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Piet N.l. Lens - One of the best experts on this subject based on the ideXlab platform.

  • NO Removal in Continuous BioDeNOx Reactors: Fe(II)EDTA2- Regeneration, Biomass Growth, and EDTA Degradation
    Biotechnology and bioengineering, 2006
    Co-Authors: Peter Van Der Maas, Paula Van Den Brink, Sudarno Utomo, Bram Klapwijk, Piet N.l. Lens
    Abstract:

    BioDeNOx is a novel technique for NOx removal from industrial flue gases. In principle, BioDeNOx is based on NO absorption into an aqueous Fe(II)EDTA2- solution combined with biological regeneration of that scrubber liquor in a bioreactor. The technical and economical feasibility of the BioDeNOx concept is strongly determined by high rate biological regeneration of the aqueous Fe(II)EDTA2- scrubber liquor and by EDTA degradation. This investigation deals with the Fe(II)EDTA2- regeneration capacity and EDTA degradation in a lab-scale BioDeNOx reactor (10-20 mM Fe(II)EDTA2-, pH 7.2 ± 0.2, 55°C), treating an artificial flue gas (1.5 m3/h) containing 60-155 ppm NO and 3.5-3.9% O2. The results obtained show a contradiction between the optimal redox state of the aqueous FeEDTA solution for NO absorption and the biological regeneration. A low redox potential (below -150 mV vs. Ag/AgCl) is needed to obtain a maximal NO removal efficiency from the gas phase via Fe(II)EDTA2- absorption. Fe(III)EDTA- reduction was found to be too slow to keep all FeEDTA in the reduced state. Stimulation of Fe(III)EDTA- reduction via periodical sulfide additions (2 mM spikes twice a week for the conditions applied in this study) was found to be necessary to regenerate the Fe(II)EDTA2- scrubber liquor and to achieve stable operation at redox potentials below -150 mV (pH 7.2 ± 0.2). However, redox potentials of below -200 mV should be avoided since sulfide accumulation is unwanted because it is toxic for NO reduction. Very low values for biomass growth rate and yield, respectively, 0.043/d and 0.009 mg protein per mg ethanol, were observed. This might be due to substrate limitations, that is the electron acceptors NO and presumably polysulfide, or to physiological stress conditions induced by the EDTA rich medium or by radicals formed in the scrubber upon the oxidation of Fe(II)EDTA2- by oxygen present in the flue gas. Radicals possibly also induce EDTA degradation, which occurs at a substantial rate: 2.1 (±0.1) mM/d under the conditions investigated

  • Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions.
    Nitric oxide : biology and chemistry, 2006
    Co-Authors: Isabella Manconi, Peter Van Der Maas, Piet N.l. Lens
    Abstract:

    Abstract Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2− (25 mM, pH 7.2, 55 °C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2− complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2− bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3–2.3 g VSS/l), sulfide (from 15 μM to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state.

Hatice Dogan Buzoglu - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Low–surface Tension EDTA Solutions on the Bond Strength of Resin-based Sealer to Young and Old Root Canal Dentin
    Journal of endodontics, 2017
    Co-Authors: Cigdem Dik Güzel, Emel Uzunoglu, Hatice Dogan Buzoglu
    Abstract:

    Abstract Introduction The purpose of this study was to evaluate the effect of low–surface tension EDTA solutions on the push-out bond strength of resin-based sealer to young and old root canal dentin. Methods Root canals from 64 (n = 32 age  60 years old) extracted, decoronized, single-rooted human teeth were prepared with ProTaper rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to size F4 using 3 mL 2.5% sodium hypochlorite (NaOCl) between each file. Each group was divided into 4 subgroups as follows: 3 mL EDTA, REDTA (17% EDTA + 0.84 g cetyltrimethylammonium bromide; Sigma-Aldrich, St Louis, MO), EDTA-T (17% EDTA + 1.25% sodium lauryl ether sulfate, Sigma-Aldrich), and saline as the control (n = 8). The final irrigation was completed with 3 mL saline after 3 mL NaOCl in the experimental groups and 3 mL saline in the control group. After root canal filling with gutta-percha (GP) cones/AH Plus sealer (Dentsply, Petropolis, RJ, Brazil), samples were stored at 37°C and 100% humidity for 2 weeks. One-millimeter-thick horizontal sections from the coronal and midthirds of each root were sliced, and push-out bond strength values were measured using a universal testing machine. Data were analyzed using 2-way analysis of variance followed by the Bonferroni test (P  Results EDTA-T, REDTA, and EDTA significantly increased the bond strength values of GP/AH Plus to the root canal dentin compared with saline in both young and old groups (P  Conclusions The bond strength values of GP/AH Plus could be altered depending on age and the type of EDTA compounds.

  • Effect of low-surface-tension EDTA solutions on the wettability of root canal dentin.
    Oral surgery oral medicine oral pathology oral radiology and endodontics, 2011
    Co-Authors: Zeliha Yilmaz, Hatice Dogan Buzoglu, Berna Basbag, Menemşe Gümüşderelioğlu
    Abstract:

    Objective This study was conducted to evaluate the effect of reducing the surface tension of ethylenediaminetetraacetic acid (EDTA) solutions on the wettability of root canal dentin. Study design Forty-two extracted teeth were sectioned at the crown, and the apical third and remaining mid-root portion was bisected longitudinally. The root halves were embedded in resin blocks. The experimental groups were treated with 17% EDTA, EDTA-T, and REDTA alone or followed by 2.5% NaOCl. Surface free energies of samples were calculated by measuring contact angles. Surface tension measurements of all solutions were performed with pendant drop method. Results The addition of surfactant to the EDTA solution significantly decreased the surface tension of solutions (P Conclusions The use of low-surface-tensioned EDTA compounds alone or in combination with NaOCl increased the wettability of root canal dentin.

Guohua Jing - One of the best experts on this subject based on the ideXlab platform.

  • Reduction of ethylenediaminetetraacetic acid iron(III) by Klebsiella sp. FD-3 immobilized on iron(II, III) oxide poly (styrene-glycidyl methacrylate) magnetic porous microspheres: effects of inorganic compounds and kinetic study of effective diffusio
    Bioresource Technology, 2014
    Co-Authors: Zuoming Zhou, Xiaoyan Wang, Tianming Lin, Guohua Jing
    Abstract:

    Fe3O4 poly (styrene-glycidyl methacrylate) magnetic porous microspheres (MPPMs) were introduced to immobilize Klebsiella sp. FD-3, an iron-reducing bacterium applied to reduce Fe(III)EDTA. The effects of potential inhibitors (S2−, SO32−, NO3−, NO2− and Fe(II)EDTA-NO) on Fe(III)EDTA reduction were investigated. S2− reacted with Fe(III)EDTA as an electron-shuttling compound and enhanced the reduction. But Fe(III)EDTA reduction was inhibited by SO32− and Fe(II)EDTA-NO due to their toxic to microorganisms. Low concentrations of NO3− and NO2− accelerated Fe(III)EDTA reduction, but high concentrations inhibited the reduction, whether by free or immobilized FD-3. The immobilized FD-3 performed better than freely-suspended style. The substrate mass transfer and diffusion kinetics in the porous microspheres were calculated. The value of Thiele modulus and effectiveness factors showed that the intraparticle diffusion was fairly small and neglected in this carrier. Fe(III)EDTA reduction fitted first-order model at low Fe(III)EDTA concentration, and changed to zero-order model at high concentrations.

  • Evaluation of Fe(III)EDTA and Fe(II)EDTA-NO reduction in a NOx scrubber solution by magnetic Fe3O4-chitosan microspheres immobilized microorganisms
    Biotechnology and Bioprocess Engineering, 2014
    Co-Authors: Zuoming Zhou, Xiaoyan Wang, Guohua Jing
    Abstract:

    A two-stage bioreduction system containing magnetic-microsphere-immobilized denitrifying bacteria and iron-reducing bacteria was developed for the regeneration of scrubbing solutions for NO x removal. In this process, a higher bioreduction rate and a better tolerance of inhibition of bacteria were achieved with immobilized bacteria than with free bacteria. This work focused on evaluation of the effects of the main components in the scrubbing solution on Fe(III)EDTA (EDTA: ethylenediaminetetraacetate) and Fe(II)EDTA-NO reduction, with an emphasis on mass transfer and the kinetic model of Fe(III)EDTA and Fe(II)EDTA-NO reduction by immobilized bacteria. It was found that Fe(II)EDTA-NO had a strong inhibiting effect, but Fe(II)EDTA had no effect, on Fe(III)EDTA reduction. Fe(II)EDTA accelerated Fe(II)EDTA-NO reduction, whereas Fe(III)EDTA had no effect. This showed that the use of the two stages of regeneration was necessary. Moreover, the effect of internal diffusion on Fe(III)EDTA and Fe(II)EDTANO reduction could be neglected, and the rate-limiting step was the bioreduction process. The reduction of Fe(III)EDTA and Fe(II)EDTA-NO using immobilized bacteria was described by a first-order kinetic model. Bioreduction can therefore be enhanced by increasing the cell density in the magnetic chitosan microspheres.

Peter Van Der Maas - One of the best experts on this subject based on the ideXlab platform.

  • NO Removal in Continuous BioDeNOx Reactors: Fe(II)EDTA2- Regeneration, Biomass Growth, and EDTA Degradation
    Biotechnology and bioengineering, 2006
    Co-Authors: Peter Van Der Maas, Paula Van Den Brink, Sudarno Utomo, Bram Klapwijk, Piet N.l. Lens
    Abstract:

    BioDeNOx is a novel technique for NOx removal from industrial flue gases. In principle, BioDeNOx is based on NO absorption into an aqueous Fe(II)EDTA2- solution combined with biological regeneration of that scrubber liquor in a bioreactor. The technical and economical feasibility of the BioDeNOx concept is strongly determined by high rate biological regeneration of the aqueous Fe(II)EDTA2- scrubber liquor and by EDTA degradation. This investigation deals with the Fe(II)EDTA2- regeneration capacity and EDTA degradation in a lab-scale BioDeNOx reactor (10-20 mM Fe(II)EDTA2-, pH 7.2 ± 0.2, 55°C), treating an artificial flue gas (1.5 m3/h) containing 60-155 ppm NO and 3.5-3.9% O2. The results obtained show a contradiction between the optimal redox state of the aqueous FeEDTA solution for NO absorption and the biological regeneration. A low redox potential (below -150 mV vs. Ag/AgCl) is needed to obtain a maximal NO removal efficiency from the gas phase via Fe(II)EDTA2- absorption. Fe(III)EDTA- reduction was found to be too slow to keep all FeEDTA in the reduced state. Stimulation of Fe(III)EDTA- reduction via periodical sulfide additions (2 mM spikes twice a week for the conditions applied in this study) was found to be necessary to regenerate the Fe(II)EDTA2- scrubber liquor and to achieve stable operation at redox potentials below -150 mV (pH 7.2 ± 0.2). However, redox potentials of below -200 mV should be avoided since sulfide accumulation is unwanted because it is toxic for NO reduction. Very low values for biomass growth rate and yield, respectively, 0.043/d and 0.009 mg protein per mg ethanol, were observed. This might be due to substrate limitations, that is the electron acceptors NO and presumably polysulfide, or to physiological stress conditions induced by the EDTA rich medium or by radicals formed in the scrubber upon the oxidation of Fe(II)EDTA2- by oxygen present in the flue gas. Radicals possibly also induce EDTA degradation, which occurs at a substantial rate: 2.1 (±0.1) mM/d under the conditions investigated

  • Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions.
    Nitric oxide : biology and chemistry, 2006
    Co-Authors: Isabella Manconi, Peter Van Der Maas, Piet N.l. Lens
    Abstract:

    Abstract Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2− (25 mM, pH 7.2, 55 °C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2− complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2− bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3–2.3 g VSS/l), sulfide (from 15 μM to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state.

Jiti Zhou - One of the best experts on this subject based on the ideXlab platform.

  • reduction of fe ii edta no using paracoccus denitrificans and changes of fe ii edta in the system
    Journal of Chemical Technology & Biotechnology, 2013
    Co-Authors: Yu Zhang, Mingxiang Chen, Xiyang Dong, Jiti Zhou
    Abstract:

    BACKGROUND: In the BioDeNOX technology for NOX removal from flue gas, bioreduction of Fe(II)EDTA-NO and Fe(III)EDTA are core processes. In this study, a newly isolated strain, Paracoccus denitrificans, was used to reduce Fe(II)EDTA-NO with glucose and Fe(II)EDTA as donor electrons. To better understand the change law of Fe(II)EDTA, the process of Fe(II)EDTA-NO reduction by P. denitrificans with glucose and Fe(II)EDTA as electron donors was investigated, and the factors that might affect Fe(II)EDTA concentration were studied. RESULTS: For the bioreduction process of Fe(II)EDTA-NO, P. denitrificans could use glucose and Fe(II)EDTA as electron donors. At different stages, primary electron donors were different, thereby affecting the concentration of Fe(II)EDTA in the system. It was also proved that this strain not only reduced Fe(III)EDTA with glucose as the electron donor but also secreted several substances that reacted with Fe(III)EDTA, resulting in increased Fe(II)EDTA concentration in the solution. CONCLUSIONS: This work has shown that P. denitrificans can reduce Fe(II)EDTA-NO and Fe(III)EDTA simultaneously to regenerate NOX absorption solution. © 2012 Society of Chemical Industry