Solutions In Organic Solvents Research Articles

Cleaning of Water Surface from Oil and Oil Products in Arctic Conditions

The results of obtaining and studying the properties of the composite for elimination of oil and petroleum products on water areas at low temperatures on the basis of oligomer obtained from urea resin and treated with polymer solution in organic solvent are presented. It is concluded that the proposed composite has a high degree of purification from oil and petroleum products, which does not change when the temperature drops to -40 °С.

Post-Synthetic Modification of Porous Organic Cages for Enhanced Iodine Adsorption Performance.

The capture of radioactive iodine species from nuclear waste is crucial for environmental protection and human health. Porous organic cages (POCs), an emerging porous material, have showed potential in iodine adsorption due to the advantages of tunable pores and processibility. However, integrating multiple desirable characteristics into a single POC through bottom-up assembly of pre-designed building blocks remains challenging. Post-synthetic modification (PSM) offers an alternative approach, enabling the introduction of various functions into a single POC. Herein, a viable and highly efficient three-step PSM strategy to modify a representative POC (CC3), is presented. The modified POC, OFT-RCC36+6Br-, features a charged confined space, electron-rich heteroatom, and halide ions, exhibiting significantly enhanced iodine vapor uptake compared to the parental cage. The universality of the PSM strategy has been verified by successfully modifying two other POCs. The iodine adsorption behaviors of three modified cage adsorbents in organic solvent and aqueous solution have also been investigated, all of which exhibited improved performance, especially in comparison to ionic cages modified through direct protonation. This work provides an effective PSM strategy for POCs to facilitate iodine adsorption. More importantly, the introduction of a new PSM strategy enriches the functional diversity of POCs, potentially broadening their future applications.

A novel coumarin based fluorescent sensor for high-sensitive detection of Cu2+ and water as well as applications in food and environmental analysis

A novel fluorescent sensor (SZ) based on coumarin was designed and synthesized for the detection of Cu2+ in DMSO/H2O solution (9/1, v/v, pH = 7.4, HEPES = 10 mM) and water in organic solvents. The sensor exhibited a low detection limit of 9.6 × 10−8 mol/L and a short response time (30 s) for Cu2+ in DMSO/H2O solution. SZ showed a red-shift in emission wavelength in more polar solvents and demonstrated high sensitivity in detecting water in various solvents including tetrahydrofuran, acetone, ethanol, methanol and acetonitrile with the lowest detection limit in ethanol as low as 0.0035 % (v/v). The mechanism for water detection by SZ was identified to be polarity dependent. Moreover, SZ was effectively employed for detecting alcohol content in Chinese Baijiu, as well as water content in sugar and salt samples. Notably, SZ has the capability to determine Cu2+ in soil and environmental water samples, showing a wide range of potential applications.

Solvation Enthalpies and Free Energies for Organic Solvents through a Dense Neural Network: A Generalized-Born Approach

A dense artificial neural network, ESE-ΔH-DNN, with two hidden layers for calculating both solvation free energies ΔG°solv and enthalpies ΔH°solv for neutral solutes in organic solvents is proposed. The input features are generalized-Born-type monatomic and pair electrostatic terms, the molecular volume, and atomic surface areas of the solute, as well as five easily available properties of the solvent. ESE-ΔH-DNN is quite accurate for ΔG°solv, with an RMSE (root mean square error) below 0.6 kcal/mol and an MAE (mean absolute error) well below 0.4 kcal/mol. It performs particularly well for alkane, aromatic, ester, and ketone solvents. ESE-ΔH-DNN also exhibits a fairly good accuracy for ΔH°solv prediction, with an RMSE below 1 kcal/mol and an MAE of about 0.6 kcal/mol.

Raman Microscopic Investigation of Organic Solvent Concentration Profiles in Proton Exchange Membranes and Their Permeability

Direct alcohol fuel cells (DAFCs) suffer from severe problems related to the employed polymer electrolyte membranes, such as fuel crossover, resulting in low faradaic efficiency and performance of the fuel cell.1,2,3 We introduce a 3D-printed diffusion cell setup, which is capable of determining the interaction of membranes and organic solvents via confocal Raman microscopy.4 Thus, the suitability of proton exchange membranes (PEMs) for usage in DAFCs can be evaluated. In this setup, the membrane is clamped between two flow channels, similar to the flow field plates of a fuel cell. The donor channel is filled with an organic solvent-water mixture, and the receptor channel is filled with water. Depth scans through the membrane and the two flow channels provide concentration profiles of the organic solvent within the membrane, which are used to calculate membrane properties such as permeability and sorption coefficient (see Fig. 1).In this study, the membrane-solvent interactions between standard unreinforced and composite PEMs and various organic solvent solutions, such as 2-propanol, acetone, and ethanol, are investigated. All membranes analyzed show a preference for organic solvent absorption from 1 M solutions, with sorption coefficients ranging from 2.5 to 3.0. In addition to the absorption, the organic solvents permeate through the membrane. The corresponding permeabilities range from 10-5 to 10-4 cm² s-1. However, the permeabilities of the membranes for different solvents do not scale with their sorption coefficients, in contrast to the membrane swelling.This diffusion cell setup is an accessible and fast pre-screening method, which can enhance the development and evaluation of new ion exchange membranes for use in DAFCs and related applications.

Diffusion and structure of propylene carbonate-metal salt electrolyte solutions for post-lithium-ion batteries: From experiment to simulation.

The diffusion of cations in organic solvent solutions is important for the performance of metal-ion batteries. In this article, pulsed field gradient nuclear magnetic resonance experiments and fully atomistic molecular dynamic simulations were employed to study the temperature-dependent diffusive behavior of various liquid electrolytes representing 1M propylene carbonate solutions of metal salts with bis(trifluoromethylsulfonyl)imide (TFSI-) or hexafluorophosphate (PF6-) anions commonly used in lithium-ion batteries and beyond. The experimental studies revealed the temperature dependence of the diffusion coefficients for the propylene carbonate (PC) solvent and for the anions following an Arrhenius type of behavior. It was observed that the PC molecules are the faster species. For the monovalent cations (Li+, Na+, K+), the PC solvent diffusion was enhanced as the cation size increased, while for the divalent cations (Mg2+, Ca2+, Sr2+, Ba2+), the opposite trend was observed, i.e., the diffusion coefficients decreased as the cation size increased. The anion diffusion in LiTFSI and NaTFSI solutions was found to be similar, while in electrolytes with divalent cations, a decrease in anion diffusion with increasing cation size was observed. It was shown that non-polarizable charge-scaled force fields could correspond perfectly to the experimental values of the anion and PC solvent diffusion coefficients in salt solutions of both monovalent (Li+, Na+, K+) and divalent (Mg2+, Ca2+, Sr2+, Ba2+) cations at a range of operational temperatures. Finally, after calculating the radial distribution functions between cations, anions, and solvent molecules, the increase in the PC diffusion coefficient established with the increase in cation size for monovalent cations was clearly explained by the large hydration shell of small Li+ cations, due to their strong interaction with the PC solvent. In solutions with larger monovalent cations, such as Na+, and with a smaller solvation shell of PC, the PC diffusion is faster due to more liberated solvent molecules. In the salt solutions with divalent cations, both the anion and the PC diffusion coefficients decreased as the cation size increased due to an enhanced cation-anion coordination, which was accompanied by an increase in the amount of PC in the cation solvation shell due to the presence of anions.

A Hydrophilic Metal Azolate Coordination Polymer for In Situ Encapsulation of Haloalkane Dehalogenase with Enhanced Enzymatic Performance.

Encapsulating enzymes within metal-organic frameworks such as zeolitic imidazolate framework-8 (ZIF-8) has been demonstrated to enhance enzymatic performance under harsh conditions. However, by computer-aided analysis, we revealed that highly hydrophobic organic ligands and unfavorable metal ions could greatly impair the activity of haloalkane dehalogenase DhaA by directly interacting with the catalytic sites, causing an extremely low activity of DhaA after encapsulating within ZIF-8. We also found that the presence of a protecting polymer could protect DhaA from the damage of organic ligands and metal ions and that a positively charged amino acid could increase the DhaA activity. Based on the simulations and experimental observations, we have designed to coencapsulate DhaA with poly(vinylpyrrolidone) (PVP) and lysine (Lys) within the amorphous Co-based metal azolate coordination polymer (CoCP). The as-prepared immobilized enzyme (DhaA/PVP/Lys@CoCP) exhibited significantly increased activity (91.5 times higher than that of DhaA@ZIF-8), dramatically enhanced thermostability at 50-70 °C, greatly improved catalytic performance in several organic solvent solutions, and good recyclability (over 75% of the initial activity after 10 cycles). The superiority of the immobilized enzyme was also demonstrated with a substrate frequently detected in the real world. In addition to the protective effect of PVP and positive effect of Lys, experimental and computational investigations unveiled other two favorable aspects that contributed to the enhanced enzymatic performance: (1) high hydrophilicity of the immobilization material and (2) the use of Co2+ with a minimal negative effect on DhaA. The research has thus provided a promising immobilized DhaA with favorable catalytic performance and great potential in industrial applications.

Blueshift of the CN stretching vibration of acetonitrile in solution: computational and experimental study.

Acetonitrile, a polar molecule that cannot form hydrogen bonds on its own, interacts with solvent molecules mainly through the lone pair of its nitrogen atom and the π electrons of its CN triple bond [Correction added on 17 July 2024, after first online publication: Acetole has been changed to Acetonitrile in the preceeding sentence.]. Interestingly, acetonitrile exhibits an unexpected strengthening of the triple bond's force constant in an aqueous environment, leading to an upshift (blueshift) in the corresponding stretching vibration: this effect contrasts with the usual consequence of hydrogen bonding on the vibrational frequencies of the acceptor groups, that is, frequency redshift. This investigation elucidates this phenomenon using Raman spectroscopy to examine the behavior of acetonitrile in organic solvent, water, and silver ion aqueous solutions, where an even more pronounced upshift is observed. Raman spectroscopy is particularly well suited for analyzing aqueous solutions due to the minimal scattering effect of water molecules across most of the vibrational spectrum. Computational approaches, both static and dynamical, based on Density Functional Theory and hybrid functionals, are employed here to interpret these findings, and accurately reproduce the vibrational frequencies of acetonitrile in different environments. Our calculations also allow an explanation for this unique behavior in terms of electric charge displacements. On the other hand, the study of the interaction of acetonitrile with water molecules and metal ions is relevant for the use of this molecule as a solvent in both chemical and pharmaceutical applications.

Solvent-Exchange Triggered Solidification of Peptide/POM Coacervates for Enhancing the On-Site Underwater Adhesion

Peptide-based biomimetic underwater adhesives are emerging candidates for understanding the adhesion mechanism of natural proteins secreted by sessile organisms. However, there is a grand challenge in the functional recapitulation of the on-site interfacial spreading, adhesion and spontaneous solidification of native proteins in water using peptide adhesives without applied compressing pressure. Here, a solvent-exchange strategy was utilized to exert the underwater injection, on-site spreading, adhesion and sequential solidification of a series of peptide/polyoxometalate coacervates. The coacervates were first prepared in a mixed solution of water and organic solvents by rationally suppressing the non-covalent interactions. After switching to a water environment, the solvent exchange between bulk water and the organic solvent embedded in the matrix of the peptide/polyoxometalate coacervates recovered the hydrophobic effect by increasing the dielectric constant, resulting in a phase transition from soft coacervates to hard solid with enhanced bulk cohesion and thus compelling underwater adhesive performance. The key to this approach is the introduction of suitable organic solvents, which facilitate the control of the intermolecular interactions and the cross-linking density of the peptide/polyoxometalate adhesives in the course of solidification under the water line. The solvent-exchange method displays fascinating universality and compatibility with different peptide segments.

Zinc complexes of chloroquine and hydroxychloroquine versus the mixtures of their components: Structures, solution equilibria/speciation and cellular zinc uptake

The zinc complexes of chloroquine (CQ; [Zn(CQH+)Cl3]) and hydroxychloroquine (HO-CQ; [Zn(HO-CQH+)Cl3]) were synthesized and characterized by X-Ray structure analysis, FT-IR, NMR, UV–Vis spectroscopy, and cryo-spray mass spectrometry in solid state as well as in aqueous and organic solvent solutions, respectively. In acetonitrile, up to two Zn2+ ions bind to CQ and HO-CQ through the tertiary amine and aromatic nitrogen atoms (KN-aminCQ = (3.8 ± 0.5) x 104 M−1 and KN-aromCQ = (9.0 ± 0.7) x 103 M−1 for CQ, and KN-aminHO-CQ = (3.3 ± 0.4) x 104 M−1 and KN-aromHO-CQ = (1.6 ± 0.2) x 103 M−1 for HO-CQ). In MOPS buffer (pH 7.4) the coordination proceeds through the partially deprotonated aromatic nitrogen, with the corresponding equilibrium constants of KN-arom(aq)CQ = (3.9 ± 1.9) x 103 M−1and KN-arom(aq)HO-CQ = (0.7 + 0.4) x 103 M−1 for CQ and HO-CQ, respectively. An apparent partition coefficient of 0.22 was found for [Zn(CQH+)Cl3]. Mouse embryonic fibroblast (MEF) cells were treated with pre-synthesized [Zn((HO-)CQH+)Cl3] complexes and corresponding ZnCl2/(HO-)CQ mixtures and zinc uptake was determined by application of the fluorescence probe and ICP-OES measurements. Administration of pre-synthesized complexes led to higher total zinc levels than those obtained upon administration of the related zinc/(hydroxy)chloroquine mixtures. The differences in the zinc uptake between these two types of formulations were discussed in terms of different speciation and character of the complexes. The obtained results suggest that intact zinc complexes may exhibit biological effects distinct from that of the related zinc/ligand mixtures.

A millimeter water-in-oil droplet as an alternative back exchange prevention strategy for hydrogen/deuterium exchange mass spectrometry of peptides/proteins.

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a versatile bioanalytical technique for protein analysis. Since the reliability of HDX-MS analysis considerably depends on the retention of deuterium labels in the post-labeling workflow, deuterium/hydrogen (D/H) back exchange prevention strategies, including decreasing the pH, temperature, and exposure time to protic sources of the deuterated samples, are widely adopted in the conventional HDX-MS protocol. Herein, an alternative and effective back exchange prevention strategy based on the encapsulation of a millimeter droplet of a labeled peptide solution in a water-immiscible organic solvent (cyclohexane) is proposed. Cyclohexane was used to prevent the undesirable uptake of water by the droplet from the atmospheric vapor through the air-water interface. Using the pepsin digest of deuterated myoglobin, our results show that back exchange kinetics of deuterated peptides is retarded in a millimeter droplet as compared to that in the bulk solution. Performing pepsin digestion directly in a water-in-oil droplet at room temperature (18-21 °C) was found to preserve more deuterium labels than that in the bulk digestion with an ice-water bath. Based on the present findings, it is proposed that keeping deuterated peptides in the form of water-in-oil droplets during the post-labelling workflow will facilitate the preservation of deuterium labels on the peptide backbone and thereby enhance the reliability of the H/D exchange data.

ЭКСТРАКЦИЯ ЦЕЗИЯ И СТРОНЦИЯ ИЗ АЗОТНОКИСЛЫХ РАСТВОРОВ КРАУН-ЭФИРАМИ В ТЯЖЕЛЫХ РАЗБАВИТЕЛЯХ

The extraction ability of crown-ethers has been studied with respect to cesium and strontium from nitric acid solutions in heavyweight polar organic solvents: chloroform; 1,2-dichloroethane; bis(2-chloroethyl)ether; nitrobenzene; 1,1,7-trihydrododecafluoroheptyl alcohol. Using bis(2-chloroethyl)ether as a new polar solvent in the extraction processes of dibenzo21-crown-7 and 4,4' (5')-ditretbutyldibenzo-18-crown-6, rather high distribution coefficients of cesium are achieved (DCs) from solutions with a nitric acid concentration of 1-5 mol / dm3. In the extraction of dicyclohexyl-18-crown-6 strontium, the highest DSr values were obtained, using chlorine-substituted hydrocarbons and bis(2-chloroethyl)ether with an extraction maximum of 1-3 mol / dm3 HNO3, depending on the diluent used. Extraction systems based on selective crown-ethers in a solvent mixture for the joint extraction of cesium and strontium from chemically complex nitric acid solutions are proposed.

Concentration of Aqueous Solution of Organic Solvents by Osmotically Assisted Reverse Osmosis (OARO)

Concentration of Aqueous Solution of Organic Solvents by Osmotically Assisted Reverse Osmosis (OARO)

Voltammetry in Microemulsion Formed by Electron Donor Solution in Organic Solvent|Ionic Liquid Microdroplets in Aqueous Electrolyte

Oxygen reduction reaction (ORR)1 or hydrogen evolution reaction (HER)2 at liquid|liquid interface provide the possibility of separation of their products: hydrogen peroxide or hydrogen.3,4 Typically, these reactions are studied at single interface formed between immiscible electrolyte solutions in quiescent conditions. In such geometry the frequency of successful reaction events when highly hydrophobic electron donor (i.e. decamethylferrocene (DMFc) or excited form of decamethylruthenocene (DMRc)) dissolved in organic phase meet proton from aqueous phase is rather limited. Importantly, electrochemical recycling of electron donor at electrode positioned close to the liquid|liquid interface increases efficiency of this reaction.5,6 The use of microemulsion is promising higher efficiency alternative, because of extended interfacial area of numerous organic droplets. As efficient electron exchange between oxidized form of electron donor and the electrode is crucial for biphasic ORR and HER one has to focus on electrochemical studies of DMFc or DMRc in emulsions.are important. Voltammetric signal of various redox probes as ferrocene or ferrocene surfactants in quiescent emulsions is similar to that in single phase with some variation of peak density currents or redox potential.7-11 Other studies focused on chronoamperometric experiments to detect collisions of redox probe (e.g. ferrocene12) containing droplets with the electrode surface. It was found that the addition of an hydrophobic ionic liquid, typically trihexyltetradecyl-phosphonium bis(trifluoro-methylsulfonyl) amide to the organic phase as stabiliser and electrolyte, does not influence the magnitude of the electrochemical signal.13 Here we will report results of electrochemical studies of emulsion prepared from aqueous HClO4 and DMFc or DMRc and trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) imide (IL-PI) solution in toluene. As aqueous phase acid solution was selected, because in biphasic ORR or HER it serves as a source of protons. During the measurements the microemulsion was stirred to achieve faster droplets transport towards the electrode surface. Results will be compared with these obtained in a single organic phase.Voltammograms obtained with glassy carbon disc electrode indicate reversible oxidation/reduction of the redox probe similar to the seen with an electrode immersed in single organic phase. During continuous scanning redox only small change of peak currents is seen. Importantly, when after experiment in emulsion working electrode was transferred to aqueous HClO4, the voltammetric signal is still seen, but the peak currents are significantly smaller. This may indicate the redox reaction in liquid film formed on the electrode surface. Formation of liquid organic film is confirmed by the results of chronoamperometric experiments. When the electrode is set at potential corresponding to the oxidation of the redox probe, of the current is seen after c.a. 100 s drop, what may indicate the gradient of redox probe concentration. As DMFc is insoluble in water this points out on gradient of organic phase close to the glassy carbon surface.14 In turn voltammetric current related to electroreduction of highly hydrophilic hexacyanoferrate(III) is significantly diminished in emulsion as compared to pure aqueous electrolyte indicating partial coverage of the GC surface by hydrophobic film.Other effects related with electrochemical behavior of studied emulsions will be also presented and discussed.

FERROCENE DISPROPORTIONATION REACTIONS IN A PLASMA-LIQUID SYSTEM WITH A ROTATING GLIDING DISCHARGE

A plasma-liquid system with the activation of H2O distillate and 0.1 M ferrocene solution in organic solvents (ethanol, acetonitrile) with a rotating gliding discharge plasma was studied. The research was conducted using various plasma-forming gases (air, Ar, N2, CO2). Determination of plasma parameters was performed by plasma emission spectroscopy methods. It was shown that the plasma of both the rotating gliding discharge and the plasma of the secondary discharge supported by the gliding discharge are non-isothermal. The study of the physicochemical properties of the synthesis products was performed by adsorption, luminescence analysis, polarimetry, chromatographymass spectrometry and NMR methods. It was found that cyclopentadiene ligands of ferrocene disproportionate into saturated cyclic hydrocarbons (cyclopentane and pentane). Also, as a result of plasma chemical synthesis, aromatic compounds (benzene and its derivatives) are formed.

β-Glucosidase on clay minerals: Structure and function in the synthesis of octyl glucoside

β-Glucosidase is a biological macromolecule that catalyzes the hydrolysis of various glycosides and oligosaccharides. It may also be used to catalyze the synthesis of glycosides under suitable conditions. Carrier-bound β-glucosidase can enhance the enzymatic activity in the synthesis of glycosides in organic solvent solutions, although the molecular mechanism regulating activity is yet unknown. This study investigated the impact of utilizing montmorillonite (Mmt), attapulgite (Attp), and kaolinite (Kao) as carriers on the activity of β-glucosidase from Prunus dulcis (PdBg). When Attp was used as carriers, the molecular dynamic (MD) simulations found the distance between pNPG and the active site residues E183 and E387 was minimally impacted by the adsorptions, hence PdBg maintained about 81.3 ± 0.89 % of its native activity. Out of the three clay minerals, the relative activity of PdBg loaded on Mmt was the lowest because of the highest electrostatic energy. The substrate channel of PdBg on Kao is directed towards the surface, limiting the accessibility of substrates. Secondary structure and conformation studies revealed that the conformational stability of PdBg in solvent solutions was enhanced by coupling to Attp. Unlike dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF) and 1,2-dimethoxyethane (DME), tert-butanol (t-BA) did not penetrate into the active site of PdBg interfering with its binding to the substrate. The maximum yield of n-octyl-β-glucoside (OGP) synthesis catalyzed by Attp-immobilized PdBg reached 48.3 %.

A novel interfacial polymerization assisted phase inversion process for the facile fabrication of ion-selective nanofiltration membranes

Interfacial polymerization (IP) and non-solvent induced phase inversion (NIPS) are the two most commonly used mainstream technologies to fabricate separation membranes. Taking their advantages, we developed a simple, facile and scalable method to integrate the IP and NIPS processes together for the fabrication of ion-selective nanofiltration membranes. Herein, amphiphilic polysulfone block hyperbranched polyglycerol (PSf-b-hPG) copolymer was synthesized and blended with polyethylene imide (PEI) to prepare a polymer casting solution in organic solvents. After casted into the liquid film of PSf-b-hPG and PEI blending solution, it was then immersed into a cross-linking solution with 0.2 wt.% trimethylchloride (TMC) in n-hexane for the generation of the polyamide layer first on top of the liquid film, and finally transferred into a water coagulation bath for the formation of the porous matrix of PSf-b-hPG membrane. The fabricated membrane exhibited a high water permeance of 12.57 L m-2h−1 bar−1 and a high separation factor of 25.08 towards Mg2+ and Li+ ions, which is superior to the perm-selectivity of the most reported nanofiltration membranes. This novel and facile process can be directly applied to the NIPS manufacturing line, eliminating a separate IP production line and holding immense potentials and advantages in scale-up production.

Rational surface charge engineering of haloalkane dehalogenase for boosting the enzymatic performance in organic solvent solutions

Biocatalysis in organic solvents (OSs) has numerous important applications, but native enzymes in OSs often exhibit limited catalytic performance. Herein, we proposed a computation-aided surface charge engineering strategy to improve the catalytic performance of haloalkane dehalogenase DhaA in OSs based on the energetic analysis of substrate binding to the DhaA surface. Several variants with enhanced OS resistance were obtained by replacing negative charged residues on the surface with positive charged residue (Arg). Particularly, a four-substitution variant E16R/E93R/E121R/E257R exhibited the best catalytic performance (five-fold improvement in OS resistance and seven-fold half-life increase in 40% (vol) dimethylsulfoxide). As a result, the overall catalytic performance of the variant could be at least 26 times higher than the wild-type DhaA. Fluorescence spectroscopy and molecular dynamics simulation studies revealed that the residue substitution mainly enhanced OS resistance from four aspects: (a) improved the overall structural stability, (b) increased the hydrophobicity of the local microenvironment around the catalytic triad, (c) enriched the hydrophobic substrate around the enzyme molecule, and (d) lowered the contact frequency between OS molecules and the catalytic triad. Our findings validate that computation-aided surface charge engineering is an effective and ingenious rational strategy for tailoring enzyme performance in OSs.

Cationic Polymers Remarkably Boost Haloalkane Dehalogenase Activity in Organic Solvent Solutions and the Molecular Implications.

Applications of haloalkane dehalogenase DhaA in biocatalysis are limited by its unfavorable performance in organic solvents. Our previous work proved that mutations of surface positive-charged residues enhanced the organic solvent resistance of DhaA, which inspired us to explore the effect of cationic polymers on DhaA in organic solvents. Remarkably boosted performance was achieved in different organic solvent solutions by introducing cationic polymers, for example, there was a 6.1-fold activity increase with poly(allylamine hydrochloride) and a 5.5-fold activity increase with poly(ethylene imine) in 40 vol.% dimethylsulfoxide. The presence of cationic polymers protected DhaA from damage by organic solvents and increased the substrate concentration around the enzyme-polymer complex. Fluorescence spectroscopy and molecular dynamics simulations revealed that the binding of cationic polymers onto DhaA weakened the interactions between organic solvents and DhaA, decreased the organic solvent solvation level around DhaA, and enhanced the structural stability of DhaA in organic solvents. This comprehensive understanding of the effect of cationic polymers on DhaA can help to broaden the applications of DhaA in organic solvent-involved biocatalysis.

A robust superhydrophobic-superoleophilic PDMS/Al2O3/CM composite ceramic membrane: Stability, efficient emulsified oil/water separation, and anti-pollution performance

To address the issue of membrane fouling and low separation efficiency of ceramic membrane (CM) commonly encountered in oil/water separation, the implementation of a robust superhydrophobic coating on the surface of CM represents a viable and efficacious strategy. This study presented a facile approach for the fabrication of a durable superhydrophobic-superoleophilic composite coating on the surface of CM by the in-situ growth of needle-shaped alumina (Al2O3) followed by the impregnation of a polydimethylsiloxane (PDMS) coating. Various characterization techniques, such as FESEM, XPS, CLSM, bubble point porometer, contact angle etc. were used to characterize the microstructure, surface composition, pore size distribution, and surface characteristics of the PDMS/Al2O3/CM. The mechanical, chemical, and thermal stability were evaluated by means of sandpaper abrasion, tape peeling, immersion tests including organic solvent, acid, and base solutions, and heat treatment. The separation performance, anti-pollution property, and reusability of the modified CM were evaluated by oil/water mixture and water-in-oil emulsion. And the oil/water separation model and anti-fouling mechanism was also elaborated. The results indicated that a homogeneous needle Al2O3 cluster with a micro/nano dual-scale hierarchical roughness was grown on the surface of the CM, and the further introduction of PDMS gave the modified CM excellent superhydrophobicity with a water contact angle (WCA) of ∼160° and a water rolling angle (WOA) of 7.6°. The PDMS/Al2O3/CM composite membrane exhibited remarkable capability in segregating oil/water mixtures, including emulsified water-in-oil. The separation efficiency remained above 99 %, even after 15 cycles of separation. This study presents a simple technique for fabricating a robust superhydrophobic coating onto the Al2O3-based CM surface, which exhibits the potential for application to other ceramic membrane substrates. And the anticipated outcome of this developing is a broad spectrum of industrial applications for emulsified oil/water purification.