Hydrogen-bonded Network Structure Research Articles

High-Branched Natural Polysaccharide Flaxseed Gum Binder for Silicon-Based Lithium-Ion Batteries with High Capacity.

Silicon-based anodes heavily depend on the binder to preserve the unbroken electrode structure. In the present work, natural flaxseed gum (FG) is used as a binder of silicon nanoparticles (SiNPs) anode for the first time. Owing to a large number of polar groups and a rich branched structure, this material not only anchors tightly to the surface of SiNPs through bonding interactions but also formed a hydrogen bonding network structure among molecules. As a result, the FG binder can endow the silicon electrode with stable interfacial adhesion and outstanding mechanical properties. In addition, FG with a high viscosity facilitates the homogeneous dispersion of the electrode components. When FG is used as a binder, the cycling performance of the Si anode is greatly improved. After one hundred cycles at an applied current density of 1 A g-1, the electrode continues to display remarkable electrochemical properties with a significant cyclic capacity (2213mAh g-1) and initial Coulombic efficiency (ICE) of 89.7%.

High pH Stability and Ultralong‐Lived Room Temperature Phosphorescence Carbon Dots in Aqueous Environment

AbstractLong‐lived room temperature phosphorescence (RTP) materials have many potential applications in areas such as luminescent lighting, biological imaging, and information security owing to their unique optical properties. However, traditional RTP materials are challenged by the fact that their phosphorescence can be easily quenched by dissolved oxygen and solvent‐assisted relaxation, making it difficult for them to emit phosphorescence in aqueous solutions, particularly in extreme pH environments. In this study, a multicolor RTP carbon dot‐based composite material (u‐CDs) is developed with urea and 3‐aminophenylboronic acid as raw materials. This material exhibits ultra‐long phosphorescence emission lifetime and high pH stability by constructing a rigid hydrogen bond network structure in an aqueous environment. The u‐CDs have an optimal emission of 448 nm, a quantum yield of 21.6%, a phosphorescence lifetime of 2.35 s, and an afterglow time of more than 50 s. With such unique properties, u‐CDs have great potential for applications in anti‐counterfeiting, information encryption, and 3D printing.

Superior strength, highly stretchable, bionic self-healing polyurethane and its composites for flexible conductivity and self-cleaning applications

Balancing the exceptional mechanical strength and repair efficiency of self-healing materials presents a significant challenge to unlocking their full potential in practical applications. Inspired by natural spider silk and cartilage, multiple dynamic hydrogen bonds were introduced into the pre-prepared polyurethane (PU). Then modifided graphene oxide (GO) nanosheets with dynamic hydrogen bonds were added into the prepared PU to form composites (AU-PU/GDU) to establish a dense hydrogen bond network structure, providing strong interfacial interactions. The AU-PU/GDU film exhibits excellent tensile strength (39.6 MPa), high elongation at break (1155.6 %), and outstanding repair efficiency (90.3 %). Using AU-PU/GDU as the flexible base, a superhydrophobic conductive composite coating (F-AU-PU/GDU) with a contact angle greater than 150° was prepared by incorporating superhydrophobic nanomaterials. This work lays the foundation for the development of multifunctional materials through the creation of self-healing superhydrophobic conductive composite coatings, which have a wide range of potential applications.

Hydrogen-bonded cytosine-endowed supramolecular polymeric nanogels: Highly efficient cancer cell targeting and enhanced therapeutic efficacy

We demonstrate that cytosine moieties within physically cross-linked supramolecular polymers not only manipulate drug delivery and release, but also confer specific targeting of cancer cells to effectively enhance the safety and efficacy of chemotherapy—and thus hold significant potential as a new perspective for development of drug delivery systems. Herein, we successfully developed physically cross-linked supramolecular polymers (PECH-PEG-Cy) comprised of hydrogen-bonding cytosine pendant groups, hydrophilic poly(ethylene glycol) side chains, and a hydrophobic poly(epichlorohydrin) main chain. The polymers spontaneously self-assemble into a reversibly hydrogen-bonded network structure induced by cytosine and directly form spherical nanogels in aqueous solution. Nanogels with a high hydrogen-bond network density (i.e., a higher content of cytosine moieties) exhibit outstanding long-term structural stability in cell culture substrates containing serum, whereas nanogels with a relatively low hydrogen-bond network density cannot preserve their structural integrity. The nanogels also exhibit numerous unique physicochemical characteristics in aqueous solution, such as a desirable spherical size, high biocompatibility with normal and cancer cells, excellent drug encapsulation capacity, and controlled pH-responsive drug release properties. More importantly, in vitro experiments conclusively indicate the drug-loaded PECH-PEG-Cy nanogels can selectively induce cancer cell-specific apoptosis and cell death via cytosine receptor-mediated endocytosis, without significantly harming normal cells. In contrast, control drug-loaded PECH-PEG nanogels, which lack cytosine moieties in their structure, can only induce cell death in cancer cells through non-specific pathways, which significantly inhibits the induction of apoptosis. This work clearly demonstrates that the cytosine moieties in PECH-PEG-Cy nanogels confer selective affinity for the surface of cancer cells, which enhances their targeted cellular uptake, cytotoxicity, and subsequent induction of programmed cell death in cancer cells.

Hydrated Electron Dynamics and Stimulated Raman Scattering in Water Induced by Ultrashort Laser Pulses.

For this study, we employed intense 400 nm, 100 fs pulses linearly propagated through a 50 cm water medium, initially self-stretching the excitation pulses to 2.50 ps. Subsequently, the self-stretched 2.50 ps pulses were focused into deionized water, and we conducted transient absorption experiments to measure and investigate the dynamics of hydrated electrons in water. The excess electrons generated were injected into the hydrogen bond network of the water cluster, leading to the observation of saturated hydrated electrons. Additionally, we observed the emergence of the forward stimulated Raman scattering (SRS) of water molecules. We report the experimental observation of a weak forward SRS emission at 463 nm (corresponding to 3400 cm-1), indicative of the ordinary OH stretching vibration in the liquid phase. Moreover, we observed an intense forward SRS emission at 460 nm in water, corresponding to two anomalous Raman shifts at 3260 cm-1 and 3355 cm-1. These anomalous Raman shifts resulted from changes in the hydrogen bond network structure. We determine that the formation of not fully hydrated and saturated hydrated electrons plays a crucial role in producing this phenomenon.

Guiding the Formation of Metal-Organic Structures of 1,4-Diaminoanthraquinone through Surface-Based Cu Atoms.

The gradual guidance of the formation of metal-organic structures through surface-based Cu atoms for 1,4-diaminoanthraquinones (DAQs) has been studied by scanning tunneling microscopy (STM) at room temperature. On the Ag(110) surface, the transition from a hydrogen-bond network structure to metal-organic coordination structures of DAQs can be induced by introducing foreign copper atoms. Due to the weak interaction between DAQs and Ag(110), thermal treatment easily leads to the desorption of DAQs from the surface. To address this challenge, Cu(111) is selected as the substrate. Under thermal driving and in the presence of copper adatoms, the hydrogen-bond network structure of DAQs on the surface gradually undergoes a transition into a metal-coordinated structure, eventually leading to the formation of metal-organic complexes through amino dehydrogenation. It is demonstrated that the construction of a metal-organic coordination structure on metal surfaces is a result of the competition among factors such as metal atoms, functional groups of molecules, surface chemical activity, and temperature.

Optimizing Interplanar Spacing, Oxygen Vacancies and Micromorphology via Lithium‐Ion Pre‐Insertion into Ammonium Vanadate Nanosheets for Advanced Cathodes in Aqueous Zinc‐Ion Batteries

AbstractAmmonium vanadates, featuring an N─H···O hydrogen bond network structure between NH4+ and V─O layers, have become popular cathode materials for aqueous zinc‐ion batteries (AZIBs). Their appeal lies in their multi‐electron transfer, high specific capacity, and facile synthesis. However, a major drawback arises as Zn2+ ions tend to form bonds with electronegative oxygen atoms between V─O layers during cycling, leading to irreversible structural collapse. Herein, Li+ pre‐insertion into the intermediate layer of NH4V4O10 is proposed to enhance the electrochemical activity of ammonium vanadate cathodes for AZIBs, which extends the interlayer distance of NH4V4O10 to 9.8 Å and offers large interlaminar channels for Zn2+ (de)intercalation. Moreover, Li+ intercalation weakens the crystallinity, transforms the micromorphology from non‐nanostructured strips to ultrathin nanosheets, and increases the level of oxygen defects, thus exposing more active sites for ion and electron transport, facilitating electrolyte penetration, and improving electrochemical kinetics of electrode. In addition, the introduction of Li+ significantly reduces the bandgap by 0.18 eV, enhancing electron transfer in redox reactions. Leveraging these unique advantages, the Li+ pre‐intercalated NH4V4O10 cathode exhibits a high reversible capacity of 486.1 mAh g−1 at 0.5 A g−1 and an impressive capacity retention rate of 72% after 5,000 cycles at 5 A g−1.

Water dynamics and sum-frequency generation spectra at electrode/aqueous electrolyte interfaces.

The dynamics of water at interfaces between an electrode and an electrolyte is essential for the transport of redox species and for the kinetics of charge transfer reactions next to the electrode. However, while the effects of electrode potential and ion concentration on the electric double layer structure have been extensively studied, a comparable understanding of dynamical aspects is missing. Interfacial water dynamics presents challenges since it is expected to result from the complex combination of water-water, water-electrode and water-ion interactions. Here we perform molecular dynamics simulations of aqueous NaCl solutions at the interface with graphene electrodes, and examine the impact of both ion concentration and electrode potential on interfacial water reorientational dynamics. We show that for all salt concentrations water dynamics exhibits strongly asymmetric behavior: it slows down at increasingly positively charged electrodes but it accelerates at increasingly negatively charged electrodes. At negative potentials water dynamics is determined mostly by the electrode potential value, but in contrast at positive potentials it is governed both by ion-water and electrode-water interactions. We show how these strikingly different behaviors are determined by the interfacial hydrogen-bond network structure and by the ions' surface affinity. Finally, we indicate how the structural rearrangements impacting water dynamics can be probed via vibrational sum-frequency generation spectroscopy.

Transport mechanism of uranyl nitrate in nanopore of geopolymer with different Si/Al ratios: Molecular dynamics simulation

Geopolymer is an amorphous cementitious material produced by geopolymerization using minerals or industrial waste as the main raw material under the action of activators. It can be used for safe treatment of heavy metal and radioactive pollution. This study applied molecular dynamics simulation to investigate the transport behaviour of uranyl nitrate in nanochannel of geopolymer, and focused on the influence of changes in the Si/Al ratio of geopolymer on the adsorption and diffusion of ions and water molecules. The simulation results described by density distribution, radial distribution function (RDF), hydrogen bonding network structure, mean square displacement (MSD) and diffusion coefficient. The density distribution shows that geopolymer has the strongest adsorption capacity for UO22+, followed by NO3−, and finally H2O. The results also indicate that the changes in molecular composition of geopolymer have a significant impact on kinetic characteristics of UO22+, NO3− and H2O. As the Si/Al ratio decreases, the adsorption capacity of geopolymer shows an upward trend, with the most significant improvement in the adsorption of UO22+. In addition, when the Si/Al ratio reduces, the migration rate of UO22+ and NO3− slows down. It could hinder the diffusion of ions in nanopores of geopolymer. The work could optimize the preparation of geopolymer adsorbent, and reveal the transport mechanism of uranyl nitrate in nanopore of geopolymer with different Si/Al ratios at the atomic scale.

"Soggy-Sand" Chemistry for High-Voltage Aqueous Zinc-Ion Batteries.

The narrow electrochemical stability window, deleterious side reactions, and zinc dendrites prevent the use of aqueous zinc-ion batteries. Here, aqueous "soggy-sand" electrolytes (synergistic electrolyte-insulator dispersions) are developed for achieving high-voltage Zn-ion batteries. How these electrolytes bring a unique combination of benefits, synergizing the advantages of solid and liquid electrolytes is revealed. The oxide additions adsorb water molecules and trap anions, causing a network of space charge layers with increased Zn2+ transference number and reduced interfacial resistance. They beneficially modify the hydrogen bond network and solvation structures, thereby influencing the mechanical and electrochemical properties, and causing the Mn2+ in the solution to be oxidized. As a result, the best performing Al2 O3 -based "soggy-sand" electrolyte exhibits a long lifeof 2500 h in Zn||Zn cells. Furthermore, it increases the charging cut-off voltage for Zn/MnO2 cells to 2V, achieving higher specific capacities. Even with amass loading of 10 mgMnO2 cm-2 , it yields a promising specific capacity of 189 mAh g-1 at 1 A g-1 after 500 cycles. The concept of "soggy-sand" chemistry provides a new approach to design powerful and universal electrolytes for aqueous batteries.

Interaction of Nitrogen-Rich Cations with Azotriazolone Anions through Ion Exchange Results in the Formation of Energetically Stable and Insensitive Compounds.

In our pursuit of promoting the green development of energetic materials and harnessing their functional benefits, we strive to address the inherent contradiction between energy and low sensitivity. In this regard, we have successfully constructed an azotriazole framework via environmentally friendly electrochemistry with a satisfactory yield of 62.3%. Through a simple ion-exchange process, we then synthesized nitrogen-rich salt derivatives of azotriazolone. These nitrogen-rich salts exhibit a wide range of nitrogen contents, ranging from 32.16 to 68.80%. Remarkably, crystallographic analysis of these green energy-containing salts reveals substantial advantages in terms of thermodynamic stability and low sensitivity. Experimental investigations have demonstrated a positive relationship between the nitrogen content and the pyrothermal performance of the azotriazolone derivatives. Of particular significance is compound 5, a triaminoguanidine salt, which exhibits an exceptionally high nitrogen content of 68.80%. It displays a detonation pressure of 28.2 GPa and a detonation velocity of 7939.4 m s-1. Moreover, the derivatives of azotriazolone salts demonstrate the formation of nitrogen-rich compounds, characterized by insensitive properties, attributed to the hydrogen-bonded network structures resulting from anion-cation interactions. With the exception of compound 5, which exhibits a friction sensitivity of 252 N, the remaining derivatives show a similar value of approximately 360 N. This suggests that azotriazolone serves as a promising material possessing both stabilizing properties and better detonation performance, thereby providing a favorable platform for the synthesis of novel compounds with advantageous properties.

Raman Spectrum of the Li2SO4-MgSO4-H2O System: Excess Spectrum and Hydration Shell Spectrum.

Lithium, as a green energy metal used to promote world development, is an important raw material for lithium-ion, lithium-air, and lithium-sulfur batteries. It is challenging to directly extract lithium resources from brine with a high Mg/Li mass ratio. The microstructure study of salt solutions provides an important theoretical basis for the separation of lithium and magnesium. The changes in the hydrogen bond network structure and ion association of the Li2SO4 aqueous solution and Li2SO4-MgSO4-H2O mixed aqueous solution were studied by Raman spectroscopy. The SO42- fully symmetric stretching vibration peak at 940~1020 cm-1 and the O-H stretching vibration peak at 2800~3800 cm-1 of the Li2SO4 aqueous solution at room temperature were studied by Raman spectroscopy and excess spectroscopy. According to the peak of the O-H stretching vibration spectrum, with an increase in the mass fraction of the Li2SO4 solution, the proportion of DAA-type and DDAA-type hydrogen bonds at low wavenumbers decreases gradually, while the proportion of DA-type hydrogen bonds at 3300 cm-1 increases. When the mass fraction is greater than 6.00%, this proportion increases sharply. Although the spectra of hydrated water molecules and bulk water molecules are different, the spectra of the two water molecules seriously overlap. The spectrum of the anion hydration shell in a solution can be extracted via spectrum division. By analyzing the spectra of these hydration shells, the interaction between the solute and water molecules, the structure of the hydration shell and the number of water molecules are obtained. For the same ionic strength solution, different cationic salts have different hydration numbers of anions, indicating that there is a strong interaction between ions in a strong electrolytic solution, which will lead to ion aggregation and the formation of ion pairs. When the concentration of salt solution increases, the hydration number decreases rapidly, indicating that the degree of ion aggregation increases with increasing concentration.

Unravelling hydrogen bond network in methanol-propanol mixtures via molecular dynamics simulation and experimental techniques

ABSTRACT Hydrogen-bonded networks in 1-propanol-methanol binary mixture are studied using molecular dynamics simulation along with experimental techniques (FTIR, dielectric spectroscopy and refractive index measurements) for the entire concentration range. The structure of hydrogen-bonded networks is studied through radial distribution function, hydrogen bond statistics and graph theoretical analysis from molecular dynamics. It is observed that the probability of hydrogen bonding is maximum in methanol molecules followed by hydrogen bonding between methanol and 1-propanol molecules and minimum among 1-propanol molecules, as the concentration changes. The graph theory results show the formation of linear chain hydrogen bond networks, with no caged structures, which is validated from the experimental results. Further, the deconvolution of the FTIR OH peak suggests the presence of linear multimers in all concentrations of the binary system. Average degree of the hydrogen-bonded networks from graph theory indicates a complex networks among pure alcohols and dimers between methanol and 1-propanol in their binary mixtures at all concentrations. The negative values of excess permittivity indicate that the components of the mixture interact in a manner such that the net dipole polarisation decreases.

Rapid Kinetic Interactions of Sugar and Sugar Alcohol with Sweet Taste Receptors on Live Cells Using Stopped-Flow Spectroscopy.

The subjective measurement of the dynamic perception of sweetness is a problem in food science. Herein, the rapid interactions of sugars and sugar alcohols with sweet taste receptors on living cells on a millisecond timescale were studied via stopped-flow fluorescence spectroscopy. According to the rapid-kinetic parameters, sweeteners were divided into two groups. Sweeteners in group I disrupted the hydrogen bond network structure of water, and the apparent rate constant (kobs) was in the range of 0.45-0.6 s-1. Sweeteners in group II promoted the hydrogen bond formation of water, and the kobs was mostly in the range of 0.6-0.75 s-1. For most sweeteners, the kobs of cell responses was negatively correlated with the apparent specific volume of sweeteners. The differences in the cellular responses may be attributed to the disturbance in the water structure. Experimental results showed that the kinetic parameters of sweet cell responses reflected the dynamic perception of sweetness. Rapid kinetics, solution thermodynamic analysis, and water structure analysis enriched the physicochemical study of the sweetness mechanism and can be used to objectively evaluate the dynamic perception of sweetness.

Tailoring the interfacial interaction of collagen fiber/waterborne polyurethane composite via plant polyphenol for mechanically robust and breathable wearable substrate

Collagen fiber-waterborne polyurethane composites possess great potential applications in flexible wearable devices owing to their excellent biocompatibility, flexibility, and biodegradability. However, the weak interfacial interactions which result in poor mechanical strength and breathability, have significantly hindered their practical application. Herein, high-performance collagen fiber-based wearable substrates prepares by constructing a hydrogen-bonded cross-linked network structure using bayberry tannin, a natural plant polyphenol, as a coupling bridge to bind collagen fibers and waterborne polyurethane (WPU). The dynamic rupture and reformation of sacrificial hydrogen bonds on the molecular scale effectively dissipate energy under mechanical stress, endowing these composites with remarkable toughness and ultrahigh water vapor permeability (WVP). The resultant composite’s tensile strength and WVP are 100% and 60 times higher than WPU, respectively. Additionally, this cost-effective strategy enables easy large-scale composite production. This method guides the development of high-performance, multifunctional collagen fiber-based wearable composites while advancing the tannery solid waste circular economy.

Ultralow Coefficient of Thermal Expansion and a High Colorless Transparent Polyimide Film Realized Through a Reinforced Hydrogen-Bond Network by In Situ Polymerization of Aromatic Polyamide in Colorless Polyimide.

Colorless polyimides (CPIs) are a key substrate material for flexible organic light-emitting diode (OLED) displays and have attracted worldwide attention. Here, in this paper, the dispersion and interfacial interaction of aromatic polyamide (PA) in CPI (synthesized from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2'-bis(trifluoromethyl)benzidine (TFMB)) were significantly improved by in situ polymerization, and colorless transparent macromolecular polyimide composites (CPI-PAx) were successfully prepared by PA and CPI. By adjusting the ratio of PA to CPI, a high-performance engineering plastic with excellent film-forming properties was obtained. Molecular simulations confirmed the uniform distribution of PA in CPI and its interaction in polymers. In CPI-PAx, the CPI was locked by the PA chain, and numerous molecular chains were mutually entangled to form a hydrogen-bond network structure. Due to the strong interaction between the chains imparted by the hydrogen bonds of the PA, they do not slide under external forces and heating. In addition, the additive PA has excellent dimensional stability, thermal, and mechanical properties, and CPI has outstanding optical properties, so the synthesized CPI-PAx combines the comprehensive properties of PA and CPI. The CPI-PAx has excellent thermal and mechanical properties, with a thermal decomposition temperature of 499 °C, a glass transition temperature of 385 °C, a coefficient of thermal expansion of 0.8 ppm K-1, a tensile strength of 50.9 MPa, and an elastic modulus of 3.9 GPa. Particularly, CPI-PAx has a 90% transmittance in the visible region. These data prove that the strategy of combining PA and CPI by in situ polymerization is an effective method to circumvent the bottleneck of CPI in the current flexible window application, and this design strategy is universal.

Deep eutectic solvents with N–H hydrogen bond network structure for highly efficient ammonia capture

The separation and recovery of ammonia (NH3) has been of long concern, since NH3 is not only a hazardous substance in the environment but also a critical chemical raw material. The current study developed and synthesized a series of deep eutectic solvents (DESs) using dual combinations of 1,2,3-triazole (Tri) with 1,2,4-triazle (TrZ), Imidazole (ImZ) or 1H-pyrazole (PyZ) for the absorption of ammonia. The results indicate that this kind of DESs possess satisfactory physical features, high capacities for NH3 absorption, and good selectivities of NH3/CO2, NH3/O2 and NH3/N2. At temperature of 298.15 K, TrZ + Tri (1:2) has a high absorption capacity up to 0.241gNH3·gDES−1 at 102.4 kPa, while PyZ + Tri (1:2) also shows satisfactory NH3 solubility of 0.230 gNH3·gDES−1 at 101.3 kPa, which are much greater than those of ionic liquids and DESs reported previously. TrZ + Tri (1:2) is tested to be highly reversible during ten cycles of absorption–desorption. The dissolution thermodynamic parameters of NH3 in these three DESs are calculated using a RETM equation, and the absorption mechanism is further analyzed and discussed using spectroscopic characterizations. It is especially noteworthy that quantum chemistry calculations are also used to study the interactions between NH3 and the DESs from an atomic level perspective. It is believed that the DESs developed in this study have their own potentials as absorbents for the highly efficient capture of NH3.

Polyvinyl alcohol flame retardant film based on halloysite nanotubes, chitosan and phytic acid with strong mechanical and anti-ultraviolet properties

The research of additive biomass flame retardants is becoming more and more popular. In this work, amino modified halloysite nanotubes (A-HNTs), chitosan (CS) and phytic acid (PA) were introduced into polyvinyl alcohol (PVA) matrix to construct PA/A-HNT/CS/PVA organic-inorganic composite film with hydrogen bond and covalent bond cross-linking network structure. Adding PA/A-HNT/CS can remarkably improve the mechanical strength, UV resistance and thermal stability of PVA film. Compared with control PVA film, the transmittance of composite film in ultraviolet region decreases from 90 % to <15 %, and the tensile strength raises from 19.8 MPa to 31.0 MPa. The thermal decomposition temperature of the composite film increases, the weight loss rate decreases obviously, and the carbon residue can reach 26 wt% at 700 °C. The limiting oxygen index increases from 18.5 % to 32.2 %. Furthermore, the addition of this flame-retardant system can obviously reduce the combustion intensity of PVA, and its flame-retardant grade can reach V-0. It is of great significance to expand the application of PVA and the development of biomass flame retardant.

Exploration of the interaction mechanism of lignocellulosic hybrid systems based on deep eutectic solvents

The interactions of three deep eutectic solvents (DES) choline chloride-glycerol (ChCl-GLY), ChCl-lactic acid (ChCl-LA) and ChCl-urea (ChCl-U) with cellulose-hemicellulose and cellulose-lignin hybrid systems were investigated using the simulated computational approach. Aiming to simulate DES pretreatment of real lignocellulosic biomass in nature. DES pretreatment could disrupt the original hydrogen bonding network structure among the lignocellulosic components and reconstruct the new DES-lignocellulosic hydrogen bonding network structure. ChCl-U had the highest intensity of action on the hybrid systems, removing 78.3% of the hydrogen bonds between cellulose-4-O-methyl Gluconic acid xylan (cellulose-Gxyl) and 68.4% of the hydrogen bonds between cellulose-Veratrylglycerol-b-guaiacyl ether (cellulose-VG), respectively. The increase of urea content facilitated the interaction between DES and lignocellulosic blend system. Finally, the addition of appropriate water (DES:H2O = 1:5) and DES formed the new DES-water hydrogen bonding network structure more favorable for the interaction of DES with lignocellulose.

Progressive Hydrophilic Processes of the Pyrite Surface in High-Alkaline Lime Systems.

Pyrite, as a disturbing gangue mineral in the beneficiation of valuable sulfide minerals and coal resources, is usually required to be depressed for floating in flotation practice. Specifically, the depression of pyrite is achieved by causing its surface to be hydrophilic with the assistance of depressants, normally with inexpensive lime used. Accordingly, the progressive hydrophilic processes of the pyrite surface in high-alkaline lime systems were studied in detail using density functional theory (DFT) calculations in this work. The calculation results suggested that the pyrite surface is prone to hydroxylation in the high-alkaline lime system, and the hydroxylation behavior of the pyrite surface is beneficial to the adsorption of monohydroxy calcium species in thermodynamics. Adsorbed monohydroxy calcium on the hydroxylated pyrite surface can further adsorb water molecules. Meanwhile, the adsorbed water molecules form a complex hydrogen-bonding network structure with each other and with the hydroxylated pyrite surface, which makes the pyrite surface further hydrophilic. Eventually, with the adsorption of water molecules, the adsorbed calcium (Ca) cation on the hydroxylated pyrite surface will complete its coordination shell surrounded by six ligand oxygens, which leads to the formation of a hydrophilic hydrated calcium film on the pyrite surface, thus achieving the hydrophilization of pyrite.