Comparative analyses of mitogenomes in the social bees with insights into evolution of long inverted repeats in the Meliponini.

The insect mitogenome is typically a compact circular molecule with highly conserved gene contents. Nonetheless, mitogenome structural variations have been reported in specific taxa, and gene rearrangements, usually the tRNAs, occur in different lineages. Because synapomorphies of mitogenome organizations can provide information for phylogenetic inferences, comparative analyses of mitogenomes have been given increasing attention. However, most studies use a very few species to represent the whole genus, tribe, family, or even order, overlooking potential variations at lower taxonomic levels, which might lead to some incorrect inferences. To provide new insights into mitogenome organizations and their implications for phylogenetic inference, this study conducted comparative analyses for mitogenomes of three social bee tribes (Meliponini, Bombini, and Apini) based on the phylogenetic framework with denser taxonomic sampling at the species and population levels. Comparative analyses revealed that mitogenomes of Apini and Bombini are the typical type, while those of Meliponini show diverse variations in mitogenome sizes and organizations. Large inverted repeats (IRs) cause significant gene rearrangements of protein coding genes (PCGs) and rRNAs in Indo-Malay/Australian stingless bee species. Molecular evolution analyses showed that the lineage with IRs have lower d N/ d S ratios for PCGs than lineages without IRs, indicating potential effects of IRs on the evolution of mitochondrial genes. The finding of IRs and different patterns of gene rearrangements suggested that Meliponini is a hotspot in mitogenome evolution. Unlike conserved PCGs and rRNAs whose rearrangements were found only in the mentioned lineages within Meliponini, tRNA rearrangements are common across all three tribes of social bees, and are significant even at the species level, indicating that comprehensive sampling is needed to fully understand the patterns of tRNA rearrangements, and their implications for phylogenetic inference.

Mechanistic Insight into the Promotion of the Low-Temperature NH3-SCR Activity over NiMnFeOx LDO Catalysts: A Combined Experimental and DFT Study.

Mn-based catalysts have attracted much attention in the field of the low-temperature NH3 selective catalytic reduction (NH3-SCR) of NO. However, their poor SO2 resistance, low N2 selectivity, and narrow operation window limit the industrial application of Mn-based oxide catalysts. In this work, NiMnFeOx catalysts were prepared by the layered double hydroxide (LDH)-derived oxide method, and the optimized Ni0.5Mn0.5Fe0.5Ox catalyst had the best denitration activity, excellent N2 selectivity, a wider active temperature range (100-250 °C), higher thermal stability, and better H2O and/or SO2 resistance. A transient reaction revealed that Ni0.5Mn0.5Fe0.5Ox inhibited the NH3 + O2 + NOx pathway to generate N2O, which may be the main reason for its improved N2 selectivity. Combining experimental measurements and density functional theory (DFT) calculations, we elucidated at the atomic level that sulfated NiMnFeOx (111) induces the adjustment of the acidity/basicity of up and down spins and the ligand field reconfiguration of the Mn sites, which improves the overall reactivity of NiMnFeOx catalysts. This work provides atomic-level insights into the promotion of NH3-SCR activity by NiMnFeOx composite oxides, which are important for the practical design of future low-temperature SCR technologies.

Hydrolysis of Carbonyl Sulfide in Blast Furnace Gas Using Alkali Metal-Modified γ-Al2O3 Catalysts with High Sulfur Resistance.

A carbonyl sulfide (COS) hydrolysis catalyst can play an efficient role in blast furnace gas (BFG), but the life of the catalyst is greatly shortened due to the presence of O2 and H2S in the atmosphere, so improving the sulfur resistance of the catalyst is the key to application. In this work, alkali metals Na and K modified γ-Al2O3 catalysts to improve COS hydrolysis efficiency and sulfur resistance by adding an alkaline center. Compared with γ-Al2O3 catalysts, the COS hydrolysis efficiency of the modified catalysts in the experiment was improved by 12% in the presence of H2S and O2. The main cause of catalyst sulfur poisoning is the presence of O2, which intensifies both the total amount of sulfur deposition and the proportion of sulfate. It is found that the NaOH/Al2O3 catalyst shows better sulfur resistance than the KOH/Al2O3 catalyst for two reasons: first, the support of Na can significantly improve the medium-strong alkaline site, which is the adsorption site of H2S. This is equivalent to increasing the "sulfur capacity" of H2S adsorption and reducing the impact of sulfur deposition on the main reaction. Second, the elemental sulfur is more easily produced on the NaOH/Al2O3 catalyst, but the sulfur is further oxidized to sulfate and sulfite on the KOH/Al2O3 catalyst. The molecular diameter of elemental sulfur is smaller than that of sulfate. Therefore, the NaOH/Al2O3 catalyst has better sulfur resistance.

Visualizing the role of applied voltage in non-metal electrocatalysts.

Understanding how applied voltage drives the electrocatalytic reaction at the nanoscale is a fundamental scientific problem, particularly in non-metallic electrocatalysts, due to their low intrinsic carrier concentration. Herein, using monolayer molybdenum disulfide (MoS2) as a model system of non-metallic catalyst, the potential drops across the basal plane of MoS2 (ΔVsem) and the electric double layer (ΔVedl) are decoupled quantitatively as a function of applied voltage through in-situ surface potential microscopy. We visualize the evolution of the band structure under liquid conditions and clarify the process of EF keeping moving deep into Ec, revealing the formation process of the electrolyte gating effect. Additionally, electron transfer (ET) imaging reveals that the basal plane exhibits high ET activity, consistent with the results of surface potential measurements. The potential-dependent behavior of kf and ns in the ET reaction are further decoupled based on the measurements of ΔVsem and ΔVedl. Comparing the ET and hydrogen evolution reaction imaging results suggests that the low electrocatalytic activity of the basal plane is mainly due to the absence of active sites, rather than its electron transfer ability. This study fills an experimental gap in exploring driving forces for electrocatalysis at the nanoscale and addresses the long-standing issue of the inability to decouple charge transfer from catalytic processes.

Assessment of particulate matter inhalation during the trip process with the considerations of exercise load.

A Particulate Matter (PM) inhalation model considering exercise load is established to evaluate the impact of PM on residents' travel health. The study chooses PM detectors to collect PM concentrations at the various transportation space, including walking, bicycle, bus, taxi, and subway. A multiple linear regression model revised by road greening is utilized to study the influence factors that have a potential impact on the PM concentration. The air inhalation model with the consideration of exercise load can be acquired by connecting the heart rate (HR) and individual characteristics. The PM2.5 and PM10 inhalation for a complete trip of traveler can be estimated using the proposed model based on air inhalation per time unit, travel time, and PM concentration. The analysis results using the experimental data in Xi'an indicate that PM concentrations in taxi carriage, bus carriage, and subway carriage are significantly different from those obtained from environmental monitoring stations. However, the difference is not significant in the locations of sidewalk, non-motorized lane, taxi station, bus station, subway concourse, and subway platform. PM concentration and humidity in background environment have a positive influence on the increase of PM concentration in transportation environment, while temperature and wind speed are negative. The mean values of air inhalation per time unit for male and female using each mode are in the range of 9.6-26.8 L/min and 9.8-27.8 L/min, respectively. Exposure time in non-motorized transportation has a large effect on PM inhalation of travelers, walking connections and waiting in motorized transportation are the main contributing states to PM inhalation of travelers. The results of the study can be used to predict travelers' PM inhalation in completed trips, and provide recommendations for travelers to choose a healthier mode.

Multi-process and multi-pollutant control technology for ultra-low emissions in the iron and steel industry.

The iron and steel industry is not only an important foundation of the national economy, but also the largest source of industrial air pollution. Due to the current status of emissions in the iron and steel industry, ultra-low pollutant emission control technology has been researched and developed. Liquid-phase proportion control technology has been developed for magnesian fluxed pellets, and a blast furnace smelting demonstration project has been established to use a high proportion of fluxed pellets (80%) for the first time in China to realize source emission reduction of SO2 and NOx. Based on the characteristics of high NOx concentrations and the coexistence of multiple pollutants in coke oven flue gas, low-NOx combustion coupled with multi-pollutant cooperative control technology with activated carbon was developed to achieve efficient removal of multiple pollutants and resource utilization of sulfur. Based on the characteristics of co-existing multiple pollutants in pellet flue gas, selective non-catalytic reduction (SNCR) coupled with ozone oxidation and spray drying adsorption (SDA) was developed, which significantly reduces the operating cost of the system. In the light of the high humidity and high alkalinity in flue gas, filter materials with high humidity resistance and corrosion resistance were manufactured, and an integrated pre-charged bag dust collector device was developed, which realized ultra-low emission of fine particles and reduced filtration resistance and energy consumption in the system. Through source emission reduction, process control and end-treatment technologies, five demonstration projects were built, providing a full set of technical solutions for ultra-low emissions of dust, SO2, NOx, SO3, mercury and other pollutants, and offering technical support for the green development of the iron and steel industry.

Promoting effect of Fe/La loading on γ-Al2O3 catalyst for hydrolysis of carbonyl sulfur.

Catalytic hydrolysis of carbonyl sulfur (COS) from blast furnace gas is one of the keys to achieving ultra-low emission in the iron-steel industry. To improve the COS hydrolysis activity on γ-Al2O3 catalyst at low temperature, catalysts with Fe or La as the active component were prepared by the impregnation method, the physical and chemical properties of the catalyst were characterized by ICP, XRF, XRD, BET, and TPD. The hydrolysis activity of COS and sulfur resistance ability on various catalysts were investigated in a fixed bed reactor combined with gas chromatography. The results show that the addition of Fe or La improves the COS hydrolysis activity due to the increase in alkaline sites on the catalyst surface. The roles of various alkaline sites on catalysts have been recognized. The weak alkaline center is the reaction site of COS hydrolysis, the middle and strong alkaline centers are the adsorption and oxidation sites of H2S. The Fe/Al2O3 catalyst has higher hydrolytic activity and oxidative capacity for H2S removal due to forming more sulfate species on Fe. The La/Al2O3 catalyst has higher hydrolysis efficiency in that H2S rapidly desorbs from the catalyst surface to the gas phase, and then, the activity of reaction sites is recovered. This provides an idea for the preparation of sulfur-resistant catalysts.

The promoting/inhibiting effect of water vapor on the selective catalytic reduction of NOx.

In the field of nitrogen oxides (NOx) abatement, developing selective catalytic reduction (SCR) catalysts that can operate stably in the practical conditions remains a big challenge because of the complexity and uncertainty of actual flue gas emissions. As water vapor is unavoidable in the actual flue gas, it is indispensable to explore its effect on the performance of SCR catalysts. Many studies have proved that the effects of H2O on de-NOx activity of SCR catalysts were indeed observed during SCR reactions operated under wet conditions. Whether the effect is promotive or inhibitory depends on the reaction conditions, catalyst types and reducing agents used in SCR reaction. This review focuses on the effect of H2O on SCR catalysts and SCR reaction, including promoting effect, inhibiting effect, as well as the effecting mechanism. Besides, various strategies for developing a water-resistant SCR catalyst are also included. We hope that this work can give a more comprehensive insight into the effects of H2O on SCR catalysts and help with the rational design of water-resistant SCR catalysts for further practical application in NOx abatement field.

Emission characteristics of volatile organic compounds during a typical top-charging coking process.

The emission of volatile organic compounds (VOCs) from coking industry severely reduces air quality. Using both offline and online methods, the emissions of 124 VOCs and non-methane hydrocarbon (NMHC) in a typical top-charging coke oven were analyzed during the coking process (emissions form the coke oven flue gas, charging, pushing, coke dry quenching, and topside of the coke oven). The concentrations of VOCs in coke oven flue gas and exhaust gas during charging were the highest, which reached 98.2 mg/m3 and 136.6 mg/m3, respectively. This was followed by the concentrations of exhaust gases sourced from the topside of the coke oven, pushing, and coke dry quenching, which were 12.0 mg/m3, 1.8 mg/m3, and 0.8 mg/m3, respectively. The main components of VOCs for the different exhaust emission sources were significantly different. The ozone formation potentials (OFPs) of coke oven flue gas and exhaust gas during charging were the largest, and unsaturated hydrocarbons such as alkenes and benzenes were the main source of ground-level ozone. These data can support researchers in developing adsorption, catalytic oxidation, and other technologies for the removal of VOCs generated by the coking process.

Rubusdianchuanensis sp. nov. (Rosaceae) from Sichuan and Yunnan, southwest China.

Rubusdianchuanensis, a new name for the species previously named as R.vicarius by W. O. Focke in 1911, is proposed. A detailed description, illustrations, and remarks on its phenology, ecology, and geographic distribution are provided. This raspberry (subg. Idaeobatus) is endemic to China and was only found in Sichuan and Yunnan, southwest China. Morphologically, it is most similar to R.ovatisepalus but clearly differs from the latter by having leaf densely white or grey tomentose abaxially, usually leaf-like bracts at the base of inflorescence, 1-6 cm long pedicels, and triangular-ovate sepals with acute to caudate apex.

Carbon consumption and regeneration of oxygen-containing functional groups on activated carbon for flue gas purification.

High carbon consumption is an important factor restricting the wide application of activated carbon technology for flue gas purification. A fixed-bed reactor combined with a Fourier transform infrared (FTIR) spectrometer was used to explore the source of carbon consumption at various SO2 concentrations and cyclic adsorption-regeneration times. The results demonstrate that carbon consumption originates from two sources and is mainly determined by the reaction of H2SO4 and C at high SO2 concentrations and by the thermal decomposition of oxygen-containing functional groups at low SO2 concentrations. An interesting observed phenomenon is that carbon consumption does not increase as the SO2 concentration increases. The conversion mechanism reveals that carboxylic and anhydride groups are converted to phenol and quinone groups, which do not easily decompose with increasing SO2 concentration. In the process of cyclic adsorption-regeneration, it is discovered that the carbon consumption in the first cycle is several times higher than that in the following cycles due to the decomposition of functional groups from the activated carbon itself. The regeneration mechanism of functional groups has been elucidated. The carboxylic acid and the phenolic hydroxyl on the surface of activated carbon are consumed in the regeneration process and formed again from the conversion of carbonyl groups in the next adsorption process under the roles of O2 and H2O. It is proposed that the functional groups are regenerated in the adsorption process rather than in the regeneration process.

Carbon consumption and adsorption-regeneration of H2S on activated carbon for coke oven flue gas purification.

Carbon consumption of activated carbon varies with sulfur-containing products. In this work, differential thermogravimetric (DTG), electron paramagnetic resonance (ESR), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD) we re used to reveal the adsorption-regeneration process of H2S and the effect of adsorption products on carbon consumption. The results show that H2S reacts with the C=C bond to form the C-S bond as an intermediate state, followed by the formation of elemental sulfur. It directly sublimates at approximately 380 °C, about 30 °C higher than the decomposition temperature of H2SO4. In the thermal regeneration process, the elemental sulfur in the form of monoclinic sulfur (S8) first breaks into infinitely long chain molecules (S∞) and then into small molecules, finally into sulfur vapor. The desorption of elemental sulfur consumes less oxygen and carbon functional groups, reducing the chemical carbon consumption by 59.8% than H2SO4; moreover, the compressive strength reduces less due to its slight effect on the disordered graphitic structure. H2S also reacts with the C=O bond to form H2SO3 or H2SO4. The desorption of H2SO3 does not require carbon consumption. The decomposition of H2SO4 needs to react with the C=C bond to release SO2, CO2, and CO, and the compressive strength of activated carbon significantly decreases. The carbon consumption originates from two aspects; the one from the regeneration of sulfur-containing products is more than twice the other one from the decomposition of oxygen-containing functional groups.

Coupling mechanism of activated carbon mixed with dust for flue gas desulfurization and denitrification.

To clarify the effect of coking dust, sintering dust and fly ash on the activity of activated carbon for various industrial flue gas desulfurization and denitrification, the coupling mechanism of the mixed activated carbon and dust was investigated to provide theoretical reference for the stable operation. The results show that coking dust had 34% desulfurization efficiency and 10% denitrification efficiency; correspondingly, sintering dust and fly ash had no obvious desulfurization and denitrification activities. For the mixture of activated carbon and dust, the coking dust reduced the desulfurization and denitrification efficiencies by blocking the pores of activated carbon, and its inhibiting effect on activated carbon was larger than its own desulfurization and denitrification activity. The sintering dust also reduced the desulfurization efficiency on the activated carbon while enhancing the denitrification efficiency. Fly ash blocked the pores of activated carbon and reduced its reaction activity. The reaction activity of coking dust mainly came from the surface functional groups, similar to that of activated carbon. The reaction activity of sintering dust mainly came from the oxidative property of Fe2O3, which oxidized NO to NO2 and promoted the fast selectively catalytic reduction (SCR) of NO to form N2. Sintering dust was activated by the joint action of activated carbon, and both had a coupling function. Sintering dust enhanced the adsorption and oxidation of NO, and activated carbon further promoted the reduction of NOx by NH3; thus, the denitrification efficiency increased by 5%-7% on the activated carbon.

Recent advances in layered double hydroxides (LDHs) derived catalysts for selective catalytic reduction of NOx with NH3.

In recent years, layered double hydroxides (LDHs) derived metal oxides as highly efficient catalysts for selective catalytic reduction of NOx with NH3 (NH3-SCR) have attracted great attention. The high dispersibility and interchangeability of cations within the brucite-like layers make LDHs an indispensable branch of catalytic materials. With the increasingly stringent and ultra-low emission regulations, there is an urgent need for highly efficient and stable low-medium temperature denitration catalysts in markets. In this contribution, we have critically summarized the recent research progress in the LDHs derived NH3-SCR catalysts, including their ability for NOx removal, N2 selectivity, active temperature window, stability and resistance to poisoning. The advantages and defects of various types of LDHs-derived catalysts are comparatively summarized, and the corresponding modification strategies are discussed. In addition, considering the importance of the catalyst's resistance to poisoning in practical applications, we discuss the poisoning mechanism of each component in flue gases, and provide the corresponding strategies to improve the poisoning resistance of catalysts. Finally, from the perspective of practical applications and operation cost, the regeneration measures of catalysts after poisoning is also discussed. We hope that this work can give timely technical guidance and valuable insights for the applications of LDHs materials in the field of NOx control.

A review of the catalysts used in the reduction of NO by CO for gas purification.

The reduction of NO by the CO produced by incomplete combustion in the flue gas can remove CO and NO simultaneously and economically. However, there are some problems and challenges in the industrial application which limit the application of this process. In this work, noble metal catalysts and transition metal catalysts used in the reduction of NO by CO in recent years are systematically reviewed, emphasizing the research progress on Ir-based catalysts and Cu-based catalysts with prospective applications. The effects of catalyst support, additives, pretreatment methods, and physicochemical properties of catalysts on catalytic activity are summarized. In addition, the effects of atmosphere conditions on the catalytic activity are discussed. Several kinds of reaction mechanisms are proposed for noble metal catalysts and transition metal catalysts. Ir-based catalysts have an excellent activity for NO reduction by CO in the presence of O2. Cu-based bimetallic catalysts show better catalytic performance in the absence of O2, in that the adsorption and dissociation of NO can occur on both oxygen vacancies and metal sites. Finally, the potential problems existing in the application of the reduction of NO by CO in industrial flue gas are analyzed and some promising solutions are put forward through this review.

Carbon consumption mechanism of activated coke in the presence of water vapor.

To reduce chemical carbon consumption in activated coke technology used for flue gas purification, the carbon consumption mechanism of commercial activated coke in the presence of water vapor was studied. A fixed-bed reactor and a Fourier transform infrared (FTIR) spectrometer were combined to study the amount of carbon consumption. Temperature-programmed desorption (TPD) coupled with in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectra were used to investigate functional group changes of activated coke. The sources and factors influencing carbon consumption in various adsorption atmospheres and in the N2 regeneration atmosphere were compared. Carbon consumption during the adsorption and regeneration process was mainly due to the release of C-O and C=C groups. The addition of H2O increased the formation of carbonates and carboxylic acids during the adsorption process, which decomposed during the regeneration process, thereby increasing carbon consumption. Carbon consumption was reduced during regeneration in an H2O-SO2 adsorption atmosphere, mainly because of the formation of C-S bonds, which reduced the formation of CO2. The C-N bonds generated in an H2O-NO adsorption atmosphere were decomposed during the regeneration process, thereby increasing carbon consumption. In a complex atmosphere of SO2, NO, NH3, and H2O, SO2 was absorbed by NH3, and the amount of carbon consumption was consistent with that in the NO atmosphere during the regeneration process. The total carbon consumption in various adsorption atmospheres ranged from 85.4 to 125.2 µmol/g. Compared with an anhydrous atmosphere, chemical carbon consumption increased by 6.5-14.3% in the presence of H2O. Chemical carbon consumption was reduced by decreasing the H2O concentrations, which provides a reference concept for reducing the operating cost of the activated coke process in industry.

Study on the denitrification performance of FexLayOz/activated coke for NH3-SCR and the effect of CO escaped from activated coke at mid-high temperature on catalytic activity.

Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel FexLayOz/AC catalysts was prepared by the incipient wetness impregnation for NH3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NOx conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH3-TPD, H2-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO3 and oxygen vacancies were produced on the catalysts' surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NOx removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NOx removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NOx removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015~0.007%/min at 300-400 °C. Hence, 4% Fe0.3La0.7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.

Formation of sulfur trioxide during the SCR of NO with NH3 over a V2O5/TiO2 catalyst.

The oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) is an undesirable reaction that occurs during the selective catalytic reduction (SCR) of nitrogen oxides (NO x ) with ammonia (NH3), which is a process applied to purify flue gas from coal-fired power plants. The objectives of this work were to establish the fundamental kinetics of SO3 formation over a V2O5/TiO2 catalyst and to illustrate the formation mechanism of SO3 in the presence of NO x , H2O and NH3. A fixed-bed reactor was combined with a Fourier transform infrared (FTIR) spectrometer and a Pentol SO3 analyser to test the outlet concentrations of the multiple components. The results showed that the rate of SO2 oxidation was zero-order in O2, 0.77-order in SO2 and -0.19-order in SO3 and that the apparent activation energy for SO2 oxidation was 74.3 kJ mol-1 over the range of studied conditions. Based on in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectroscopy, X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) tests, the SO3 formation process is described here in detail. The adsorbed SO2 was oxidized by V2O5 to produce adsorbed SO3 in the form of bridge tridentate sulfate, and the adsorbed SO3 was desorbed to the gas phase. NO x promoted the oxidation of the adsorbed SO2 due to the promotion of the conversion of low-valent vanadium to high-valent vanadium. In addition, the desorption of the adsorbed SO3 was inhibited by H2O or NH3 due to the conversion of tridentate sulfate to the more stable bidentate sulfate or ammonium bisulfate. Finally, the mechanism of the influence of NO x , H2O and NH3 on the formation of gaseous SO3 was proposed.

Evaluation of sulfur trioxide detection with online isopropanol absorption method.

Measurement of the SO3 concentration in flue gas is important to estimate the acid dew point and to control corrosion of downstream equipment. SO3 measurement is a difficult question since SO3 is a highly reactive gas, and its concentration is generally two orders of magnitude lower than the SO2 concentration. The SO3 concentration can be measured online by the isopropanol absorption method; however, the reliability of the test results is relatively low. This work aims to find the error sources and to evaluate the extent of influence of each factor on the measurement results. The test results from a SO3 analyzer showed that the measuring errors are mainly caused by the gas-liquid flow ratio, SO2 oxidation, and the side reactions of SO3. The error in the gas sampling rate is generally less than 13%. The isopropanol solution flow rate decreases 3% to 30% due to the volatilization of isopropanol, and accordingly, this will increase the apparent SO3 concentration. The amount of SO2 oxidation is linearly related to the SO2 concentration. The side reactions of SO3 reduce the selectivity of SO42- to nearly 73%. As sampling temperature increases from 180 to 300°C, the selectivity of SO42- decreases from 73% to 50%. The presence of H2O in the sample gas helps to reduce the measurement error by inhibiting the volatilization of the isopropanol and weakening side reactions. A formula was established to modify the displayed value, and the measurement error was reduced from 25%-54% to less than 15%.

Adsorption and desorption of SO2, NO and chlorobenzene on activated carbon.

Activated carbon (AC) is very effective for multi-pollutant removal; however, the complicated components in flue gas can influence each other's adsorption. A series of adsorption experiments for multicomponents, including SO2, NO, chlorobenzene and H2O, on AC were performed in a fixed-bed reactor. For single-component adsorption, the adsorption amount for chlorobenzene was larger than for SO2 and NO on the AC. In the multi-component atmosphere, the adsorption amount decreased by 27.6% for chlorobenzene and decreased by 95.6% for NO, whereas it increased by a factor of two for SO2, demonstrating that a complex atmosphere is unfavorable for chlorobenzene adsorption and inhibits NO adsorption. In contrast, it is very beneficial for SO2 adsorption. The temperature-programmed desorption (TPD) results indicated that the binding strength between the gas adsorbates and the AC follows the order of SO2>chlorobenzene > NO. The adsorption amount is independent of the binding strength. The presence of H2O enhanced the component effects, while it weakened the binding force between the gas adsorbates and the AC. AC oxygen functional groups were analyzed using TPD and X-ray photoelectron spectroscopy (XPS) measurements. The results reveal the reason why the chlorobenzene adsorption is less affected by the presence of other components. Lactone groups partly transform into carbonyl and quinone groups after chlorobenzene desorption. The chlorobenzene adsorption increases the number of C=O groups, which explains the positive effect of chlorobenzene on SO2 adsorption and the strong NO adsorption.