Evaluation of NO Removal from Flue Gas by a Chemical Absorption

16 Jun 2014 - Department of Chemical and Biological Engineering, Zhejiang University Yuquan Campus, Hangzhou, Zhejiang 310027, People,s. Republic of ...
0 downloads 0 Views 867KB Size
Download PDF
Article pubs.acs.org/EF

Evaluation of NO Removal from Flue Gas by a Chemical Absorption− Biological Reduction Integrated System: Complexed NO Conversion Pathways and Nitrogen Equilibrium Analysis Wei Li,†,‡ Lei Zhang,†,‡ Nan Liu,*,† Yun Shi,†,‡ Yinfeng Xia,†,‡ Jingkai Zhao,† and Meifang Li† †

Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Institute of Industrial Ecology and Environment, Department of Chemical and Biological Engineering, Zhejiang University Yuquan Campus, Hangzhou, Zhejiang 310027, People’s Republic of China ‡ Institute of Environmental Engineering, Zhejiang University Zijingang Campus, Hangzhou, Zhejiang 310058, People’s Republic of China ABSTRACT: The conversion of complexed nitrogen oxide [Fe(II)EDTA−NO] is the core process in the chemical absorption− biological reduction (CABR) integrated system. Additionally, flue gas of power plants in China contains 3−8% oxygen (O2), which plays a dominant role in the system. However, previous studies on the reduction of complexed NO were conducted in strictly anaerobic vials. Nitrogen utilization for microorganism growth was not taken into consideration. In this study, the mechanism and conversion pathways of complexed NO were investigated with 0−10% O2. Results demonstrated that, with O2, except for being complexed as Fe(II)EDTA−NO, a part of NO was oxidized to NO2. Then, Fe(II)EDTA−NO and NO2 were oxidized to NO2−/NO3− via nitrosification/nitrification or direct chemical reaction, and NO2−/NO3− were reduced to N2 by complexed NO-reducing bacteria. Besides, 75% of nitrogen was discharged by gas, mainly as N2. There was 18 and 3% of nitrogen accumulated in biological and liquid phases, respectively. 4Fe(II)EDTA + O2 + 2H 2O → 4Fe(III)EDTA + 4OH−

1. INTRODUCTION Anthropogenic emissions of nitrogen oxides (NOx) have various negative impacts on ecosystems and human health, such as acid deposition, eutrophication, fog, haze, urban ozone smoke, ozone depletion, and loss of biodiversity.1−4 Besides, because of a large amount of NOx emission, massive economic costs have been consumed on repairing environmental damage5,6 in the past decade. Hence, it is crucial to develop effective and environmentally friendly NOx control measures. Nowadays, several technologies have been developed to remove NOx from industrial flue gas,7 including selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), adsorption, and absorption. As well-established and used in industrial applications,8,9 SCR and SNCR suffer from prohibitive cost and the risk of secondary pollution.7,10−12 Therefore, a chemical absorption−biological reduction (CABR) integrated system13,14 has been proposed as a promising NOx abatement technique. To improve the gas− liquid mass-transfer process, this approach uses Fe(II)EDTA (EDTA = ethylenediaminetetraacetic acid) as a complexed absorbent to form Fe(II)EDTA−NO (complexed NO). Then, complexed NO can be converted to N2 by microorganisms, and the complexed absorbent can be regenerated for reuse. The main reactions15−17 are shown as follows: Fe(II)EDTA + NO ⇔ Fe(II)EDTA−NO

(3)

24Fe(III)EDTA + C6H12O6 + 24OH− microorganism

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯→ 24Fe(II)EDTA + 18H 2O + 6CO2

The advantages of this approach are that it enhances NO gas− liquid mass transfer via complex absorption and easily regenerates absorbent using a biological approach.16,17 CABR has been intensively studied in recent years because of its high removal efficiency and environmentally friendly characteristics. Li et al.13 demonstrated that the NO removal efficiency was about 90% with the inlet gas of 1000 mL min−1, 100−350 mL m−3 NO, and 3% O2 in the biological tower. Mi and Gao et al.18,19 used a biofilm electrode reactor to improve the reduction of Fe(III)EDTA, and the reduction efficiencies of Fe(II)EDTA−NO and Fe(III)EDTA were up to 85 and 78%, respectively, with an electricity current at 30 mA. These results confirmed that this approach had great potential on NO removal. Because NO is chelated with Fe(II)EDTA, Fe(II)EDTA− NO is the target pollutant in the CABR integrated system. Some of the previous studies focused on the reduction pathway of complexed NO. van der Mass et al.20−22 reported that Fe(II)EDTA−NO was reduced to N2 with N2O as the intermediate and described the denitrification pathway in the similar system shown as follows:

(1)

12Fe(II)EDTA−NO + C6H12O6

Received: March 24, 2014 Revised: June 15, 2014 Published: June 16, 2014

microorganism

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯→ 12Fe(II)EDTA + 6N2 + 6H 2O + 6CO2 (2) © 2014 American Chemical Society

(4)

4725

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730

Energy & Fuels

Article

NO3− → NO2− → NO → N2O → N2

reducing bacteria was finished, the same procedure was followed to culture a biofilm of the complexed NO-reducing bacteria. The concentration of NO was increased from 0 to 670 mg m−3, which the concentration of typical flue gas of power plants in China contained. The biofilm formation was indicated by the change of the outlet NO concentration. This process aimed to obtain highly activated Fe(III)reducing bacteria and complexed NO-reducing bacteria with a reducing efficiency of 90% in the biopacking tower. 2.3. Experimental Procedure. As indicated in Figure 1, the experimental device consists of a gas distribution system, a biopacking

The result was in agreement with that by Zhang et al.14,17 The experiments were conducted in strictly anaerobic vials. However, the experiments in vials were different from industrial experiments. Industrial flue gases in China generally contained 3−8% oxygen,17 which imposed a great effect on both of the complexed NO conversion pathways and the microorganism. When the effect of O2 on the aerobic denitrifying process was investigated, Jiang et al.23 found that O2 enhanced the total efficiency in part by chemical oxidation and in part by the strain activities. However, this study did not delve into the influence of O2 on NO reduction pathways. The effect of O2 on the facultative microorganism in the CABR integrated system could not be simply deduced from that on the aerobic microorganism in experiments by Jiang et al. Thus, Fe(II)EDTA−NO reduction mechanism in the CABR system under aerobic conditions remained unsubstantiated in the literature. Additionally, as the sole nitrogen source in the system, Fe(II)EDTA−NO was of great significance on the microbial growth. Little information can be obtained on Fe(II)EDTA−NO utilization for microorganism growth. Therefore, it is critical to investigate the complete conversion pathways of Fe(II)EDTA−NO under an aerobic environment in the CABR integrated system. For a systematical understanding of Fe(II)EDTA−NO conversion, this paper explored the complete conversion pathways of complexed NO in the CABR integrated system. Under different concentrations of O2 (0−10%, v/v), various NO analogues and nitrogen utilization for microorganism growth were investigated. Moreover, the complete conversion pathways of complexed NO and the nitrogen equilibrium analysis were proposed.

Figure 1. Configuration of the lab-scale bioreactor: (1) gas cylinder, (2) mass flow controller, (3) mixing chamber, (4) biopacking tower, (5) absorbent storage tank, (6) thermostatic water bath, (7) absorbent recycle pump, (8) rotameter, (9) cold trap, and (10) NOx analyzer.

2. EXPERIMENTAL SECTION

tower, an absorbent storage tank, an absorbent recycle pump, a constant temperature water recycle pump, and a NOx analyzer. The PPR biopacking tower was equipped with a liquid distirbutor on the top and a gas distributor on the bottom to create a uniform counterflow. The solution tank was connected to the bioreactor as the bottom. The simulated flue gas consisted of O2 (0−10%, v/v), CO2 (15%, v/v), NO (0−670 mg m−3), and balance N2. These gases were then mixed in a blender with a flow rate of 2 L min−1. The absorbent was continuously pumped from the tank to the top of the tower at a flow rate of 40 L h−1. The total volume of the absorbent that contained 10 mmol L−1 of Fe(III)EDTA was 4 L, and the initial pH was adjusted to 6.8−7.2. The tower temperature was controlled at 323 ± 0.5 K with a constant-temperature water jacket to simulate the typical flue gas temperature (313−323 K)24,25 in power plants of China after the flue gas desulfurization (FGD) process. 2.4. Analytical Methods. The concentrations of ferrous ions, including Fe(II)EDTA and Fe(III)EDTA, were determined by a modified 1,10-phenanthroline colorimetric method at 510 nm.13 To determine the total amount of iron, ferric ions were reduced to ferrous ions by hydroxylamine hydrochloride (NH2OH·HCl) when the pH was lower than 2. The Fe(III) concentration was calculated by the difference between total Fe and Fe(II). The concentrations of NO and NO2 were determined using a chemiluminescent NOx analyzer (Thermo, model 42i-HL). The concentrations of NO2− and NO3− were determined by Metrom IC 861 (Asupper 5 250) when the flow rate was 0.7 mL min−1 at 11.0 MPa pressure. The concentration of NH4+ was determined by Nessler’s reagent spectrophotometric method. The concentration of N2O was determined by a model Madur Electronics Photon II flue gas analyzer (Austria). The concentration of N 2 was determined by Agilent 7890 gas chromatography.

2.1. Chemicals. Na2EDTA·2H2O (99%), FeSO4·7H2O (99.5%), and D-C6H12O6 (99.5%) were analytical-grade pure and were purchased from Shanghai Chemical Reagent Co., China. NO (5%) in N2, N2 (99.999%), CO2 (99.999%), and O2 (99.999%) were provided by Zhejiang Jingong Gas Co., China. All other chemicals were analytical-grade reagents, commercially available, and used without further purification. 2.2. Medium and Microorganism. The nutrient media used for cultivation contains glucose (1000 mg L−1), KH2PO4 (300 mg L−1), MgCl2 (100 mg L−1), Na2SO3 (70 mg L−1), CaCl2 (20 mg L−1), and trace components (2 mL L−1). The trace components for the bacteria growth include MnCl2·4H2O (990 mg L−1), CuSO4·5H2O (250 mg L−1), CoCl2 (240 mg L−1), NiCl2·6H2O (190 mg L−1), ZnCl2 (100 mg L−1), and H3BO4 (14 mg L−1). Fe(III)EDTA and Fe(II)EDTA−NO complexed solution were prepared according to the study by Li et al.16 The complexed NO-reducing bacteria Pseudomonas sp. DN-2 (GenBank accession DQ811956)14 and Fe(III)-reducing bacteria Escherichia coli FR-2 (GenBank accession EU693909)16 were activated in our previous study to obtain the recovered strains. The mixed culture was inoculated in a 500 mL glass serum vial filled with the basal medium that contains 3 mmol L−1 Fe(II)EDTA−NO and 10 mmol L−1 Fe(III)EDTA. The pH value was adjusted to 6.8, and the mix culture was continuously stirred using a rotary shaker at 140 rpm and 313 K. The biofilter was started up with 4 L of Fe(III)EDTA (10 mmol L−1) medium inoculated with 200 mg [dry cell weight (DCW)] L−1 Fe(III)-reducing bacteria E. coli. After the iron reduction rate sustained above 1 mmol L−1 h−1,16,17 the biofilter was loaded with simulated flue gas consisting of O2 (0−10%, v/v), CO2 (15%, v/v), NO (0−670 mg m−3), and balance N2. The bacteria activity was indicated by a Fe(III)EDTA reduction rate. Once the biofilm formation of Fe(III)4726

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730

Energy & Fuels

Article

3. RESULTS AND DISCUSSION 3.1. Steady-State Operation in the CABR Integrated System. On the basis of the previous findings,21,26 O2 plays an important role in this system. Actual flue gas normally contains 3−8% O2.17 Thus, before the experiment on complexed NO conversion pathways, the system had to be acclimated at the concentration of 1−10% O2. Figure 2 gives the details.

Figure 3. Change of outlet NO2, N2O, and N2 concentrations during 90 h of steady-state operation: (blue circles) NO removal efficiency (%), (black squares) NO2 concentration (mg m−3), (red squares) N2O concentration (mg m−3), and (green triangles) N2 concentration (mg m−3) [NO, 670 mg m−3; O2, 0−10% (v/v); gas flow rate, 2 L min−1; VL, 40 L h−1; T, 323 K; and pH, 6.8−7.2].

the carrier gas to obtain an accurate measurement of N2 production. As shown in Figure 3, when the inlet NO concentration was at 670 mg m−3, the average NO removal efficiency was 90%. The outlet N2 concentration was 169−208 mg m−3, and the average conversion rate was 60.15%. Conspicuously, there was the production of N2. Particularly without O2, the final average conversion rate was 64.34%. That means, under an anaerobic environment, the main production of complexed NO was N2. As indicated in Figure 3, outlet NO2 gradually increased with the increase of O2. This may be due to the chemical oxidation of NO with the change of O2.30,31 The paper by Jiang et al.23 could be supportive to the chemical formation of NO2, although the microorganism of experiments by Jiang et al. was aerobic. However, because the previous studies in the anaerobic denitrifying system20−22 were conducted in the absence of O2, NO2 was not detected or referenced. From Figure 3, when O2 was higher than 5%, the concentration of outlet NO2 could arrive at about 6 mg m−3. Thus, NO2, as another pathway of NO conversion in the CABR integrated system under aerobic conditions, cannot be negligible. With reference to the studies by Sugata et al.29 and Sun et al.,32 NO2 was more readily removed than NO because of its high solubility. Although the complex absorption puzzled the situation, a small amount of NO2 formation could be deduced to foster the NO removal for the CABR integrated system. From Figure 3, with the inlet NO concentration of 670 mg m−3, the outlet N2O concentration was 0 mg m−3. However, Zhang et al.14 reported that the N2O accumulation was detected and was a function of the cultivation time. It may relate to the longer biological chain in the bioreactor. N2O was the significant intermediate in the denitrifying process.33,34 Parameters such as pH, carbon source, and sulfide pose impacts on the transient accumulation of N2O. In the experiment, the transient accumulation of N2O may be due to the following reasons. First, it was reported35 that the N2O production rate in the riparian ecosystem was the highest at the pH of 5. When the pH was higher than 6.8, there was almost no N2O. Whereas the pH was controlled from 6.8 to 7.2 in our experiments, the lack of N2O may be reasonable. Besides, Itokawa et al.36 investigated the influence of COD/N on the N2O production in the wastewater denitrifying process. The results came out

Figure 2. Steady-state operation in the CABR integrated system: (blue circles) NO removal efficiency (%) and (magenta squares) Fe(II) concentration (mmol L−1).

It is seen from Figure 2 that both the Fe(II) concentration and the NO removal efficiency showed an increasing trend with 0% O2. When O2 gradually increased to 10%, the Fe(II) concentration and the NO removal efficiency were declining and finally stabilized at around 2 mmol L−1 and 90%, respectively. This indicates that the system remained at a high NO removal efficiency once the bacteria on the biofilm accommodated to the gradual increase of the O2 concentration. The biofilter was ready for further investigation. 3.2. Morphological Analysis of the Nitrogen Conversion. The increase of the O2 concentration is advantageous to the chemical oxidation step in the NO removal process.23 A small amount of O2 is beneficial to the metabolism of the fulcative bacteria to some extent. However, O2 poses a negative effect on both NO reduction27,28 and the denitrifying microorganism.26 If there is O2, NO can be oxidized to NO2 in the gas or liquid phase.29,30 NO2 can be absorbed rapidly and has a high oxidization rate in the liquid phase.31,32 Then, NO2 can be eliminated by the denitrifying microorganism. Without O2, NO can be removed directly by the denitrifying microorganism.7 According to the previous studies20,21 in vials, N2O and N2 are the intermediate and final products, respectively. Besides, the products may include the accumulation of NO2−−N and NO3−−N in the liquid phase and the accumulation of biomass nitrogen in biofilm. The confirmation of these hypotheses shown above would require further investigation. The analysis in detail on the production of the substance is presented as follows. 3.2.1. Nitrogen Analysis of Gaseous Products. Figure 3 shows the change of the outlet N2 , NO 2, and N 2O concentrations at different O2 concentrations. N2 was the desirable product of complexed NO reduction. The N2 production was of great significance to understand the complexed NO conversion pathways. Argon gas was used as 4727

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730

Energy & Fuels

Article

being abated, the reduction pathways of NO2− and NO3− under an aerobic environment were the same as those in the absence of O2. The denitrifying process in the CABR integrated system was anaerobic. Thus, the reduction of NO3− and NO2− could be substantiated by the change in the concentration of dissolved oxygen (DO) in the absorbent under similar conditions to those by Zhang et al.39 In the experiment, when inlet O2 was 1−5%, the concentration of DO was gradually dropping to 0 mg L−1 after 0.5 h. With 8% O2, the DO concentration declined to 0 mg L−1 after 3 h. Because the oxidation of Fe(II) consumed dissolved oxygen, the environment could be viable for the facultative denitrifying bacteria in the biofilm. 3.2.3. Nitrogen Analysis of Biological Products. To investigate the effect of O2 on biomass, microbial samples were collected at different O2 concentrations (0−10%, v/v). As shown in Figure 2, the microbial activity on reducing NO and Fe(III)EDTA was fairly high. The results indicated a great biofilm growth. According to Figure 5, the biomass of the film was soaring with the increase of O2. The biomass could only be 319.33 mg with 0% O2, while the biomass was increased to 466.88 mg with 10% O2.

that, when COD/N was lower than 3.5, 20−30% of nitrogen was converted to N2O. This illustrated that, with an insufficient supply of the carbon source, there was the accumulation of N2O. The value of COD/N in our experiments was 4.42, which would not lead to the accumulation of N2O. Third, as reported by Manconi et al.,37 sulfide, either dosed to the medium or formed during the batch incubation from endogenous sulfur sources, induced the accumulation of intermediate N2O. Sulfate and sulfite were found to be reduced to sulfide. In our experiments, although sulfate and sulfite were dosed as the nutrient and trace media, the amounts were too small to affect the production of N2O. Therefore, we deduced that the accumulation of N2O in our experiments may be eliminated via adjusting the experimental parameters, as described above. Although the existence of O2 poses a negative effect on the reduction, NO was still reduced to N2 in the aerobic system and the accumulation of N2O was not detected. Nowadays, during NO reduction, many SCR catalysts produce a massive accumulation of N2O,38 resulting in secondary pollution. This may be one of the advantages for the CABR integrated system over SCR. 3.2.2. Nitrogen Analysis of Liquid Products. The existence of O2 was vital to the formation of NO2− and NO3−. The change in the NO2− and NO3− concentrations at different O2 concentrations is shown in Figure 4. Along with the increase of

Figure 5. Biomass amount at different O2 concentrations.

Figure 4. Change of TN, NH4+−N, NO2−−N, and NO3−−N concentrations during 90 h of steady-state operation: (blue circles) TN concentration (mg L−3), (green circles) NO2−−N concentration (mg L−3), (red squares) NH4+−N concentration (mg L−3), and (black stars) NO3−−N concentration (mg L−3) [NO, 670 mg m−3; O2, 0− 10% (v/v); gas flow rate, 2 L min−1; VL, 40 L h−1; T, 323 K; and pH, 6.8−7.2].

It is obviously noted that the growth rate of microorganisms accelerated with the rise of the O2 concentration. The phenomenon may be attributed to the massive growth of facultative bacteria in the system along with increasing O2. The speculation had to be confirmed in the future experiments on the molecular biology basis. Despite increasing the biomass, the rising O2 concentration led to the declining amount of NO reduction according to the above experiments. 3.3. NO Conversion Pathways. During the process of NO removal in the CABR integrated system, it combined direct chemical reactions and biological catalysis. On the basis of the product analysis above, the complexed NO conversion pathways were assumed, as described in Figure 6. As shown in Figure 6, the complexed NO conversion pathways consisted of chemical oxidation, biological nitrification, and biological denitrification. Under typical experimental conditions, complexed NO was reduced to N2 via biological denitrification rather than merely transferring nitrogen from the gas phase to liquid phase. Also, there was no accumulation of

O2, the concentrations of NO2− and NO3− both showed an uptrend. No accumulation of NO2− and NO3− was observed when the concentration of O2 was below 3%. The result herein in the biopacking tower was in accordance with that of van der Mass et al.,20,21 which was conducted in strictly anaerobic vials. At first, most NO may be converted to NO3− and NO2− via nitrification. A significantly higher amount of NO3− was observed than that of NO2−. Then, NO3− and NO2− were converted via denitrification. When the concentration of O2 was above 3%, NO2− and NO3− began to accumulate remarkably. The reduction process was bogged down with the presence of O2. On one hand, this is due to the competitive inhabitation between O2 and NO2− or NO3−.27,28 On the other hand, the activity of denitrifying microorganisms was inhibited.25 Despite 4728

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730

Energy & Fuels

Article

Figure 6. NO conversion pathways.

N2O in products. On the basis of the product analysis of complexed NO, the following conclusions were obtained: Without O2, the main reduction product of Fe(II)EDTA− NO was N2. With O2, particularly above 2%, except for being complexed as Fe(II)EDTA−NO, a part of NO was oxidized to NO2. Then, Fe(II)EDTA−NO and NO2 were oxidized to NO2−/NO3− via nitrosification/nitrification or direct chemical reaction, and NO2−/NO3− were reduced to N2 by complexed NO-reducing bacteria according to

Figure 7. Nitrogen equilibrium under 90 h of steady-state operation.

described in previous literature as far as we know. However, the nitrogen source exerted a considerable influence on the biological system. Besides, as shown in Table 1, nitrogen in liquid phase was mainly in the form of NO3−. There was no N2O in exhaust gas. Only a little amount of outlet nitrogen was NO2.

NO → complexed NO/NO2 → NO2− → NO3− → NO2− → NO → N2O → N2

4. CONCLUSION Without O2, the main reduction product of Fe(II)EDTA−NO was N2. With O2, particularly above 2%, except for being complexed as Fe(II)EDTA−NO, a part of NO was oxidized to NO2. Then, Fe(II)EDTA−NO and NO2 were oxidized to NO2−/NO3− via nitrosification/nitrification or direct chemical reaction, and NO2−/NO3− were reduced to N2. The main pathway was shown as follows:

Because there were different approaches for NO degradation, many kinds of denitrifying microorganisms may coexist with complexed NO-reducing bacteria. The existence of O2 bated the synthesis of dissimilation nitrate reductase in respiration. However, it did not affect the synthesis of assimilation nitrate reductase.40 HNO3 → HNO2 → HNO → HN(OH)2 → NH3OH

NO → complexed NO/NO2 → NO2− /NO3− → NO

→ NH3

→ N2O → N2

3.4. Nitrogen Equilibrium Analysis. Under the typical experimental conditions [NO, 670 mg m−3; O2, 0−10% (v/v); gas flow rate, 2 L min−1; VL, 40 L h−1; T, 323 K; and pH, 6.8− 7.2], the equilibrium analysis of nitrogen during 90 h of operation is shown in Table 1. According to Table 1 and Figure 7, about 75% of nitrogen was discharged by gas after 90 h of operation. A total of 64% of inlet NO was converted to environmentally benign N2. Also, 18 and 3% of nitrogen were accumulated in biological and liquid phases, respectively. Thus, the second priority of inlet NO was being a nitrogen source for the microorganisms, which was not

No outlet N2O was observed. In the steady CABR integrated system, about 64% of nitrogen was discharged as N2. Meanwhile, 18 and 3% of nitrogen remained in biological and liquid phases, respectively.

■

AUTHOR INFORMATION

Corresponding Author

*Fax: 86-571-87952513. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

Table 1. Nitrogen Equilibrium under 90 h of Steady-State Operation inlet nitrogen amount T (h) 16 32 38 46 56 64 72 80 93 total

outlet nitrogen amount (mg)

O2 (%)

inlet nitrogen amount (mg)

N2

NO2

NO

biological nitrogen

liquid nitrogen

outlet nitrogen amount

difference between inlet and outlet

0 2 3 4 5 6 7 8 10

599.20 599.20 224.70 299.60 374.50 299.60 299.60 299.60 486.85 3482.85

407.58 403.45 188.00 193.22 231.22 181.41 173.95 175.30 275.20 2229.33

0.00 0.00 0.99 2.01 2.51 4.01 6.02 7.01 13.00 35.55

34.75 38.11 19.65 28.40 43.89 35.20 35.71 40.81 62.50 339.02

79.03 83.41 47.37 50.30 67.45 57.73 57.85 61.66 136.62 641.42

15.40 20.01 7.64 9.59 11.24 9.44 11.77 13.00 21.47 119.56

536.76 544.98 263.65 283.52 356.31 287.79 285.30 297.78 508.79 3364.88

62.44 54.22 −38.95 16.08 18.19 11.81 14.30 1.82 −21.94 117.97

4729

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730

Energy & Fuels

■

Article

(30) Ting, T.; Stanger, R.; Wall, T. Int. J. Greenhouse Gas Control 2013, 18, 15−22. (31) Awad, H. H.; Stanbury, D. M. Int. J. Chem. Kinet. 1993, 25, 375− 381. (32) Sun, W. Y.; Wang, Q. Y.; Ding, S. I.; Su, S. J.; Jiang, W. J.; Zhu, E. G. Sep. Purif. Technol. 2013, 118, 576−582. (33) Ye, R. W.; Averill, B. A.; Tiedje, J. M. Appl. Environ. Microbiol. 1994, 60, 1053−1058. (34) Zumft, W. G. Microbiol. Mol. Biol. Rev. 1997, 61, 533−616. (35) van den Heuvel, R. N.; Bakker, S. E.; Jetten, M. S. M.; Hefting, M. M. Geobiology 2011, 9, 294−300. (36) Itokawa, H.; Hanaki, K.; Matsuo, T. Water Res. 2001, 35, 657− 664. (37) Manconi, I.; van der Maas, P.; Lens, P. N. L. Nitric Oxide 2006, 15, 40−49. (38) Joubert, E.; Menezo, J. C.; Duprez, D.; Barbier. J. Catal. 2001, 16, 225−229. (39) Zhang, S. H. Ph.D Thesis, Zhejiang University, Hangzhou, China, 2010 (in Chinese). (40) Alefounder, P. R.; Ferguson, S. J. Biochem. J. 1980, 192, 231− 240.

ACKNOWLEDGMENTS The work was sponsored by the National Natural Science Foundation of China (21276233 and 21306166), the project funded by the China Postdoctoral Science Foundation (2013M541783), and the Postdoctoral Science Preferential Funding of Zhejiang Province, China (BSH1301019).

■

REFERENCES

(1) Derwent, R. G.; Metcalfe, S. E.; Whyatt, J. D. Ambio 1998, 27, 518−527. (2) Kurvits, T.; Marta, T. Environ. Pollut. 1998, 102, 187−194. (3) Volz, A.; Kley, D. Nature 1988, 332, 240−242. (4) Solomon, S.; Portmann, R. W.; Sanders, R. W.; Daniel, J. S.; Madsen, W.; Bartram, B.; Dutton, E. G. J. Geophys. Res. 1999, 104, 12047−2058. (5) Mauzerall, D. L.; Sultanc, B.; Kima, N.; Bradforda, D. F. Atmos. Environ. 2005, 39, 2851−2866. (6) Zhang, Q. Y.; Wei, Y. M.; Chen, Y. X.; Guo, H. J. Zhejiang Uni. 2007, 8, 1816−1825. (7) Jin, Y. M.; Veiga, M. C.; Kennes, C. J. Chem. Technol. Biotechnol. 2005, 80, 483−494. (8) DueHansen, J.; Boghosian, S.; Kustov, A.; Fristrup, P.; Tsilomelekis, G.; Stahl, K.; Christensen, C.; Fehrmann, R. J. Catal. 2007, 251, 459−473. (9) Liu, F. D.; Asakura, K.; He, H.; Liu, Y. C.; Shan, W. P.; Shi, X. Y.; Zhang, C. B. Catal. Today. 2011, 164, 520−527. (10) Uehn, N. D. Power Eng. 1994, 98, 23−27. (11) Srivastava, R. K.; Neuffer, W.; Grano, D.; Khan, S.; Staudt, J. E.; Jozewicz, W. Environ. Prog. 2005, 24, 181−197. (12) Lee, G. W.; Shon, B. H.; Yoo, J. G.; Jung, J. H.; Oh, K. J. J. Ind. Eng. Chem. 2008, 14, 457−467. (13) Li, W.; Wu, C. Z.; Shi, Y. J. Chem. Technol. Biotechnol. 2006, 81, 306−311. (14) Zhang, S. H.; Mi, X. H.; Cai, L. L.; Jiang, J. L.; Li, W. Appl. Microbiol. Biotechnol. 2008, 79, 537−544. (15) Demmink, J. F.; van Gils, I. C. F.; Beenackers, A. A. C. M. Ind. Eng. Chem. Res. 1997, 36, 4914−4927. (16) Li, W.; Wu, C. Z.; Zhang, S. H.; Shao, K.; Shi, Y. Environ. Sci. Technol. 2007, 41, 639−644. (17) Zhang, S. H.; Cai, L. L.; Mi, X. H.; Jiang, J. L.; Li, W. Environ. Sci. Technol. 2008, 42, 3814−3820. (18) Mi, X. H.; Gao, L.; Zhang, S. H.; Cai, L. L.; Li, W. Bioresour. Technol. 2009, 100, 2940−2944. (19) Gao, L.; Mi, X. H.; Zhou, Y.; Li, W. Bioresour. Technol. 2011, 102, 2605−2609. (20) van der Maas, P.; van de Sandt, T.; Klapwijk, B.; Lens, P. Biotechnol. Prog. 2003, 19, 1323−1328. (21) van der Maas, P.; Harmsen, L.; Weelink, S.; Klapwijk, B.; Lens, P. J. Chem. Technol. Biotechnol. 2004, 79, 835−841. (22) van der Maas, P.; Manconi, I.; Klapwijk, B.; Lens, P. Biotechnol. Bioeng. 2008, 100, 1099−1107. (23) Jiang, R.; Huang, S. B.; Chow, A. T.; Yang, J. J. Hazard. Mater. 2009, 164, 432−441. (24) Yang, Y. L.; Huang, S. B.; Liang, W.; Zhang, Y. Q.; Huang, H. X.; Xu, F. Q. J. Hazard. Mater. 2012, 203/204, 326−332. (25) Wu, Z. D.; Huang, S. B.; Yang, Y. L.; Xu, F. Q.; Zhang, Y. Q.; Jiang, R. Aerosol Air Qual. Res. 2013, 12, 1126−1132. (26) Lee, B. D.; Apel, W. A.; Smith, W. A. Environ. Prog. 2001, 20, 157−167. (27) Kieft, T. L.; Fredrickson, J. K.; Onstott, T. C.; Gorby, Y. A.; Kostandarithes, H. M.; Bailey, T. J.; Kennedy, D. W.; Li, S. W.; Plymale, A. E.; Spadoni, C. M.; Gray, M. S. Appl. Environ. Microbiol. 1999, 65, 1214−1221. (28) Zhang, S. H.; Cai, L. L.; Liu, Y.; Shi, Y.; Li, W. Appl. Microbiol. Biotechnol. 2009, 82, 557−563. (29) Sugata, P. T.; Mohammad, P. Ind. Eng. Chem. Res. 2013, 52, 16032−16043. 4730

dx.doi.org/10.1021/ef500652g | Energy Fuels 2014, 28, 4725−4730