Water molecular activity management towards stable Zn anodes

Zinc-based aqueous batteries(ZABs)have attracted wide interest and become a hot topic in the field of secondary batteries due to their low cost,high safety,and environmental friendliness.However,challenges pertaining to zinc anodes,such as dendrites growth and side reactions,which are associated with the high activity of freedom water molecules in the aqueous electrolyte,significantly hinder the advancement of ZABs.In recent years,strategies aimed at regulating water molecular activity have been demonstrated to address the above issues effectively.Nevertheless,there is a lack of systematic summary regarding the electrolyte engineering and the functional mechanisms for stabilizing zinc anodes from the point of view of water molecular activity management.Hence,this review comprehensively introduces strategies for regulating water activity through the electrolyte engineering to achieve side reaction-suppressed ZABs,including the latest research on aqueous zinc-metal batteries,the origin of critical zinc-related problems,and the development of technological and electrolyte additives.Lastly,various strategies were summarized from different perspectives to improve the performance of zinc metal anodes.This work is expected to present the latest outline and inspire future innovation in electrolyte technologies.

Water Photomolecular Evaporation Due to Light-Mediated Ortho-Para Spin Transitions

Recent discoveries have revealed a groundbreaking phenomenon where light alone, without any thermal input, can induce water evaporation, termed the “photomolecular effect”. This study explores a novel hypothesis that this effect can be explained by ortho-para magnetic spin interactions in water molecules within the water-air interface layer. Water molecules, consisting of hydrogen and oxygen, exhibit different nuclear spin states: ortho-(triplet) and para-(singlet). The interaction of polarized light with these spin states may induce transitions between the rotational levels of ortho- and para-forms due to catalysts like triplet oxygen (O2) in its inhomogeneous magnetic field. Resonance pumping at 532 nm (~18,797 cm−1) due to the transition v1-v2-v3 ~ 0-8-2 (~18,796 cm−1) results in an increase in molecular energy sufficient to overcome intermolecular forces at the water surface, thereby causing evaporation. The proposed ortho-para conversion mechanism involves spin-orbit coupling and specific resonance conditions. This theory provides a quantum mechanical perspective on the photomolecular effect, potentially offering insights into natural processes such as cloud formation and climate modeling, as well as practical applications in solar desalination and industrial drying. Further experimental validation is required to confirm the role of spin interactions in light-induced water evaporation.

Molecular simulation of penetration separation for ethanol/water mixtures using two-dimensional nanoweb graphynes

Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation performance of liquid ethanol–water mixtures across polyporous two-dimensional γ-graphyne sheets. It was found that, in the mixture, ethanol with larger molecular diameter permeates faster through the graphyne pores than water. The simulations demonstrate that pristine graphynes could act as highly-efficient ethanol-permselective membranes for separation of ethanol–water mixtures, with ethanol permeability remarkably higher than conventional membranes. This separation mechanism is distinctly different from the molecular-size dependent sieving process. The stronger hydrophobic interfacial affinity between graphyne and ethanol makes ethanol molecules preferentially adsorb on graphyne surface and selectively penetrate through graphyne pores. This penetration mechanism provides new understanding of molecular transport through atomically thick two-dimensional nanoporous membranes and this work is expected to be valuable in the potential development of highly-efficient membranes for liquid-phase mixture separation.

Molecular Geochemical Evidence for the Origin of Natural Gas from Dissolved Hydrocarbon in Ordovician Formation Waters in Central Ordos Basin

Having studied the biomarker composition and maturity of dissolved hydrocarbons from Ordovician formation waters, the authors presented molecular geochemical evidence for the controversial origin of natural gases in central Ordos Basin.The dissolved hydrocarbons in Well Shan 12 and Well Shan 78 are relatively high in abundance of tricylic terpane, pregnane series and dibenzothiophene series and low in Pr/Ph and hopane/sterane ratios, indicating the source input of marine carbonates. In contrast, the dissolved hydrocarbons in Well Shan 81 are free from tricyclic terpane and pregnane series, with trace dibenzothiophene series and high Pr/Ph and higher hopane/sterane ratios, which are the typical features of terrestrial organic matter. Furthermore, Well Shan 37 and Well Shan 34 are between the two situations, having a mixed source of marine carbonate and terrestrial organic matter. The maturity of biomarkers also supports the above suggestions. These results are consistent with the geological background and source rock distribution in this region.

Ordered water monolayer on ionic model substrates studied by molecular dynamics simulations

The molecular behaviors of interfacial water molecules at the solid/liquid interface are of a fundamental significance in a diverse set of technical and scientific contexts,thus have drawn extensive attentions.On certain surfaces,the water monolayer may exhibit an ordered feature,which may result in the novel wetting phenomenon.In this article,based on the molecular dynamics simulations,we make a detailed structure analysis of the ordered water monolayer on ionic model surface with graphene-like hexagonal lattices under various charges and unit cell sizes.We carefully analyze the water density profiles and potential of mean force,which are the origin of the special hexagonal ordered water structures near the solid surface.The number of hydrogen bonds of the ordered water monolayer near the solid surface is carefully investigated.

Torsional Characteristics of Single Walled Carbon Nanotube with Water Interactions by Using Molecular Dynamics Simulation

The torsional characteristics of single walled carbon nanotube(SWCNT) with water interactions are studied in this work using molecular dynamics simulation method. The torsional properties of carbon nanotubes(CNTs) in a hydrodynamic environment such as water are critical for its key role in determining the lifetime and stability of CNT based nano-fluidic devices. The effect of chirality, defects and the density of water encapsulation is studied by subjecting the SWCNT to torsion. The findings show that the torsional strength of SWCNT decreases due to interaction of water molecules and presence of defects in the SWCNT. Additionally,for the case of water molecules encapsulated inside SWCNT, the torsional response depends on the density of packing of water molecules. Our findings and conclusions obtained from this paper is expected to further compliment the potential applications of CNTs as promising candidates for applications in nano-biological and nano-fluidic devices.

Effect of an external electric field on liquid water using molecular dynamics simulation with a flexible potential

Molecular dynamics simulations of liquid water were performed at 258 K and density of 1.0 g/cm^3 under different strengths of an external electric field, ranging from 0 to 8.0×10^9V/m, to investigate the influence of an external field on structural and dynamic properties of water. The flexible simple point charge model is used for water molecules. An enhancement of the water hydrogen bond structure with increasing strength of the electric field has been deduced from the radial distribution functions and the analysis of hydrogen bond structure. With increasing field strength, water system has a more perfect structure, which is shnilar to ice structure. However, the electrofreezing phenomenon of liquid water has not been detected because of a too large self-diffusion coefficient. The self-diffusion coefficient decreases remarkably with increasing strength of electric field, and the self-diffusion coefficient is anisotropic.

Understanding self-accelerated water diffusion within poly-lactic acid via molecular dynamics simulation

Poly-lactic acid(PLA) is widely used as a controlled drug release material and the diffusion property of water within the polymer matrix is closely related to the drug release profile. This paper studies the water diffusion in PLA by molecular dynamic simulations. Free volume analysis indicates that water molecules are expected to fill in the free volumes of the polymer matrix forming water clusters at low water content. Along with the increase of the water concentration, the polymer starts to swell and the density of the system starts to drop.Due to the high mobility of water within water cluster, the calculated diffusion coefficient dramatically increases along with the incensement of water content. Thus, we conclude that the diffusion of water is a self-accelerate process, with higher mobility of water in the case where more water exists.

深部煤层气水赋存机制、环境及动态演化

准确认识深部条件下气体和水分的赋存状态、相对含量及分布特征,对煤层气高效勘探开发具有重要指导意义。基于理论模型、分子模拟和气水演变分析,明确了煤层中气、水的赋存状态,揭示了气、水动态运聚界限和动态演化过程。考虑煤-水界面作用、水的可动性及赋存状态,煤中水可分为可动水(重力水和毛细水)、束缚水(吸附水、沸石水、结晶水和层间水)、结构水,其中毛细水、重力水和吸附水由孔隙主导,沸石水、结构水、结晶水和层间水由矿物主导。分子模拟结果显示,水分子在0.7 nm孔隙中可以饱和充填,吸附和解吸路径一致,在更大孔隙中出现弱吸附层和自由态。水分子吸附过程表现为单分子含氧基团吸附、单层强吸附、多层弱吸附、水团簇形成和充填孔隙等阶段。甲烷分子在1.5 nm孔隙可存在3层稳定充填吸附,在较大孔隙中(>1.5 nm)即以单层吸附和游离态共存,游离态在介孔及更大孔隙中普遍存在。结合上述吸附-游离气存在界限,改进了游离气和吸附气理论计算公式,为含气量计算提供新思路。深部热成因煤层气是煤大规模生排烃之后的残余气,在排烃过程中发生气驱水和水分蒸发扩散,残余水分为束缚水和结构水,后期无法改变。假定静水压力20 MPa,在0、5、10、15和20 MPa储层压力下,外来水分可入侵最大孔径为7、9、13、27 nm和不侵入。受差异保存条件控制,煤成气除了形成超压和欠压等差异含气系统外,还可能在煤系形成多类型含气模式。上述研究明确了煤层气、水微观赋存机制及形成演化模式,对深部煤层气富集特征及高效开发设计具有指导意义。

Alkali Treatment of Commercial Silicoaluminophosphate Molecular Sieves (SAPO_-34) Enhances the Water Adsorption and Desorption Properties

Commercial silicoaluminophosphate molecular sieves (SAPO-34) received alkali treatment with either NaOH (0.2, 0.01, 0.005, or 0.001 M) or NH4OH (0.005 M). Treatment with NaOH (0.005 M) increased the water adsorption initial rate of SAPO-34 by 1.4-fold. The alkali treatment introduced Na+ adsorption sites into the SAPO-34. The desorption ratio (adsorption at 30°C and desorption at 100°C) was 88.2% higher than the original rate (84.3%). On the other hand, after alkali treatment of SAPO-34 using NH4OH (0.005 M), calcination resulted in the highest desorption ratio at 91.3%. When combined with calcination, alkali treatment with NH4OH introduced H+adsorption sites into SAPO-34, H+ adsorption sites feature low levels of interaction with water, which enhanced the desorption ratio, but decreased the initial adsorption rate. These results indicate that treating commercial SAPO-34 with 0.005 M NaOH enhances both the adsorption and desorption behaviors.

Utilizing Water Treatment Residuals for Phosphorus Removal:Batch Trials,Column Trials and Effects of Three Low-Molecular-Weight Organic Acids

Phosphorus( P) has been recognized as a major limited nutrient responsible for the eutrophication of surface waters. Water treatment residuals( WTRs) are safe by-products of water treatment plants and are cost-efficient adsorbents. In this study, batch experiments and column experiments based on WTRs were employed to study the characteristics of P adsorption and the effects of lowmolecular-weight organic acids( LMWOAs)( citric acid, oxalic acid,and tartaric acid) on P adsorption. Different models of adsorption were used to describe equilibrium and kinetic data. The adsorption data were fitted well by a pseudo-second order kinetic model. The adsorption process was determined to be controlled by three steps of diffusion mechanisms through the intra-particle model.The adsorption equilibrium was well described by the Langmuir,Freundlich,Redlich-Peterson,and Sips isotherm models. Batch and continuous flow experiments indicated that the LMWOAs exhibited inhibitory action,and as pH increased,the inhibitory action became weaker for all the three acids. The effect of LMWOAs concentration was not significant on inhibition. The effects of LMWOAs were closely related to reaction time.

不同分子质量水溶性壳聚糖在纸质文献加固中的应用研究

本研究采用乙酸酐制备了不同分子质量的水溶性壳聚糖(WSC-3、WSC-10、WSC-20、WSC-30和WSC-60)并用作修复液,探究其对纸质文献加固及耐老化的效果。结果表明,与未经加固处理的纸张(原纸)相比,采用不同分子质量的水溶性壳聚糖加固处理后,纸张的强度性能有所提升,白度下降幅度较小,色差变化较小,pH值和碱储量均增加。纸张加速老化后,与原纸相比,加固处理后纸张的强度性能下降幅度明显较小,其中WSC-30加固处理后纸张的抗张指数、撕裂指数、零距抗张强度的保留率分别提升了9.7、7.4、4.5个百分点,外观形貌、白度和色差等相差较小。

沙柳木粉基高效吸附材料对煤矿废水中Fe(Ⅱ)和Mn(Ⅱ)作用特性及机理

针对煤矿酸性废水中含有较高质量浓度铁离子和锰离子的问题,以沙柳木粉为主要原料,遵循农林废弃物提取再利用原则,经过NaOH、Na2SO3等溶液处理后获得脱木素木粉(DWF),通过微波辅助-原位合成的手段,制备了一种针对煤矿废水中Fe(Ⅱ)和Mn(Ⅱ)的吸附剂(AA-DWFPAM)。借助扫描电子显微镜(SEM)、N_(2)吸附-脱附、傅里叶变换红外光谱(FTIR)和红外热重联用(TG-FTIR)对产物的微观结构、反应机理、热稳定性进行了分析,探讨了AA-DWF-PAM的最佳吸附条件、吸附动力学、吸附等温线,研究了AA-DWF-PAM对Fe(Ⅱ)和Mn(Ⅱ)的吸附特性和吸附机理。表征实验结果表明:AA-DWF-PAM整体存在较多孔洞并呈现网状结构,且比表面积(BET)为150.83 m^(2)/g,说明改性后的吸附剂具有较大的比表面积,能够为Fe(Ⅱ)和Mn(Ⅱ)吸附提供较多位点和空间;此外,AA-DWF-PAM热解气态产物主要有H_(2)O、CO_(2)以及少量CO,裂解温度较高,其结构稳定性较强。吸附特性实验研究表明:AA-DWF-PAM用量为4 g/L、溶液pH=4、吸附时间达到200 min,以及Fe(Ⅱ)、Mn(Ⅱ)初始质量浓度为100 mg/L和80 mg/L时,为AA-DWFPAM的最佳吸附条件;经过计算得知,AA-DWF-PAM更接近于伪二级动力学假设,吸附主要控制过程为化学过程,且吸附过程更符合Langmuir方程的单层分子吸附,Fe(Ⅱ)和Mn(Ⅱ)的理论最大吸附量分别为192.29 mg/g和123.65 mg/g;通过Materials Studio对吸附过程进行分子模拟和量子化学计算得知,吸附过程中—NH_(2)、—COOH以及—OH官能团起到静电吸附作用。因此,合理利用农林废弃物,为煤矿酸性废水治理提供了新途径,开发的AA-DWF-PAM吸附剂,能够有效处理煤矿酸性废水中的铁锰离子。

Coupling metal oxide nanoparticle catalysts for water oxidation to molecular light absorbers

Water oxidation, as a mandatory reaction of solar fuels conversion systems, requires the use of light absorbers with electronic properties that are well matched with those of the multi-electron catalyst in order to achieve high efficiency. Molecular light absorbers offer flexibility in fine tuning of orbital energetics,and metal oxide nanoparticles have emerged as robust oxygen evolving catalysts. Hence, these material choices offer a promising approach for the development of photocatalytic systems for water oxidation.However, efficient charge transfer coupling of molecular light absorbers and metal oxide nanoparticle catalysts has proven a challenge. Recent new approaches toward the efficient coupling of these components based on synthetic design improvements combined with direct spectroscopic observation and kinetic evaluation of charge transfer processes are discussed.

MOLECULAR DYNAMICS SIMULATIONS OF FILLED AND EMPTY CAGE-LIKE WATER CLUSTERS IN LIQUID WATER AND THEIR SIGNIFICANCE TO GAS HYDRATE FORMATION MECHANISMS

Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetimes of these clusters are calculated according to their Lindemann index δ (t) using the criteria of δ≥0.07. For both the filled and empty clusters, we find the dynamics of bulk water determines the lifetimes of cage-like water clusters, and that the lifetime of 512 62 cage-like cluster is the same as that of 512 cage-like cluster. Although the methane molecule indeed makes the filled cage-like cluster more stable than the empty one, the empty cage-like cluster still has chance to be long-lived compared with the filled clusters. These observations support the labile cluster hypothesis on the formation mechanisms of gas hydrates.

Development of a competitive format sorbent assay for the determination of parathion in water using molecular imprinted polymer as specific sorbent carrier

A rapid,simple,and reliable competitive molecular imprinted polymer sorbent assay（MIPSA） was developed and validated for measurement of parathion in water samples.This assay employed a molecular imprinted polymer（MIP） that was synthesized with non-covalent imprinting method as capture reagent and p-aminoparathion conjugate of horseradish peroxidase（para-HRP） as an enzyme label.The assay depended on a competitive binding reaction between the enzyme conjugate and analyte for the binding sites of the MIP.The optimized analysis conditions of 10 ng mL-1 para-HRP and 10 mg mL-1 polymer were found.The assay was acceptable to detect parathion in water samples under the optimized conditions,with a limit of detection of 50 ng mL-1.Mean analytical recoveries of added parathion in water samples ranged from 101.2%to 105%.The precision of the assay was satisfactory; relative standard deviation ranged from 4.3%to 6%.

Effect of hydrophobicity on the water flow in carbon nanotube-A molecular dynamics study

This work focuses on the study of the effect of hydrophobicity on the water flow in carbon nanotubes(CNTs)using a molecular dynamics(MD)approach for a wide range of potential applications such as water purification and high efficiency of nanofluid energy absorption systems(NEAS).The hydrophobicity between liquid water and surface of CNTs was characterized by interaction-energy-coefficient(IEC)—a parameter describing the energy interaction strength between water molecules and carbon atoms.It is shown that the static contact angles between water and carbon surface decrease from 155° to 44°when the values of IEC increase from 0.042 kJ/mol to 2.196 kJ/mol.In addition,the pressure drops in CNT became independent of IEC when the IEC value was higher than 1.192 kJ/mol for a given flow rate.It was found that the hydrophobicity of CNT surface has a significant impact on the pressure drop of water flow in the CNTs and MD method provides a quantitative evaluation of the impact.

Molecular dynamics simulation of the interaction of ethanol-water mixture with a Pt surface

An analysis of the molecular dynamics of ethanol solvated by water molecules in the absence and presence of a Pt surface has been performed using DL_POLY_2.19 code. The structure and diffusion properties of an ethanol–water system have been studied at various temperatures from 250 to 600 K. We have measured the self-diffusion coefficients of the 50:50% ethanol–water solution;in the absence of a Pt surface our results show an excellent agreement–within an error of 7.4% – with the experimental data. An increase in the self-diffusion coefficients with the inclusion of a Pt surface has been observed. The estimation of the diffusion coefficients of both water and ethanol in the presence of a Pt surface shows that they obey the Arrhenius equation;the calculated activation energies of diffusion of ethanol and water are 2.47 and 2.98 Kcal/mole, respectively. The radial distribution function graphs and density profiles have been built;their correlations with the self-diffusion coefficients of both ethanol and water molecules are also illustrated.

水蒸气在褐煤孔隙中的吸附行为:试验研究与分子动力学模拟

深入理解水在褐煤上的吸附是褐煤干燥提质技术的理论基础之一。采用傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)和低温氮吸附/脱附试验分析了褐煤的含氧官能团和孔隙结构,利用水蒸气吸附/脱附试验和分子动力学(MD)模拟探究了水蒸气在褐煤孔隙中的吸附行为。研究结果表明:褐煤样品丰富的含氧官能团和较多的微孔、中孔(孔径约2 nm),为水蒸气提供了吸附位点和吸附场所。水蒸气在煤样上的吸附过程可分为3个阶段。第1阶段,相对蒸气压(P/P_(0))<0.21,水分子直接吸附于含氧官能团上,此时的吸附速度最大;第2阶段(P/P_(0)=0.21~<0.71),水分子与已吸附的水分子相互作用,促使水团簇逐渐生长;第3阶段(P/P_(0)≥0.71),水团簇填充孔隙,并发生毛细凝聚,此时的吸附速度略大于第2阶段。根据Dent模型对水蒸气吸附等温线的拟合结果,吸附类型属于多级吸附,包括初级吸附(第1阶段)和次级吸附(第2、3阶段)。初级吸附能(-48.77 kJ/mol)显著大于水的液化热(E L=-43.99 kJ/mol),而次级吸附能(-42.28 kJ/mol)略小于E L,表明吸附于褐煤的水呈液态。水蒸气脱附过程存在明显的脱附迟滞现象,表明水蒸气吸附稳定,较难去除,其中高压迟滞发生在P/P_(0)≈0.4~0.9,主要由毛细凝聚和“墨水瓶”效应引起;而低压迟滞发生在P/P_(0)<0.4,由水分子与含氧官能团间强相互作用引起。MD模拟结果与水蒸气吸附/脱附等温线分析结果一致,水分子优先吸附在孔隙中,与孔隙壁的含氧官能团形成氢键,且其扩散系数(2.98×10^(-5)cm^(2)/s)与液态水的分子扩散系数相近。

不同温度下二氧化硫与乙烷水合物体系的模拟研究

采用分子动力学模拟计算方法,在10 MPa的压力条件下,对二氧化硫和乙烷水合物体系,分别在275、285、295、305 K等不同温度下的变化情况进行模拟研究。预测了二氧化硫、乙烷、水的扩散系数,探讨了密度、氢键数和配位数等结构性质。结果表明,水受到温度的影响较大,二氧化硫明显比乙烷更容易与水结合,乙烷被水和二氧化硫排挤而大量聚集,能够达到利用二氧化硫置换和收集乙烷的目的。