Experimental Study on Aqueous Phase Entrainment in a Mixer-settler with Double Stirring Mode

The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production. Current researches usually focus on changing the structure of the mixer-settler without making a breakthrough towards gravity clarification. In this paper, in order to improve the efficiency of clarification, a mixer-settler with double stirring mode was designed and manufactured by adding a stirring device in the settler after reducing the volume of the settler. The innovation of this research involves adopting the ultraviolet-visible spectrophotometer to investigate the quantity of aqueous phase entrainment at the settler outlet in order to measure the clarification degree. Experimental results show that the clarification effect with stirring is better than that without stirring. The clarification effect is ameliorated as the stirring speed increases. Generally, the clarification effect shows a best condition when the offset distance is 12.5 cm, making the phase entrainment reduced to less than 0.1%. When the clearance over the tank bottom is 7 cm and 10 cm, respectively, the quantity of aqueous phase entrainment is better than the case with a clearance of 4 cm. The results show that the stirring paddle close to the mixed phase zone can better promote the two-phase separation.

Stability and activity of carbon nanofiber-supported catalysts in the aqueous phase reforming of ethylene glycol

Nickel, cobalt, copper and platinum nanoparticles supported on carbon nano-fibers were evaluated with respect to their stability, catalytic activity and selectivity in the aqueous phase reforming of ethylene glycol （230 ℃, autogenous pressure, batch reactor）. The initial surface-specific activities for ethylene glycol reforming were in a similar range but decreased in the order of Pt （15.5 h-1 ） 〉Co（13.0 h 1 ） 〉Ni（5.2 h-1） while the Cu catalyst only showed low dehydrogenation activity. The hydrogen molar selectivity decreased in the order of Pt （53%）〉Co（21%）〉Ni （15%） as a result of the production of methane over the latter two catalysts. Over the Co catalyst acids were formed in the liquid phase while alcohols were formed over Ni and Pt. Due to the low pH of the reaction mixture, especially in the case of Co （as a result of the formed acids）, significant cobalt leaching occurs which resulted in a rapid deactivation of this catalyst. Investigations of the spent catalysts with various techniques showed that metal particle growth is responsible for the deactivation of the Pt and Ni catalysts. In addition, coking might also contribute to the deactivation of the Ni catalyst.

An alternate aqueous phase synthesis of the Pt3Co/C catalyst towards efficient oxygen reduction reaction

Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction(ORR)for the application in low temperature fuel cells and beyond,thus their facile and green synthesis is highly demanded.Herein we initially report an alternate aqueous phase one-pot synthesis of such catalysts(containing nominally ca.20 wt.%Pt)based on dimethylamine borane(DMAB)reduction.The as-obtained electrocatalyst(denoted as Pt3Co/C-DMAB)is compared with the ones obtained by NaBH4 and N2H4·H2O reduction(denoted as Pt3Co/C-NaBH4 and Pt3Co/C-N2H4·H2O,respectively)as well as a commercial Pt/C,in terms of the structure and electrocatalytic property.It turns out that Pt3Co/C-DMAB exhibits the highest ORR performance among all the tested samples in an O2-saturated 0.1 mol/L HClO4,with the mass activity(specific activity)ca.4(6)times as large as that for Pt/C.After 10000 cycles of the accelerated degradation test,the half-wave potential for ORR on Pt3Co/C-DMAB decreases only by 4 mV,in contrast to 24 mV for that on Pt/C.Pt3Co/C-NaBH4 or Pt3Co/C-N2H4·H2O shows a specific activity comparable to that for Pt3Co/C-DMAB,but a mass activity similar to that for Pt/C.ICP-AES,TEM,XRD and XPS characterizations indicate that Pt3Co nanoparticles are well-dispersed and alloyed with a mean particle size of ca.3.4±0.4 nm,contributing to the prominent electrocatalytic performance of Pt3Co/C-DMAB.This simple aqueous synthetic route may provide an alternate opportunity for developing efficient practical electrocatalysts for ORR.

Effect of initial nickel particle size on stability of nickel catalysts for aqueous phase reforming

The deactivation behavior by crystallite growth of nickel nanoparticles on various supports（carbon nanofibers, zirconia, Si C, α-Al2O3 and γ-Al2O3） was investigated in the aqueous phase reforming of ethylene glycol. Supported Ni catalysts of ~10 wt% were prepared by impregnation of carbon nanofibers（CNF）,Zr O2, SiC, γ-Al2O3 and α-Al2O3. The extent of the Ni nanoparticle growth on various support materials follows the order CNF ~ ZrO2〉 SiC 〉 γ-Al2O3〉〉 α-Al2O3 which sequence, however, was determined by the initial Ni particle size. Based on the observed nickel leaching and the specific growth characteristics; the particle size distribution and the effect of loading on the growth rate, Ostwald ripening is suggested to be the main mechanism contributing to nickel particle growth. Remarkably, initially smaller Ni particles（~12 nm） supported on α-Al2O3 were found to outgrow Ni particles with initially larger size（~20 nm）. It is put forward that the higher susceptibility with respect to oxidation of the smaller Ni nanoparticles and differences in initial particle size distribution are responsible for this behavior.

Selective Synthesis and Advanced Characteristic of CdSe Semiconductor Quantum Dots by Aqueous Phase

This work mainly investigated the influences of some factors, such as, synthesis methods, precursor alteraatives, and vacuum heat-treating process, etc, on the fluorescent characteristics of the semiconductor quantum dots synthesized by aqueous phase. The research results indicate that the fluorescent characteristic of water- solution sample prepared from Na2 SO3 precursor was sensitive to water bath heating time, and specially, its photohuninescence spectrum shows the unique phenomenon of double excitation and emission peaks. Meanwhile, the fluorescent characteristic of water- solution sample prepared from NaBH4 precursor is slightly influenced by water bath heating time, and the sugface of CdSe quantum dots could be passivated by the excessive amount of NaBH4 precursor, which results in the effective decrease of surface traps and great enhancement of quantum yield. Furthermore, the fluorescent emission peaks of samples could be sharpened by vacuum heat-treating process, with its spectral full width at half of maximum （FWHM） around 30- 40 run, so the emission peaks become redshifi, of which the intensity greatly increases.

AQUEOUS PHASE SYNTHESIS OF(RC_5H_4)_2Ti(O_2CC_6H_4X)_2

Nine complexes(RC_5H_4)_2Ti(O_2CC_6H_4X)_2(R=H,CH_3;X=H,o-Cl,o-OH, o-NH_2,o-NHPh)have been conveniently prepared by the reaction of (RC_5H_4)_2TiCl_2 with 2 equiv.sodium salts of corresponding carboxylic acid in aqueous solution containing acetylacetone.The carboxylate ligands in the complexes coordinate to titanium atom in monodentate mode.

Chlorine-radical Induced Oxidation of Glyoxal and Glyoxal-S(IV) Adducts in the Aqueous Phase

A laser flash photolysis study of the reactivity of Cl˙with glyoxal, glyoxal mono- and dibisulfite adducts, 1-hydroxy-2, 2-diol-ethanesulfonate and 1, 2-dihydroxy-1, 2-ethanedi sulfonate in the aqueous phase was carried out. The obtained rate constants can be used for atmospheric modeling.

Adaptable "bubble particles" prepared by green aqueous phase reshaping for completely removing odor

Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers.However,current micro/nano particles loading approaches are often hindered by issues such as uneven distribution,unsatisfactory stability and complicate procedure.In this work,we present an aqueous phase reshaping method that only utilizes the moisture to fabricate the"bubble particles",which could perfectly cater to the topography of the substrate.The green preparation of bubble particles adopts an absolutely zero-pollution method,realizing the firm loading of particles on the substrate.Integrating the preparation and loading of particles overcomes the traditional complicate process,while the aqueous phase reshaping ensures uniform and firm loading of the"bubble particles"onto the substrate.Our mechanism demonstrates a significant enhancement in the interface relation after aqueous phase reshaping,with a 121-fold increase in contact surface area achieved by reducing the height by 1μm.Furthermore,we explore for the first time the influence of the nature of the receiving substrate on the interface morphology of particles during electrostatic spraying,which has important guiding significance for the interface relationship of electrostatic spraying and even electrostatic spinning materials.We also screen out the natural antibacterial essential oil linalool as the effective specialized antibacterial agent,which can specifically inhibit the odor-producing Proteus in urine,with an antibacterial rate of up to 100%.Taken together,this simple,ecofriendly method for fabricating functional materials with optimal interface stability appears highly promising for use in various products formed by electrostatic spraying/spinning.

Effects of persulfate-assisted hydrothermal treatment of municipal sludge on aqueous phase characteristics and phytotoxicity

Hydrothermal technology (HT) has received much attention in recent years as a process to convert wet organic waste into hydrochar.The aqueous phase (HTAP) produced by this process is still a burden and has become a bottleneck issue for HT process development.In this study,we provide the?rst investigation of the HTAP characteristics,phytotoxicity,and their correlation with persulfate (PS)(PS,2.0 mmol/g TS)-assisted municipal sludge HT.The results showed that PS accelerated the hydrolysis of protein substances and increased the concentration of NH_(4)^(+)by 13.4%to 190.5%and that of PO_(4)^(3-)by 24.2%to 1103.7%in HTAP at hydrothermal temperatures of 120 to 240℃.PS can reduce the phytotoxicity of HTAP by reducing aldehydes,ketones,N heterocyclic compounds,and particle size and by increasing its humi?cation index.The maximum values of the root length and biomass of pakchoi(Brassica chinensis L.) seedlings occurred when electrical conductivity was 0.2 mS/cm of HTAP.This work provided a new strategy for the selection and design of HTAP management strategies.

Catalytic hydrogenation of aromatic nitro compounds by functionalized ionic liquids-stabilized nickel nanoparticles in aqueous phase:The influence of anions

Two kinds of nickel nanoparticles (NPs) well-dispersed in aqueous phase have been conveniently prepared by reducing nickel(II) salt with hydrazine in the presence of amino group (-NH2) functionalized ionic liquids:1-(3-aminopropyl)-2,3-dimethylimidazolium bromide ([AMMIM][Br]) and 1-(3-aminopropyl)-2,3-dimethylimidazolium acetate ([AMMIM][AcO]).The Ni(0) particles are composed of smaller ones which assemble in a blackberry-like shape.The Ni nanoparticles stabilized with [AMMIM][AcO] are much larger than those stabilized with [AMMIM][Br],and the former unexpectedly give much higher activity in the selective hydrogenation of citral and nitrobenzene (NB) in aqueous phase.The Ni(0) nanocatalysts dispersed in aqueous phase are stable enough to be reused at least five times without significant loss of catalytic activity and selectivity during the catalytic recycles.

Reaction mechanism of aqueous-phase conversion of γ-valerolactone(GVL) over a Ru/C catalyst

The present work explores the reaction pathways of γ-valerolactone(GVL) over a supported ruthenium catalyst. The conversion of GVL in aqueous phase over a 5% Ru/C catalyst was investigated in a batch reactor operating at 463 K under 500–1000 psi of H2. The main reaction products obtained under these conditions were 2-butanol(2-BuOH), 1,4-pentanediol(1,4-PDO), 2-methyltetrahydrofuran(2-MTHF) and 2-pentanol(2-PeOH). A complete reaction network was developed, identifying the primary and/or secondary products. In this reaction network, production of 2-BuOH via decarbonylation of a ring-opened surface intermediate CH3CH(O*)–(CH2)2–CO*is clearly the dominant pathway. From the evolution of products as a function of reaction time and theoretical(DFT) calculations, a mechanism for the formation of intermediates and products is proposed. The high sensitivity of 2-BuOH production to the presence of CO, compared to a much lower effect on the production of the other products indicates that the sites responsible for decarbonylation are particularly prone to CO adsorption and poisoning. Also, since the decarbonylation rate is not affected by the H2 pressure it is concluded that the direct decarbonylation path of the CH3CH(O*)–(CH2)2–CO*intermediate does not required a previous dehydrogenation step, as is the case in decarbonylation of short alcohols.

A simple catalyst for aqueous phase Suzuki reactions based on palladium nanoparticles immobilized on an ionic polymer

Palladium nanoparticles immobilized on a cross-linked imidazolium-containing polymer were evaluated as a catalyst for Suzuki carbon-carbon cross-coupling reactions using water as the solvent. The nanocatalysts show good catalytic activities for aryl iodides and aryl bromides and moderate activity with aryl chloride substrates. Coupling of sterically hindered substrates could also be achieved in reasonable yields. The heterogeneous catalyst is stable, can be stored without precautions to exclude air or moisture, and can be easily recycled and reused.

Aqueous Phase Synthesis and Fluorescence Properties of Inverted Core/Shell ZnSe/CdSe Nanocrystals

We report a facile aqueous phase synthesis for prepar-ing water-soluble inverted core/shell ZnSe/CdSe semiconductor nanocrystals. The samples were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),and their optical properties were investigated by using UV-vis-NIR spectropho-tometer and fluorescence spectrophotometer. The results indicate that the synthesized ZnSe/CdSe nanocrystals are inverted core/shell structure with diameter of about 5 nm. Furthermore,their absorption band-edge is red-shifted with the growth of CdSe shell; correspondingly,their emission wavelength can be tuned from 460 nm to 604 nm.

Novel Vesicular Aqueous Two-Phase Systems

The interesting phenopmena of two aqueous phases coexisting in dilute aqueous solutions of sodium undecenoate-dodecyltrimethylammo brodride ndxture and sodium laurate-dodecyltrimethylammonium brondde mixture were investigated. Vesicles existing in both phases were shown by TEM images. The vesicles are dispersed in lower phase and flocculated in upper phase. Multilamellar structure of vesicles was found in the upper phase of sodium laurate-dodecyltrimethylammonium bromide system.

Partition coefficient prediction of Baker's yeast invertase in aqueous two phase systems using hybrid group method data handling neural network

A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG(1500–6000 Da), p H(4.0–7.0), percentage of PEG(10.0–20.0 w/w), percentage of MgSO_4(8.0–16.0 w/w), percentage of the cell homogenate(10.0–20.0 w/w) and the percentage of MnSO_4(0–5.0 w/w) added as cosolute. The network evaluation was carried out comparing the partition coefficients obtained from the hybrid GMDH neural network with the experimental data using different statistical metrics. The hybrid GMDH neural network model showed better fitting(AARD = 32.752%) as well as good generalization capacity of the partition coefficients of the ATPS than the original GMDH network approach and a BPANN model. Therefore hybrid GMDH neural network model appears as a powerful tool for predicting partition coefficients during downstream processing of biomolecules.

Phase Equilibria of the Aqueous Systems Containing Lithium and Carbonate Ions

1 Introduction Alkaline lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous for their high concentration of lithium,potassium,magnesium,boron(Ma,2000).In recent years,as a new energy material,lithium and its compounds are widely used in the new area,such as aerospace industry,nuclear

Solid–liquid Phase Equilibria in the Aqueous Ternary System Containing Lithium,Potassium,and Sulfate ions at 288.15 K

1 Introduction Salt lakes are widely distributed in the western of China,especially in the area of Qinghai-Xizang(Tibet)Plateau.A series of salt lakes in the Qaidam Basin,located in Qinghai Province,China,is famous for their abundance of lithium,potassium and boron resources(Zheng et al,1988;Deng et al,2012).It is well known that the

Rate Constants for the Reactions of NO_3~.and SO_4^(._) Radicals with Oxalic Acid and Oxalate Anions in Aqueous Solution

Rate constants for the reactions of NO3 and SO4 radicals with oxalic acid and oxalate anions in aqueous solution have been measured using pulse radiolysis and laser flash photolysis.

Co encapsulated N-doped carbon nanotubes as robust catalyst for valorization of levulinic acid in aqueous media

The construction of an acid resistant catalyst for synthesis of γ-valerolactone from levulinic acid in aqueous media is an important but highly challenging goal.Herein,an efficient Co@NCNT-800(after 800℃ pyrolysis) catalyst was constructed by confining Co in N-doped carbon nano-tubes(NCNT) from low cost materials by a facile strategy.Combined with the characterization results and control experiments,the in situ formed Co and Co-Ox, but not Co-Nx, proved to be the main synergistic active sites of the catalyst.It was also found that Co species are completely isolated within the bamboo-like NCNT,which could protect the metal nanoparticles from agglomeration and leaching in the strong acid reaction system.The γ-valerolactone yield of no less than 99.9% can be obtained under a relatively mild condition,and the catalytic performance has not been significantly reduced within five cycles.Therefore,this work may pave a way for the design of robust non-noble catalyst,and has potential for the production of γ-valerolactone from biomass in large-scale industries.

Surfactant Distribution in the Clouding of TX114

Distribution of TX114 between coacervate and aqueous phases in clouding of various initial TX114 concentrations was studied. Effects of temperature and salinity （Na2SO4） on the distribution of TX114 concentration were also investigated. Differing from the nonionic surfactant C12E10, the distribution of TX114 is sensitive to the temperature, and it is observed that the TX114 concentration in the aqueous phase （Caq） does not depend on the initial TX114 concentration apparently at 45℃, and the Caq decreases with an increase of NazSO4 concentration. Low initial TX114 concentration in unclouded solutions, high Na2SO4 concentration, and temperature are suggested to control the surfactant loss in large-scale cloud point extraction applications.