High Content Of Na Research Articles

Synthesis and performance evaluation of temperature and salt-resistant organic/inorganic composite copolymers

ABSTRACT Ordinary polymers have poor adaptability in high-temperature and high-salt reservoir environments due to their properties. Organic/inorganic composite copolymer microspheres have the advantages of both of them, which are expected to break through their applicability limitations in such oil reservoirs. Therefore, its preparation and performance have always been of great concern to researchers. In this paper, AM/AMPS/Si-St ternary copolymers were synthesized by precipitation polymerization; then modified nano-silica particles were added to synthesize AM/AMPS/Si-St/g-SiO2 organic/inorganic composite quaternary copolymers. FT-IR and SEM characterized the copolymers to confirm that they were prepared successfully. Experiments were carried out to investigate the concentration and ratio of monomers, which showed that the Weissenberg effect could be avoided. The number of polymer molecules could be stabilized under AM concentration of 12 wt%, AM/AMPS/Si-St ratio of 8:1:1, nano silica of 3.3% and the modification conditions of KH570:SiO2 = 1:1. The experiments of temperature and salt resistance of two copolymers were evaluated and compared were conducted by using viscosity and particle size as parameters. The results showed that quaternary copolymers could increase the viscosity retention rate by about 10% compared with ternary copolymers under high content of Na+ and Mg2+. When the two copolymers were placed at 150°C, the appearance and morphology of the terpolymer changed obviously. Through the SEM image of the quaternary copolymers, it could be seen that although the spherical shape of the microsphere had been gradually lost, no degradation occurred, and the stable time of the modified microspheres had been effectively extended.

Study on the Influence of Mining Activities on the Quality of Deep Karst Groundwater Based on Multivariate Statistical Analysis and Hydrochemical Analysis.

Long-term mining activities have changed the hydrogeochemical evolution process of groundwater and threatened the safe use of groundwater. By using the methods of hydrochemistry and multivariate statistical analysis, this study determined the hydrogeochemical evolution mechanism affecting the quality of karst groundwater by analyzing the conventional hydrochemistry data of the karst groundwater of the Carboniferous Taiyuan Formation in Hengyuan Coal Mine in the recent 12 years. The results show that, under the disturbance of mining, the quality of karst groundwater in Taiyuan Formation is poor, mainly because the contents of Na++K+ and SO42- are too high to allow usage as drinking water. The reason for the high content of SO42- in karst groundwater lies in the dissolution of gypsum and the oxidation of pyrite, and the high content of Na++K+ lies in the cation exchange. Influenced by the stratum grouting, the circulation of karst groundwater is improved, the cation exchange is weakened, and the desulfurization is enhanced. In the future, it is predicted that the hydrochemical type of karst groundwater in Taiyuan Formation in the study area will evolve from SO4-Ca·Mg type to HCO3-Ca Mg type.

Fluoride contamination, spatial variation, and health risk assessment of groundwater using GIS: a high-density survey sampling in Weifang City, North China.

The present study, with the aid of GIS, utilizes high-density groundwater (GW) sampling data (1398 samples) to analyze the spatial variation characteristics of GW fluoride in Weifang City (WFC), and evaluate the health risks associated with drinking water routes. The concentration of fluoride in the GW of WFC is observed to be between 0.08 and 9.16mg/L, with a mean value of 0.62mg/L. The fluoride concentration of a total of 192 GW samples exceeded the limit of China's GW quality standards (1mg/L), accounting for 14.74%. The GW fluoride concentration in most areas of WFC is less than 1mg/L. However, the relatively high-value zones are mostly concentrated in the upper reaches of Wen River, the east of Shouguang, the southeast of Anqiu, the east of Qingzhou, the east of Fangzi, and the southeast and northwest of Gaomi. The hydrochemical types of GW in WFC are mostly HCO3-Ca·Mg and SO4·Cl-Ca·Mg, while GW samples with hydrochemical types HCO3-Na and SO4·Cl-Na are characterized by high fluoride content. The hydrochemical characteristics of GW in WFC are mostly dominated by rock weathering. In addition, the northern coastal plain is evidently influenced by seawater intrusion. The concentration of fluoride in GW is affected by the dissolution of fluorine-containing minerals, cation exchange, and alkaline environmental factors. The effect of GW by seawater intrusion and very high content of Na+ will decrease the fluoride content of the GW through cation exchange. Health risk assessment demonstrated that the mean values of non-carcinogenic hazard quotient (HQ) for infants, children, teenagers, and adults were 0.52, 0.35, 0.31, and 0.30, respectively. In addition, the distribution characteristics of GW fluoride in high health risk areas (HQ > 1) in WFC are further consistent with the spatial variation of GW fluoride content. Overall, the health risk distribution area of GW fluoride in WFC is decreasing in the following order: infants > children > teenagers > adults.

Fluorescent AgNCs Formed on Bifunctional DNA Template for Potassium Ion Detection

In this study, we examined properties of silver nanoclusters, which are AgNCs stabilized by DNA oligonucleotide scaffold containing G-quadruplex-forming sequences: human telomeric (Tel22) or thrombin-binding aptamer (TBA). Thus, we obtained two fluorescent probes abbreviated as Tel22C12-AgNCs and TBAC12-AgNCs, which were characterized using absorption, circular dichroism and fluorescence spectroscopy. Both probes emit green and red fluorescence. The presence of silver nanoclusters did not destabilize the formed G-quadruplexes. The structural changes of probes upon binding K+ or Na+ ions cause quenching in their red emission. Green emission was slightly quenched only in the case of Tel22C12-AgNCs; on the contrary, for TBAC12-AgNC’s green emission, we observed an increasing fluorescence signal. Moreover, the Tel22C12-AgNCs system shows not only a higher binding preference for K+ over Na+, but it was able to monitor small changes in K+ concentrations in the buffer mimicking extracellular conditions (high content of Na+ ions). These results suggest that Tel22C12-AgNCs exhibit the potential to monitor transmembrane potassium transport.

Multiple Strategies toward Advanced P2-Type Layered NaxMnO2 for Low-Cost Sodium-Ion Batteries

Due to the high specific capacity and fast sodium-ion diffusion path, P2-type transition layered oxides have become the most promising cathode material for sodium-ion batteries (SIBs). However, poor service life, irreversible phase transitions, sensitivity to moisture, low energy density, and inevitable high-cost metals (nickel, cobalt, etc.) have slowed their development. In this work, on account of low-cost cathode alternatives to SIBs, an example of P2-type layered NaxMnO2 (NLCM) has been demonstrated, in which Li+ and Cu2+ cosubstituted in transition metal layer sites suppressed the ordered arrangement of Na+/vacancies and stabilized the structure. Furthermore, the electrochemical performance of the layered transition metal oxide was improved by optimizing the Na content in the P2-type material to 0.83 per mole. The high content of Na in the host improves the structural stability during the high-voltage stage. Li and Cu cosubstitution also activates the anion redox reaction and reduces the first-cycle coulomb efficiency, which is beneficial for commercial applications. P2-Na0.83Li0.13Cu0.2Mn0.67O2 (NLCM-083) provides a reversible capacity of 150 mA h g–1 in the voltage window of 2–4.5 V at 26 mA g–1 and 90.7 mA h g–1 at 1.0 C rate after 200 cycles with a capacity retention of about 84.6%, which demonstrated the potential of NLCM-083 as a high-performance working electrode for high-voltage SIBs.

The Mineral Composition of Milk from High-Yielding Dairy Cows Depending on the Month of Lactation and Udder Health

The aim of this study was to determine the effects of the month of lactation and udder health of high-yielding Polish Holstein-Friesian (PHF) cows on daily milk production and the content of K, Ca, Na, Mg and Zn in milk. The experimental materials comprised 380 milk samples collected from 38 cows. The highest average daily milk yield (49.1 kg) was noted in cows in the second month of lactation and, considering udder health, in cows whose milk contained 201,000 to 400,000 somatic cells per mL on average (denoting risk of mastitis). The K content of milk increased (p < 0.05) in successive months of lactation, whereas the opposite trend was observed in the Zn content of milk. The average content of Ca (842 mg∙dm−3), Na (344.5 mg dm−3) and Mg (98.5 mg dm−3) in milk was below the lower limits of the normal physiological ranges. Milk from cows with healthy udders (≤200,000 somatic cells per mL) had the highest concentration of K, whereas the levels of Na and Zn were highest in milk from cows with clinical mastitis (> 1 mln somatic cells per mL). Udder inflammation was accompanied by an increase in the levels of Na and Zn in milk. The high content of Na and Zn in milk can be an additional indicator of mastitis in cows.

Facile synthesis of tetragonal NaV2O5·H2O nanosheets co-intercalated by high content of Na+ and H2O for boosted lithium storage

NaxV2O5·yH2O have been considered to be very promising electrode materials in the energy storage field by virtue of their V4+/V5+ mixed valences and co-intercalated Na+/H2O. However, the as-reported NaxV2O5·yH2O usually present the low content of Na+ and the anisotropy of Li+ diffusion in the plane direction. Herein, we successfully synthesize a tetragonal NaV2O5·H2O nanosheets co-intercalated by high content of Na+ and H2O via a simple one-step hydrothermal method under broad synthesis conditions, where S2- reductant has been proved to bevery significantforits successful synthesis. With the synergistic effect of the isotropy of tetragonal lattice in the plane direction, and the co-intercalated high content of Na+ and H2O, NaV2O5·H2O nanosheets as anode material for lithium-ion batteries exhibit excellent electrochemical performance. The initial discharge and charge capacities are up to 859 and 607 mA h g−1 at 100 mA g−1, and the capacity is maintained at 473 mA h g−1 after 500 cycles, which are outperform other reported layered sodium/lithium vanadate, lithium titanate, lithium/titanium niobate and graphite. In addition, we also reveal that the active material during cycling process is the LixNayV2O5·H2O with stable crystal structure and morphology, and the Li+ storage process is coequally determined by diffusion and pseudocapacitive behavior.

Minerals assessment and sodium control in hamburger by fast and green method and chemometric tools

The aim of this study was to investigate the feasibility of applying near infrared spectroscopy (NIR), associated with multivariate calibration, which is characterized as a fast and green technique, to evaluate Fe, Ca, K and Na in commercial hamburger samples and for sodium control, according to the law. PLS models obtained by NIR to predict the essential mineral content showed Standard Error of Prediction (SEP) values from 0.34 to 68.01 mg/kg; RE from 0.5 to 2.78% and R2cal from 0.85 to 0.96. PLS-DA were performed in order to classify samples regarding sodium content control and it was concluded that the classification model was efficient with high selectivity and sensitivity. The results showed that the PLS models-discriminant and regression-associated to NIR vibrational spectroscopy technique can be successfully used to control essential minerals Fe, Ca and K besides of quantify and detect hamburger with high content of Na, with shorter analysis time after simple sample preparation by grinding.

New Findings of Rare Minerals in Alkaline Rocks of Ukrainian Shield

Over recent years, new rare minerals have been discovered in the alkaline rocks of the Ukrainian Shield. Agpaitic varieties of alkaline magmatic and metasomatic rocks turned out to be especially abundant in rare minerals. Numerous findings are related to alkaline metasomatites which are considered to be fenites and apofenite albitites of the Dmytrivka quarry. It is well known primarily by the presence of various accessory (Nb, REE, and Zr) minerals, as well as silicate and oxide minerals that are rare for Ukraine. The most common albite microcline fenites of this quarry are characterized by rare-earth mineralization, whereas the concentration of REE decreases in apofenite albitites and Zr and Nb increase. New rare minerals were also found in the essentially albite rock with astrophyllite, alkaline pyroxene and amphibole of the Malatersa massif and agpaitic phonolites of the Oktyabrsky massif. In the rocks of the mentioned massifs and occurrences of alkaline rocks the most interesting are the findings of the perraultite — jinshajiangite series. They were found in three points of the Azov area and include 1) perraultite and jinshajiangite in the alkaline metasomatites of the Dmytrivka quarry; 2) only perraultite in agpaitic phonolites of the Oktyabrsky massif (Kam’yana gully); 3) jinshajiangite in a veined albite rock among the gabbro of the Malatersa massif. Baotite and minerals of the hejtmanite — bafertisite series were also found in the metasomatites of the Dmytrivka quarry. The latter belong to intermediate varieties in terms of MnO (10-17 wt.%) and FeO (10-17 wt.%) which distinguishes them from Fe-rich bafertisite from other regions. A silicate mineral with high content of Na, Zr, Mn and elevated Ti and Nb is rarely observed as small inclusions in the kupletskite grains from alkaline metasomatite of the Dmytrivka quarry. According to the chemical composition it was previously diagnosed as janhaugite. Tainiolite was found in some occurrences of alkaline metasomatites in the Azov region. In addition small aggregates of the REE-enriched epidote were found in fenites of the Kaplany village, which is probably the first finding in Ukraine. Two new Zr minerals have been found in the aegirine syenites of the Korsun-Novomyrhorod pluton: elpidite and mineral with a high content of Y2O3 (13-14 wt.%) (Y-hagatalite ?).

Reduction of Na and K contents in bio-heavy oil using micro-/nano-sized CO2 bubbles

Co-combustion of bunker-C oil and bio-heavy oil for power generation provides a strategic way for mitigating the environmental burdens (climate change) due to the intrinsic carbon neutrality of bio-heavy oil. Prior to the co-combustion process, the high content of Na and K in heavy oil should be removed for the operational safety. Given that the washing process has been currently practiced for metal removal, it is desirable to develop the chemical-free washing process. Note that H2SO4 was commonly used during the washing process. To this end, this study laid great emphasis on the possible use of CO2 for the washing process. To increase the removal efficiency of Na and K, this study particularly employed micro-/nano-sized CO2 bubbles. To access the in-depth insights, a computational fluid dynamics (CFD) simulation was conducted prior to a lab-scale experimental work. The CFD simulation suggests that CO2 bubbling expedited the mixability during the washing process. Also, the CFD simulation suggested that the CO2 bubbling effects could be enhanced because the high viscosity of bio-heavy oil cancelled out the buoyancy force. A lab-scale experimental work was also in good agreement with the CFD simulation. In the presence of CO2 bubbles, 80% of Na and K was removed when the volumetric ratio of water and bio-heavy oil was 8. Even under the volumetric ratio condition of 0.125, the metal removal efficiency was not substantially reduced. Thus, all experimental findings signify that metal removal by micro-/nano-sized CO2 bubbling should be done by a cascade system.

Effect of co-precipitation pH on the electrochemical properties of Prussian blue electrode materials for sodium-ion batteries

Prussian blue analogues (PBA) are promising cathode materials because of their low-cost and wide diffusion tunnels for sodium ion batteries. However, several key challenges, such as low actual capacity and high voltage instability, restrain their further development. Here, we investigate the influence of pH value on the electrochemical performances of Na2MnFe(CN)6 cathodes during co-precipitation process. When the pH equals to 3.0, the sample shows the high content of sodium, low contents of interstitial water molecules and Fe(CN)6 defects, which achieves a high discharge capacity (~130.6 mAh g−1) and a capacity retention of 72% after 100 cycles at 1C. As the pH becomes 9.0, the sample exhibits an excellent high-rate capability, and the discharge capacity can still remain about 92% when the rate goes back to 0.1C from 5C. Besides, the sample also reveals capacity retention of about 80% after 100 cycles at 1C, which shows the best stability among all samples. The enhanced performances could be mainly ascribed to two aspects: on the one hand, the high content of Na+ contributes to high specific capacity; on the other hand, less Fe(CN)6 defects are beneficial to Na+ ion diffusion and stabilize the structure during the Na+ insertion/extraction process.

Co-combustion of Municipal Sludge and Zhundong Coal: Ash Formation Characteristics

ABSTRACTZhundong coal (ZD), which has a high content of Na and low ash fusion temperature (AFT), causes a serious problem of slagging in boilers. P-rich municipal sludge has suitable properties for managing problems with alkali metals, but its insufficient utilization makes sludge management harder. Thus, co-combustion of municipal sludge and ZD may be a suitable approach to solve the problems. Different proportions of sludge were added to ZD at 900°C in different contents of O2 in a laboratory-scale tube furnace experimental system. The transformation of the minerals, the AFTs of residual ashes, and changes of the sodium retention ratio were investigated, respectively. The test results indicate that the ash fusibility of ZD and the sodium retention ratio can be improved because of the generated high-melting-point phosphates, such as Ca2.71Mg0.29(PO4)2, Ca5(PO4)3(OH), Ca9Fe(PO4)7, and Ca9MgNa(PO4)7. With increases in the proportion of sludge in blended samples, the AFTs increase, but the extent of the increase tends to be reduced. Modified sludge with a lower SiO2/Al2O3 ratio is more favorable for the improvement of the AFT. It is observed that 20% oxygen is the most suitable environment of those tested for co-combustion, avoiding the disadvantages of excessively high or low oxygen content.

Mineral abundances quantification to reveal the swelling property of the black cotton soil in Kenya

Abstract This research provides a combination method in quantifying mineral abundances of the black cotton soil (BCS) to reveal its swelling property. The soil was sampled from a roadbed to be built in Niarobi, Kenya, and was found to experience large volumetric expansion (~166%) due to the moisture variation. The wet-chemical analyses and X-ray characterizations (XRD) were undertaken to study the chemical compositions and mineral phases that are presented in the BCS. The quantification of minerals was determined by combining chemical compositions, physical properties (cation-exchange capacity = 75.5 meq 100 g−1, hydroxyl water loss = 10.5%) and the phase identification. A local regression relationship was proposed based on the mass balance of major elements. The BCS was found to consist with clay minerals as nontronite (17.3 wt.%), smectite (10.9% wt.%), chlorite (21.7 wt.%) and interstratified chlorite/smectite (31.9 wt.%). The nonclay minerals of quartz and feldspar were determined to have proportions of 10.2 wt.% and 8.4 wt.%, respectively. This evaluation was also confirmed by the electron microprobe analysis (EMPA) linked with a graphic software and experimentally by the multiple-step precipitation plus additional alkaline/acid and other chemicals treatments. The high content of Na, Ca-based clay minerals found in this work accounts for the large volumetric expansion when the BCS is exposed to water.

Ash Deposition and Alkali Metal Migration during Zhundong High-alkali Coal Gasification

Abstract Ash deposition is particularly serious during Zhundong coal combustion/gasification due to its high alkali metal content, which causes great troubles and limits its utilization. This paper focuses on the ash deposition characteristics and migration disciplinarian of akali metal during Zhundong coal gasification varing with different conditions, such as ash deposition temperature, gasification temperature, O 2 /coal, steam/coal, and deposition time. Experimental result indicates that gasification conditions play a significant role on ash deposition. The root cause of severe fouling is the high content of Na in Zhundong coal, most of which is water-soluble. Besides, the contents of Na, Fe, S, Cl in ash are obviously changed with flue gas temperature increasing, indicating these elements have great influence on ash deposition, and the migration of Na, Fe and Cl presents similar variation during deposition. In addition, Na deposits mainly above 873 K, and Fe gains enrichment in ash at various temperatures. With the increase of gasification temperature, the content of Na in the ash is increased, which could exacerbate ash deposition. Both O 2 /coal and steam/coal have a certain influence on migration of elements, and the increases of O 2 /coal and steam/coal can relieve the ash fouling phenomena. Deposited ash on heating surface will react with Na in flue gas at high temperature, leading to the increase of content of Na in the ash with deposition time increasing.

Investigation on ash deposition characteristics during Zhundong coal combustion

The reserves of Zhundong (ZD) coal in China are huge. However, the high content of Na and Ca induces serious slagging and fouling problems. In this study, the ZD coal was burned in a DTF (drop tube furnace), and the ashes collected at different gas temperature with non-cooling probe were analyzed to obtain the ash particle properties and their combination mode. The results showed that Na, Ca and Fe are the main elements leading to slagging when the gas temperature is about 1000 °C during ZD coal combustion, but their mechanisms are quite different. Some sodium silicates and aluminosilicates and calcium sulfate keep molten state in the ashes collected at 1000 °C. These molten ash particles may impact and adhere on the bare tube surface, and then solidified quickly. With the growth of slag thickness, the depositing surface temperature is increased. The molten ash particles might form a layer of molten film, which could capture the other high fusion temperature particles. The Fe2O3 sphere were captured by the formed molten slag and then they blended together to form a new molten slag with lower melting temperature.

Influence of sodium-based materials on the slagging characteristics of Zhundong coal

Zhundong coal from the Zhundong coalfield in in Xinjiang, China, is charactered by high content of Na. Na-related slagging of Zhundong coal is unclear. The aim of this study is to determine the influence of Na-based materials on the slagging characteristics of the coal. The raw coal was prepared by first removing Na by chemical extraction and subsequently impregnating it with the Na-based materials, such as NaCl, Na2SO4 and NaAc. Laboratory slagging experiments in a muffle furnace were conducted using the mixtures of prepared Zhundong coal and quartz sand. It was found that the Na-based materials affected the slagging behavior of the coal in the order NaAc/Na2SO4 > NaCl. For the mixtures with the NaCl additive, fusion was most noticeable at 900 °C. However, for the mixtures soaked with Na2SO4 and NaAc, a monotonically increasing relationship was indicated between the degree of slagging and the temperature. Adding the Na-based materials to the coal resulted in increased Na content in the residual ash, especially in the instances with Na2SO4 and NaAc additives. The formation of silicates, which were ascribed to the reactions between the Na-based materials and the SiO2, was the primary cause of slagging. Various mineral elements, especially Fe, were captured by Na2O, derived from the decomposition of Na2SO4 or the combustion of NaAc, to exist in the form of a low-melting temperature eutectic. Additionally, the presence of Fe, Ca, K, and Mg in the ash aggravated slagging under the influence of Na2O.

Quantum chemistry mechanism study on preventing slag‐bonding via modifying the material surface properties

AbstractA huge amount of coal with high content of Na and K in ash was found in Xinjiang Province, China. However, the most serious ash fouling/slagging problems of that kind of coal usually cause the increasing of operating costs and energy consumption in a power plant. In order to clarify the mechanism of the effect on ash deposition behavior on different material surfaces, the experimental study, as well as quantum chemistry calculation, was used in this study. The results show that the nickel‐based material can significantly alleviate the ash deposition of high‐alkali coal. The adsorption energy between Na atom and NiO is much higher than that between Na atom and Fe2O3. The much lower system energy between Na atom and Fe2O3 will cause more stable system of Na‐Fe2O3. However, for nickel‐based material, the electrons of Na‐NiO system are being at a higher energy status, which will cause the system to stay at a relative unstable status. The quantum chemistry calculation results can well explain the phenomena of the experimental result. Furthermore, the interaction mechanisms between Na and Al‐based materials were also calculated to predict the effect of Al‐based material on preventing ash fouling and slagging. Copyright © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

THE PROBLEM OF CARBONATITES AND CARBONATITE COMPLEXES

By analysis of publisked and authors data the conclusion was made that primary chemical composition of carbonatites was predo minautly alkali-carbonate similar to ones of carbonatites and tuffs of Oldoinyo Lengai volcano (with high content of Na 2 CO 3 , K 2 CO 3 , CaCO 3 and subordinately MgCO 3 , FeCO 3 ). Such carbonatite melts reacted on country rocks (more often granitoids) and caused a fenitization of them while residual components СаСО 3 , MgCO 3 and FeCO 3 crystallizel as well known types of carbonatites (calcitic, dolomitic, ankeritic). Intrusive carbonatite complexes consist of such ultrabasic and alkaline racks as olivinites (rarely dunites), jacupiragitespyroxenites, melilitites, ijolites-melteigites, nepheline and alkaline syenites, phoscorites and carbonatites wich can be present in different combination (completely alone or two types of mentioned rocks). Silicate alkaline melts (of melilitite, melanephelinite types) related to carbonatite magmas were normatively and modally unsaturated with SiO 2 and feldsparless. Basalt melts are not able to generate carbonatites. Carbonatites different from visually similar calciphyres and marbles by geochemical peculiarities and ore potential.

Poly (vinyl chloride)/montmorillonite hybrid membranes for total-heat recovery ventilation

Poly (vinyl chloride)/sodium montmorillonite (Na+-MMT) hybrid membranes with varied Na+-MMT content were prepared using casting processes for potential use in total heat recovery ventilation systems. The impact of Na+-MMT content on the morphology, thermal stability, mechanical property, gas transmission, pore diameters and total heat exchange effectiveness of the membranes were studied. It was observed that hybrid membranes with high content of Na+-MMT tended to have large roughness, improved thermal stability, high water vapor transmission as well as good temperature and enthalpy exchange effectiveness. With increasing Na+-MMT content, although the water desorption activation energy increased steadily together with the increased hydrophilic nature of the membranes, the water transmission rates increased dramatically caused by the introduction of larger pores in the systems. Balancing the requirement of low gas permeation, good water vapor and heat exchange effectiveness and mechanical properties, hybrid membranes with 60% Na+-MMT content seemed to have the highest potential to be used as Total Heat Recovery membranes in energy saving ventilation systems.

Application and Perspective of Ionic Liquids on Rare Earths Green Separation

This review summarizes recent applications of ionic liquids (ILs) as ‘green’ solvents and extractants in the extraction and separation of Rare Earths (REs), which are widely used in a variety of high-tech products in mining, separation, and smelting can greatly damage the environment. Conventional imidazolium-based ILs as diluents are more active than non-coordinating solvents such as kerosene and n-heptane in the extraction of REs including the co-existing thorium. Imidazolium cations can be involved in REs cation exchange or in forming new complexes with REs(III) ions. Quaternary ammonium- and phosphonium-based ILs with functional anions could be considered as bifunctional IL extractants (Bif-ILEs) for the separation of REs due to their following properties: the capacity to undergo facile synthesis route, high extraction ability and selectivity, low acid-base consumption, and easy stripping. The inner synergistic neutral complex extraction of Bif-ILEs will effectively avoid the production of ammonia-nitrogen or high content of Na+ or Ca2+ in wastewater, which is partly caused by the “saponification” of acidity extractant, such as P507, during the REs industrial separation process. The large amount of wastewater production must be prohibited because of “Emission Standards of Pollutants from Rare Earths Industry” promulgated by China's Ministry of Environment Protection (MOP) in 2011. Serving as extractants, additives, and templates, ILs are likewise used in the preparation of functionalized adsorption materials (i.e., sol-gel silica, Amberlite XAD series resins, IL modified Merrifield resin). These adsorption materials also show high efficiency in the enrichment of dilute leach liquor of the weathered crust elution-deposited REs ore and the enhanced separation of high-value adding heavy REs. The huge environmental challenges from highly polluted REs hydrometallurgy in China require the greener separation technique to solve these issues, and the novel ILs-based separation materials and techniques in both liquid/liquid and liquid/solid extraction and separation of various REs resources are expected to demonstrate the potential practical applications in the future.