Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent therma...Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent thermal stability and high-voltage short-pulse initiation performance. However, the solid phase ripening of ultrafine HNS leads to a degradation in its impact detonation performance. Previous studies have indicated that residual dimethyl formamide(DMF), which is present in ultrafine HNS prepared using the recrystallization method, affects ultrafine HNS ripening. The mechanism of residual solvent effects on solid phase ripening of ultrafine HNS is unclear. In this work, the specific surface area(SSA) derived from small angle X-ray scattering(SAXS) was utilized for kinetic fitting analysis to explore the mechanism by which residual solvents enhance the solid phase ripening of ultrafine HNS. The results of the SSA measured by insitu SAXS under conditions of 150℃ for 40 h revealed that the sample with 0.2% residual DMF exhibited a 21.51% decrease in SSA, whereas the sample with only 0.04% residual DMF showed a decrease of 15.66%.Furthermore, the higher amounts of residual DMF accelerated the reduction in SSA with time. Kinetic fitting analysis demonstrated that reducing residual DMF would lower both the activation energy and the pre-exponential factor, consequently decreasing the rate constant of solid phase ripening. The mechanism was speculated that it primarily facilitated the Ostwald ripening(OR). Additionally, contrast variation small angle X-ray scattering(CV-SAXS) confirmed that coating of ultrafine HNS particles is an effective method for inhibiting ripening, significantly reducing both the rate and extent of ripening of ultrafine HNS. This study predicts how residual solvents impact the solid phase ripening process of ultrafine HNS and proposes strategies for enhancing the long-term stability of ultrafine explosives.展开更多
Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics...Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.展开更多
Highly efficient organic solar cells(OSCs)are normally produced using the halogenated solvents chloroform or chlorobenzene,which present challenges for scalable manufacturing due to their toxicity,narrow processing wi...Highly efficient organic solar cells(OSCs)are normally produced using the halogenated solvents chloroform or chlorobenzene,which present challenges for scalable manufacturing due to their toxicity,narrow processing window and low boiling point.Herein,we develop a novel high-speed doctor-blading technique that significantly reduces the required concentration,facilitating the use of eco-friendly,non-halogenated solvents as alternatives to chloroform or chlorobenzene.By utilizing two widely used high-boiling,non-halogenated green solvents-o-xylene(o-XY)and toluene(Tol)-in the fabrication of PM 6:L 8-BO,we achieve power conversion efficiencies(PCEs)of 18.20%and 17.36%,respectively.Additionally,a module fabricated with o-XY demonstrates a notable PCE of 16.07%.In-situ testing and morphological analysis reveal that the o-XY coating process extends the liquid-to-solid transition stage to 6 s,significantly longer than the 1.7 s observed with Tol processing.This prolonged transition phase is crucial for improving the crystallinity of the thin film,reducing defect-mediated recombination,and enhancing carrier mobility,which collectively contribute to superior PCEs.展开更多
The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible t...The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible to selectively leach zinc from the ores by heap leaching. The zinc concentration of leach solution in the first leaching cycle is 32.57 g/L, and in the sixteenth cycle the zinc concentration is 8.27g/L after solvent extraction. The leaching solution is subjected to solvent extraction, scrubbing and selective stripping for enrichment of zinc and removal of impurities. The pregnant zinc sulfate solution produced from the stripping cycle is suitable for zinc electrowinning. Extra-pure zinc metal was obtained in the electrowinning test under conventional conditions.展开更多
A plumbomicrolite concentrate(PMC)was leached with the mixture of HF and H2SO4,HF and HNO3 acids,respectively.Optimal conditions ensuring high recovery of tantalum and niobium(up to 99%)into solution,and radionuclides...A plumbomicrolite concentrate(PMC)was leached with the mixture of HF and H2SO4,HF and HNO3 acids,respectively.Optimal conditions ensuring high recovery of tantalum and niobium(up to 99%)into solution,and radionuclides into insoluble residue were determined.Fluoride-sulfuric acid and fluoride-nitric acid schemes were proposed for PMC leaching by an extractive separation of tantalum form niobium,lead and impurities,and production of high-purity tantalum compounds.Octanol-1 was used as an extractant.Optimal conditions for production of high-purity tantalum strip solutions were defined for all stages(extraction-scrubbing-stripping).Produced tantalum compounds,such as tantalum pentoxide and potassium heptafluotanthalate,comply with the norms for high-purity substances in terms of impurities content.Final choice of the PMC processing scheme is determined by its profitability.展开更多
In order to obtain high-quality spherical RDX crystal particles,the RDX crystals were suspended in a mixed solvent of cyclohexanone and cyclohexane,subsequently a solvent etching study was carried out under the action...In order to obtain high-quality spherical RDX crystal particles,the RDX crystals were suspended in a mixed solvent of cyclohexanone and cyclohexane,subsequently a solvent etching study was carried out under the action of vibration/acoustic flow coupled flow field,which generated by resonance acoustic mixing.The effects of solvent ratio,temperature,acceleration and experiment time on morphology as well as particle size of RDX crystals were studied.Not only were the morphology,particle size distribution and crystal form of RDX crystals determined,but also the thermal decomposition performance and mechanical sensitivity of spherical RDX were examined and discussed.Results indicated that under the process of solvent/non-solvent volume ratio at 1:2,temperature of 40℃,acceleration of 40 g and experiment time of 4 h,α-type RDX crystal with sphericity of 0.92 can be obtained.Furthermore,the median particle size(D_(50))of spherical RDX crystals is 215.8 μm with a unimodal particle size distribution(size span 1.34).For one thing,the thermal decomposition peak temperature of spherical RDX is about 2.5℃ higher than that of raw RDX,and apparent activation energy reaches 444.68 kJ/mol.For another thing,impact sensitivity and friction sensitivity of spherical RDX are 18.18% and 33.33% lower than that of raw RDX,respectively.It demonstrates that safety of spherical RDX under thermal,impact and friction stimuli has been improved.展开更多
The solvent extraction of copper and zinc from the bioleaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated. The influences of extractant content, aqueous pH value, phase ratio and (equi...The solvent extraction of copper and zinc from the bioleaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated. The influences of extractant content, aqueous pH value, phase ratio and (equilibration) time on metals extraction were studied. The results show that LIX984 has a higher selectivity for copper than for iron, zinc and other metals, and has the copper extraction rate above 97%, while the zinc and iron extraction rate is less than 1.6% respectively. Zinc extraction is carried out following the copper extraction from the raffinate. The zinc extraction with di(2-ethylhexyl) phosphoric acid(D2EHPA) is low due to its poor cation exchange. A sodium salt of D2EHPA is used and the zinc extraction rate is enhanced to above 98%. Though iron (Ⅲ) is strongly extracted before the extraction of zinc by D2EHPA, it is difficult to strip iron from the organic phase by sulfuric acid. The zinc stripping rate is above 99% with 100g/L sulfuric acid, while that of iron is 0.16%. Hence, the separation of zinc from iron can be achieved by the selective stripping.展开更多
Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) an...Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) and TBP was proposed for extraction.The results show the species extracted into the organic phase were found to be mainly BiCl_3·x TBP(x=2 or 3).Thermodynamic parameters of the extraction reaction were obtained from the thermodynamics analysis,which illustrates that higher temperatures show a negative effect on the extraction.Extraction isotherm was obtained with 2.16 mol/L TBP for a typical solution containing 0.1 mol/L of bismuth and 1.0 mol/L of hydrochloric acid.About 98.5 % of bismuth has been extracted from the leaching solution under the optimum condition.Moreover,oxalate was explored as a precipitation stripping agent for BiCl_3·x TBP(x=2 or 3) complexes,by which Bi(Ⅲ) was stripped in the form of Bi_2(C_2O_4)_3·7H_2O.A stripping efficiency of 99.3% was obtained in only one stage at the phase ratio of 1 and TBP also could be recycled.Therefore,the method is an efficient,effective and highly selective approach to extract Bi(Ⅲ) and to recover metal bismuth.展开更多
Many of the physical and functional properties of RDX and HMX explosives are related to the crystalline structure of these materials. Crystalline defects affect the quality of the explosives. Therefore, in order to en...Many of the physical and functional properties of RDX and HMX explosives are related to the crystalline structure of these materials. Crystalline defects affect the quality of the explosives. Therefore, in order to enhance the quality of these materials, it is necessary to form crystals with the lowest defects. In this research, we report the optimization of recrystallization process of RDX and HMX by statistical techniques. The solvent/anti-solvent procedure was used for recrystallization of HMX and RDX particles. The four parameters of i) ratio of anti-solvent to solvent, ii) ratio of solute to solvent, iii) aging time, and iv)cooling rate of mixture, were optimized by Taguchi analysis design. Taguchi L16 orthogonal array was used with sixteen rows corresponding to the number of tests in four columns at four levels. The apparent density of recrystallized of RDX and HMX particles was considered as the quality characteristic with the concept of "the larger-the-better". The obtained graphs showed that the studied parameters were optimized in ratio 1:1 for anti-solvent to solvent, ratio 0.1 g,m L^(-1) for solute to solvent, aging time of 2 h and cooling rate of 1℃,min^(-1). Also, the correlation between the investigated parameters and apparent density of crystals were studied by multiple linear regressions(MLR) method for obtaining a model of prediction of apparent density. The P-values were indicated that in confidence level of 95%, the null hypothesis is rejected and a meaningful addition is observed in the proposed model.展开更多
A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the des...A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the desired and standard beta(β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly(ethylene glycol)-400(PEG-400) polymer and coconut fatty acid diethanolamide(lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.展开更多
Drying is a complicated physical process which involves simultaneous heat and mass transfer in the removal of solvents inside propellants.Inappropriate drying techniques may result in the formation of a hard skin laye...Drying is a complicated physical process which involves simultaneous heat and mass transfer in the removal of solvents inside propellants.Inappropriate drying techniques may result in the formation of a hard skin layer near the surface to block the free access of most solvent through for long stick propellants with large web thickness,which lead to lower drying efficiency and worse drying quality.This study aims to gain a comprehensive understanding of drying process and clarify the mechanism of the blocked layer near the propellant surface.A new three-dimensional coupled heat and mass transfer(3D-CHMT)model was successfully developed under transient conditions.The drying experiment results show that the 3DCHMT model could be applied to describe the drying process well since the relative error of the content of solvent between simulation and experiment values is only 5.5%.The solvent behavior simulation demonstrates that the mass transfer process can be divided into super-fast(SF)and subsequent minorfast(MF)stages,and the SF stage is vital to the prevention of the blocked layer against the free access for solvent molecules inside propellant grains.The effective solvent diffusion coefficient(Deff)of the propellant surface initially increases from 3.4×10^(-6)to 5.3×10^(-6)m^(2)/s as the temperature increases,and then decreases to 4.1×10^(-8)m^(2)/s at 60-100 min.The value of Deffof surface between 0-1.4 mm has a unique trend of change compared with other regions,and it is much lower than that of the internal at100 min under simulation conditions.Meanwhile,the temperature of the propellant surface increases rapidly at the SF stage(0-100 min)and then very slowly thereafter.Both the evolution of Deffand temperature distribution demonstrate that the blocked layer near the propellant surface has been formed in the time period of approximately 0-100 min and its thickness is about 1.4 mm.To mitigate the formation of blocked layer and improve its drying quality of finial propellant products effectively,it should be initially dried at lower drying temperature(30-40℃)in 0-100 min and then dried at higher drying temperature(50-60℃)to reduce drying time for later drying process in double base gun propellants.The present results can provide theoretical guidance for drying process and optimization of drying parameters for long stick propellants with large web thickness.展开更多
The separation of cobalt and nickel in the ammoniacal sulfate solution by non equilibrium solvent extraction with a phosphate (P303) as extractant was studied. In the experiment, the effects of equilibrium pH value in...The separation of cobalt and nickel in the ammoniacal sulfate solution by non equilibrium solvent extraction with a phosphate (P303) as extractant was studied. In the experiment, the effects of equilibrium pH value in aqueous phase, contact time of the two phases, the air blowing time for feed liquor in the open beaker on percentage extraction of cobalt and nickel and percentage reextraction of nickel from the loaded organic phase with dilute H 2SO 4. etc were studied. The results showed that: Co(Ⅱ) can be oxidized to Co(Ⅲ) ammino complex by adding (NH 4) 2S 2O 8 or blowing air to the aqueous phase, and Co(Ⅲ) ammino complex is a kind of kinetically inert complex. Its extractive speed is very slow, while the nickel′s is much faster than that of cobalt. By controlling the contact time of the two phases, nickel can be separated from cobalt by non equilibrium solvent extraction. Then nickel was reextracted from the loaded organic phase with dilute H 2SO 4.展开更多
The extraction of zinc from zinc sulfate solution was investigated, using 20% saponified D2EHPA as an extractam and 260^# sulfonate kerosene as a diluent. The solution was stirred for 8 min at phase ratio （Vσ/Va） o...The extraction of zinc from zinc sulfate solution was investigated, using 20% saponified D2EHPA as an extractam and 260^# sulfonate kerosene as a diluent. The solution was stirred for 8 min at phase ratio （Vσ/Va） of 1.0：1.0, initial pH of 2.0 and stirring speed of 200 r/min. The results show that 75% zinc can be extracted from the zinc sulfate solution when the concentration of zinc is 18.7 g/L after being settled for 10 min. 88.60% zinc can be stripped by 196 g/L sulfuric acid, and zinc ion can be separated from ferric ion.展开更多
For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylamm...For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylammonium chloride R 4NCl) in toluene was investigated. The experiments were carried out under conditions of 25 ℃, Nb(Ⅴ) concentration 0.01 mol/L, pH 10.7 13.8, R 4NCl concentration 0.02 0.14 mol/L. It has been found that the distribution ratio of niobium increases with increasing R 4NCl concentration and with decreasing KCl concentration, but it shows maximum value at pH value of about 12 and decreases below or above this pH value. Distribution ratio of niobium goes up to over 1 000 in appropriate conditions, and so it has been proved that R 4NCl is an effective extractant for extraction of niobium from alkali solution.展开更多
Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use o...Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use of colloidal liquid aphrons (CLA) together with colloidal gas aphrons (CGA). The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer etc. In this paper, PDSE process, CLA and CGA are systematically reviewed and the potential applications of CLA, CGA and PDSE for the various areas of separation as well as the latest development in this area are discussed.展开更多
This work investigated the separation of potassium from sodium in alkaline solution using substituted phenol-based extractants.Superior potassium extraction was achieved with 4-tert-butyl-2-(α-methylbenzyl)phenol(t-B...This work investigated the separation of potassium from sodium in alkaline solution using substituted phenol-based extractants.Superior potassium extraction was achieved with 4-tert-butyl-2-(α-methylbenzyl)phenol(t-BAMBP)than 4-sec-butyl-2-(α-methylbenzyl)phenol(BAMBP).The optimum conditions for the extraction were 1 mol/L t-BAMBP,3:1 volumetric phase ratio(O/A),and two extraction stages.After cross-current extraction,the extraction ratio of potassium reached 90.8%.After scrubbing with deionised water at phase ratio of 4:1 and scrubbing stage of 4,a sodium scrubbing efficiency of 88.2%was obtained.After stripping using 1 mol/L H_(2)SO_(4) at phase ratio of 3:1,the stripping efficiency of potassium reached 94.2%.The potassium/sodium(K/Na)concentration ratio increased 14.3 times from 0.15 in the feed solution to 2.3 in the stripping solution.The efficient separation of potassium from sodium in alkaline solution was achieved via solvent extraction with t-BAMBP.展开更多
The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereeva...The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.展开更多
The unfavorable growth and agglomeration of micro-particles of RDX explosive was almost observed in manufacture process. For preventing of growth of micro-particles and agglomeration in anti-solvent crystallization pr...The unfavorable growth and agglomeration of micro-particles of RDX explosive was almost observed in manufacture process. For preventing of growth of micro-particles and agglomeration in anti-solvent crystallization process, the effect of additives glucose, sucrose and poly ethylene glycol-2000 and wetting solvent of isopropyl alcohol were studied. Taguchi experimental design was used for optimization of the operating conditions. The type of additive, the amount of additive(%wt.), solvent of wetting and wetting time were selected for optimization of the conditions. By using 4 factor and 3 levels, 27 experiments were conducted(L27). Results showed that in the presence of 2 %wt. of sucrose additive and isopropyl alcohol solvent, the agglomerations of particles were decreased so that a decrease 30-50% in the average of particles size was seen. Addition additives were effective in storage container and for reduce the agglomeration of particles during storage. Also, the agglomeration rate of particles was reduced over time at optimized conditions. Imaging optical microscopy, scanning electron microscopy(SEM), and particle size analyzer(PSA) methods were used for particles size analyzing as a response in statistical optimization and quality control of the final product. The sensitivity to some mechanical and shock stimuli on the RDX in presence of sucrose additive was tested and the obtained results showed the insignificant effect of additive on the safety properties of pure RDX.展开更多
基金the Presidential Foundation of CAEP(Grant No.YZJJZQ2023005)the National Natural Science Foundation of China(Grant No.22375191).
文摘Nowadays, ultrafine explosives are widely used in military fields. Ultrafine 2,2',4,4',6,6'-hexanitrostilbene(HNS) has emerged as an optimal primer for explosion foil initiators due to its excellent thermal stability and high-voltage short-pulse initiation performance. However, the solid phase ripening of ultrafine HNS leads to a degradation in its impact detonation performance. Previous studies have indicated that residual dimethyl formamide(DMF), which is present in ultrafine HNS prepared using the recrystallization method, affects ultrafine HNS ripening. The mechanism of residual solvent effects on solid phase ripening of ultrafine HNS is unclear. In this work, the specific surface area(SSA) derived from small angle X-ray scattering(SAXS) was utilized for kinetic fitting analysis to explore the mechanism by which residual solvents enhance the solid phase ripening of ultrafine HNS. The results of the SSA measured by insitu SAXS under conditions of 150℃ for 40 h revealed that the sample with 0.2% residual DMF exhibited a 21.51% decrease in SSA, whereas the sample with only 0.04% residual DMF showed a decrease of 15.66%.Furthermore, the higher amounts of residual DMF accelerated the reduction in SSA with time. Kinetic fitting analysis demonstrated that reducing residual DMF would lower both the activation energy and the pre-exponential factor, consequently decreasing the rate constant of solid phase ripening. The mechanism was speculated that it primarily facilitated the Ostwald ripening(OR). Additionally, contrast variation small angle X-ray scattering(CV-SAXS) confirmed that coating of ultrafine HNS particles is an effective method for inhibiting ripening, significantly reducing both the rate and extent of ripening of ultrafine HNS. This study predicts how residual solvents impact the solid phase ripening process of ultrafine HNS and proposes strategies for enhancing the long-term stability of ultrafine explosives.
基金the National Natural Science Foundation of China(Grant No.22075146).
文摘Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.
基金Project(2022YFB3803300)supported by the National Key Research and Development Program of ChinaProjects(U23A20138,52173192)supported by the National Natural Science Foundation of China+1 种基金Project(GZC20233148)supported by the Postdoctoral Fellowship Program of CPSF,ChinaProject(140050043)supported by the Central South University Postdoctoral Research Funding,China。
文摘Highly efficient organic solar cells(OSCs)are normally produced using the halogenated solvents chloroform or chlorobenzene,which present challenges for scalable manufacturing due to their toxicity,narrow processing window and low boiling point.Herein,we develop a novel high-speed doctor-blading technique that significantly reduces the required concentration,facilitating the use of eco-friendly,non-halogenated solvents as alternatives to chloroform or chlorobenzene.By utilizing two widely used high-boiling,non-halogenated green solvents-o-xylene(o-XY)and toluene(Tol)-in the fabrication of PM 6:L 8-BO,we achieve power conversion efficiencies(PCEs)of 18.20%and 17.36%,respectively.Additionally,a module fabricated with o-XY demonstrates a notable PCE of 16.07%.In-situ testing and morphological analysis reveal that the o-XY coating process extends the liquid-to-solid transition stage to 6 s,significantly longer than the 1.7 s observed with Tol processing.This prolonged transition phase is crucial for improving the crystallinity of the thin film,reducing defect-mediated recombination,and enhancing carrier mobility,which collectively contribute to superior PCEs.
文摘The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible to selectively leach zinc from the ores by heap leaching. The zinc concentration of leach solution in the first leaching cycle is 32.57 g/L, and in the sixteenth cycle the zinc concentration is 8.27g/L after solvent extraction. The leaching solution is subjected to solvent extraction, scrubbing and selective stripping for enrichment of zinc and removal of impurities. The pregnant zinc sulfate solution produced from the stripping cycle is suitable for zinc electrowinning. Extra-pure zinc metal was obtained in the electrowinning test under conventional conditions.
基金Project supported by the Federal Research Centre of Kola Science Centre of the Russian Academy of Sciences,Russian。
文摘A plumbomicrolite concentrate(PMC)was leached with the mixture of HF and H2SO4,HF and HNO3 acids,respectively.Optimal conditions ensuring high recovery of tantalum and niobium(up to 99%)into solution,and radionuclides into insoluble residue were determined.Fluoride-sulfuric acid and fluoride-nitric acid schemes were proposed for PMC leaching by an extractive separation of tantalum form niobium,lead and impurities,and production of high-purity tantalum compounds.Octanol-1 was used as an extractant.Optimal conditions for production of high-purity tantalum strip solutions were defined for all stages(extraction-scrubbing-stripping).Produced tantalum compounds,such as tantalum pentoxide and potassium heptafluotanthalate,comply with the norms for high-purity substances in terms of impurities content.Final choice of the PMC processing scheme is determined by its profitability.
文摘In order to obtain high-quality spherical RDX crystal particles,the RDX crystals were suspended in a mixed solvent of cyclohexanone and cyclohexane,subsequently a solvent etching study was carried out under the action of vibration/acoustic flow coupled flow field,which generated by resonance acoustic mixing.The effects of solvent ratio,temperature,acceleration and experiment time on morphology as well as particle size of RDX crystals were studied.Not only were the morphology,particle size distribution and crystal form of RDX crystals determined,but also the thermal decomposition performance and mechanical sensitivity of spherical RDX were examined and discussed.Results indicated that under the process of solvent/non-solvent volume ratio at 1:2,temperature of 40℃,acceleration of 40 g and experiment time of 4 h,α-type RDX crystal with sphericity of 0.92 can be obtained.Furthermore,the median particle size(D_(50))of spherical RDX crystals is 215.8 μm with a unimodal particle size distribution(size span 1.34).For one thing,the thermal decomposition peak temperature of spherical RDX is about 2.5℃ higher than that of raw RDX,and apparent activation energy reaches 444.68 kJ/mol.For another thing,impact sensitivity and friction sensitivity of spherical RDX are 18.18% and 33.33% lower than that of raw RDX,respectively.It demonstrates that safety of spherical RDX under thermal,impact and friction stimuli has been improved.
基金Project(50321402) supported by the National Natural Science Foundation of China
文摘The solvent extraction of copper and zinc from the bioleaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated. The influences of extractant content, aqueous pH value, phase ratio and (equilibration) time on metals extraction were studied. The results show that LIX984 has a higher selectivity for copper than for iron, zinc and other metals, and has the copper extraction rate above 97%, while the zinc and iron extraction rate is less than 1.6% respectively. Zinc extraction is carried out following the copper extraction from the raffinate. The zinc extraction with di(2-ethylhexyl) phosphoric acid(D2EHPA) is low due to its poor cation exchange. A sodium salt of D2EHPA is used and the zinc extraction rate is enhanced to above 98%. Though iron (Ⅲ) is strongly extracted before the extraction of zinc by D2EHPA, it is difficult to strip iron from the organic phase by sulfuric acid. The zinc stripping rate is above 99% with 100g/L sulfuric acid, while that of iron is 0.16%. Hence, the separation of zinc from iron can be achieved by the selective stripping.
基金Project(2011AA061002)supported by the High-Tech Research and Development Program of ChinaProject(2010SK2010)supported by the Key Program of Science and Technology of Hunan Province,ChinaProject supported by the Hunan Nonferrous Metals Fund,China
文摘Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) and TBP was proposed for extraction.The results show the species extracted into the organic phase were found to be mainly BiCl_3·x TBP(x=2 or 3).Thermodynamic parameters of the extraction reaction were obtained from the thermodynamics analysis,which illustrates that higher temperatures show a negative effect on the extraction.Extraction isotherm was obtained with 2.16 mol/L TBP for a typical solution containing 0.1 mol/L of bismuth and 1.0 mol/L of hydrochloric acid.About 98.5 % of bismuth has been extracted from the leaching solution under the optimum condition.Moreover,oxalate was explored as a precipitation stripping agent for BiCl_3·x TBP(x=2 or 3) complexes,by which Bi(Ⅲ) was stripped in the form of Bi_2(C_2O_4)_3·7H_2O.A stripping efficiency of 99.3% was obtained in only one stage at the phase ratio of 1 and TBP also could be recycled.Therefore,the method is an efficient,effective and highly selective approach to extract Bi(Ⅲ) and to recover metal bismuth.
文摘Many of the physical and functional properties of RDX and HMX explosives are related to the crystalline structure of these materials. Crystalline defects affect the quality of the explosives. Therefore, in order to enhance the quality of these materials, it is necessary to form crystals with the lowest defects. In this research, we report the optimization of recrystallization process of RDX and HMX by statistical techniques. The solvent/anti-solvent procedure was used for recrystallization of HMX and RDX particles. The four parameters of i) ratio of anti-solvent to solvent, ii) ratio of solute to solvent, iii) aging time, and iv)cooling rate of mixture, were optimized by Taguchi analysis design. Taguchi L16 orthogonal array was used with sixteen rows corresponding to the number of tests in four columns at four levels. The apparent density of recrystallized of RDX and HMX particles was considered as the quality characteristic with the concept of "the larger-the-better". The obtained graphs showed that the studied parameters were optimized in ratio 1:1 for anti-solvent to solvent, ratio 0.1 g,m L^(-1) for solute to solvent, aging time of 2 h and cooling rate of 1℃,min^(-1). Also, the correlation between the investigated parameters and apparent density of crystals were studied by multiple linear regressions(MLR) method for obtaining a model of prediction of apparent density. The P-values were indicated that in confidence level of 95%, the null hypothesis is rejected and a meaningful addition is observed in the proposed model.
基金financial support of this work by Malek-ashtar University of Technology(I.R.Iran)Grant No.1395064
文摘A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the desired and standard beta(β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly(ethylene glycol)-400(PEG-400) polymer and coconut fatty acid diethanolamide(lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.
基金supported by the National Natural Science Foundation of China(Grant No.22075146)。
文摘Drying is a complicated physical process which involves simultaneous heat and mass transfer in the removal of solvents inside propellants.Inappropriate drying techniques may result in the formation of a hard skin layer near the surface to block the free access of most solvent through for long stick propellants with large web thickness,which lead to lower drying efficiency and worse drying quality.This study aims to gain a comprehensive understanding of drying process and clarify the mechanism of the blocked layer near the propellant surface.A new three-dimensional coupled heat and mass transfer(3D-CHMT)model was successfully developed under transient conditions.The drying experiment results show that the 3DCHMT model could be applied to describe the drying process well since the relative error of the content of solvent between simulation and experiment values is only 5.5%.The solvent behavior simulation demonstrates that the mass transfer process can be divided into super-fast(SF)and subsequent minorfast(MF)stages,and the SF stage is vital to the prevention of the blocked layer against the free access for solvent molecules inside propellant grains.The effective solvent diffusion coefficient(Deff)of the propellant surface initially increases from 3.4×10^(-6)to 5.3×10^(-6)m^(2)/s as the temperature increases,and then decreases to 4.1×10^(-8)m^(2)/s at 60-100 min.The value of Deffof surface between 0-1.4 mm has a unique trend of change compared with other regions,and it is much lower than that of the internal at100 min under simulation conditions.Meanwhile,the temperature of the propellant surface increases rapidly at the SF stage(0-100 min)and then very slowly thereafter.Both the evolution of Deffand temperature distribution demonstrate that the blocked layer near the propellant surface has been formed in the time period of approximately 0-100 min and its thickness is about 1.4 mm.To mitigate the formation of blocked layer and improve its drying quality of finial propellant products effectively,it should be initially dried at lower drying temperature(30-40℃)in 0-100 min and then dried at higher drying temperature(50-60℃)to reduce drying time for later drying process in double base gun propellants.The present results can provide theoretical guidance for drying process and optimization of drying parameters for long stick propellants with large web thickness.
文摘The separation of cobalt and nickel in the ammoniacal sulfate solution by non equilibrium solvent extraction with a phosphate (P303) as extractant was studied. In the experiment, the effects of equilibrium pH value in aqueous phase, contact time of the two phases, the air blowing time for feed liquor in the open beaker on percentage extraction of cobalt and nickel and percentage reextraction of nickel from the loaded organic phase with dilute H 2SO 4. etc were studied. The results showed that: Co(Ⅱ) can be oxidized to Co(Ⅲ) ammino complex by adding (NH 4) 2S 2O 8 or blowing air to the aqueous phase, and Co(Ⅲ) ammino complex is a kind of kinetically inert complex. Its extractive speed is very slow, while the nickel′s is much faster than that of cobalt. By controlling the contact time of the two phases, nickel can be separated from cobalt by non equilibrium solvent extraction. Then nickel was reextracted from the loaded organic phase with dilute H 2SO 4.
基金Project(50774094) supported by the National Natural Science Foundation of China
文摘The extraction of zinc from zinc sulfate solution was investigated, using 20% saponified D2EHPA as an extractam and 260^# sulfonate kerosene as a diluent. The solution was stirred for 8 min at phase ratio （Vσ/Va） of 1.0：1.0, initial pH of 2.0 and stirring speed of 200 r/min. The results show that 75% zinc can be extracted from the zinc sulfate solution when the concentration of zinc is 18.7 g/L after being settled for 10 min. 88.60% zinc can be stripped by 196 g/L sulfuric acid, and zinc ion can be separated from ferric ion.
文摘For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylammonium chloride R 4NCl) in toluene was investigated. The experiments were carried out under conditions of 25 ℃, Nb(Ⅴ) concentration 0.01 mol/L, pH 10.7 13.8, R 4NCl concentration 0.02 0.14 mol/L. It has been found that the distribution ratio of niobium increases with increasing R 4NCl concentration and with decreasing KCl concentration, but it shows maximum value at pH value of about 12 and decreases below or above this pH value. Distribution ratio of niobium goes up to over 1 000 in appropriate conditions, and so it has been proved that R 4NCl is an effective extractant for extraction of niobium from alkali solution.
基金Supported by National Natural Science Foundation of China(No. 29676021 and No. 29836130 ).
文摘Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use of colloidal liquid aphrons (CLA) together with colloidal gas aphrons (CGA). The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer etc. In this paper, PDSE process, CLA and CGA are systematically reviewed and the potential applications of CLA, CGA and PDSE for the various areas of separation as well as the latest development in this area are discussed.
基金Projects(52034002,U1802253)supported by the National Natural Science Foundation of ChinaProject(2019YFC1908401)supported by the National Technology Support Project of China。
文摘This work investigated the separation of potassium from sodium in alkaline solution using substituted phenol-based extractants.Superior potassium extraction was achieved with 4-tert-butyl-2-(α-methylbenzyl)phenol(t-BAMBP)than 4-sec-butyl-2-(α-methylbenzyl)phenol(BAMBP).The optimum conditions for the extraction were 1 mol/L t-BAMBP,3:1 volumetric phase ratio(O/A),and two extraction stages.After cross-current extraction,the extraction ratio of potassium reached 90.8%.After scrubbing with deionised water at phase ratio of 4:1 and scrubbing stage of 4,a sodium scrubbing efficiency of 88.2%was obtained.After stripping using 1 mol/L H_(2)SO_(4) at phase ratio of 3:1,the stripping efficiency of potassium reached 94.2%.The potassium/sodium(K/Na)concentration ratio increased 14.3 times from 0.15 in the feed solution to 2.3 in the stripping solution.The efficient separation of potassium from sodium in alkaline solution was achieved via solvent extraction with t-BAMBP.
基金Project ( 2001AA218011) supported by the National High Technology Development "863" Program of China
文摘The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.
基金the research committee of Malek-ashtar University of Technology (MUT) for supporting this work
文摘The unfavorable growth and agglomeration of micro-particles of RDX explosive was almost observed in manufacture process. For preventing of growth of micro-particles and agglomeration in anti-solvent crystallization process, the effect of additives glucose, sucrose and poly ethylene glycol-2000 and wetting solvent of isopropyl alcohol were studied. Taguchi experimental design was used for optimization of the operating conditions. The type of additive, the amount of additive(%wt.), solvent of wetting and wetting time were selected for optimization of the conditions. By using 4 factor and 3 levels, 27 experiments were conducted(L27). Results showed that in the presence of 2 %wt. of sucrose additive and isopropyl alcohol solvent, the agglomerations of particles were decreased so that a decrease 30-50% in the average of particles size was seen. Addition additives were effective in storage container and for reduce the agglomeration of particles during storage. Also, the agglomeration rate of particles was reduced over time at optimized conditions. Imaging optical microscopy, scanning electron microscopy(SEM), and particle size analyzer(PSA) methods were used for particles size analyzing as a response in statistical optimization and quality control of the final product. The sensitivity to some mechanical and shock stimuli on the RDX in presence of sucrose additive was tested and the obtained results showed the insignificant effect of additive on the safety properties of pure RDX.
