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Rajender S Varma - One of the best experts on this subject based on the ideXlab platform.

  • Protocol encompassing ultrasound/Fe3O4 nanoparticles/persulfate for the removal of tetracycline antibiotics from aqueous environments
    Clean Technologies and Environmental Policy, 2019
    Co-Authors: Mahammad Malakotian, Pouria Karimi, Nima Firouzeh, Seyedeh Nastaran Asadzadeh, Mehrdad Khatami, Mohammad Ahmadian, Mohammad Reza Heidari, Rajender S Varma
    Abstract:

    The presence of residual antibiotics in the environment is one of the major global concerns, and it is imperative to control their discharge in water bodies. The present study used a combination of Fe3O4 nanoparticles/persulfate in conjunction with ultrasound to address this problem; the influence of effective parameters in the remediation process, persulfate concentration, nanoparticle concentrations, initial antibiotic concentration, contact time and pH was investigated. The highest removal rate of tetracycline antibiotic was observed at pH 10, the amount of magnetic nanoparticles being (0.3 g/L), with persulfate concentration at 4 mM for the removal of antibiotic concentration at 10 mg/L; TC and COD removal efficiency is 92.99 and 79.85%, respectively. The deployment of sonocatalytic process, along with the use of magnetite nanoparticles and Persulfates as oxidizing agents, appears to be an effective means for decreasing the high-level tetracycline concentration in water.Graphic abstract

  • Protocol encompassing ultrasound/Fe_3O_4 nanoparticles/persulfate for the removal of tetracycline antibiotics from aqueous environments
    Clean Technologies and Environmental Policy, 2019
    Co-Authors: Mahammad Malakotian, Pouria Karimi, Nima Firouzeh, Seyedeh Nastaran Asadzadeh, Mehrdad Khatami, Mohammad Ahmadian, Mohammad Reza Heidari, Rajender S Varma
    Abstract:

    The presence of residual antibiotics in the environment is one of the major global concerns, and it is imperative to control their discharge in water bodies. The present study used a combination of Fe_3O_4 nanoparticles/persulfate in conjunction with ultrasound to address this problem; the influence of effective parameters in the remediation process, persulfate concentration, nanoparticle concentrations, initial antibiotic concentration, contact time and pH was investigated. The highest removal rate of tetracycline antibiotic was observed at pH 10, the amount of magnetic nanoparticles being (0.3 g/L), with persulfate concentration at 4 mM for the removal of antibiotic concentration at 10 mg/L; TC and COD removal efficiency is 92.99 and 79.85%, respectively. The deployment of sonocatalytic process, along with the use of magnetite nanoparticles and Persulfates as oxidizing agents, appears to be an effective means for decreasing the high-level tetracycline concentration in water. Graphic abstract

Chenju Liang - One of the best experts on this subject based on the ideXlab platform.

  • Treatment of Trichloroethylene by Adsorption and Persulfate Oxidation in Batch Studies
    Industrial & Engineering Chemistry Research, 2009
    Co-Authors: Chenju Liang, Ya-ting Lin, Wu-hang Shih
    Abstract:

    For remediation of trichloroethylene (TCE) contaminated groundwater, activated carbon (AC) has been used to adsorb and reduce the TCE concentration and to manage contaminant migration. Additionally, AC may also act as an activator of the electron-transfer mediator in activating persulfate anion (S2O82−) to generate sulfate radical (SO4−·) for contaminant destruction. The objective of the present research was to examine the combined use of AC and persulfate to treat TCE. The degradation of persulfate in the presence of AC follows a first-order kinetic behavior, and the faster persulfate degradation is observed when elevated AC dosage is used. Higher initial persulfate concentration results in a decrease of the persulfate degradation rate. Upon persulfate oxidation, the AC surface properties are altered including: an increase in acidity of surface concentration, a decrease in pHzpc, and a slight decrease in the surface area. The results of a study of adsorption kinetics and isotherms suggest that the adsorp...

  • ph dependence of persulfate activation by edta fe iii for degradation of trichloroethylene
    Journal of Contaminant Hydrology, 2009
    Co-Authors: Chenju Liang, Chingping Liang, Chichin Chen
    Abstract:

    Abstract The ability of free ferrous ion activated persulfate (S 2 O 8 2− ) to generate sulfate radicals (SO 4 − ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4 − with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+ . This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2 O 8 2− and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

  • pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene.
    Journal of Contaminant Hydrology, 2009
    Co-Authors: Chenju Liang, Chingping Liang, Chichin Chen
    Abstract:

    Abstract The ability of free ferrous ion activated persulfate (S 2 O 8 2− ) to generate sulfate radicals (SO 4 − ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4 − with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+ . This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2 O 8 2− and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

  • A rapid spectrophotometric determination of persulfate anion in ISCO
    Chemosphere, 2008
    Co-Authors: Chenju Liang, Chiu-fen Huang, Nihar Mohanty, Rama Mohan Kurakalva
    Abstract:

    Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site.

  • Trichloroethylene Degradation by Zero Valent Iron Activated Persulfate Oxidation
    Environmental Engineering Science, 2008
    Co-Authors: Chenju Liang, Ming-chun Lai
    Abstract:

    The present study describes the use of zero valent iron (Fe0 ) as a source for ferrous ion activated persulfate (PS) oxidation of trichloroethylene (TCE). The experimental results indicated that in the absence of TCE there was a lag time for persulfate decomposition when the reaction was activated by Fe0 . An initial pH drop in the Fe0 /PS system to acidic conditions was accompanied by the persulfate decomposition and a decrease in oxidation-reduction potential (ORP) values. Furthermore, in the TCE/Fe0 /PS system, the rapid TCE degradation was accompanied by the rapid persulfate decomposition and chloride ion formation as evidence of TCE mineralization. SEM images of Fe0 before and after persulfate oxidation exhibited significant corrosions of Fe0 . Acicular aggregate formation in the absence of TCE and coarse aggregate formation in the presence of TCE were observed. Moreover, the XRD spectrum revealed the formation of magnetite over the surface of Fe0 after contact with persulfate. Thus, Fe0 activated pe...

Pei C. Chiu - One of the best experts on this subject based on the ideXlab platform.

  • degradation of 2 4 dinitrotoluene by persulfate activated with zero valent iron
    Science of The Total Environment, 2010
    Co-Authors: Seung-gu Kang, Pei C. Chiu
    Abstract:

    The oxidation of 2,4-dinitrotoluene (DNT) by persulfate (S(2)O(8)(2-)) activated with zero-valent iron (Fe(o)) was studied through a series of batch experiments. The mechanism for Fe(o) activation was investigated by comparing with Fe(2+), and the effects of persulfate-to-iron ratio and pre-reduction on DNT oxidation were examined. DNT was stable in the presence of persulfate and transformed only when Fe(o) was added. Most DNT was degraded oxidatively by Fe(o)-activated persulfate, whereas direct reduction of DNT by Fe(o) was unimportant. The rate of DNT degradation increased with higher Fe(o) dose, presumably due to increasing activation of persulfate by Fe(o) and Fe(2+). In contrast to the Fe(o)-persulfate system, where complete oxidation DNT was achieved, only persulfate than DNT, suggesting that converting the nitro groups of NACs to amino groups prior to oxidation can greatly enhance their oxidation. This suggests that a sequential Fe(o) reduction-persulfate oxidation process may be an effective strategy to promote NAC degradation.

  • Degradation of 2,4-dinitrotoluene by persulfate activated with zero-valent iron.
    The Science of the total environment, 2010
    Co-Authors: Seung-gu Kang, Pei C. Chiu
    Abstract:

    The oxidation of 2,4-dinitrotoluene (DNT) by persulfate (S(2)O(8)(2-)) activated with zero-valent iron (Fe(o)) was studied through a series of batch experiments. The mechanism for Fe(o) activation was investigated by comparing with Fe(2+), and the effects of persulfate-to-iron ratio and pre-reduction on DNT oxidation were examined. DNT was stable in the presence of persulfate and transformed only when Fe(o) was added. Most DNT was degraded oxidatively by Fe(o)-activated persulfate, whereas direct reduction of DNT by Fe(o) was unimportant. The rate of DNT degradation increased with higher Fe(o) dose, presumably due to increasing activation of persulfate by Fe(o) and Fe(2+). In contrast to the Fe(o)-persulfate system, where complete oxidation DNT was achieved, only

Chichin Chen - One of the best experts on this subject based on the ideXlab platform.

  • ph dependence of persulfate activation by edta fe iii for degradation of trichloroethylene
    Journal of Contaminant Hydrology, 2009
    Co-Authors: Chenju Liang, Chingping Liang, Chichin Chen
    Abstract:

    Abstract The ability of free ferrous ion activated persulfate (S 2 O 8 2− ) to generate sulfate radicals (SO 4 − ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4 − with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+ . This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2 O 8 2− and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

  • pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene.
    Journal of Contaminant Hydrology, 2009
    Co-Authors: Chenju Liang, Chingping Liang, Chichin Chen
    Abstract:

    Abstract The ability of free ferrous ion activated persulfate (S 2 O 8 2− ) to generate sulfate radicals (SO 4 − ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4 − with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+ . This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2 O 8 2− and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

Mahammad Malakotian - One of the best experts on this subject based on the ideXlab platform.

  • Protocol encompassing ultrasound/Fe3O4 nanoparticles/persulfate for the removal of tetracycline antibiotics from aqueous environments
    Clean Technologies and Environmental Policy, 2019
    Co-Authors: Mahammad Malakotian, Pouria Karimi, Nima Firouzeh, Seyedeh Nastaran Asadzadeh, Mehrdad Khatami, Mohammad Ahmadian, Mohammad Reza Heidari, Rajender S Varma
    Abstract:

    The presence of residual antibiotics in the environment is one of the major global concerns, and it is imperative to control their discharge in water bodies. The present study used a combination of Fe3O4 nanoparticles/persulfate in conjunction with ultrasound to address this problem; the influence of effective parameters in the remediation process, persulfate concentration, nanoparticle concentrations, initial antibiotic concentration, contact time and pH was investigated. The highest removal rate of tetracycline antibiotic was observed at pH 10, the amount of magnetic nanoparticles being (0.3 g/L), with persulfate concentration at 4 mM for the removal of antibiotic concentration at 10 mg/L; TC and COD removal efficiency is 92.99 and 79.85%, respectively. The deployment of sonocatalytic process, along with the use of magnetite nanoparticles and Persulfates as oxidizing agents, appears to be an effective means for decreasing the high-level tetracycline concentration in water.Graphic abstract

  • Protocol encompassing ultrasound/Fe_3O_4 nanoparticles/persulfate for the removal of tetracycline antibiotics from aqueous environments
    Clean Technologies and Environmental Policy, 2019
    Co-Authors: Mahammad Malakotian, Pouria Karimi, Nima Firouzeh, Seyedeh Nastaran Asadzadeh, Mehrdad Khatami, Mohammad Ahmadian, Mohammad Reza Heidari, Rajender S Varma
    Abstract:

    The presence of residual antibiotics in the environment is one of the major global concerns, and it is imperative to control their discharge in water bodies. The present study used a combination of Fe_3O_4 nanoparticles/persulfate in conjunction with ultrasound to address this problem; the influence of effective parameters in the remediation process, persulfate concentration, nanoparticle concentrations, initial antibiotic concentration, contact time and pH was investigated. The highest removal rate of tetracycline antibiotic was observed at pH 10, the amount of magnetic nanoparticles being (0.3 g/L), with persulfate concentration at 4 mM for the removal of antibiotic concentration at 10 mg/L; TC and COD removal efficiency is 92.99 and 79.85%, respectively. The deployment of sonocatalytic process, along with the use of magnetite nanoparticles and Persulfates as oxidizing agents, appears to be an effective means for decreasing the high-level tetracycline concentration in water. Graphic abstract