Release Of Na Research Articles

Physiological responses of Microcystis aeruginosa against the algicidal bacterium Pseudomonas aeruginosa

Proliferation of cyanobacteria in aquatic ecosystems has caused water security problems throughout the world. Our preliminary study has showed that Pseudomonas aeruginosa can inhibit the growth of cyanobacterium, Microcystis aeruginosa. In order to explore the inhibitory mechanism of P. aeruginosa on the cell growth and synthesis of intracellular substances of M. aeruginosa, concentrations of Chlorophyll-a, intracellular protein, carbohydrate, enzyme activities and ion metabolism of M. aeruginosa, were investigated. The results indicated that 83.84% algicidal efficiency of P. aeruginosa was achieved after treatment for 7 days. The strain inhibited the reproduction of M. aeruginosa by impeding the synthesis of intracellular protein and carbohydrate of cyanobacterium, and only a very small part of intracellular protein and carbohydrate was detected after exposure to P. aeruginosa for 5 days. P. aeruginosa caused the alteration of intracellular antioxidant enzyme activity of M. aeruginosa, such as catalase, peroxidase. The accumulation of malondialdehyde aggravated membrane injury after treatment for 3 days. P. aeruginosa also affected the ion metabolism of cyanobacteria. The release of Na+ and Cl− was significantly enhanced while the uptake of K+, Ca2+, Mg2+, NO3− and SO42− decreased. Surface morphology and intracellular structure of cyanobacteria and bacterial cells changed dramatically over time as evidenced by electron microscope (SEM) and transmission electron microscope (TEM) analysis. These results revealed that the algicidal activity of P. aeruginosa was primarily due to the fermentation liquid of P. aeruginosa that impeded the synthesis of intracellular protein and carbohydrate, and damaged the cell membrane through membrane lipid peroxidation.

Binding Site Protonation and Uphill Occlusion Control the Na+/K+-Pump Selectivity

The Na+/K+-pump resides in the plasma membrane and maintains the physiological K+ and Na+ concentration gradient across the cell membrane. It operates via a ping-pong mechanism, making iterative transitions between inward-facing (E1) and outward-facing (E2) conformations. The E1 conformation binds three Na+ from the cytosol and exports them using the energy from ATP hydrolysis. The release of Na+ and the binding of K+ at the extracellular side trigger the structural transition to the occluded E2 state, which imports two K+, as the pump returns to the E1 conformation. Although the general features of the pumping cycle are known, the detailed mechanism governing the selectivity in different states of the pump is not well understood. Using free energy molecular dynamics simulations based on the crystal structures of the pump in its E1 and E2 states, the current study reveals a switch in the binding site protonation state upon the E1-E2 transitions, giving the ion binding site its specificity when the pump is in different states. Ion selectivity of the states along the pump cycle has also been calculated. The relative binding free energy of Na+ and K+ in the binding sites calculated along the conformational transition of the protein reveals a self-correcting mechanism that ensures the selectivity and the stoichiometry of the pumping cycle.

Kinetic, equilibrium and thermodynamic studies of Ni(II) ions sorption on sulfuric acid treated Lagenaria vulgaris shell

Chemically modified Lagenaria vulgaris shell (ccLVB) was tested as a new sorbent for the removal of Ni(II) from aqueous solution, in batch conditions. The sorption process was very fast reaching equilibrium in about 20 min. Ni(II) sorption is almost invariant in the pH range from 3 to 6. Sorption kinetics followed pseudo-second order, intraparticle diffusion and Chrastil?s models, which suggest that both surface reaction and diffusion were the rate-limiting steps. Equilibria experimental results are well fitted by Langmuir and Temkin sorption isotherm models, indicating mixed adsorption process. The maximum biosorption capacity of ccLVB for Ni(II) was found to be 84.51 mg g-1. The calculated thermodynamic parameters showed that the biosorption of nickel on ccLVB was feasible, spontaneous and exothermic at 25-45?C. The desorption experiments showed that the ccLVB could be reused for five cycles without significant loss in sorption capacity. Release of Na+ ions from the biosorbent during sorption of Ni(II) reveals that the main sorption mechanism is ion exchange. Presented study suggests that ccLVB can be used effectively for the removal of Ni(II) ions from aqueous solution.

Existence and release of sodium in Zhundong coal: effects of treating temperature and silica additives

Zhundong coalfield is the largest integrated coal basin in China and has been only recently discovered. Zhundong coal contains a high amount of sodium, which induces severe slagging. In this study, the existence and transformation of alkali and alkali earth metals in Zhundong coal were investigated, and the effects of treating temperature and silica additives were determined. The results show that most of the Na and partial Ca species in raw Zhundong coal and ash were soluble. Sulphates were found in ash and did not decompose until 1,150°C. In the ash prepared at 500°C, a specific amount of MgCa(CO3)2 was found in the ash and decomposed at >600°C. The release of Na during ashing is mainly attributed to water-soluble Na because of the insignificant change in the acid-soluble and insoluble Na content in ash with increasing treating temperature. Silica additives have an effective function in capturing Na species at high temperatures. With increasing additive mass, the relative content of water-soluble Na is significantly reduced, but more water-insoluble Na is retained in the residual ash. [Received: May 10, 2014; Accepted: August 21, 2014]

The initial dissolution rates of simulated UK Magnox–ThORP blend nuclear waste glass as a function of pH, temperature and waste loading

AbstractThe first comprehensive assessment of the dissolution kinetics of simulant Magnox–ThORP blended UK high-level waste glass, obtained by performing a range of single-pass flow-through experiments, is reported here. Inherent forward rates of glass dissolution were determined over a temperature range of 23 to 70°C and an alkaline pH range of 8.0 to 12.0. Linear regression techniques were applied to the TST kinetic rate law to obtain fundamental parameters necessary to model the dissolution kinetics of UK high-level waste glass (the activation energy (Ea), pH power law coefficient (η) and the intrinsic rate constant (k0)), which is of importance to the post-closure safety case for the geological disposal of vitreous products. The activation energies based on B release ranged from 55 ± 3 to 83 ± 9 kJ mol–1, indicating that Magnox–THORP blend glass dissolution has a surface-controlled mechanism, similar to that of other high-level waste simulant glass compositions such as the French SON68 and LAW in the US. Forward dissolution rates, based on Si, B and Na release, suggested that the dissolution mechanism under dilute conditions, and pH and temperature ranges of this study, was not sensitive to composition as defined by HLW-incorporation rate.

Alterations in perivascular innervation function in mesenteric arteries from offspring of diabetic rats.

We have reported that exposure to a diabetic intrauterine environment during pregnancy increases blood pressure in adult offspring, but the mechanisms involved are not completely understood. This study was designed to analyse a possible role of perivascular sympathetic and nitrergic innervation in the superior mesenteric artery (SMA) in this effect. Diabetes was induced in pregnant Wistar rats by a single injection of streptozotocin. Endothelium-denuded vascular rings from the offspring of control (O-CR) and diabetic rats (O-DR) were used. Vasomotor responses to electrical field stimulation (EFS), NA and the NO donor DEA-NO were studied. The expressions of neuronal NOS (nNOS) and phospho-nNOS (P-nNOS) and release of NA, ATP and NO were determined. Sympathetic and nitrergic nerve densities were analysed by immunofluorescence. Blood pressure was higher in O-DR animals. EFS-induced vasoconstriction was greater in O-DR animals. This response was decreased by phentolamine more in O-DR animals than their controls. L-NAME increased EFS-induced vasoconstriction more strongly in O-DR than in O-CR segments. Vasomotor responses to NA or DEA-NO were not modified. NA, ATP and NO release was increased in segments from O-DR. nNOS expression was not modified, whereas P-nNOS expression was increased in O-DR. Sympathetic and nitrergic nerve densities were similar in both experimental groups. The activity of sympathetic and nitrergic innervation is increased in SMA from O-DR animals. The net effect is an increase in EFS-induced contractions in these animals. These effects may contribute to the increased blood pressure observed in the offspring of diabetic rats.

Sequential substitution of K(+) bound to Na(+),K(+)-ATPase visualized by X-ray crystallography.

Na+,K+-ATPase transfers three Na+ from the cytoplasm into the extracellular medium and two K+ in the opposite direction per ATP hydrolysed. The binding and release of Na+ and K+ are all thought to occur sequentially. Here we demonstrate by X-ray crystallography of the ATPase in E2·MgF42−·2K+, a state analogous to E2·Pi·2K+, combined with isotopic measurements, that the substitution of the two K+ with congeners in the extracellular medium indeed occurs at different rates, substantially faster at site II. An analysis of thermal movements of protein atoms in the crystal shows that the M3–M4E helix pair opens and closes the ion pathway leading to the extracellular medium, allowing K+ at site II to be substituted first. Taken together, these results indicate that site I K+ is the first cation to bind to the empty cation-binding sites after releasing three Na+.

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the “Dr. Eduardo J. Usunoff” Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO3-Ca type, in the middle basin it is HCO3-Na, and in the lower basin it is ClSO4–NaCa and Cl–Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO2, calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30m depth.

Ion-exchange breakthrough curves for single and multi-metal systems using marine macroalgae Pelvetia canaliculata as a natural cation exchanger

In this study, single and multi-metal ion-exchange systems, Na+/H+/Cd2+, Na+/H+/Pb2+, Na+/H+/Cu2+, Na+/H+/Zn2+ and Na+/H+/Cd2+/Pb2+/Cu2+/Zn2+, were studied in continuous mode using a fixed-bed column packed with Na-loaded macroalgae Pelvetia canaliculata as natural cation exchanger. Breakthrough curves were obtained for all the systems operating at inlet metal concentrations of 20mg/L. For the single metal ion-exchange systems, the service capacity obtained was 329, 107, 120 and 184 bed volumes for Zn2+, Cu2+, Cd2+ and Pb2+, respectively. Desorption, using 0.1M HNO3 as eluent, was fast and near to 100% of effectiveness, using only 10 bed volumes of eluent, achieving maximum metal concentrations at the column outlet of 2.8 3.8, 1.5 and 1.8g/L for Cd2+, Pb2+, Cu2+ and Zn2+ ions, respectively. In the multi-metal sorption process, Cd and Zn break through the column faster than Cu and Pb due to its lower affinity for the biosorbent. An overshoot in the Cd and Zn outlet concentrations was observed for the multi-metal system and explained by the competitive uptake with Pb and Cu ions. Biosorption of Cd2+, Pb2+, Cu2+ and Zn2+ by P. canaliculata pre-loaded with sodium is based on an ion-exchange mechanism accompanied by the release of Na+ into the liquid phase. A mass transfer model, including the mass balances to the packed bed column and thin plate algal particles, assuming a LDF model, and complementary equations (as mass action law equilibrium relations, initial and boundary equations), was able to fit well the experimental data. Finally, an ion-exchange pilot plant was tested for the treatment of a multi-metal synthetic solution using the natural macroalgae.

Na+/K+-ATPase Pumping Mechanism: Insights from Simulations

The Na+/K+-ATPase resides in the plasma membrane and maintains the physiological K+ and Na+ concentration gradient across the cell membrane. It functions via a ping-pong mechanism, making iterative transitions between inward-facing (E1) and outward-facing (E2) conformations. The E1 conformation binds three Na+ from the cytosol and exports them using the energy from ATP hydrolysis. The release of Na+ and the binding of K+ at the extracellular side trigger the structural transition to the E2(K2) state, which imports two K+, followed by the pump returning to the E1 conformation. Although the broad features of the pumping cycle are known, the transition mechanisms between the conformational states and why a given state preferentially binds K+ or Na+, two monovalent cations of very similar radius, is not understood. Starting from the available x-ray structures of the Na+/K+-ATPase and the SERCA Ca2+-pump, we use anisotropic network model pathway calculations and targeted molecular dynamics simulations to generate atomic models of the outward facing Na+/K+-ATPase, Na3E2-P and K2E2-P. Qualitative support of the models comes from a recent Na+/K+-ATPase x-ray structure and previous mutagenesis data. In addition to this, the gating charge and dissociation constants of the extracellular Na+/K+ binding calculated using the models are in excellent agreement with experimental data as well. The model generation process also produces the occlusion/de-occlusion transition pathways upon ion binding. To study the change in ion selectivity during the occlusion/de-occlusion process, free energy perturbation calculations are performed. The results reveal the molecular determinants of the 3Na-2K stoichiometry of the Na+/K+-ATPase.

Nicotinic acetylcholine receptors control acetylcholine and noradrenaline release in the rodent habenulo-interpeduncular complex.

Background and purposeNicotinic acetylcholine receptors (nACh receptors) play a central role in the habenulo-interpeduncular system. We studied nicotine-induced release of NA and ACh in the habenula and interpeduncular nucleus (IPN).Experimental approachThe habenula and IPN were loaded with [3H]-choline or [3H]-NA and placed in superfusion chambers. [3H]-ACh release was also stimulated using nicotinic agonists, electrical pulses and elevated [KCl]o in hippocampal and cortical slices from rats, wild-type mice and mice lacking α5, α7, β2, or β4 nACh receptor subunits. Finally, we analysed nACh receptor subtypes in the IPN using immunoprecipitation.Key resultsNicotine induced release of [3H]-ACh in the IPN of rats and mice. This release was calcium-dependent but not blocked by tetrodotoxin (TTX); moreover, [3H]-ACh release was abolished in β4-knockout mice but was unaffected in β2- and α5-knockout mice. In contrast, nicotine-induced release of [3H]-NA in the IPN and habenula was blocked by TTX and reduced in both β2-knockout and β4-knockout mice, and dose–response curves were right-shifted in α5-knockout mice. Although electrical stimuli triggered the release of both transmitters, [3H]-ACh release required more pulses delivered at a higher frequency.Conclusions and implicationsOur results confirm previous findings that β4-containing nACh receptors are critical for [3H]-ACh release in the mouse IPN. Experiments using α5-knockout mice also revealed that unlike in the hippocampus, nicotine-induced [3H]-NA release in the habenulo-interpeduncular system is altered in this knockout model. As α5-containing nACh receptors play a key role in nicotine intake, our results add NA to the list of transmitters involved in this mechanism.

Hydrogeochemical characterization of groundwater aquifer in Al-Madinah Al-Munawarah City, Saudi Arabia

In the Al Madinah Al Munawarah city, urbanization has accelerated rapidly over the last few decades which has caused both decline of groundwater level and deterioration of groundwater. The city is located in the center of sedimentary basin that consists of alluvial deposits originated from the erosion of surrounding igneous rocks. It has been grown very rapidly both in population and land use. The hydrogeological and hydrogeochemical characteristics of Al Madinah Al Munawarah city have been studied. The only recharge source of the groundwater of the study area is rainwater. Concentrations of total dissolved solids, major constituents, and trace elements in groundwater increased significantly after construction of industrial area to the south of the city near Wadi Al Aqiq and after increasing the urbanization, indicating an important pollutant process over the study area. The EC and TDS values ranged widely from 1,179.83 to 9,843.03 μmohs/cm and from 755.09 to 6,299.54 mg/l, respectively. Such a wide range of EC and TDS values indicate that the hydrochemistry of groundwater is controlled by various hydrochemical processes such as agricultural and farm activities, industrial development, landfills leachate, septic tanks, and wastewater of municipal and domestic consumption. Hydrochemical facies of groundwaters change broadly from a Ca-SO4 type in southwestern part near Wadi Al Aqiq to a Na-Cl type in both southeastern part at Harrat Rahat and northern part of the study area. Values of Na/Cl ratio indicate that silicate weathering and halite dissolution are the main processes resulting in release of Na into groundwater. Nitrate originates from fertilizers application and leakage of sewage with the highest value of 261 mg/l. Groundwater samples from southeastern part have high levels of heavy metals which render them unsafe for drinking purposes as compared with WHO guidelines. Where the maximum concentration values reach 0.850 mg/l for Fe, 0.120 mg/l for As, 0.985 mg/l for Ba, 1.030 mg/l for V, and 0.890 mg/l for Al. These high concentrations are mainly derived from leakage from the unlined industrial wastewater disposal site located to the southwest of the city. Disposal of industrial wastewater in such insecure landfill should be prohibited and the landfill should be properly designed to prevent further groundwater pollution.

Effect of 1-naphthaleneacetic acid on organic acid exudation by the roots of white lupin plants grown under phosphorus-deficient conditions

The effect of NAA (1-naphthaleneacetic acid) on organic acid exudation in white lupin plants grown under phosphorus deficiency was investigated. Plants were sampled periodically for collecting of organic acids (citrate, malate, succinate), and also were used to study the effect on proton extrusion and release of Na(+), K(+), Ca(2+) and Mg(2+). The tissues were later processed to quantify the organic acids in tissues, the phosphorus content and the effects on plant biomass. The exogenous addition of NAA led to an increase in organic acid exudation, but this response was not proportional to the concentration of the dose applied, noticing the largest increments with NAA 10(-8)M. In contrast the increase in root weight was proportional to the dose applied, which shows that with higher doses the roots produced are not of proteoid type. Proton extrusion and the release of cations were related to the NAA dose, the first was proportional to the dose applied and the second inversely proportional. Regarding the analysis of tissues, the results of citrate and phosphorus content in shoots show that the overall status of these parts are the main responsible of the organic acids exuded. NAA served as an enhancer of the organic acid exudation that occurs under phosphorus deficient conditions, with a response that depends on the dose applied, not only in its magnitude, but also in the mechanism of action of the plant hormone.

Phosphate-based glass fiber vs. bulk glass: Change in fiber optical response to probe in vitro glass reactivity

This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca–P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca–P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca–P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca–P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ.

The Migration Characteristics of Sodium during Biomass Combustion

During biomass combustion, alkali metals are partly released to the gas phase and form low melting point compound, which may enrich to the heat exchangers and cause heavy sinters in the incinerator. The aim of this study is to obtain quantitative data on the migration of sodium by measuring the content of sodium remained in the combustion products using AAS. Three groups of biomass ashes were produced respectively to investigate the influence of combustion temperature, fuel thickness and kaolin addition. The results indicate that, rising temperature enhances Na release from the biomass to the gas phase, while increasing the fuel thickness does the opposite. The reaction of kaolin and Na to generate a high melting point material inhibits the migration of Na, which reduces the biomass sintering in the incinerator.

Evidence for TiON sputtered surfaces showing accelerated antibacterial activity under simulated solar irradiation

New evidence is reported for TiON sputtered polyester surfaces activated by sunlight irradiation leading to the accelerated bacterial inactivation in the minute range. The absorption in Kubelka–Munk units of the TiON film was observed to be directly proportional to the time of Escherichia coli inactivation as detected by diffuse reflection spectroscopy (DRS). TiON layers were characterized by electron microscopy and by high angle angular dark field (HAADF) showing the continuous coverage of the polyester fibers by the TiON film. Ti4+/Ti3+ redox catalysis was detected on the TiON surface by the XPS shifts during the bacteria inactivation process. Production of HO radicals on TiON–polyester as a function of sunlight irradiation was determined following the fluorescence of 2-hydroxyterephthalic acid. Release of Na and K-ions was determined by ICP-MS and provides the evidence that cell wall damage is a preceding step leading the bacterial inactivation. A stable performance of the TiON films was observed during repetitive bacterial inactivation.

Regulating Environmental Factors of Nutrients Release from Wheat Straw Biochar for Sustainable Agriculture

AbstractOne mechanism by which biochar application enhances soil nutrient availability is through direct nutrients release from biochar. However, factors controlling the release processes are poorly understood. In this study, the effects of pH, biochar to water ratio, temperature, ionic strength, and equilibration time on the release of PO, NO, NH, K+, Na+, Ca2+, and Mg2+ from biochar were evaluated in simulated experiments. The release of PO, K+, Ca2+, and Mg2+ was significantly affected by extraction pH, suggesting that their release from biochar was pH dependent or an H+‐consuming process. Correlation analysis indicated that PO and Ca2+, PO and Mg2+, and Ca2+ and Mg2+ were co‐solubilized with increasing soil acidity. To a lesser extent, the recovery of the nutrients was also affected by the ratio of biochar to water: more nutrients were soluble with more water supply. In contrast, the release of Na was not affected by pH while the concentration increased with decreasing biochar to water ratio. Meanwhile, other factors (temperature, ionic strength, and equilibration time) had less effect on nutrient release from biochar. Under the influence of pH, the patterns of NO and PO release from biochar were different: extractable NO concentration was not affected by the pH but more PO was released in strongly acidic conditions. Our data suggested that P was mainly retained in inorganic forms while N was in organic forms in biochar. We conclude that environmental factors have marked influences on nutrients release from biochar.

In-situ Measurement of Sodium and Potassium Release during Oxy-Fuel Combustion of Lignite using Laser-Induced Breakdown Spectroscopy: Effects of O2 and CO2 Concentration

Laser-induced breakdown spectroscopy (LIBS) was used in this study to measure quantitatively the sodium (Na) and potassium (K) release from burning coal particles under oxy-fuel combustion environments. A specially designed laminar premixed burner was employed to provide a postflame environment with different O-2 and CO2 concentrations, in which the effects of O-2 and CO2 on the release of Na and K during coal oxy-fuel combustion were studied systematically. For the devolatilization stage, neither O-2 nor CO2 had significant influence on the Na and K release. The release of Na and K during the char stage, however, changed significantly at different O-2 and CO2 concentrations. Under these experimental conditions, when the O-2 concentration increased from 3.9% to 10.6%, the peak concentration of Na at the char stage increased from 15.2 mg/m(3) to 33.7 mg/m(3), and the maximum concentration of K increased from 6.2 mg/m(3) to 11.7 mg/m(3). When the CO2 concentration increased from 35.8% to 69.4%, the release of Na and K was inhibited during the char stage, with the peak concentration decreasing from 8.9 mg/m(3) to 6.9 mg/m(3) for Na and from 3.7 mg/m(3) to 2.4 mg/m(3) for K. During the ash stage, the release of Na and K decreased with the O-2 concentration, whereas it increased with the CO2 concentration. (Less)

Chemical Equilibrium Prediction on Release of Na,K,Cl and S-Species during Gasification of Biomass, Soft and Hard Chinese Coal at Elevated Temperature and Pressure by Fact Sage

The release of alkali species can cause of severe problem of hot corrosion during gasification especially at high temperature and pressure. The direct use of coal may harmful for power plants. The aim of work to obtained comprehensive knowledge prior utilization of coal. Therefore, thermodynamic equilibrium calculations were performed by Fact Sage 5.2 and simulated the gasification environment at elevated temperature and pressure. Four hard and soft Chinese coal such as Yungui (Vad<6.6%), Xiao Tun(Vad<11.1), Datong (Vad <23.18), Ping Zhuan (Vad<31.84) ,and Saw dust (Vad<68.80) and Saw dust char (Vad<3.39) belongs to anthracite, Sub-bituminous, lignite, biomass and biomass char were selected and releasing order was calculated by plotting mole fraction of each species Vs temperature (1000 to 1400°C) at 1 bar and VS pressure (5 to 15bar ) at 1000°C. On the basis of predicted releasing order the H2S species can be predicted most stable species for gasification at elevated temperature and pressure. The high released amount of SO2, H2S, NaCl, KCl and HCl was obtained for YUN, DAT,SAD and SADChar at (1400°C-1000°C) temperature and (15-5bar) pressure. Comparing with high pressure the predicted release of KCl and HCl was observed higher but SO2, H2S, and NaCl release was found lower than elevated temperature during combustion process. The above available predicted information is valuable for development of hot gas cleaning technology.

Release of Alkali Metal, Sulfur, and Chlorine Species during High-Temperature Gasification of Coal and Coal Blends in a Drop Tube Reactor

Investigations on the release of Na, K, S, and Cl species form a crucial element in designing control measures and developing hot-gas-cleaning strategies for coal gasification systems. A large body of useful data has already been delivered in this area, but the underlying reaction mechanisms are not yet sufficiently understood. To complement recently performed basic investigations with a flow tube furnace, a lab-scale drop tube reactor was used. The experiments were performed at 1300 °C in an atmosphere of He (carrier gas) and 5 vol % O2. Two hard coals and two blends of these coals were gasified during the experiments. In situ hot gas analysis of inorganic trace elements was performed by molecular beam mass spectrometry.