressed in this study by incorporating geochemical reactions into electrokinetic remediation modeling. A one-dimensional transport model was developed to predict the transport and speciation of heavy metals (chromium, nickel, and cadmium) in soil during electrokinetic remediation as a function of time and space. The model incorporates: (1) pH-dependent adsorption of contaminants to the soil surface; (2) sensitivity of soil surface potential and electroosmotic flow to the pore water properties; and (3) synergistic effects of multiple chemical species on electrokinetic remediation. The model considers that: (1) Electrical potential in the soil is constant with time; (2) surface complexation reactions are applicable in the highly concentrated clay suspensions; (3) the effect of temperature is negligible; and (4) dissolution of soil constituents is negligible. The predicted pH profiles, electroosmotic flow, and transport of chromium, nickel, and cadmium in kaolin soil during electrokinetic remediation were found to reasonably agree with the bench-scale electrokinetic experimental results. The predicted contaminant speciation and distribution (aqueous, adsorbed, and precipitated) allow for an understanding of the transport processes and chemical reactions that control electrokinetic remediation. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A1%2891 [...]

Fenton-like oxidation of polycyclic aromatic hydrocarbons in soils using electrokinetics / Krishna R. Reddy in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 10 (Octobre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1429–1439 Titre : Fenton-like oxidation of polycyclic aromatic hydrocarbons in soils using electrokinetics Type de document : texte imprimé Auteurs : Krishna R. Reddy, Auteur ; Kalyan S. Chandhuri, Auteur Année de publication : 2009 Article en page(s) : pp. 1429–1439 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : ElectrokineticsHydrocarbonsSoil  pollutionClaysRemediationOrganic  compoundsOxidation Résumé : An integrated electrochemical oxidation process that utilizes electrokinetics (EK) to deliver the oxidant (5–10% hydrogen peroxide, H2O2 ) and chelant [40 mM of ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA)] or iron chelate (1.4 mM Fe-EDTA or Fe-DTPA) to oxidize polycyclic aromatic hydrocarbons (PAHs) in soils was investigated. Batch and bench-scale EK experiments were conducted using: (a) kaolin, a low permeability clayey soil, spiked with phenanthrene at 500 mg/kg, and (b) former manufactured gas plant (MGP) soil, a high buffering silty soil, contaminated by a variety of PAHs (1493 mg/kg). Batch experiments showed that chelant solutions dissolve native iron minerals to form soluble Fe-chelates that remain available even at higher pH conditions of soil for the Fenton-like oxidation of the PAHs. In EK experiments, a 5–10% H2O2 solution was delivered from the anode and a chelant solution or iron-chelate was delivered from the cathode. Preflushing of soil with 5% ethanol and ferrous sulfate (1.4 mM) prior to oxidant delivery was also investigated. An electric potential of 2 VDC/cm was applied in all tests to induce electroosmotic flow for 5–8 days for kaolin and 25 days for the MGP field soil. In the absence of any chelating agent, phenanthrene oxidation was catalyzed by native iron present in kaolin soil, and 49.8–82.3% of phenanthrene was oxidized by increasing H2O2 concentration from 5–10%. At 5% H2O2 concentration, phenanthrene oxidation was not increased by using 40 mM EDTA, 40 mM DTPA or 1.4 mM Fe-DTPA, but it increased to 70% using 1.4 mM Fe-EDTA. Maximum phenanthrene oxidation (90.5%) was observed by 5% ethanol preflushing and then treating with 5% H2O2 at the anode and 1.4 mM Fe-EDTA at the cathode. However, preflushing with 1.4 mM ferrous sulfate did not improve phenanthrene oxidation. The results with the MGP field soil indicated that delivery of 5% H2O2 alone resulted in oxidation of 39.8% of total PAHs (especially 2- and 3-ring PAHs). The use of EDTA and Fe-EDTA did not increase PAHs oxidation in this soil. Overall, the results reveal that an optimized in situ combined technology of EK and Fenton-like process has the potential to oxidize PAHs in low permeability and/or high buffering soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000109 [article] Fenton-like oxidation of polycyclic aromatic hydrocarbons in soils using electrokinetics [texte imprimé] / Krishna R. Reddy, Auteur ; Kalyan S. Chandhuri, Auteur . - 2009 . - pp. 1429–1439. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1429–1439 Mots-clés : ElectrokineticsHydrocarbonsSoil  pollutionClaysRemediationOrganic  compoundsOxidation Résumé : An integrated electrochemical oxidation process that utilizes electrokinetics (EK) to deliver the oxidant (5–10% hydrogen peroxide, H2O2 ) and chelant [40 mM of ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA)] or iron chelate (1.4 mM Fe-EDTA or Fe-DTPA) to oxidize polycyclic aromatic hydrocarbons (PAHs) in soils was investigated. Batch and bench-scale EK experiments were conducted using: (a) kaolin, a low permeability clayey soil, spiked with phenanthrene at 500 mg/kg, and (b) former manufactured gas plant (MGP) soil, a high buffering silty soil, contaminated by a variety of PAHs (1493 mg/kg). Batch experiments showed that chelant solutions dissolve native iron minerals to form soluble Fe-chelates that remain available even at higher pH conditions of soil for the Fenton-like oxidation of the PAHs. In EK experiments, a 5–10% H2O2 solution was delivered from the anode and a chelant solution or iron-chelate was delivered from the cathode. Preflushing of soil with 5% ethanol and ferrous sulfate (1.4 mM) prior to oxidant delivery was also investigated. An electric potential of 2 VDC/cm was applied in all tests to induce electroosmotic flow for 5–8 days for kaolin and 25 days for the MGP field soil. In the absence of any chelating agent, phenanthrene oxidation was catalyzed by native iron present in kaolin soil, and 49.8–82.3% of phenanthrene was oxidized by increasing H2O2 concentration from 5–10%. At 5% H2O2 concentration, phenanthrene oxidation was not increased by using 40 mM EDTA, 40 mM DTPA or 1.4 mM Fe-DTPA, but it increased to 70% using 1.4 mM Fe-EDTA. Maximum phenanthrene oxidation (90.5%) was observed by 5% ethanol preflushing and then treating with 5% H2O2 at the anode and 1.4 mM Fe-EDTA at the cathode. However, preflushing with 1.4 mM ferrous sulfate did not improve phenanthrene oxidation. The results with the MGP field soil indicated that delivery of 5% H2O2 alone resulted in oxidation of 39.8% of total PAHs (especially 2- and 3-ring PAHs). The use of EDTA and Fe-EDTA did not increase PAHs oxidation in this soil. Overall, the results reveal that an optimized in situ combined technology of EK and Fenton-like process has the potential to oxidize PAHs in low permeability and/or high buffering soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000109