Alkali Alkaline Earth Research Articles

Improving the yield of levoglucosan platform chemical from the pyrolysis of date pits waste biomass through pre-treatments

Lignocellulosic biomass, as the primary carbon source, serves as the foundation for the entire biorefinery concept. In this regard, date pits constitute an important category of biomass waste in many parts of the world. Levoglucosan, also known as 1,6-anhydro-β-d-glucopyranose (LG), is a significant sugar derivative and a platform chemical produced as a primary product in the cellulose pyrolysis process. Aiming to further improve the yield of levoglucosan from pyrolysis of date pits, pre-treatment methods were carried out via washing crushed date pits with different concentrations of selected acids (sulfuric acid: 1 M/3 M, nitric acid:1 M/3 M), and with hot water. The chemical and elemental compositions of the five considered samples were thoroughly analyzed and characterized by a wide array of ultimate and proximate techniques such as Neutral Detergent Fiber (NDF %), ASH content and organic Matter (%), and Mineral Nutrients Profile (ppm). By utilizing Py-GC/MS system, the product distribution from pyrolysis of raw and treated date pits was obtained at a range of temperatures between 300 and 500 °C. Compared to the raw date pits, pyrolysis of treated date pits pre-treated by 1 M H2SO4 acid exhibited a dramatic increase in the concentration of levoglucosan due to the profound removal of the various categories of minerals in date pits and an increase in the NDF %. A positive correlation prevails between the removal efficiency of alkali/alkaline earth metals (AAEMs) and the yield of LG. The former catalyzes ring-opening reaction that results in the destruction of sugar derivatives. On the other hand, pre-treatment with water also increases the yield of LG compared to raw date pits, but to a lesser extent. Outcomes demonstrated herein convey a practical method to enhance the production of commodity chemicals from waste biomass.

Study of synergistic behavior during bituminous coal-cow manure co-gasification: The role of intrinsic AAEM and organic matter

Co-thermal chemical conversion of coal and biomass is one of the important ways to realize efficient and clean utilization of coal. In this study, a typical Ningdong coal-Yangchangwan bituminous coal and cow manure were used to study the synergistic effect of intrinsic alkali, alkaline earth metals (AAEM) and organic matter on the co-gasification of coal and biomass by thermogravimetry analyzer (TG). The results showed that AAEM had obvious synergistic promotion effect on the gasification of a bituminous coal-cow manure mixture in the isothermal gasification (1000 ℃), whereas the organic matter will show the opposite effect on the process. To further investigate the effect of organic matter on the gasification process, the influence of organic matter on non-isothermal (25-1000 ℃) gasification reaction was investigated with heating rate of 10 ℃ /min, the kinetic parameters of the gasification reaction were obtained by Coats-Redfern method. The increase of biomass mass fraction in the sample facilitates the migration of alkali metals from the material to the solid phase. The possible mechanism of the synergistic effect of intrinsic AAEM/organic matter on the co-gasification process was proposed.

Structure-Prediction-Oriented Synthesis of Thiophosphates as Promising Infrared Nonlinear Optical Materials.

Oriented synthesis of functional materials is a focus of attention in material science. As one of the most important function materials, infrared nonlinear optical materials with large second harmonic generation effects and broad optical band gap are in urgent need. In this work, directed by the theoretical structure prediction, the first series of non-centrosymmetric (NCS) alkali-alkaline earth metal [PS4]-based thiophosphates LiCaPS4 (Ama2), NaCaPS4 (P21), KCaPS4 (Pna21), RbCaPS4 (Pna21), CsCaPS4 (Pna21) were successfully synthesized. Comprehensive characterizations reveal that ACaPS4 could be regarded as promising IR NLO materials, exhibiting wide band gap (3.77-3.86 eV), moderate birefringence (0.027-0.064 at 1064 nm), high laser-induced damage threshold (LIDT, ~10×AGS), and suitable phase-matching second harmonic generation responses (0.4-0.6×AGS). Structure-properties analyses illustrate that the Ca-S bonds show non-ignorable covalent feature, and [PS4] together with [CaSn] units play dominant roles to determine the band gap and SHG response. This work indicates that Li-, Na- and K- analogs may be promising infrared nonlinear optical material candidates, and this is the first successful case of "prediction to synthesis" involving infrared (IR) nonlinear optical (NLO) crystals in the thiophosphate system and may provide a new avenue to the design and oriented synthesis of high-performance function materials in the future.

Structural, Electromagnetic and Thermodynamic Analysis of Ion Pollutants Adsorption in Water by Gallium Nitride Nanomaterial: a Green Chemistry Application

Gallium nitride (Ga–N) nanocage can effectively remove alkali and alkaline earth metal ions from water. Therefore, it has been found a selective competition for metal cations in the Ga–N. The electronic, magnetic and thermodynamic properties of alkali-alkaline earth metal ion-adsorbed Ga–N have been investigated using density functional theory. The results denote that alkali/alkaline earth-metal ion-adsorbed Ga–N systems are stable compounds, with the most stable adsorption site being the center of the cage ring. In addition, because of charge transfer from Ga–N to the alkali/alkaline earth-metal cations show clear n-type adsorbing behavior. The absorption of alkali metal atoms on alkali/alkaline earth-metal cations occur via chemisorption. In this article, the behavior of trapping of main group cations of Li+, Na+, K+, Be2+, Mg+ and Ca2+ by gallium nitride nanocone was observed for sensing the water metal cations. The essence of covalent traits for these clusters has displayed the similar energy value and image of the PDOS for the p states of N, the d states of Ga and s orbitals of metal cations including Li+, Na+, K+/Be2+, Mg2+ and Ca2+ through water treatment. The partial density of states (PDOS) can also estimate a certain charge assembly between Li+, Na+, K+/Be2+, Mg2+ and Ca2+ and Ga–N which indicate the complex dominant of metallic features and an exact degree of covalent traits between alkali/alkaline earth-metal cations and gallium nitride nanocage. Furthermore, the NMR spectroscopy has indicated the remarkable peaks around metal elements of Li+, Na+, K+, Be2+, Mg+ and Ca2+ through the trapping in the Ga–N during ion detection and removal from water; however, there are some fluctuations in the chemical shielding behaviors of isotropic and anisotropy attributes. In addition, all accounted \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta G_{R}^{o}$$\\end{document} amounts are very close, which demonstrate the agreement of the measured specifications by all methodologies and the reliability of the computing values.

Co-gasification of coal and biomass: synergistic effects on gasification reactivity induced by inherent organic components

ABSTRACT It is widely recognized that the synergistic effects during co-gasification process of coal and biomass are caused by the inherent alkali/alkaline earth metals (AAEM). However, the compositions of biomass and coal are complex, with main components being not only AAEM, but also aromatic, aliphatic, and heteroatom-containing compounds. Therefore, whether these organic components can also result in synergistic effects during co-gasification is necessary to be investigated. In this work, to reveal the reaction characteristics of organic components in co-gasification process, two raw materials with little content of ash were selected. The gasification behaviors of coal and biomass were studied and the influences of blending ratio and gasification temperature were mainly examined. The results showed that gasification reactivity of pure biomass was the strongest and its carbon conversion reached 100% within 33 min. With the increase of biomass ratio, gasification reactivity of mixtures was gradually enhanced, which could be ascribed to active functional groups, porous structures, and incompact macromolecular structures of biomass. At high temperature, the gasification reactivity difference was lessened among different samples. As for coal, the reactivity index at 800°C was 0.012. With the increase of biomass blending ratio from 25% to 100%, the reactivity index slowly went up to 0.023 at maximum. When temperature rose to 900°C, the reactivity index was enlarged nearly eight times compared with that of 800°C. At temperatures tested, the shrinking core mode was appropriate to describe gasification process, especially for coal and coal/biomass mixtures. Kinetic analysis showed the theoretical activation energies were all higher than the experimental values, indicating that the interaction between coal and biomass diminished activation energy. The synergy index suggested that gasification reactivity of coal was indeed enhanced during co-gasification process. However, a high-temperature environment might cover up the positive roles of biomass and the synergistic effect was hence weakened. In conclusion, the synergistic effects during co-gasification process could be induced by the organic components in coal and biomass.

Volatile-char interactions during biomass pyrolysis: Effects of AAEMs removal and KOH addition in char

The effects of Alkali/alkaline earth metals (AAEMs) removal and KOH addition in char on formation and distribution of wheat straw pyrolysis products during volatile-char interactions were studied in a fixed-bed reactor. The results showed that after AAEMs removal from char, significant interactions between volatiles and char still existed, as its non-condensable gas yield greatly increased with less detectable organics observed in bio-oil compared to pure wheat straw pyrolysis. XPS results indicated that more aromatic carbon structures (C-Cprimary) were exposed on char surface after AAEMs removal, which might act as active sites during the interactions. KOH addition in char exhibited much bigger cracking performance than its interior K in char, resulting in a significant reduction in bio-oil yield and a great increase in non-condensable gas yield. KOH addition in char might promote decarboxylation, decarbonylation and sugar-ring opening reactions, leading to the decrease of linear acids and carbonyls and anhydrosugars and the increase of phenols and other aromatics in bio-oil. The cracking/decomposition of furans, cyclopentenones, and phenols and other aromatics would also be largely enhanced with the increasing amount of KOH addition. In addition, KOH in char could act as a catalyst for the char self-reforming by volatiles during the interactions.

Exploring binding chemistry of alkali/alkaline earth cations in solution through modulation of intramolecular charge-transfer in an excited ambidentate organic fluorophore.

Studying the metal-ligand monoligation of alkali/alkaline earth metals (AMs) in solution represents a significant challenge due to the low stabilization of their complexes and the absence of an effective strategy to identify this type of weak binding. Herein, we show that the modulation of the intramolecular charge-transfer (ICT) in an excited ambidentate organic fluorophore is a convenient strategy to characterize the binding chemistry of AM cations in solution through simple steady-state fluorescence and fluorescence lifetime measurements. The key points of the fluorophore as a metal-binding probe were the location of diverse coordination functionalities with different binding abilities (ionic-, pseudo-covalent- and non-covalent-probes) along the donor-acceptor (D-A) chain and the occurrence of an intramolecular charge-transfer (ICT) mechanism upon excitation. The binding of these functionalities with AM-cations generated selective and specific fluorescence responses, which were quantifiable and allowed us to recognize the primary, secondary and tertiary interactions for all the AM cations in the solution. The relative binding affinities for each one of the functionalities with AM cations was estimated, and a general and consistent perspective of the binding of AMs as a function of their location in the Periodic Table, hardness property and ionic radius was established. The binding preferences of the AM cations were supported by DFT calculations. Our strategy allowed us to validate the binding dynamics of AMs in solution for three types of key ligations, which opens a new perspective to recognize weak intermolecular interactions derived from acidic species and rationally design selective AM-cation probes using an ICT-based ambidentate organic fluorophore.

Investigation of Multicomponent Fluoridated Borate Glasses through a Design of Mixtures Approach.

Due to their enhanced dissolution, solubility and reaction speed, borate glasses offer potential advantages for the design and development of therapeutic ion-release systems. However, the field remains poorly understood relative to traditional phosphosilicate and silicate bioglasses. The increased structural complexity and relative lack of published data relating to borates, particularly borofluorates, also decreases the accuracy of artificial intelligence models, which are used to predict glass properties. To develop predictive models for borofluorate networks, this paper uses a design of mixtures approach for rapid screening of composition–property relationships, including the development of polynomial equations that comprehensively establish the predictive capabilities for glass transition, density, mass loss and fluoride release. A broad range of glass compositions, extending through the boron anomaly range, were investigated, with the inclusion of 45 to 95 mol% B2O3 along with 1–50 mol% MgO, CaO and Na2O as well as 1–30% KF and NaF. This design space allows for the investigation of the impact of fluorine as well as mixed alkali–alkaline earth effects. Glass formation was found to extend past 30 mol% KF or NaF without a negative impact on glass degradation in contrast to the trends observed in phosphosilicates. The data demonstrates that fluoroborate materials offer an exceptional base for the development of fluoride-releasing materials.

Screening of Potential Additives for Alleviating Slagging and Fouling during MSW Incineration: Thermodynamic Analysis and Experimental Evaluation

The formation of slagging and fouling during municipal solid waste (MSW) incineration not only significantly affects heat transfer, but also results in shortened operating cycles. In order to solve the issues, the effect of different additives on the migration and transformation patterns of alkali/alkaline earth metals (AAEM) and chlorine during MSW incineration is screened based on the Gibbs energy minimization method. The effect of potential additives on the ash fusion temperature and combustion reactivity of MSW char is subsequently verified and evaluated by experimental methods. The thermodynamic equilibrium analysis shows that Al(NO3)3, Ca(NO3)2, and Mg(NO3)2 have great potential to increase the ash fusion temperature. The experimental investigation confirms that the addition of Al(NO3)3, Ca(NO3)2, and Mg(NO3)2 significantly increases the ash fusion temperature. The order of increasing the ash fusion temperature by different additives is Mg(NO3)2 > Ca(NO3)2 > Al(NO3)3. The addition of Mg(NO3)2 significantly increased the initial deformation temperature, softening temperature, hemispheric temperature, and flow temperature of ash from 1180, 1190, 1200, and 1240 °C to 1220, 1230, 1240, and 1260 °C, respectively. The addition of Cu(NO3)2, Fe(NO3)3, and KMnO4 significantly decreases the temperature at the maximum weight loss rate of MSW char, while increasing the maximum weight loss rate. Additionally, Cu(NO3)2 shows the best performance in improving the combustion reactivity of MSW char. The addition of Cu(NO3)2 evidently increases the maximum weight loss rate from 0.49 to 0.54% °C−1. Therefore, it is concluded that Mg(NO3)2 and Cu(NO3)2 are supposed to be the most potential candidates for efficient additives. This study presents an efficient and economical method to screen potential additives for alleviating slagging and fouling during MSW incineration.

Metal salts used as an efficient catalyst to reduce the ring opening polymerization temperature of benzoxazines

An attempt was made to develop low-temperature curing aniline-based benzoxazines (BA-a/BF-a) using various transition metal salts, such as FeCl3, CoCl2, NiBr2, CuCl2, ZnCl2, Zn(OAc)2, CdCl2 and Alkali–Alkaline earth metal salts, such as LiCl, KI and CaCl2 and main group metal salt AlCl3 as an efficient catalyst. The findings of the DSC analysis revealed that the main group and transition metal salts had outstanding catalytic activity and were able to reduce the curing temperature of benzoxazines (BA-a/BF-a). Among the various metal salts, FeCl3, AlCl3, ZnCl2 and Zn(OAc)2 exposed excellent catalytic behavior in lowering the curing temperature of benzoxazines to 145 °C (BA-a) and 150 °C (BF-a) from 217 to 218 °C, respectively. The thermal stability and flame retardant characteristics of the resultant polybenzoxazines (PBz’s), are also studied and included in this work. In the presence of catalysts, the initial degradation temperature almost same, residual char yield increased from 27 to 55%, and the flame retardant properties increased to 39.5 from 28.5 for the resultant PBz’s.

Towards directional pyrolysis of xylan: Understanding the roles of alkali/alkaline earth metals and pyrolysis temperature

To identify the roles of alkali/alkaline earth metals (AAEM) and reaction temperature during pyrolysis of hemicellulose, the effects of AAEM doping on the pyrolysis behaviors, kinetics, and product yields of xylan at different pyrolysis temperatures were assessed. The results demonstrated that the yields of anhydrosugars from pyrolysis of xylan were dependent on the AAEM cations and their doping concentrations. Demineralization achieved the directional conversion of xylan into xylosan at 300 °C. The doping of even 0.05 mmol/g AAEM significantly suppressed their formation. The yields of xylosan from pyrolysis of xylan doped with different AAEM cations decreased in the following order: Mg2+<Ca2+<Na+<K+. The formation of light oxygenates from pyrolysis of xylan was determined by the pyrolysis temperature rather than the doping of AAEM. Elevating pyrolysis temperature significantly improved their yields whilst reducing the yields of anhydrosugars. Aromatics were only observed during the pyrolysis of xylan at 900 °C. Mg and Na exhibited higher catalytic activity for suppressing the formation of aromatics. Pyrolysis kinetic analysis showed that the doping of AAEM increased the activation energy for the pyrolysis of xylan. These findings suggest that pyrolysis of AAEM-free hemicellulose at low temperatures is the key to achieving directional pyrolysis of hemicellulose into anhydrosugars.

Ab initio studies of the effect of pressure on the structure, electronic and elastic properties of carbonates of alkali-alkaline earth metals

Density functional theory with a gradient PBE functional and dispersion correction D3(BJ) in the basis of localized orbitals of the CRYSTAL17 package was used to study the effect of pressure on the structural, electronic, and elastic properties of K2Ca(CO3)2, K2Mg(CO3)2, Na2Ca2(CO3)3, Na2Mg(CO3)2. The parameters of the third-order Birch--Murnaghan equation of state are determined, and it is shown that the equilibrium volume and compressibility modulus depend linearly on the average cation radius. Under pressure, the widths of the upper valence bands increase maximally in K2Ca(CO3)2 and minimally in Na2Ca2(CO3)3, while the centers of gravity of the cationic states shift by ~0.2 eV. Elastic constants and polycrystalline moduli are calculated, which increase with decreasing average cation radius. The shear modulus for K2Ca(CO3)2 and K2Mg(CO3)2 decreases with increasing pressure, and this leads to anomalous behavior of the longitudinal and transverse acoustic wave velocities. Keywords: ab initio calculations, buchliite, eithelite, shortite, equation of state, elastic moduli, density of states, pressure.

Mineral transformation during rapid heating and cooling of Zhundong coal ash

Zhundong (ZD) coalfield has a large number of coal reserves. However, the severe fouling and slagging problems that occurred in ZD coal-fired utility boilers have seriously hindered the large-scale utilization of ZD coal. Deep understanding of the mineral transformation of ZD coal during combustion and its impact on fouling and slagging can provide technical support for fouling and slagging prevention in utility boilers. In this paper, a novel temperature and atmosphere controlling method was proposed to study ash deposition. Wucaiwan (WCW) coal ash samples in different atmospheres and temperatures were collected efficiently by the established single thermocouple high-temperature online microscope observation test rig. The influence of rapid heating and cooling on the mineral transformation of WCW coal ash samples was systematically investigated using XRD and SEM-EDS, respectively. The effects of SO2 in the flue gas on the mineral transformation and the sulphates generation of the coal ash were analysed by comparing the experimental results in oxidizing atmosphere and simulated flue gas atmosphere. The experimental results showed that the microscopic morphology, mineral and element conversion of coal ash samples during heating and cooling were quite different. Compared with oxidizing atmosphere, SO2 in the flue gas significantly increase the S content of ash at 600 °C−1200 °C and the amount of molten minerals on the quenched ash sample surface during cooling. These results indicate that SO2 can promote the sulfation reactions of alkali/alkaline earth metal (AAEM) on the quenched ash sample surface and restrain the decomposition of S-containing minerals in ash cooling. The investigation also reveals that the molten AAEM sulphate on the ash surface is mainly generated at 800 °C−900 °C. The present study not only provides the fundamental understandings of mineral transformation but also guides industrial applications to reduce the risk of ash deposition.

Luminescence-site symmetry correlations in Dy3+ doped alkali-alkaline earth orthoborates of the type XZBO3 with X = Li, Na, K and Z = Mg, Ca, Ba

A systematic investigation of the luminescence properties of Dy3+ doped alkali-alkaline earth orthoborates of the stoichiometric composition XZBO3 with X = Li, Na, K and Z = Mg, Ca, Ba was conducted. XRD diffractograms show that the compounds LiMgBO3, LiCaBO3, LiBaBO3, NaMgBO3, NaCaBO3, NaBaBO3, and KMgBO3 could be produced in high purity. Relatively intense luminescence was observed only for the phases LiCaBO3, NaMgBO3, NaCaBO3 and NaBaBO3. Micro Raman investigations show that the Dy3+ luminesence mainly originates from the orthoborate phase in these samples. Photo-luminescence spectroscopy of LiCaBO3, NaCaBO3 and NaBaBO3 shows the typical Dy3+ emission with the prominent emission peak in the yellow spectral range around 575 nm. A second, but much less intense peak is observed at around 485 nm (cyan). The luminescence emission spectrum of Dy3+:NaMgBO3 is much different: here, the highest emission intensity is observed at about 485 nm. It is proposed that the Dy3+ ions occupy the Na positions in this crystal phase which has a much higher symmetry than the alkaline earth positions in the other examined crystal phases. This is supported by broadened and more split up peaks in the excitation and emission spectra of Dy3+:NaMgBO3 suggesting a much stronger local crystal field at the rare earth position in this compound. The results are additionally compared to spectroscopic data of different well known Dy3+ doped crystalline compounds and Dy3+ and Eu3+ doped alkali-alkaline earth orthoborates from other publications, which offer further insight into the relation between the crystallographic sites of the doped rare earth ions and their luminescence.

The Roles of Alkali/Alkaline Earth Metals in the Materials Design and Development for Hydrogen Storage

ConspectusHydrogen storage for onboard applications has been recognized as a grand challenge for the large-scale implementation of hydrogen fuel cell vehicles. Tremendous research efforts have thus been devoted to the design and development of hydrides of lightweight elements (HLEs). A prominent feature of these materials is the indispensable ingredient of alkali/alkaline earth cations. Alkali alkaline earth metals (AMs) are highly reactive and have a rich coordination chemistry. As a matter of fact, an AM cation can form a complete range of compounds with hydrogenous anions, such as H–, [NH2]−, [BH4]−, [AlH4]−, [NH2BH3]−, [TMHX]−, [R-CH2–NH]−, [R-CH2–O]−, etc., and, thus, tune the Al–H, N–H, B–H, and C–H bond strengths for hydrogen storage.In this Account, our research efforts in the development of AM amide-hydride composites, AM amidoboranes, and metalorganic hydrides for hydrogen storage are reviewed. A partial substitution of the H in NH3 by AM gives rise to solid AM amides or imides. Those compounds can react with AM hydride (AMH) to produce H2. This is driven by the redox reaction between a protic H (N) and hydridic H (AM). A variety of amide-hydride composites holding promise for hydrogen storage were thus developed, including LiNH2-hydride, Mg(NH2)2-hydride, and complex amide-hydride composites. For amidoboranes, the substitution of H (N) in ammonia borane (AB) by AM transforms the molecular crystal AB into amidoboranes with an ionic crystal structure, leading to significant changes in terms of charge distribution, bond length, intermolecular forces, and so on, which in turn results in enhanced dehydrogenation properties. For metalorganic hydrides, through reacting AM compounds (usually AM hydride) with aliphatic, carbocyclic, or heterocyclic organic hydrides having “reactive protic H”, corresponding metalorganic hydrides are formed. Because of the electron-donating nature of AM, the strengths of the C–H bond in metal-organic hydrides can be modulated.For each material system, we will introduce the synthesis of materials, show their performances, correlate the hydrogen storage property to a crystal and/or electronic structure, and especially highlight the functions of AM in tuning the thermodynamic and/or kinetic properties of HLEs. At the end of the Account, challenges and a future research direction of the hydrogen storage field are discussed.

Computational Exploration of the Direct Reduction of CO2 to CO Mediated by Alkali Metal and Alkaline Earth Metal Chloride Anions

Computational Exploration of the Direct Reduction of CO₂ to CO Mediated by Alkali Metal and Alkaline Earth Metal Chloride Anions

A review on the migration and transformation of heavy metals influence by alkali/alkaline earth metals during combustion

Alkali/alkaline earth metals (AAEMs) are widely present in various solid fuels. During the combustion process, the AAEMs undergo complex physical and chemical reactions with heavy metals and other minerals in the fuel, thereby affecting the migration and transformation of heavy metals. This paper mainly introduced the influence of AAEMs on the migration and transformation of As, Se, Pb and Cr, including the influence of alkali metals and alkaline earth metals on the migration and transformation of heavy metals, and the influence of particle agglomeration and coherence on heavy metal emissions. AAEMs can inhibit the volatilization of heavy metals. The combination of alkali metals and Cl elements reduces the production of PbCl2. The presence of alkali metals is beneficial to improve the adsorption efficiency of kaolin for Pb. AAEMs can form stable compounds with As and Se. However, at the same time, it should be noted that in the partial combination products of AAEMs and Cr, Cr exists in a hexavalent state and has high toxicity. AAEMs play a role in promoting and inhibiting the occurrence of agglomeration, respectively. An appropriate content of alkali metals is beneficial to reduce the release of heavy metals. By summarizing the influence of AAEMs on the migration and transformation of heavy metals, it is hoped to provide ideas for reducing the harm of heavy metals.

Effects of Water Washing and Deashing on the Combustion Characteristics of the Zhundong Lignite

ABSTRACT To examine the effects of water washing and acid-based deashing on the structure as well as combustion characteristics of Zhundong lignite, this study used high-speed planar laser-induced fluorescence measurements (OH-PLIF) with a specific burner and characterization techniques including XRD, BET, and ICP-AES as the method. The results indicated that both water washing and deashing can remove the ash and the main mineral alkali metals. Compared with RC, the total amount of OH release from WWC and UCC was increased attributing to the addition of combustibles and volatiles. The ignition of WWC and UCC was faster than that of RC, while the burning rate followed the opposite order. Experimental result confirms that the alkali metal and alkaline earth metals play a catalytic role in coal combustion. Meanwhile, the increase of the BET surface area and the reduction of ash are conducive to heat transfer, which is favorable for the ignition of pulverized coal.

Application of Phosphate Precipitation for Removing Strontium and Barium from Alkali Chloride Based Melts

The reaction of solutions of barium and strontium chlorides in LiCl–KCl, NaCl–KCl, and NaCl–KCl–CsCl based melts with sodium orthophosphate was studied at 450 and 750oC. The initial phosphate-to-alkaline earth molar ratio varied from 0.5 to 14 and the excess of phosphate required for the complete conversion of AECl2 (AE = Sr, Ba) to phosphates as well as phase composition of the phosphates produced were determined. Normal orthophosphates alongside with lithium phosphate were formed in lithium chloride containing melts, whilst double alkali–alkaline earth phosphates and chloro-phosphates were obtained in NaCl–KCl and NaCl–KCl–CsCl based melts. Size of the particles comprising solid precipitates was determined; the values varied from 0.1 to tens microns. Increasing the initial PO4 3– : AE2+ molar ratio did not have a pronounced effect on the particle size.

Synergy of Hydrothermal and Organic Acid Washing Treatments in Chinese Fir Wood Vinegar Preparation.

Pretreatment is an effective method to change the pyrolysis behavior and improve the product properties of biomass. In this study, the effects of hydrothermal treatment (HTT) and hydrothermal treatment combined with organic acid washing (HTT-A) on Chinese fir waste (CF) pyrolysis and preparation of wood vinegar (WV) were investigated. The results indicated that HTT promoted the decomposition of hemicellulose and disrupted the chemical structure, while HTT-A partly removed the lignin as well as hemicellulose. HTT-A showed a more effective removal efficiency of alkali/alkaline earth metals (AAEMs) than HTT. Both HTT and HTT-A delayed the initial decomposition temperature but promoted the pyrolysis process. The yields of WVs increased after HTT and HTT-A, while the moisture contents reduced, obviously. HTT increased the relative contents of phenols from 47.04 to 59.85% but reduced the relative contents of acids from 24.31 to 18.38%, whereas HHT-A reduced the relative contents of phenols but increased those of aldehydes. In addition, HTT and HTT-A showed the different effects on chemical compositions of WVs, especially for phenolic and acid compounds. This study indicated that HTT and HTT-A were the efficient methods to produce WVs with target chemical components, which would be conducive to the efficient application of WVs.