Synthesis of Molecularly Imprinted Polymers and Adsorption of NO2 in

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Synthesis of Molecularly Imprinted Polymers and Adsorption of NO2 in Flue Gas Yi Zhao, Han Wang, and Siqi Hao Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b01401 • Publication Date (Web): 26 Jul 2017 Downloaded from http://pubs.acs.org on July 30, 2017

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Industrial & Engineering Chemistry Research

Synthesis of Molecularly Imprinted Polymers and Adsorption of NO2 in Flue Gas Yi Zhaoa,*, Han Wanga, Siqi Hao b a

School of Environmental Science & Engineering, North China Electric Power University,

Beijing 102206, People’s Republic of China b

Department of Chemical Engineering, Chengde Petroleum College, Chengde 067400,

People’s Republic of China *Corresponding author. Tel: +86-010-61771331; fax: +86-019-61771331. E-mail address: [email protected] (Y. Zhao) Abstract Molecularly imprinted polymers (MIP1 and MIP2) were synthesized using acrylamide as functional monomer, acetic acid and ethanedioic acid as template respectively. Textural properties of MIPs and non-imprinted polymer (NIP) were characterized by N2 adsorption experiment, thermo-gravimetric analysis and Fourier transform infrared spectroscopy. NO2 basic adsorption condition was set as 40℃ of the temperature, 100ml/min of the flow rate and 1000ppm of the NO2 concentration through fixed-bed breakthrough experiments, and at this condition, NO2 adsorption capacity of MIP1, MIP2 and NIP was 0.58, 0.63 and 0.51 mg/g respectively. The NO2 adsorption performance was nearly unaffected by O2, however SO2 and CO2 inhibited NO2 adsorption severely. H2O molecule had less negative effect on

*

Corresponding author E-mail address: [email protected]; phone: +86-010-61771331; fax: +86-019-61771331 1

ACS Paragon Plus Environment


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NO2 adsorption because of the large number of hydrophobic groups –(CH2-CH)n– in polymers and the hydrogen bond force between H2O molecules. Keywords: NO2 adsorption; polymer adsorbent; flue gas purification; molecular imprinting

2


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1. Introduction Nitrogen dioxide (NO2) is formed from oxide reaction of nitric oxide (NO) [1, 2] that mainly results from fossil industrial synthesis and fuel combustion processes, thus NO2 is produced in a huge amount every year. NO2 has a strong smell and exerts toxic effects on vegetation and human health, besides, it also contributes to the formation of acid rain, photochemical fog and ozone. Generally, NOx is removed by selective catalytic reduction (SCR) method [3,4] or selective non-catalytic reduction (SNCR) method [5,6] in power plants, and these methods use reducing reaction to change NOx into N2 and H2O. However, SCR and SNCR methods usually have the disadvantages of high reaction temperature, catalyst poisoning and ammonia escape. Recently, as another catalytic reduction approach, photocatalyic reduction that selectively reduced NOx by reductants, such as NH3, H2, CO and hydrocarbons in the presence of light was investigated for NOx removal [7-9]. However, the low efficiency, limitation of lighting equipment and high operating cost existed in these methods make them difficult to apply in industry. To solve these problems in the reduction processes, the oxidation methods [10-13] have widely been concerned, in which, NOx is oxidized to soluble nitrogenous species and absorbed by alkaline solutions. These methods can obtain well NOx removal efficiency, but some reported researches have the disadvantages of higher reagent prices and releasing secondary environmental pollutants [14,15]. Some kinds of adsorption materials such as zeolites [16], metal-organic frameworks (MOFs) [17] and activated carbons [18,19] could adsorb NO2 and exhibit well NO2 adsorption behavior. Ebrahim and Bandosz [17] synthesized zirconium-carboxylic ligand-based porous materials modified with –NH2 groups to separate NO2. The results 3



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suggested that water enhanced the NO2 adsorption process, and introducing Lewis basic sites by incorporation of –NH2 groups promoted chemical reactions on the surface, besides, amine (–NH2) or carbonyl (–C=O) groups in urea directly interacted with NO2 molecules in both moist and dry conditions, which leaded to the formation of surface bound nitrates. Kazmierczak et al. [19] studied that using micro radiation to deal with the activated carbons obtained from sawdust, and the results showed that NO2 adsorption properties of activated carbons depended on the temperature of activation, the conditions of adsorption and a suitable choice of the pyrolysis, and the activation of sawdust could give the adsorbents high NO2 capacity in dry and wet conditions respectively. In the adsorption methods above, NO2 was bonded with the adsorbents and transformed to the stable compound. We consider that NOx molecular is a kind of resource in industry, so developing a new method that can capture NO2 for further reuse has an application prospect. In our work, two kinds of relative low cost molecularly imprinted polymers were prepared with different templates to adsorb NO2 from flue gas. Surface area analyzer, thermo-gravimetric analyzer and FT-IR spectra were used to analyze the characteristic of the adsorbents. A series of adsorption experiments were carried out to investigate the effect of the temperature, gas flow rate and NO2 feed concentration on NO2 adsorption breakthrough curves and adsorption capacity. Besides, the effect of coexisted gases such as H2O, O2, SO2, and CO2 was also studied by breakthrough experiments.

2. Materials and Experiments 2.1 Chemicals and gases Acetic acid, ethanedioic acid, acrylamide (AAM), azodiisobutyronitrile (AIBN), 4


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acetonitrile (AN), toluene, methanol, and hydrochloric acid (HCl, 20 wt%) used in the experiments were analytical reagent grade and purchased from Kermel Chemical Reagent Ltd.

(Tianjin);

ethylene

glycol

dimethacrylate

(EGDMA)

was

obtained

from

Aladdin-Reagent (Shanghai, China). High purity water (>18 MΩ) was produced by lab water purification system (Changfeng Co., Ltd., Beijing). The gases used in the experiments were supplied by North Special Gas Co., Ltd. 2.2 Synthesis of MIP1 and MIP2 MIP1 was prepared as follows: 3 mmol acetic acid and 12 mmol AAM were dissolved in 20 ml AN/toluene (3/1, v/v) solution for 2 h with agitation followed by adding 30mmol EDGMA and 50mg AIBN. After that the mixture was well dispersed by ultrasonic device for 15min and purged with N2 for another 20 min to deoxidization. Then the mixture was sealed and reacted for 24 h at 70 ºC, and the solid polymer was formed. The polymers were grounded and screened to 50-150 μm, and washed with HCl/methanol (1/9, v/v) solution to remove template molecules. The washing procedure was repeated for several times until the template molecules could not be detected in the filtrate, and then the remaining polymer particles were washed with high purity water to neutral and dried overnight under vacuum at 120 ºC. The synthetic process of MIP2 was the same as that of MIP1, except for using ethanedioic acid instead of acetic acid as template molecule. In order to compare with MIPs to discuss the effect of the templates to the structure of the polymers and NO2 adsorption capacity, non-imprinted polymers (NIP) were also prepared by the same synthetic method except no templates were added. 5



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2.3 Characterization Nitrogen adsorption/desorption isotherms were obtained on a surface area and pore size analyzer (Beckman Coulter SA 3100, USA) at liquid nitrogen temperature. The Brunauer-Emmett-Teller (BET) method and the Barrett-Joyner-Halenda (BJH) model of the adsorption isotherm were used to calculate the surface area, the pore size distribution and the pore volume. Total pore volume was calculated from the amount of absorbed N2 at P/P0=0.99. Thermo-gravimetric analysis (TGA) (Netzch STA 449C, German) was used to characterize the thermal stability of the adsorbents. Adsorbents were pre-dried at 120 ℃ before thermal characterization to remove moisture. 10 mg of the adsorbents were heated from 25 to 600 ℃ in highly pure N2 atmosphere at a flow rate of 30ml/min. The Fourier transform infrared (FTIR) spectra of samples were collected on a FTIR spectrometer (Bruker Optics –Tensor II, German). 2.4 NO2 adsorption measurement NO2 adsorption experiments were conducted on a self-assembled fixed-bed reactor (a quartz glass tube of 5 mm i.d. and 200 mm length wound with a heating tape) at atmospheric pressure as shown in Figure 1, and the adsorption conditions of the reactor are shown in Table 1. 1 g of the adsorbent was loaded in the reactor, and glass wool was filled to prevent the adsorbent flowing away at both sides of the reactor. The adsorption temperature was monitored by two thermal couples which were located at the inlet and outlet of the reactor to control the temperature within ±0.5℃. Prior to each measurement, the adsorbent was activated by high purity N2 with a flow rate of 80 ml/min at 120℃ for 3 6


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h to eliminate impurities. The NO2 concentration at the outlet of the reactor was measured by a multi-functional flue gas analyzer (ecom-J2KNpro, German), and the NO2 adsorption capacity was calculated by integration of the breakthrough curve. The integral equation of breakthrough curve is displayed in Eq. (1): Qs=

(1)

where Qs is the saturated adsorption capacity of NO2 over adsorbents (mg/g); F represents the influent velocity of NO2 (m3/min); m is the weight of adsorbents (g); C0, C represent the concentration of the influent and effluent NO2 (mg/m3), respectively; t is the adsorption time (min). The effect of H2O, O2, CO2, and SO2 in simulated flue gas to NO2 adsorption capacity of MIP1 and MIP2 was investigated at the basic NO2 adsorption condition, and the concentration of H2O, O2, SO2, and CO2 was varied in succession severally.

3. Results and discussion 3.1 Preparation and characterization of MIP1 and MIP2 The structure of molecularly imprinted adsorbents is shown in Figure 2, and the distinction between MIP1 and MIP2 is the distance of adjacent functional monomers due to different templates. In the synthetic process, the functional monomers (AAM) arranged in a complementary configuration around templates (ethanotic acid or ethanedioic acid) by self-association, forming the complex, in which, the oxygen atom of templates was bonded to the hydrogen atom of amino groups in functional monomers, while the cross-linker was added, then a porous polymer contained nascent imprint sites was formed. After that, 7



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templates were removed by washing with HCl/methanol solution; finally, the vacant imprinted sites were formed. During the reaction between the imprinted adsorbent and NO2, the lone pair electrons in –NH2 of the absorbent were affected by the delocalization π bond of three-center and four-electron in NO2, and skew to NO2 to form –NH2+NO2- as the unstable intermediate by weak coordination interaction, thus NO2 molecule was adsorbed by the adsorbents. N2 adsorption isotherms and pore distribution curves of the prepared adsorbents are shown in Figure 3. The specific surface area (SBET), pore volume (Vp), and average pore diameter (dp) are summarized in Table 1. The isotherms for all the adsorbents are of type Ⅱ characteristics (see Figure 2A), suggesting that the adsorption processes are all multilayer reversible adsorption. As shown in Figure 2B, SBET, Vp, and dp of adsorbents vary with the different template molecules, and dp mainly varies from 20nm to 70nm, which matches with the isotherms of adsorbents. Compared MIPs with NIP, it was found that although the specific area was very weakly improved by adding templates, the pore structure of MIPs could be strongly affected, in which, the templates played a structure-directing role and helped the complex to form ordered structure, resulting in the more regular arrangement of functional monomers. Meanwhile, from the result of N2 isothermal adsorption experiment that MIPs have larger N2 adsorption volume than NIP, it can be concluded that MIPs also have larger adsorption volumes. Thus it can be considered that the regular arrangement of functional monomers and larger N2 adsorption volume of MIPs by adding templates are beneficial to enhance NO2 adsorption capacity. 8


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Figure 4 shows the TGA curves of adsorbents and no obvious mass loss is observed in the temperature range from 25 to 250 ℃ due to the pre-drying process for adsorbents. There are no obvious differences between the TGA curves of the three adsorbents, proving that when the functional monomer is the same, template has little impact on thermo-stability. Only 5% weight loss of adsorbents occurs at 320 ℃ for the adsorbents suggesting that the adsorbents can be applied in the relatively high temperature condition. The FTIR spectra of MIP1 are displayed in Figure 5, and due to the same chemical component of all the adsorbents, the FTIR spectra of MIP2 and NIP are not given here. As shown in Figure 5, the peaks at 2960cm-1, 1450cm-1, and 1390cm-1 are the saturated C-H stretching vibration, saturated C-H bending vibration, and rocking vibration of methyl and methyne for the adsorbents due to the opening of C=C to form C-C in the process of cross linking. The phenomena that the adsorption peak of C=C vibration is not observed in the area of 1660-1600 cm-1 also suggests that all C=C bonds of AAM and EDGMA are broken, and the strong peak at 1725 cm-1 is attributed to the unsaturated ester in the cross linker. There is a peak at 1680 cm-1 resulting from the N-H stretching vibration, which provides the evidence that the amine group of AAM is reserved on the surface of adsorbents after polymerization reaction. 3.2 The effect of experimental conditions on NO2 adsorption and determination of the basic operating conditions Figure 6 and Figure 7 present the breakthrough curves of MIP1 and MIP2 obtained at different experimental conditions respectively, and the breakthrough curves are described 9



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by three parameters that are tb, q, and Za. Among them, tb is defined as the time corresponding to Coutlet/Cinlet=0.1, q is NO2 saturated adsorption capacity, Za is the length of mass transfer zone calculated from the formula raised by Treybal (eq. 2) [20]. In general, the larger value of tb and q, the higher NO2 adsorption capacity becomes; the larger value of Za, the lower effective utilization rate of the adsorbent is in actual operation. (2) where, te is the time (min) when Coutlet/Cinlet is equal to 0.9; Z is the length of the reactor (120mm). As seen in Table 2, NO2 adsorption capacity of MIP2 is better than that of MIP1 at the fixed experiment condition, which may be due to the distinction of used templates. In the preparation process, MIP1 used acetic acid as templates, while MIP2 used ethanedioic acid containing two –COOH groups. Hence, MIP2 could combine more functional groups when the mole number of template was the same and that made MIP2 have more –NH2 groups than MIP1 to adsorb NO2. The data in Table 2 show that tb and q all decrease greatly with increase of the temperature, which may be resulting from the weak interaction between NO2 and the adsorbents. Hence, tb and q are affected significantly by the temperature. Za presented an opposite trend with increase of the temperature below 40℃, however when the temperature continued to rise, the value of Za increased again, indicating that excessive low temperature was against to the efficient use of the adsorbents because of lower reactivity between functional groups and NO2 molecule. However, excessive high temperature was also not 10


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beneficial to the efficient use of the adsorbent, which would decrease the rate of reaction between NO2 and –NH2. Though the lower temperature, the higher NO2 adsorption capacity for both MIP1 and MIP2, in practical application process, to avoid the energy consumption resulted from flue gas cooling and ensure the efficient use of the adsorbents, 40 ℃ was chosen here as a basic temperature in the following laboratory experiments. The adsorption capacity of MIP1 and MIP2 get the largest value at 120 and 100 ml/min respectively, as shown in Table 2, and the value of Za also increases with increase of the flow rate. The excessive low flow rate was negative for NO2 adsorption because NO2 molecules concentration at unit volume would cause that the adsorption sites in deep of the adsorbents could not be touched due to low concentration impetus, and on the other hand, the value of Za all increased with the increasing flow rate, so the excessive high flow rate did not contribute to the effectively using of adsorbents owing to the short retention time of NO2 stream. Thus, 100 ml/min was decided in the experiment as the basic flow rate condition. For both MIP1 and MIP2, the increase of NO2 feed concentration can improve the NO2 partial pressures, thus the adsorption capacity under the highest NO2 feed concentration is the best, according with Henry’s law, as shown in Table 2. However, higher feed concentration of NO2 makes mass transfer zone (Za) get longer, which is not beneficial to efficient utilization of the adsorbent. This phenomenon can be explained by the diffusion mechanism of NO2 in a fixed-bed [21]. When the NO2 feed concentration increased, the hydrodynamic behavior of the flue gas was changed, and the diffusion 11



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resistance became higher because of the increase of gas viscosity, leading to the decrease of diffusion rate and then the mass transfer zone increased. Hence, the NO2 of 1000 ppm was chosen as the basic concentration condition, according to the experimental results. For comparing the adsorption ability between MIPs and the non-imprinted adsorbent (NIP), the breakthrough curves of NIP at different experimental conditions were also tested, as shown in Figure 8. The corresponding parameters of breakthrough curves and NO2 adsorption capacities are listed in Table 2, it can be concluded that NIP has smaller values of tb and q than MIPs at each experimental condition, while NIP has the same variation tendency of Za with MIPs when adsorption condition changes. Those phenomena suggested that in the preparation process of MIPs, adding template could help them get more regular pores which was conducive to better NO2 adsorption capacity, and changing experimental conditions had the same effect to the length of mass transfer zone (Za) of porous materials MIPs and NIP. The reported NO2 adsorption capacities in MOFs [17] and carbon-based materials [18,19] at dry condition ranged from 3 to 79 mg/g, which were larger than those in MIPs. However, in these reports, the adsorbed NO2 formed stable nitrate species by the function of complicated surface groups and released NO causing air pollution in these adsorption processes, so that NO2 could not be reused. 3.3 Effect of coexistent gases on NO2 adsorption performance of MIP1 and MIP2 3.3.1 Effect of H2O on NO2 adsorption of MIP1 and MIP2 The breakthrough curves of NO2 affected by coexistent gases at the basic experimental 12


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condition are shown in Figure 9. Figure 9 (A1 and A2) shows the NO2 breakthrough curves of MIP1 and MIP2 at water concentration of 0%, 5%, 10%, 15% and 20%, and the calculated NO2 adsorption capacities of MIP1 are 0.58, 0.56, 0.55, 0.53 and 0.52mg/g, and those of MIP2 are 0.64, 0.62, 0.60, 0.58 and 0.57mg/g, respectively. The decrease of the adsorption capacity of MIP1 and MIP2 could be explained by the surface property of adsorbents and NO2 adsorption mechanism, that was. the amine active sites existed on the surface of MIP1 and MIP2 could interact with water molecule to form hydrogen bonds in theory and this made NO2 adsorption capacity decrease. On the other hand, the adsorption capacity did not decrease sharply, that was because the interaction between H2O and the adsorbents was interfered and reduced by large number of hydrophobic groups –(CH2-CH)n– around the amide, and the hydrogen bonds between water molecules would weaken the interaction between amide group and water molecule, that all made the adsorbed water on the surface of amide groups decrease, thus water molecules did not occupy too much effective amide groups for NO2 adsorption. It could be also concluded that MIP2 had larger decreasing rate of NO2 adsorption capacity than MIP1, which was because of different ratio of hydrophilic group (–NH2) to the hydrophobic functional group (–(CH2-CH)n–), and the high ratio of hydrophilic group (–NH2) in adsorbent made MIP2 had stronger ability to combine with water molecule thus the negative effect of water molecule to NO2 adsorption of MIP2 was larger than that of MIP1. 3.3.2 Effect of O2 on NO2 adsorption of MIP1 and MIP2 NO2 breakthrough curves of MIP1 and MIP2 obtained at five O2 concentrations are 13



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shown in Figure 9 (B1 and B2), and the corresponding calculated NO2 adsorption capacities are 0.58, 0.58, 0.58, 0.58 and 0.57 mg/g for MIP1, and 0.62, 0.62, 0.63, 0.63 and 0.63 mg/g for MIP2. The data indicated that there were only slightly fluctuations on NO2 adsorption capacity with variation of O2 concentration for both MIP1 and MIP2, thus it could be considered that O2 had little influence on NO2 adsorption capacity, which could be explained by that the diatomic O2 molecule had the character of non-polar, chemical and physical stability at the normal temperature. Moreover, the amide groups in MIP1 and MIP2 could not form hydrogen bonds with the stable O2, that made O2 hard to interact with the adsorbents. 3.3.3 Effect of SO2 on NO2 adsorption of MIP1 and MIP2 Figure 9 (C1 and C2) presents the NO2 breakthrough curves of MIP1 and MIP2 with SO2 concentrations of 0, 100, 150, 200, and 250 mg/m3, respectively. The NO2 adsorption capacities of MIP1 were 0.58, 0.56, 0.54, 0.52 and 0.50 mg/g, and those of MIP2 were 0.63, 0.58, 0.54, 0.51, and 0.47 mg/g by calculating, that revealed SO2 had a severely negative effect on NO2 adsorption capacity, which was because SO2 was polar molecule, and it could effectively compete with NO2 to bind with the active adsorption sites in MIP1 and MIP2. The drop rate of NO2 adsorption capacity of MIP1 was 13.8% and that of MIP2 was 25.4%, which was because MIP2 had more alkaline amino groups than MIP1 thus SO2 was easier to combine with MIP2, so MIP2 had larger decrease rate of NO2 adsorption capacity compared to MIP1. 3.3.4 Effect of CO2 on NO2 adsorption of MIP1 and MIP2 14


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Figure 9 (D1 and D2) shows the experimental breakthrough curves of NO2 with CO2 concentration rising from 0% to 20%. By calculating, the adsorption capacities of NO2 for MIP1 were 0.58, 0.55, 0.53, 0.52, and 0.41 mg/g, and those for MIP2 were 0.63, 0.54, 0.51, 0.48 and 0.45 mg/g, suggesting that the adsorption capacity decreased obviously with an increase of CO2 concentration, and the decrease rate of NO2 adsorption capacity was 19.6% for MIP1 and that was 32.7% for MIP2, separately. Because CO2 had no polarity, larger decrease of adsorption capacity of MIP2 could be explained by the acidity of CO2 and the more proper internal structure of MIP2 for CO2. The distance between adjacent N atoms calculated from ChemBio3D model of MIP2 was in the range of 0.49 and 0.70 nm which was larger than that of MIP1 (which was 0.32 nm). The aerodynamic diameter of CO2 was 0.33 nm, thus MIP2 was more suitable for the insertion of CO2 molecule, so that CO2 could occupy more alkaline adsorption sites in MIP2 than in MIP1 to make NO2 adsorption capacity decrease. The experimental results showed that O2 and H2O in the flue gas had less effect to NO2 adsorption, but SO2 and CO2 affected NO2 adsorption obviously. In consideration of the low concentration of NO2 adsorption in the presence of SO2 and CO2, it is necessary to just their concentration by selecting the installation site of NO2 adsorption equipment. We consider that in the future application, the NO2 adsorber can be arranged after flue gas desulfurization (FGD) and CO2 capture equipments because SO2 and CO2 concentrations are basically fixed for a certain type of coal and combustion conditions of the boiler. 4. Conclusion 15



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Two kinds of molecularly imprinted adsorbents were prepared to adsorb NO2 from flue gas. In the preparing process, adding templates could make the functional monomers arranged regularly, which could improve the adsorbents structure compared to non-imprinted adsorbents. All the adsorbents displayed good thermal stability at 250 ℃, and the FTIR spectra indicated that amino groups were able to graft on the surface of the adsorbents. At the NO2 basic adsorption condition, the NO2 adsorption capacity of MIP1, MIP2 and NIP was 0.58, 0.63 and 0.51 mg/g respectively. Using ethanedioic acid as template was more favor for NO2 adsorption. NO2 adsorption capacity of MIP1 and MIP2 was nearly unaffected by O2, however, CO2 and SO2 all had inhibited effects on NO2 adsorption capacity of MIPs. H2O molecule had less negative effects to NO2 adsorption due to large number of hydrophobic groups in the adsorbents and the hydrogen bonds between H2O molecules. Acknowledgments Funding: The work was supported by a grant from the key project of the National major research and development Program of China (No. 2016YFC0203700), National Science-technology Support Plan of China (No. 2014BAC23B04-06, Beijing Major Scientific

and

Technological

Achievement

Transformation

Project

of

China

(No.Z151100002815012), the Fundamental Research Funds for the Central Universities (No.

2016XS110),

Technology

development

projects

of

Sanhe

power

plant

(SH[2015]-QT44). 16


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Molybdenum-doped Titania Nanotubes, Chem. Eng. J. 2015, 269, 60-66. [10] Zhao, Y.; Han, Y.; Ma, T.; Guo, T.; Simultaneous Desulfurization and Denitrification from Flue Gas by Ferrate(VI). Environ. Sci. Technol. 2011, 45, 4060-4065. [11] Zhao, Y.; Guo, T.; Chen, Z.; Du, Y. Simultaneous Removal of SO2 and NO using M/NaClO2 complex absorbent, Chem. Eng. J. 2010, 160, 42-47. [12] Zhao, Y.; Hao, R.; Wang, T.; Yang, C. Follow-up Research for Integrative Process of Pre-oxidation and Post-absorption Cleaning Flue Gas: Absorption of NO2, NO and SO2. Chem. Eng. J. 2015, 273, 55-65. [13] Zhao, Yi.; Hao, R.; Xue, F.; Feng, Y. Simultaneous Removal of Multi-pollutants from Flue Gas by a Vaporized Composite Absorbent, J. Hazard. Mater. 2017, 321, 500-508. [14] Wang ,Z.; Zhou, J.; Zhu, Y.; Wen, Z.; Liu, J.; Cen, K. Simultaneous Removal of NOx, SO2 and Hg in Nitrogen Flow in a Narrow Reactor by Ozone Injection: Experimental Results, Fuel Process. Technol. 2007, 88,) 817-823. [15] Yu, M.; Dong, Y.; Wang, P.; Ma, C. Progress of Effects of Chloride on Mercury Removal for Coal-fired Flue gas, Chem. Ind. Eng. Progr. 2012, 31, 1610-1614. [16] Szanyi, J.; Kwak, J.; Peden, C. The Effect of Water on the Adsorption of NO2 in Na− and Ba−Y, FAU Zeolites: A Combined FTIR and TPD Investigation. J. Phys. Chem. B. 2015, 108, 3746-3753. [17] Ebrahim, A. M.; Bandosz, T. J. Effect of Amine Modification on the Properties of Zirconium-carboxylic Acid Based Materials and Their Applications as NO2 Adsorbents at Ambient Conditions. Micropor. Mesopor. Mat. 2014, 188, 149-162. 18


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[18] Nowicki, P.; Skibiszewska, P.; Pietrzak, R. NO2 Removal on Adsorbents Prepared from Coffee Industry Waste Materials. Adsorption 2013, 19, 521-528. [19] Kazmierczak-Razna, J.; Gralak-Podemska, B.; Nowicki, P.; Pietrzak, R. The Use of Microwave Radiation for Obtaining Activated Carbons from Sawdust and Their Potential Application in Removal of NO2 and H2S. Chem. Eng. J. 2015, 269, 352-358. [20] Treybal, R. E. Mass-transfer Operations. McGraw-Hill Book Company: New York, 1968. [21] Ruthven, D. M. Principles of Adsorption and Adsorption Process. John Wiley & Sons: New York, 1984.

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Tables Table 1. Fixed-bed characteristics and operating conditions for NO2 adsorption Samples

Fixed-bed

MIP1

MIP2

NIP

Bed Height (Z)

120mm

120mm

120mm

Inside Diameter

5mm

5mm

5mm

Particle Size

0.15±0.02mm

0.15±0.02mm

0.15±0.02mm

Average Pore Size (r)

10.2nm

10.4nm

12.4nm

Particle Surface Area

195m2/g

197m2/g

187 m2/g

0.496ml/g

0.512ml/g

0.577 ml/g

Parameters

(SBET) Particle

Pore

Volume

(Vp) Operation

Adsorption Temperature

20, 40, 60, 80, 100 ℃

Gas Flow Rate

40, 60, 80, 100, 120 ml /min

NO2 Feed Concentration

500, 1000, 1500,2000 ppm

Parameter

20


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Table 2. Values of breakthrough parameters under different temperature, gas flow rate and NO2 concentration at the inlet of the absorber for MIP1, MIP2 and NIP Conc. of

Temp. (℃)

Flow rate (ml/min)

q (mg/g)

tb(s)

Za(mm)

NO2 (ppm) MIP1

MIP2

NIP

MIP1

MIP2

NIP

MIP1

MIP2

NIP

20

100

1000

0.66

0.70

0.62

135

150

130

83

74

82

40

100

1000

0.58

0.63

0.51

131

146

107

77

72

89

60

100

1000

0.47

0.53

0.38

113

131

74

78

73

110

80

100

1000

0.40

0.47

0.34

99

124

71

85

74

110

100

100

1000

0.35

0.41

0.29

88

110

62

91

79

111

40

40

1000

0.27

0.28

0.25

161

168

143

66

70

77

40

60

1000

0.38

0.39

0.35

149

154

123

69

70

86

40

80

1000

0.46

0.50

0.44

138

148

113

72

71

91

40

100

1000

0.58

0.63

0.50

131

146

107

77

72

93

40

120

1000

0.59

0.61

0.43

105

98

69

85

102

102

40

100

500

0.3

0.33

0.27

157

166

113

64

61

90

40

100

1000

0.58

0.63

0.51

131

146

107

77

72

92

40

100

1500

0.85

0.9

0.73

91

93

87

113

110

106

40

100

2000

1.07

1.11

0.92

73

75

73

127

124

120 21



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Figure Legends Figure 1. Diagram of experimental apparatus for NO2 adsorption: (1) NO2 cylinder; (2) N2 cylinder; (3) SO2 cylinder or others; (4, 5, 6) pressure deducing valves; (7-10) flow meter; (11) mixed gas cylinders; (12, 13) three-way valve; (14, 15, 16) stop valves; (17) heating box; (18) fixed-bed reactor; (19, 20) temperature controller; (21) flue gas analyzer; (22) steam generator Figure 2. The structure of MIP adsorbent Figure 3. N2 isotherms (A) and pore size distribution curves (B) of MIP1, MIP2 and NIP Figure 4. Thermal decomposition of MIP1,MIP2 and NIP during the temperature range of 250-650 ℃ Figure 5. FTIR spectra of MIP1 Figure 6. Experimental breakthrough curves of NO2 at different fixed-bed conditions for MIP1. (A) Breakthrough curves of NO2 at 20℃ (■), 40℃ (○), 60℃(▲), 80℃(▽),and 100℃(♦) respectively, the NO2 feed concentration and flow rate were 1000ppm and 100ml/min. (B)Breakthrough curves of NO2 at flow rate of 40ml/min (■), 60ml/min (○), 80 ml/min (▲), 100 ml/min (▽), and 120 ml/min (♦) respectively, the temperature and the NO2 feed concentration were 40℃ and 1000ppm; (C) breakthrough curves of NO2 under NO2 feed concentration of 250ppm(■), 500ppm(○), 1000ppm(▲), and 1500ppm(▽) respectively, the temperature and flow rate were set as 40℃ and 100ml/min Figure 7. Experimental breakthrough curves of NO2 at different fixed-bed conditions for MIP2. (A) Breakthrough curves of NO2 at 20℃ (■), 40℃ (○), 60℃(▲), 80℃(▽),and 22


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100℃(♦) respectively, the NO2 feed concentration and flow rate were 1000ppm and 100ml/min. (B)Breakthrough curves of NO2 at flow rate of 40ml/min (■), 60ml/min (○), 80 ml/min (▲), 100 ml/min (▽), and 120 ml/min (♦) respectively, the temperature and the NO2 feed concentration were 40℃ and 1000ppm; (C) breakthrough curves of NO2 under NO2 feed concentration of 250ppm(■), 500ppm(○), 1000ppm(▲), and 1500ppm(▽) respectively, the temperature and flow rate were set as 40℃ and 100ml/min Figure 8. Experimental breakthrough curves of NO2 at different fixed-bed conditions for NIP. (A) Breakthrough curves of NO2 at 20℃ (■), 40℃ (○), 60℃(▲), 80℃(▽),and 100℃(♦) respectively, the NO2 feed concentration and flow rate were 1000ppm and 100ml/min. (B)Breakthrough curves of NO2 at flow rate of 40ml/min (■), 60ml/min (○), 80 ml/min (▲), 100 ml/min (▽), and 120 ml/min (♦) respectively, the temperature and the NO2 feed concentration were 40℃ and 1000ppm; (C) breakthrough curves of NO2 under NO2 feed concentration of 250ppm(■), 500ppm(○), 1000ppm(▲), and 1500ppm(▽) respectively, the temperature and flow rate were set as 40℃ and 100ml/min Figure 9. The breakthrough curves of MIP1 affected by H2O, O2, SO2 and CO2 (A1, B1, C1 and D1) and the breakthrough curves of MIP2 affected by H2O, O2, SO2 and CO2 (A1, B1, C1 and D1) respectively

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Figure 1.

Figure 2.

24


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Figure 3.

Figure 4.

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Figure 5.

Figure 6.

26


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Figure 7.

Figure 8.

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Figure 9.

28


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TOC

29


Synthesis of Molecularly Imprinted Polymers and Adsorption of NO2 in

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