Fe-EDTA Solution Research Articles

Oxidation-complexation removal of nitric oxide by anatase titanium dioxide with exposed (0 0 1) facets ultraviolet-induced ferrous ethylenediaminetetraacetate

Ferrous ethylenediaminetetraacetate (Fe(II)EDTA) accompanied by regeneration is thought to be a very efficient method to remove nitric oxide (NO) from flue gas. However, Fe(II)EDTA regeneration requires a large amount of regenerant consumption. For this purpose, anatase titanium dioxide with exposed (001) facets by fluorination (nF-TiO2) was synthesized and combined with Fe(II)EDTA solution for NO removal with ultraviolet light (UV). The result showed that 5F-TiO2 with approximately 30 % (001) facets exposed can significantly promote NO removal of Fe(II)EDTA under UV irradiation, with an average removal efficiency of up to 94.83 % over a 60-minute period. The mechanism study indicated that the excellent removal performance of 5F-TiO2 was mainly because the moderate co-exposure of its (001) and (101) facets could greatly suppress the electron hole recombination rate, accelerate the Fe(Ⅱ)EDTA/Fe(III)EDTA cycle, and form catalytic oxidation-complexation synergism denitrification. Under this synergistic effect, NO from simulated flue gas was mainly transformed to NO3–, NO2–, NH4+, N2, and N2O. Subsequently, NO removal performance using UV/Fe(Ⅱ)EDTA/5F-TiO2 under different parameters demonstrated that appropriate oxygen concentration (3 vol%), suitable 5F-TiO2 mass (0.5 g), low temperature (30 ℃), and weak acidic environment (pH = 4) were favorable for NO removal. The kinetics demonstrated that NO removal by the UV/Fe(Ⅱ)EDTA/5F-TiO2 system was a pseudo-first-order process. Finally, UV/Fe(II)EDTA/5F-TiO2 denitrification technology shows great potential in practical applications. This work offers a new route for the greenandlow-costapplication of Fe(Ⅱ)EDTA denitrification in flue gas treatment.

Performance, kinetics and mechanism of Fe(II)EDTA regeneration with surface-fluorinated anatase TiO2 with exposed (001) facets

Fe(II)EDTA regeneration mainly referring to Fe(III)EDTA and Fe(Ⅱ)EDTA-NO reduction has a very remarkable significance for NO removal using Fe(II)EDTA solution. Here, surface-fluorinated anatase TiO2 nanosheets with exposed (001) facets (F-TiO2) was prepared and firstly served for Fe(II)EDTA regeneration with ultraviolet light. The performance and kinetics of Fe(II)EDTA regeneration had been investigated under different F-TiO2 dose, varied pH, and diverse temperatures, in which Fe(III)EDTA and Fe(II)EDTA-NO reduction rate raised and then decreased under pH increasing or F-TiO2 dose rise. High temperature was conducive to Fe(II)EDTA regeneration. Fe(III)EDTA and Fe(II)EDTA-NO reduction presented first order reaction. Moreover, the F-TiO2 still maintained an excellent reduction efficiency after three recycle. Mechanism study showed that excellent Fe(II)EDTA regeneration ability could be partly explained by the high separation efficiency of photogenerated electrons and holes of F-TiO2. The bonded NO was converted into NH4+, N2, and N2O. Finally, compared with other Fe(II)EDTA regeneration systems, photocatalytic regeneration is a more suitable alternative in Fe(II)EDTA complexation denitrification technology.

Simultaneous Reduction of NO/SO2 Gas Using Fe(II)EDTA Solution at Low Temperature Conditions and Analysis of Solution Regeneration Characteristics by Zn

Simultaneous Reduction of NO/SO2 Gas Using Fe(II)EDTA Solution at Low Temperature Conditions and Analysis of Solution Regeneration Characteristics by Zn

Iron Stress in Crop Plants and Ways to Overcome it

Iron (Fe) stress is encountered by many crops in calcareous soils with pH above 8.0, which are abundant in India. Most of the times Fe stress goes unnoticed however anyway it affects yield. Aerobic rice and upland rice nurseries also exhibit Fe stress. In many cases frequent adequate irrigation solves the problem. In Fe deficient areas adequate organic manures must be applied, while preparing the field. Application of elemental S and S-containing fertilizers also helps in overcoming Fe stress in plants. In case of serious Fe-stress, ferrous sulphate or Fe-EDTA solution can be sprayed, which effectively overcome the Fe stress problem.

Performance, Mechanism, and Kinetics of Fe(III)EDTA Reduction by Thiourea Dioxide

Reducing Fe(III)EDTA into Fe(II)EDTA has a very remarkable significance for NO removal using Fe(II)EDTA solution. Here, the reductant thiourea dioxide (TD) was first served for reducing Fe(III)EDTA...

Evaluation of Fe(iii)EDTA reduction with ascorbic acid in a wet denitrification system.

The reduction of Fe(iii)EDTA to Fe(ii)EDTA is the core process in a wet flue gas system with simultaneous desulfurization and denitrification. Herein, at first, the reductant ascorbic acid (VC) was used for reducing Fe(iii)EDTA. The feasibility of Fe(iii)EDTA reduction with ascorbic acid was investigated at different Fe(iii)EDTA concentrations, various pH values, diverse temperatures, and different molar ratios of VC to Fe(iii)EDTA. The results showed that the Fe(ii)EDTA concentration increased with an increase in the initial Fe(iii)EDTA concentration. Furthermore, the reduction efficiency increased as the mole ratio of VC to Fe(iii)EDTA was increased, and all the Fe(iii)EDTA reduction efficiencies were close to 100% when the mole ratio was more than 0.5. On the other hand, an alkaline environment did not favor the conversion of Fe(iii)EDTA by VC. The Fe(iii)EDTA conversion slightly increased as the temperature was increased. Moreover, compared with other reduction systems, ascorbic acid (VC) was found to be more powerful in reducing Fe(iii)EDTA, especially in air. In addition, VC only exhibited powerful ability in the conversion of Fe(iii)EDTA to Fe(ii)EDTA and hardly reduced Fe(ii)EDTA–NO. Finally, the stoichiometry of Fe(iii)EDTA reduction by ascorbic acid was derived. Thus, our study would offer a bridge between foundational research and industrial denitration using the combination of Fe(ii)EDTA and VC.

Evaluation of Fe(II)EDTA-NO reduction by zinc powder in wet flue gas denitrification technology with Fe(II)EDTA

Regeneration of Fe(II)EDTA, converting Fe(III)-EDTA and Fe(II)EDTA-NO to Fe(II)EDTA, is the key process in a wet flue gas denitrification technology with Fe(II)EDTA solution. In this paper, Zn powder was first employed as a reductant to reduce Fe(II)EDTA-NO. The stoichiometry and kinetics of Fe(II)EDTA-NO reduction by Zn powder were investigated with respect to Zn powder concentration, pH value, and temperature. The effect of the particle size of the Zn powder on Fe(II)EDTA-NO reduction was also investigated. The experimental results indicated that Fe(II)EDTA-NO reduction rate increased with the decrease of pH value and elevated temperature, and small particle size is beneficial to Fe(II)EDTA NO reduction. Fe(II)EDTA-NO reduction with Zn powder showed a pseudo-second-order reaction concerning Fe(II)EDTA-NO. In addition, the energy of activation (Ea) and the entropy of activation (ΔS‡) of the Fe(II)EDTA-NO reduction with Zn powder were estimated to be 19.853kJmol−1 and −135.557JK−1mol−1, respectively. Finally, the simultaneous reduction of Fe(III)EDTA and Fe(II)EDTA-NO with Zn powder was investigated. Results showed that Zn powder had better performance on simultaneous Fe(III)EDTA and Fe(II)EDTA-NO reduction as compared to the earlier related research. These fundamental researches can offer valuable guidance for industrial denitrification using mixed Fe(II)EDTA and Zn powder system.

Removal of H2S and CO2 from biogas in bench scale and the pilot scale using a regenerable Fe-EDTA solution

Although the hydrogen sulfide is present in small quantities in biogas, it’s a highly toxic and corrosive gas. Through the process of absorption with Fe-EDTA solution, H2S can be eliminated from gas flows, forming elemental sulfur. Another constituent of biogas is the CO2, it can be considered inert and it reduces energy efficiency. In this sense, this work presents a stage in bench scale with synthetic biogas and the pilot scale, of H2S from biogas purification provided of the residual biomass treatment. Both the systems utilize H2S removal method with Fe-EDTA solution produced from commercial inputs, while the CO2 is also physically absorbed in this solution. Experiments were carried out in order to find a great ratio L/G, Fe-EDTA liquid flow by gas flow, due to different Fe-EDTA concentrations. According to CCRD methodology, both bench scale and pilot scale, higher H2S removal efficiencies are obtained for high values of L/G and Fe-EDTA concentration. In bench scale using Fe-EDTA 0.2 mol L−1 and L/G 1.27, H2S removal efficiency was 99% after 35 min. On a pilot scale it was possible to obtain maximum H2S removal of 98% with CO2 removal 18%, thus, there was an increase of 17% in biogas calorific power.

Effects of slurry properties on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption in sintering plants

Simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption has become a research focus in recent years. In order to get useful data for further industrialization, in this work the practical operating conditions of the sintering plant were simulated in a pilot-scale reactor in order to explore the effects of slurry properties on simultaneous removal of SO2 and NO. It was not conducive to the absorption of NO when (NH4)2SO4 concentration and slurry temperature had been increased. The initial NO removal efficiency decreased from 90.63% to 44.12% as the (NH4)2SO4 concentration increased from zero to 3.5 mol/L. With the increasing of Fe(II)EDTA concentration, SO32− concentration and pH value of absorption liquid and the absorption capacity of NO by Fe(II)EDTA solution increased. Especially the existence of SO32− ions in slurry had significantly improved the service life of chelating agents. The NO removal efficiency only decreased by 16.46% with the SO32− concentration of 0.3 mol/L after 30-min of operation. The chloride ions had no effects on the absorption of SO2 and NO. The results indicated that changes of slurry properties had different effects on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA solution. The basic data offered by the experiments could effectively contribute to further industrial applications.

Mechanism and kinetics of Fe(II)EDTA[sbnd]NO reduction by iron powder under anaerobic condition

Reduction of Fe(II)EDTANO as well as Fe(III)EDTA is the main process for simultaneous removing nitric oxide and sulfur dioxide with Fe(II)EDTA solution. In this paper, iron powder was proposed to reduce the Fe(II)EDTANO. The mechanism and kinetics of Fe(II)EDTANO reduction by Fe powder were studied with respect to the Fe(II)EDTANO concentration, pH value, and temperature. The experimental results indicated that the bonded NO was converted to ammonium. Fe(II)EDTANO reduction by Fe powder was a first-order reaction concerning Fe(II)EDTANO. The reaction rate increased with the decrease of pH value as well as the increase of temperature. In addition, the energy of activation (Ea) and the entropy of activation (ΔS‡) of the Fe(II)EDTANO reduction by Fe powder were 23.229kJmol−1 and −215.251JK−1mol−1, respectively. Finally, the simultaneous reduction of Fe(III)EDTA and Fe(II)EDTANO by Fe powder was investigated. The results showed that Fe(III)EDTA reduction was restricted by Fe(II)EDTANO, and Fe(III)EDTA had little effect on the reduction of Fe(II)EDTANO. Besides, the reduction of Fe(II)EDTANO was the determining step in the whole process of Fe(II)EDTA regeneration. These findings can provide constructive instruction for the NO removal in industrial applications with mixed Fe(II)EDTA and Fe powder system.

Purification of Biogas for Energy Use

This work determined the absorption efficiency of H2S in the solution of Fe-EDTA in synthetic biogas flows, as well as the efficiency of physical absorption of CO2 in Fe-EDTA. Biogas was bubbled through a pseudo-catalytic solution of Fe-DTA resulting in the formation of sulfur particles. H2S absorbed in the Fe-EDTA suffered a redox reaction. The Fe-EDTA solution used was regenerated with air. It was used two types of catalysts, in order to compare the efficiency of a catalyst of Fe-EDTA synthesized in the laboratory in an inert atmosphere, in relation to a commercial catalyst containing Fe-EDTA. In the batch study, removing H2S from biogas indicated that the concentration of Fe-EDTA applies great influence on the catalytic activity. For a system operating in a continuous regimen, it was possible to completely eliminate the H2S from biogas with Fe-EDTA synthesized in laboratory. The removal of CO2 present in the biogas was also evaluated. It was possible to achieve maximum efficiency of the CO2 absorption in 90 % in steady state, it was obtained an increase of 16 % in the calorific value of biogas, from 8.03 to 9.28 kWh/m3.

Study on Metal Chelation Adsorption of NO Using Fe(II)EDTA Solution in Power Plant

The influences of concentration of metal chelation solution, pH values, the concentration of O2 supplied by some thermal power plants in Wuxi, and the concentration of SO32- on the adsorption performance were studied. The results indicated that the removal ratio improved with the increase of bulk concentration. However, when the concentration exceeded 15mmol/L, the increase rate reduced. It was found that the chelation ability enhanced with the increase of pH values as well as the decrease of oxygen concentration in the flue gas. The SO32- in the solution was beneficial to improve and extend the adsorption capacity of Fe (II) EDTA. According to the FI-IR, the carboxyl in Na2EDTA coordinated with Fe(II). XPS showed that Fe2+ was the main valence of Fe in Fe(II)EDTA. Through the calculation of fold peak area, the content of Fe2+ was 72.17%. And the existence of Fe2+ in the Fe(II)EDTA was pivotal for the complexation.

Inclusion of urea in a 59FeEDTA solution stimulated leaf penetration and translocation of 59Fe within wheat plants

The role of urea in the translocation of (59) Fe from (59) FeEDTA-treated leaves was studied in durum wheat (Triticum durum) grown for 2 weeks in nutrient solution and until grain maturation in soil culture. Five-cm long tips of the first leaf of young wheat seedlings or flag leaves at the early milk stage were immersed twice daily for 10 s in (59) FeEDTA solutions containing increasing amounts of urea (0, 0.2, 0.4 and 0.8% w/v) over 5 days. In the experiment with young wheat seedlings, urea inclusion in the (59) FeEDTA solution increased significantly translocation of (59) Fe from the treated leaf into roots and the untreated part of shoots. When (59) Fe-treated leaves were induced into senescence by keeping them in the dark, there was a strong (59) Fe translocation from these leaves. Adding urea to the (59) Fe solution did not result in an additional increase in Fe translocation from the dark-induced senescent leaves. In the experiment conducted in the greenhouse in soil culture until grain maturation, translocation of (59) Fe from the flag leaves into grains was also strongly promoted by urea, whereas (59) Fe translocation from flag leaves into the untreated shoot was low and not affected by urea. In conclusion, urea contributes to transportation of the leaf-absorbed Fe into sink organs. Probably, nitrogen compounds formed after assimilation of foliar-applied urea (such as amino acids) contributed to Fe chelation and translocation to grains in wheat.

Removal of nitric oxide and sulfur dioxide from flue gases using a FeII-ethylenediamineteraacetate solution

The combined absorption of NO and SO2 into the Fe(II)-ethylenediamineteraacetate(EDTA) solution has been realized. Activated carbon is used to catalyze the reduction of FeIII-EDTA to FeII-EDTA to maintain the ability to remove NO with the Fe-EDTA solution. The reductant is the sulfite/bisulfite ions produced by SO2 dissolved into the aqueous solution. Experiments have been performed to determine the effects of activated carbon of coconut shell, pH value, temperature of absorption and regeneration, O2 partial pressure, sulfite/bisulfite and chloride concentration on the combined elimination of NO and SO2 with FeII-EDTA solution coupled with the FeII-EDTA regeneration catalyzed by activated carbon. The experimental results indicate that NO removal efficiency increases with activated carbon mass. There is an optimum pH of 7.5 for this process. The NO removal efficiency increases with the liquid flow rate but it is not necessary to increase the liquid flow rate beyond 25 ml min−1. The NO removal efficiency decreases with the absorption temperature as the temperature is over 35 °C. The Fe2+ regeneration rate may be speeded up with temperature. The NO removal efficiency decreases with O2 partial pressure in the gas streams. The NO removal efficiency is enhanced with the sulfite/bisulfite concentration. Chloride does not affect the NO removal. Ca(OH)2 and MgO slurries have little influence on NO removal. High NO and SO2 removal efficiencies can be maintained at a high level for a long period of time with this heterogeneous catalytic process.

Burial of the Polymorphic Residue 129 in Amyloid Fibrils of Prion Stop Mutants

Misfolding of the natively α-helical prion protein into a β-sheet rich isoform is related to various human diseases such as Creutzfeldt-Jakob disease and Gerstmann-Sträussler-Scheinker syndrome. In humans, the disease phenotype is modified by a methionine/valine polymorphism at codon 129 of the prion protein gene. Using a combination of hydrogen/deuterium exchange coupled to NMR spectroscopy, hydroxyl radical probing detected by mass spectrometry, and site-directed mutagenesis, we demonstrate that stop mutants of the human prion protein have a conserved amyloid core. The 129 residue is deeply buried in the amyloid core structure, and its mutation strongly impacts aggregation. Taken together the data support a critical role of the polymorphic residue 129 of the human prion protein in aggregation and disease.

Degradation Kinetics of Fe-EDTA in Hydrogen Sulfide Removal Process

Available data on the degradation of Fe-EDTA liquid redox H2S removal processes are reviewed, and the effect of H2S molar flow rate, the initial concentration of Fe(III)EDTA, and the presence of sodium citrate in Fe-EDTA solution were investigated in this study. The semibatch with continuous flow of H2S containing biogas was used under a wide range of experimental conditions; , H2S molar flow rate, (1.08 × 10−3–3.40 × 10−3 mol/h), the initial concentration of Fe(III)EDTA, (2.17–8.16 mol/m3), and the concentration of sodium citrate, (0–300 mol/m3). The result showed that sodium citrate acted as stabilizer with a good ability to reduce the degradation rate. The degradation rate of Fe-EDTA was found to follow pseudo first-order kinetics. Empirical correlations expressed the degradation rate constant as a function of significant H2S molar flow rate, and the initial Fe(III)EDTA and sodium citrate concentration were successfully developed for the prediction of Fe-EDTA degradation rate. Moreover, the precipitated solid, called sulfur cake, was recovered, and its composition was investigated. The result revealed that the sulfur cake contained more than 98% sulfur element and almost balances with iron, and no significant EDTA was degraded into the solid form.

ABSORBSI H2S MENGGUNAKAN LARUTAN Fe-EDTA DALAM PACKED COLUMN

<p><strong><em>Abstract:</em></strong><strong><em> </em></strong><em>Gas purification from the content of H<sub>2</sub>S using Fe-EDTA (Iron Chelated Solution) gave several advantages. The advantages were the absorbent solution can be regenerated that means a cheap operation cost, the separated sulfur was a solid that is easy to handle and is save to be disposal to environment. This research was done by simulation and experimental. The simulation step was done by mathematical model arrangement representing the absorption process in packed column through mass transfer arrangement such as mass transfer equations and chemical reaction. The experimental step was done with the making of Fe-EDTA solution from FeCl<sub>2</sub> and EDTA. Then Fe-EDTA solution was flown in counter current packed column that was contacted with H<sub>2</sub>S in the methane gas. By comparing gas composition result of experiment and simulation, the value of mass transfer coefficient in gas phase ( k<sub>Ag</sub>a), mass transfer coefficient in liquid phase (k<sub>Al</sub>a) and the reaction rate constant ( k) were found. The values of mass transfer coefficient in liquid phase (k<sub>Al</sub>a) were lower than values of mass transfer coefficient in gas phase (k<sub>Ag</sub>a) and the reaction rate constant (k). It meant that H<sub>2</sub>S absorption process using Fe-EDTA absorbent solution was determined by mass transfer process in liquid phase. The higher flow rate of absorbent, the higher value of mass transfer coefficient in liquid phase. </em><em>The smaller packing diameter, the higher value of mass transfer coefficient in liquid phase.From analysis of dimension, the relation of dimensionless number between Sherwood number and flow rate of absorbent, packing diameter was</em><strong></strong></p><p> <strong><em>Keywords:</em></strong><strong><em> </em></strong><em>chemical reaction, Fe-EDTA, H<sub>2</sub>S absorption, mass transfer</em></p>

Electrochemical and corrosion behavior of carbon steel in SULFIRAN ® process

Corrosion behavior of carbon steel was evaluated in Fe-EDTA solution designed to be used in acid gas treatment process (SULFIRAN ® plant) in the temperature range between 35 °C and 45 °C. Electrochemical techniques, i.e. polarization curves and electrochemical impedance spectroscopy (EIS) were applied for laboratory evaluations. Linear polarization resistance (LPR) and weight loss techniques were used to determine the corrosion rate for pilot tests. In addition, several surface analysis techniques such as XRD, XRF, SEM and optical microscopy were employed to determine the corrosion morphology. Metallurgical and SEM investigations of the carbon steel corrosion showed corrosion-induced damages in SULFIRAN ® process. The corrosion demonstrated in the forms of severe uniform corrosion, wide shallow pits formation, under deposit corrosion, hydrogen micro-void formation, and hydrogen induced disbonding between the interfaces of the inclusion (MnS) and metal matrix. The corrosion rate of carbon steel alloy is predicted to be very high (>200 mils per year or mpy) in this process.

Recovery of copper and chelating agents from sludge extracting solutions

Removal of extraction solution containing chelated copper from printed circuit board industry sludge by cementation on powdered iron was studied. This work applied the recovery and extraction of ethylene diamine tetraacetate (EDTA) and diethylene triamine pentaacetate (DTPA) as remediation agents and metal precipitated from printed circuit board sludge extracting solutions. The recovery of copper by cementation process using powdered iron was dependent on the Fe:Cu molar ratio. Results of the experiments showed that recovery efficiencies were typical of those of a Fe:Cu molar ratio as high as 8:1 for each sludge sample. The differences of recovery efficiencies may be due to competition for active sites on the surface of the powdered iron. Copper deposits on the surface almost always occur in the form of the copper metal that are well distributed, with purified copper powder being observed in characterization with scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The recycled extract containing EDTA or DTPA was used to chelate supplementary fresh copper-containing sludge. Extraction efficiencies of copper by using Fe-precipitated EDTA or DTPA from previous cementation were higher than sequential application of the Fe-EDTA or Fe-DTPA solution. Similar copper extraction efficiencies using both pristine and reused extract containing chelants validates the enduring chelating capability of EDTA and DTPA and suggests further opportunities to employ recycled chelant to reduce its usage. This work confirmed the feasibility of copper removal from sludge chelated wastewater by cementation and subsequent recycling of chelant extraction.

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA2− regeneration, biomass growth, and EDTA degradation

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 degrees 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.