Developing non-noble catalyst synthesis under green conditions with efficient electrochemical reactions is a challenging task in green energy technologies.To meet this challenge,the synthesis of hybridized non-noble cobalt and iron in the zeolitic-imidazole framework(Co/Fe-ZIF)through a solid-state thermal(SST)method is developed.In the obtained Co/Fe-ZIF structure,iron atoms are uniformly dispersed and randomly hybridized with primary cobalt atoms and imidazole linker,similar to the structure of ZIF-67.The hybridized Co/Fe-ZIF shows potential as an electrocatalyst for oxidation evolution reaction(OER).The optimal iron-incorporating catalyst,Co/Fe_(0.2)-ZIF,demonstrates remarkable performance with a minimized overpotential of 285 mV at the current density(j)of 10 mA·cm^(-2)in 1 M KOH.The synergistic effect of iron and cobalt ions on the catalyst provides active sites that bind to intermediate(OOH^(*))more strongly and facilitate high electron charge transfer,enhancing efficient electrocatalyst.Furthermore,the synergistic Co/Fe_(0.2-)ZIF catalyst demonstrates excellent durable reaction time compared to non-iron catalyst(ZIF-67)and conventional catalyst(RuO_(2)).
The catalytic conversion of glucose to high valueadded platform chemical 5-hydroxymethylfurfural(HMF)is a promising biorefinery process,and alumina-boria catalysts are considered to be green and mild solid acid catalysts for this catalytic reaction.Here,compared to the common synthesis methods with complicated steps,we reported a simple and efficient strategy to prepare B_(2)O_(3)-Al_(2)O_(3)nanocomposites by calcining cost-effective glucose-urea deep eutectic solvent(DES)solution containing the precursors.The prepared B_(2)O_(3)-Al_(2)O_(3)nanocomposites exhibited an open three-dimensional skeleton and two-dimensional porous lamellar substructure,endowing them with a high specific surface area(228.27 m2/g).The introduction of boron changed the ratios of different aluminum species(AlⅣ,AlⅤ,and AlⅥ)and borate species(BO3 and BO4),thus further affecting the acidity and the types of acid sites of the materials.The prepared B_(2)O_(3)-Al_(2)O_(3)bifunctional acid catalysts possessing abundant Lewis acid sites and adjustable Brønsted acid sites showed complete glucose conversion and 55.38%of HMF yield under the optimum conditions.Our study proposed a concise method to synthesize alumina-boria solid acid catalysts assisted by glucose-urea DES.We hope to extend the application and prospect of this efficient and simple synthesis strategy.
The interactions between lignin oligomers and solvents determine the behaviors of lignin oligomers self-assembling into uniform lignin nanoparticles(LNPs).Herein,several alcohol solvents,which readily interact with the lignin oligomers,were adopted to study their effects during solvent shifting process for LNPs’production.The lignin oligomers with widely distributed molecular weight and abundant guaiacyl units were extracted from wood waste(mainly consists of pine wood),exerting outstanding self-assembly capability.Uniform and spherical LNPs were generated in H_(2)O-n-propanol cosolvent,whereas irregular LNPs were obtained in H_(2)O-methanol cosolvent.The unsatisfactory self-assembly performance of the lignin oligomers in H_(2)O-methanol cosolvent could be attributed to two aspects.On one hand,for the initial dissolution state,the distinguishing Hansen solubility parameter and polarity between methanol solvent and lignin oligomers resulted in the poor dispersion of the lignin oligomers.On the other hand,strong hydrogen bonds between methanol solvent and lignin oligomers during solvent shifting process,hindered the interactions among the lignin oligomers for self-assembly.
Ya MaZhicheng JiangYafei LuoXingjie GuoXudong LiuYiping LuoBi Shi
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.
Parabens are antimicrobial preservatives with extensive applications in cosmetics,toiletries,pharmaceuticals,and food.Considering the legitimate concerns relating to their potential to disrupt multiple endocrine functions,it becomes imperative to prioritize the development of innovative bioanalytical techniques for effectively monitoring their presence in biological samples.In this study,an efficient solvent bar microextraction(SBME)was established,utilizing new hydrophobic deep eutectic solvents(DEs)to determine methylparaben and propylparaben in urine and plasma samples.The DEs comprising menthol and tris(2-ethylhexyl)phosphate(M-TEHP)at various molar ratios were synthesized for the first time to enhance the extraction capacity and promote the eco-friendliness of the DE used as an extraction solvent.Fourier-transform infrared(FT-IR)and proton nuclear magnetic resonance(1H NMR)spectroscopies were employed to confirm and investigate the properties of the successful synthesis(M-TEHP)DE at a molar ratio of 1:1.The synthesized DE exhibits low microbial toxicity and can be considered an eco-friendly solvent for extraction.Furthermore,quantum-chemical calculations were utilized to predict synthesized DE's structure and interaction energy with selected parabens.The influential operational factors of DE-SBME on the extraction efficiency(EE%)of both parabens were evaluated using response surface methodology based on central composite design,and a total of 30 extraction tests were conducted to determine the optimal conditions.The optimized DE-SBME,in combination with HPLC-DAD,exhibited low detection limits(0.54–0.91μg L^(−1)),excellent linearity(R^(2)≥0.9993),precise results(RSDs≤7.6%),satisfactory recoveries(92–97%)and negligible matrix effects.Hence,it had remarkable effectiveness and applicability in determining selected parabens in real urine and plasma samples.
The rheological properties and limited flow velocities of solvent-free nanofluids are crucial for their technologically significant applications.In particular,the flow in a solvent-free nanofluid system is steady only when the flow velocity is lower than a critical value.In this paper,we establish a rigid-flexible dynamic model to investigate the existence of the upper bound on the steady flow velocities for three solvent-free nanofluid systems.Then,the effects of the structural parameters on the upper bound on the steady flow velocities are examined with the proposed structure-preserving method.It is found that each of these solvent-free nanofluid systems has an upper bound on the steady flow velocity,which exhibits distinct dependence on their structural parameters,such as the graft density of branch chains and the size of the cores.In addition,among the three types of solvent-free nanofluids,the magnetic solvent-free nanofluid poses the largest upper bound on the steady flow velocity,demonstrating that it is a better choice when a large flow velocity is required in real applications.
Weipeng HUZhengqi HANXiqiao FENGYaping ZHENGZichen DENG
