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[Display omitted] • Euchlorine-based WOS completely removes NO x on top of SO x. • SO 2 plays a synergistic role in NO x absorption. • Acidity promotes a gas–liquid dual oxidation making the de-NO x process more efficient. • WOS under acidic conditions saves 83% chemical and 70% water. • WOS can be a viable alternative to the conventional FGD-SCR plants. This paper reports the performances of a pilot-scale Wet Oxidative Scrubber (WOS) in the treatment of a simulated flue-gas containing 500 ppm v SO 2 and 1030 ppm v NO x and operated at 60 °C and 1 atm. The scrubber is fed with an oxidizing solution containing NaClO 2 at either 0.75 % or 1 % w/w initially at pH > 9 and then acidified to pH down to 3 with HCl, to obtain the additional oxidative contribution given by euchlorine species during the simultaneous absorption. Further experiments of single-component NO x absorption are performed to better understand the role exerted by SO 2 in the simultaneous absorption. These experimental tests are carried out to investigate the effect of the acidity of the chlorite-based scrubbing solution on the simultaneous absorption performance of SO 2 and NO x , highlighting the intensification with respect to the bare de-NO x system. Experiments also allow determining the optimal dosages and solution pH for a complete and optimized removal of NO x and SO x also being less energy-intensive. For a scrubbing solution under acid-induced conditions (pH = 3), the retrieved results show that the NaClO 2 molar dosage needed for a complete simultaneous removal results 3.6 times greater than the total NO x concentration in the flue-gas. This allows an interesting reduction of 83 % in oxidant consumption and a water-saving of 70 % with respect to the same process applied to the simultaneous NO x absorption but without altering the solution pH. Overall, the results confirm the enhancing role exerted by euchlorine deriving from chlorite acidification and sulfur dioxide presence in the flue-gas. [ABSTRACT FROM AUTHOR]

• Pressure drop increases with an accumulation of clogged particles. • Evolution of pressure drop varies with both pore size and structure of a filter medium. • Two mechanisms contribute to filter clogging including internal clogging and caking. • A mathematical model was developed to model pressure drop development. Flooded-bed scrubbers are commonly employed in continuous miners to capture and remove dust particles at the cutting face in underground coal mines. To date, the mechanism of filter clogging as well as the evolution of pressure drop has not been well understood. In this work, clogging of filters in a relevant flooded-bed scrubber environment have been investigated in a laboratory setting by spraying a slurry onto a filter assembly while pulling the air through. Two types of filters have been investigated, including a) a multi-layer mesh filter and 2) a fibrous woven filter. Results showed that the differential pressure (or pressure drop) increased with an accumulation of clogged particles within the filter. The timed evolution of the pressure drop varied with both pore size and pore structure of the filter medium. When dust particles were much smaller than the pore size of the filter, dust particles predominantly accumulated inside the filter pack. When dust particles had comparable or larger sizes compared with the pore (or mesh) size of the filter medium, the filter was dominantly clogged at its front layers. Experimental results were compared with a modified model to account for the development of the pressure drop across the filter. The clogging of scrubber filters may be presented in two mechanisms, namely a) internal clogging and b) caking. The present result demonstrates the fundamental mechanism of clogging of dust particles within fibrous and mesh filters during dust capture and removal by flooded-bed wet scrubbers as well as other engineering applications involving in multi-phase interaction within a porous medium. [ABSTRACT FROM AUTHOR]

In recent years, Hg re-emission from the wet scrubber has become a hot topic in the field of Hg abatement since wet scrubber has been considered as an effective way to remove Hg. In this paper, the effects of Cu ions on Hg re-emission were investigated for the first time in the presence of SO 3 2− . The effect of CuCl 3 2− was proved to directly reduce Hg 2+ to insoluble Hg 0 and to catalytically decompose Hg(SO 3 ) 2 2− to Hg 0 and SO 4 2− in the presence of SO 3 2− . When adding the Cu 2+ into solution with low concentration, Hg re-emission was increased due to the generation of Cu + from the reduction of Cu 2+ by SO 3 2− . Further increase of Cu 2+ concentration inhibited Hg re-emission, which was possibly owing to the formation of metal Cu which could absorb Hg 0 to form amalgam. The decomposition of Hg(SO 3 ) 2 2− by CuCl 3 2− and Cu + meet pseudo-first-order reaction with respect to Hg 0 and the activation energy parameters are 64.43 and 48.78 kJ/mol, respectively. Difference of electron transfer path in the decomposition of Hg(SO 3 ) 2 2− with Cu + was proposed to be the reason of low activation energy. [ABSTRACT FROM AUTHOR]

• Pilot-scale tests on WES removal of particles and SO 2 are presented. • Charged droplets and gas ionization improved SO 2 absorption rate. • WES technology is suitable for fine and ultrafine particle capture. • A comparison with model for SO 2 absorption and particle abatement in WES is proposed. This work presents experimental and modeling results on SO 2 and combustion particles' removal in a pilot-scale wet electrostatic scrubber (WES). The WES unit was operated either as: i) a conventional spray scrubber (WS); ii) with only electrified spraying (CDES), and iii) with electrified spraying and corona pre-charging (OPES) by using a model seawater as absorbing liquid. The experiments indicated a progressive improvement of the SO 2 fractional approach to equilibrium by increasing the spray charge density in CDES configurations. Corona pre-charging further increased the SO 2 absorption rate of OPES compared with CDES configuration, thanks to the parallel depletion of ionized SO 2 on the scrubber walls. The fractional approach to equilibrium increased from around 87% for WS to around 97% for OPES. Similarly, the overall particle capture increased by increasing the spray charge density and the corona pre-charging potential: for WS configuration, the particles' removal efficiency was negligible, while becoming up to 91% under OPES configuration. CDES provided intermediate performances. Experiments can be described with high accuracy for SO 2 absorption in WS and CDES configurations, and for particle capture in OPES configurations. Further efforts are needed to describe the other conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] 2 Mesh pads in scrubber using Natural gas and /Exxsol at 20, 50 and 85 bars. [•] Pressure drop, separation efficiency, separated droplet size and flooding point. [•] Re-entrainment affects separation efficiencies at high pressures. [•] Droplets deposit via inertial impaction for the /Exxsol fluid systems. [•] Droplets deposit by direct interception for Natural gas systems. [Copyright &y& Elsevier]

Abstract: Re-emission of Hg0 refers to the reduction of oxidized mercury (Hg2+) to the elemental mercury (Hg0) in a wet flue gas desulfurization process (WFGD), resulting Hg0 re-emits to the flue gas and increasing mercury emission for a coal combustion power plant. The correlations between re-emission of Hg0 and operation parameters of WFGD process, i.e., sulfur dioxide removal, oxidation air flow, and pH of FGD slurry, were investigated with mercury field data collected from two coal combustion power plants (Plant C and Plant O). At Units 31/32 of Plant C, Coupling mercury results and the plant information (PI) data suggested that an increase of the oxidation air flow in the WFGD effectively inhibited the re-emission of Hg0, and consequently increased the flue gas mercury removal efficiency from 63% to over 92%. But at Plant O, the increase of the oxidation air flow can sometimes increase Hg0 re-emission. It was further found that the re-emission of Hg0 at Plant O was strongly correlated not only to the flow rate of the oxidation air in the forced-oxidation operation conditions, but also to the amount of sulfur dioxide removed from the flue gas by the FGD scrubber (i.e., the sulfur dioxide load in the scrubber). Possible mechanisms were proposed. [Copyright &y& Elsevier]

Abstract: This paper presents a novel magnesium-based wet flue gas desulfurization (FGD) process in which sodium thiosulfate is used to inhibit the oxidation of desulfurization byproduct. Effects of different operating variables in FGD process were experimentally researched in a spray scrubber. The results showed that the magnesium-based wet FGD process was more suitable for low SO2 concentration flue gas and indicated that the adding of Na2S2O3 could slightly enhance the desulfurization process and the MgSO3 content in the byproduct could be maintained above 95% when the thiosulfate-sulfite ratio was controlled above 1:6. A desulfurization process model was established by the double-film theory of mass transfer. The calculated mass transfer coefficients were in reasonable agreement with the experimental values and the absorption process was found to be controlled by gas-film diffusion. [Copyright &y& Elsevier]

Abstract: This two part-paper investigates the performance of SEWGS (Sorption Enhanced Water Gas Shift), an innovative reactor for CO2 capture, applied to an Integrated Gasification Combined Cycle (IGCC). In part-A, different SEWGS working conditions are investigated outlining several advantages and performance differences. A comparison of two sorbents is also performed. Part B presents the economic assessment of the investigated SEWGS cases together with the reference plants selected for electricity production. Both pulverized coal and integrated gasifier combined cycle were introduced as reference technologies. Results show that with the base sorbent performances the calculated cost of CO2 avoided is about 30€/tCO2, which is lower than IGCC with CO2 capture via Selexol and pulverized coal with amine scrubbing. SEWGS allows reducing investment costs, thanks to the simultaneous CO2 and H2S separation, and efficiency penalties compared to Selexol. The adoption of a sorbent with improved performances further reduces the cost of CO2 avoided down to 23€/tCO2: advantages of new sorbent are both in terms of equipment savings and lower efficiency penalty. The optimal SEWGS carbon capture rate is between 95% and 98%. Sensitivity analysis on SEWGS equipment cost showed that increasing investment cost of 50%, the impact on cost of CO2 avoided would be minimal, about 3€/tCO2. This activity was carried out under the FP7 project CAESAR financed by the EU community. [Copyright &y& Elsevier]

Abstract: This two part-paper investigates the performance of SEWGS (Sorption Enhanced Water Gas Shift), an innovative system for CO2 capture, applied to a coal fuelled Integrated Gasification Combined Cycle (IGCC). Firstly, two reference cases based on dry feed slagging Shell gasifier, with and without CO2 capture, are defined. Conventional pulverized coal plant, where CO2 capture is carried out with amine scrubbing technology, is also presented. Subsequently, SEWGS optimal integration in IGCC plant is investigated. The optimized parameters are SEWGS carbon capture ratio, CO2 purity and number of vessels. Moreover, two different types of sorbent, Sorbent Alfa and Sorbent Beta, are considered in order to evaluate the impact of sorbent cyclic capacity on system performances. Both sorbents capture H2S together with CO2 with efficiency and equipment advantages. Results show that optimal SEWGS carbon capture ratio is in the range of 95% for both Sorbent Alfa and Sorbent Beta, with the latter achieving net electric efficiency of 40%. The resulting specific energy consumption for CO2 avoided (SPECCA) is 2.0MJ/kgCO2, which is 40% to 60% lower than reference IGCC and ASC reference cases respectively. Even Sorbent Alfa, which features a lower capacity than Sorbent Beta, achieves a SPECCA of about 2.5MJ/kgCO2 which is 30% lower than reference case, illustrating SEWGS advantages. Part B will discuss the economic assessment of the investigated cases in order to determine the CO2 avoided cost. This activity is carried out under the FP7 project CAESAR financed by the European Commission. [Copyright &y& Elsevier]

Abstract: A continuous gas and liquid flow, regenerative scrubbing process for CO2 capture was demonstrated at the bench-scale level. An aqueous ammonia-based solution captures CO2 from simulated flue gas in an absorber and releases a nearly pure stream of CO2 in the regenerator. After the regeneration, the solution of ammonium compounds is recycled to the absorber. The design of a continuous flow unit was based on earlier exploratory results from a semi-batch reactor, where a CO2 and N2 simulated flue gas mixture flowed through a well-mixed batch of ammonia-based solution. During the semi-batch tests, the solution was cycled between absorption and regeneration steps to measure the carrying capacity of the solution at various initial ammonia concentrations and temperatures. Consequentially, a series of tests were conducted on the continuous unit to observe the effect of various parameters on CO2 removal efficiency and regenerator effectiveness within the flow system. The parameters that were studied included absorber temperature, regenerator temperature, initial NH3 concentration, simulated flue gas flow rate, liquid solvent inventory in the flow system, and height of the packed-bed absorber. From this testing and subsequent testing, ammonia losses from both the absorption and regeneration steps were quantified, and attempts were made to maintain steady state during operations. Implications of experimental results with respect to process design are discussed. [Copyright &y& Elsevier]

Abstract: The effect of different additives on the re-emission of Hg0 in wet limestone-based flue gas desulfurization (WFGD) conditions is assessed. Because re-emission of elemental mercury from limestone slurries is dependent on the pH of the gypsum slurry, re-emission of elemental mercury was evaluated for different additives using gypsum slurry with a constant pH value of 7. The additives investigated included oxidizing and reducing agents (Fenton reagents and sodium thiosulfate) and also chelating agents (2,4,6 trimercaptotriazine trisodium and sodium hydrosulfide). Fenton reagents were added to prevent the reduction of oxidized mercury species as H2O2 was the precursor used to convert sulfite ions into sulfate or to oxidize Hg0. Thiosulfate were added so that mercury could be retained in the gypsum at low concentrations as insoluble HgS, while mercury is being stabilized in the liquid fraction at higher additive doses. The addition of 2,4,6 trimercaptotriazine trisodium (TMT) and NaHS in low doses prevented the reduction of oxidized mercury species as insoluble HgS and Hg3 (TMT) precipitate onto the gypsum slurry. TMT was found to be most effective additive for Hg2+ capture. [Copyright &y& Elsevier]

Abstract: In fluidized-bed gasification (FBG) of biomass and waste the temperature is maintained relatively low to prevent agglomeration. This slows down carbon conversion in conventional FBG, and a gas with relatively high concentration of tar is generated. Then the gasification efficiency is reduced and utilization of the gas is difficult in applications where the gas is cooled or compressed. In the present work the conversion of char and tar is studied to identify the main factors hindering complete conversion of the fuel into a product gas that is free from tar. It is concluded that char conversion can be increased by solids recirculation in directly heated FBG (stand-alone units) or by burning the char in a separate chamber in indirectly heated FBG. However, the tar content of the gas remains high, making gas cleaning necessary. Downstream cleaning of gas by catalytic cracking and/or scrubbing is complex and/or expensive for small to medium gasification plants, so conversion of tar within the gasifier is preferred. The optimization of conventional directly heated FBG by use of in-bed catalyst and distribution of the gasification agent to various zones of the gasifier, although improving the process, is not sufficient to attain the gas purity required for cold gas applications. Staged gasification is a suitable way to reach high char conversion, while yielding a gas with low concentration of heavy tar. Most of the staged-gasification developments proposed up to date have been based on fixed-beds, thus having relatively small capacity. A recently proposed concept to achieve almost complete tar and char conversion in fluidized bed is presented. [Copyright &y& Elsevier]

Abstract: Mercury is a toxic pollutant that has motivated environmental regulations for emissions reduction from coal-fired power plants. Acid gas wet scrubbers are known to provide the co-benefit of SO2 control and mercury removal, when mercury is found in the flue gas in the oxidized form. The aqueous ionic chemistry in the scrubbing solution can lead to transformation of the absorbed ionic mercury to the insoluble elemental mercury form, resulting in mercury re-emission and a reduction of the scrubber mercury capture efficiency. Laboratory-scale experiments were performed in a simulated batch scrubber. The experiments were carried out to simulate a forced oxidation limestone reactor. The effect of scrubber temperature and pH, ionic mercury concentration in the liquor, total sulfite, and chloride and bromide ion concentration in solution, and O2 and CO2 concentration in the gas on mercury re-emission was investigated. Of particular interest was the investigation of the impact of slurry temperature and CO2 concentration in the gas, under conditions typical of oxy-fuel combustion condition, on mercury re-emission. The results confirm that oxidized mercury is reduced by aqueous S(IV). Higher concentrations of sulfites, chloride and bromide ions inhibit oxidized mercury transformation to elemental mercury. Higher concentrations of ionic mercury in the liquor and increased scrubber temperature and pH value results in higher re-emission levels of elemental mercury. Additionally, on the impact of oxy-fuel conditions on mercury, it was found that high availability of excess oxygen in the flue gas in contact with the scrubbing solution was found to result in lower conversion of oxidized to elemental mercury. No impact from CO2 in the flue gas was found on elemental mercury re-emission. However, higher slurry temperatures under oxy-fuel combustion conditions would lead to increased elemental mercury re-emission. For completeness, the effectiveness of sulfide-based additives for abatement of elemental mercury re-emission was also demonstrated in this study. The suppression effectiveness of sodium hydrogen sulfide, sodium sulfide, TMT15® and the Nalco-8034 reagent was found at 99%, 97%, 93% and 99%, respectively. These additives promote precipitation of ionic mercury as mercury sulfide. [Copyright &y& Elsevier]

Abstract: This paper describes a lab-scale simulated scrubber that was designed and built in the laboratory at Western Kentucky University’s Institute for Combustion Science and Environmental Technology. A series of tests on slurries of CaO, CaSO3, CaSO4/CaSO3 and Na2SO3 were carried out to simulate recirculating slurries in different oxidation modes. Elemental mercury (Hg0) re-emission was replicated through the simulated scrubber. The relationship between the oxidation–reduction potential (ORP) of the slurries and the Hg0 re-emissions was evaluated. Elemental mercury re-emission occurred when Hg2+ that was absorbed in the simulated scrubber was converted to Hg0; then, Hg0 was emitted from the slurry together with the carrier gas. The effects of both the reagents and the operational conditions (including the temperature, pH, and oxygen concentrations in the carrier gas) on the Hg0 re-emission rates in the simulated scrubber were investigated. The results indicated that as the operational temperature of the scrubber and the pH value of the slurry increased, the Hg0 concentrations that were emitted from the simulated scrubber increased. The Hg0 re-emission rates decreased as the O2 concentration in the carrier gas increased. In addition, the effects of additives to suppress Hg0 re-emission were evaluated in this paper. Sodium tetrasulfide, TMT 15, NaHS and HI were added to the slurry, while Hg2+, which was absorbed in the slurry, was retained in the slurry as mercury precipitates. Therefore, there was a significant capacity for the additives to suppress Hg0 re-emission. [Copyright &y& Elsevier]

Abstract: A series of laboratory scale experiments were conducted in an FGD-batch reactor. A synthetic flue gas was produced and directed through a CaCO3 suspension contained in a glass reactor vessel. The suspension temperature was set at 54°C through a water bath. In order to observe the distribution of mercury species in the system, solid, liquid and gaseous samples were taken and analysed. For gaseous mercury determination, continuous measurements were carried out, up and downstream the reactor. Furthermore, the concentration of chlorine in the scrubber solution of the system was varied from 0 to 62g/l under different oxidative conditions. In a first approach, a concentration drop of elemental mercury coming out of the system was observed. The latter occurs only when high concentrations of Cl− are present, combined with a high O2 availability in the scrubber. It was also observed that mercury species distribution in the different phases varies, depending on the available chemical form of chlorine and oxygen concentration. [Copyright &y& Elsevier]

Abstract: Post-combustion is considered among the different options for CO2 capture as the most mature available technology. All major components of the CO2 absorption/desorption process are commercially available but at a smaller scale, and they are not integrated and optimized for the application in power plants. Therefore, it is still to be demonstrated that this process is a viable option for the capture of CO2 at power plants. The amine scrubbing process with standard solvents is highly energy demanding due to solvent regeneration and CO2 compression. This is a significant energy sink for the power plant and efficiency can be reduced up to 16%-points. In order to minimise the energy penalty, complete integration and optimization of the capture and the power plant processes are necessary. Simulations of the power plant cycle and the amine scrubbing system have been performed with specialized software. The results of the integration are discussed. [Copyright &y& Elsevier]

Abstract: Particulates in pilot-scale flue gas desulfurization (FGD) scrubber water were characterized by powder X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, and size analysis based on Stokes’ Law after settling in an equalization basin of a pilot-scale constructed wetland treatment system. Three sources were interpreted for specific particle types identified in samples analyzed: FGD wet scrubbing processes, coal combustion byproducts, and uncombusted material from coal. Gypsum (CaSO4 ·2H2O) from the FGD scrubbing process comprises ∼95% of the particulates. Iron oxide particles and cenospheres in the particulate samples are interpreted as coal combustion products. Particles interpreted as originating from unburned coal contain carbon and metals including Zn and Fe. The most abundant elements in the particulates analyzed are O, C, Ca, S, Fe, and Si, with maximum mean content of individual elements ranging from 13% to 70% among particle types. Less abundant elements include Al, K, Mg, Ti, and Mo, with maximum mean content from 0.1% to 3.8%. [Copyright &y& Elsevier]

• A novel design of wet SO x scrubber prepared for compliance with new regulations. • Identification of key parameters affecting the SO x removal efficiency. • Systematic approach to improve design quality of SO x scrubber systems. • Introduction of adjustable design variables for minimizing energy consumption. • A new design of open-loop system is proposed. Regulations on emission control of sulfur oxides (SO x) contained in exhaust gas (EG) from ships' engines enter into force. In the recent past, emission control regulations have continually been made more stringent. Consequently, there is an urgent need for novel emission abatement technologies for ship operators, to satisfy the regulations. The objective of this study was to investigate a novel design of a wet SO x scrubber prepared for compliance with the new regulations and to identify the key parameters affecting the SO x removal efficiency and design optimization. The model of wet SO x scrubber system was developed and validated using actual experimental results. On the basis of a parametric analysis, a design for an open-loop mode involving the cooling of the EG inlet temperature via an EG inlet/wash water heat exchanger is proposed. Design optimization results showed that the liquid-to-gas (L/G) ratio and EG inlet temperature could be adjusted to reduce the required power of a seawater (SW) pump by 31.72% and 51.17% for an open-loop system operated inside and outside designated emission control areas, respectively. For a closed-loop system, the adjustment of the L/G ratio, circulating wash water's (WW's) temperature, and chemical dosing flow rate reduced the amount of dose input and required power of the SW pump and circulating WW pump by 11%, 66%, and 49%, respectively. [ABSTRACT FROM AUTHOR]

• Gaseous and particulate emissions were evaluated pre- and post-scrubber. • No significant changes were seen in NOx, CO, and CO 2 emissions post-scrubber while cruising. • NOx emissions showed large reductions post-scrubber while the vessel was at-berth. • Post-scrubber SOx emissions showed dramatic reductions. • Limited PM removal efficiencies with the scrubber. This study assessed the real-world gaseous and particulate emissions for a wet scrubber retrofit to an existing container ocean-going vessel as it cruised from Tacoma Washington to Anchorage Alaska. The vessel was operated with a high sulfur heavy fuel oil and testing was performed following the ISI 8178 E2 steady test cycle. The scrubber unit provided more than a 95% removal efficiency of sulfur dioxide (SO 2) emissions across all engine loads. In contrast to the higher removal efficiencies for SO 2 emissions, the scrubber only removed approximately 10% (ISO weighted reduction) of particulate matter (PM 2.5) emissions. PM 2.5 composition was primarily composed of sulfate, followed by organic carbon (OC) and elemental carbon (EC). Pre- and post-scrubber sulfate levels were similar, indicating why the PM 2.5 removal efficiencies were low. This phenomenon was likely due to the formation of small sulfuric acid particles in the scrubber fluid that were not efficiently removed by impaction, influencing PM 2.5 mass emission measurements. [ABSTRACT FROM AUTHOR]

• Up to 80% of total inlet mercury (HgT) concentration can leave the WFGD scrubber. • The oxidised form of mercury (Hg2+) can be the main form of re-emitted mercury. • Hg in the solid phase of the slurry may be as high as 10 μg/g. • Iron (Fe) is mainly responsible for disrupting the Hg absorption in the scrubber. • Fe contributes to the partitioning of the Hg between phases and to its re-emission. • High iodine ions (I-) concentration leads to Hg re-emission in its oxidised form. The paper describes and discusses the results of research on mercury behaviour, especially its high emission, in both forms: elemental (Hg0) and oxidised (Hg2+) , from the wet flue gas desulphurisation scrubber (WFGD) in a lignite-fired power plant located in central Europe. The presented results involve the collection of lignite power plant samples (liquid, solid, gas) and different laboratory chemical analyses to try to understand the mechanism of mercury re-emission from the wet flue gas desulfurization system. It was noted that 67–80% of the total inlet mercury concentration left the WFGD scrubber. Moreover, the oxidised form of mercury was the main emitted form (about 60–70% of the total mercury concentration). The results show that mercury was found in very high concentration (10 μg/g) (range: ppm) in the WFGD solid by-products, whereas the liquid phase contained only 1 μg//l (range: ppb). Considering literature reports and presented data from the investigated power station, we believe that iron (Fe), which occurs in very high concentrations in solid WFGD samples (1.81% wt. Fe) and lignite (up to 20 g/kg Fe) is mainly responsible for disrupting the mercury absorption in the scrubber, the partitioning of the mercury between phases and leads to its reemission. Moreover, we believe also that a relatively high iodine ion concentration (130 mg/l) in the limestone slurry leads to mercury emission in its oxidised form, mainly as HgI 2 , which is highly volatile. Other minor components from limestone dissolution such as Mn, Al and Mg may additionally enhance that "complex" mercury behaviour. [ABSTRACT FROM AUTHOR]

Development of a low-cost, stable and high-efficiency method is a vital challenge for elemental mercury (Hg0) decontamination from nonferrous smelting flue gas. The ultrafine size (<10 nm) and homodisperse nanometer sulfur (Nano-sulfur) was synthesized from alkali desulfurization solution by using a facile method. The as-synthesized Nano-sulfur exhibited excellent Hg0 removal performance over the bulk sulfur and commercial sublimed sulfur. Sulfur dioxide was surprisingly proved as a promoter for Nano-sulfur to enhance the Hg0 removal in this study. Nano-sulfur dispersion showed higher than 92% removal efficiency for 119 h under high-concentration SO 2 atmosphere. The Hg0 adsorption capacity and rate of Nano-sulfur reached 242.1 mg/g and 24.6 μg/(g·min) respectively, which were both higher than other traditional adsorbents like sulfur-containing activated carbon and metal sulfides. S new was proved as the main active substance to remove Hg0, which could be continuously generated from Nano-sulfur by the reversible reaction under effect of SO 2. The gaseous Hg0 was largely transformed to colloidal phase (87.47%) and precipitated phase (10.53%) in the HgS form after wet scrubbing. This work offers a new path towards the design of nonferrous smelting flue gas Hg0 purification method by adding Nano-sulfur dispersion into the wet scrubber of existing air pollution control devices, i.e., flue gas scrubber and wet flue gas desulfurization. [ABSTRACT FROM AUTHOR]