Introduction Of Hydroxyl Group Research Articles

SIS derivative as a novel delivery system for ibuprofen

Ibuprofen is a commonly used analgesic due to its effectiveness, but its half-life is relatively short. Therefore, finding an appropriate delivery system is a significant challenge. In this study, we designed a new controlled release carrier for ibuprofen using a biocompatible poly(styrene-b-isoprene-b-styrene) triblock copolymer. For this purpose, the polyisoprene block was modified with 2-mercaptoethanol or ethanolamine to introduce hydroxyl groups. These linkers allowed the incorporation of the drug through a covalent bond. The modified copolymers were characterized using spectroscopic techniques, including 1H NMR, FTIR-ATR, and UV-Vis, which confirmed successful synthesis. The thermal method revealed that the new delivery system has a lower glass transition temperature than its precursor, verifying the incorporation of the hydrophobic drug. Furthermore, enzymatic release of ibuprofen was studied under physiological conditions and was found to be slow and sustained over time. The in vitro biocompatibility of the release system was evaluated using RAW264.7 monocytes. It was found that cells were able to adhere and proliferate onto the matrices. Additionally, the cells growing on ibuprofen-substituted SIS produced low levels of nitric oxide, a marker of cytotoxicity, when compared to cells growing on tissue culture plates. Taken together, the findings indicate that the polymer may serve as a promising delivery system for ibuprofen with potential biological applications.

One-step synthesis of hydroxyl-functionalized ionic hyper-cross-linked polymers with high surface areas for efficient CO2 capture and fixation

Ionic liquid-based functional materials have attracted significant attention for their distinctive structure in the field of CO2 capture and conversion. In this work, a series of hydroxyl-functionalized ionic hyper-cross-linked polymers are prepared through a one-step Friedel-Crafts reaction involving hypoxanthine (HX) and benzimidazole (BI) as the monomers, along with various halohydrocarbon crosslinking agents. These polymers demonstrate a high specific surface area (558–1480 m2·g−1), well-developed microporous structure, and unique ion sites, enabling them to exhibit remarkable and reversible CO2 adsorption properties. Particularly noteworthy is their CO2 adsorption capacity, which surpasses that of similar ionic polymers documented in the literature, reaching 157.5 mg·g−1 at 273 K and 1 bar. Additionally, these polymers function as recyclable catalysts in the cycloaddition reaction of CO2 and epoxides, enabling the conversion of CO2 into cyclic carbonates with yields of up to 99 % even without a co-catalyst. Mechanism investigation reveals that the introduction of hydroxyl groups in the polymer is the key to improving catalytic activity through a synergistic catalytic effect. This research provides a novel concept for designing ionic functional materials with capabilities in both CO2 adsorption and catalytic activity.

Extractive Promotion on the Synthesis of 5‐Hydroxymethylfurfural from Highly Concentrated Saccharides in Ionic Liquid

Abstract5‐Hydroxymethylfurfural (5‐HMF) is perceived as a versatile biobased platform compound. The large‐scale production of 5‐HMF in ionic liquids (ILs) is still limited due to the inefficiency with diluted carbohydrate feedstocks. The IL/extractant biphasic media are benign systems for the efficient synthesis of 5‐HMF from highly concentrated carbohydrates. This work demonstrated that the hydrogen‐bond interaction between the hydroxyl group of 5‐HMF and IL played a critical role in the dissolution of 5‐HMF. The introduction of hydroxyl group into the structure of an IL was conducive to break the mentioned hydrogen‐bond interaction, therefore improving the extraction of 5‐HMF. Ethyl levulinate (EL) was found to be an excellent extractant for separating 5‐HMF from ILs for the first time. In a system consisting of 1‐hydroxyethyl‐3‐methylimidazolium chloride, EL and water, highly concentrated (80 wt %) fructose and glucose could be efficiently converted into 5‐HMF with a yield of 82 % and 70 % at 100 °C and 120 °C, respectively. The obtained results are superior to previous works on the synthesis of 5‐HMF from highly concentrated carbohydrates, which can provide useful information on designing a process for the large‐scale refining of biomass in ILs.

Study on the mechanism of oxygen atom-related non-covalent interactions on the structure of non-fused ring acceptor molecules and their optoelectronic properties

Non-covalent interactions play a crucial role in regulating the molecular conformation and optoelectronic properties of the acceptor. In this paper, hydroxyl groups of different positions and numbers are inserted on the original non-fused ring acceptor molecule W0. Thus, eight novel molecules were designed. Density functional theory (DFT) and time-dependent DFT (TD-DFT) are used to investigate the mechanisms of non-covalent interactions between S…O on the molecular conformation, electronic structure and its optoelectronic properties. The existence of intramolecular S…O non-covalent interactions was demonstrated by the Atoms-In-Molecules topological analysis and RDG isosurface visualization. The study of the molecular conformational planarity revealed that the introduction of unilateral groups can optimize the homolateral planarity. As the number of hydroxyl insertions increases, the twisting of the two thiophene units within the central core intensifies. This also leads to an impact on the internal planarity of the central core. The electrostatic potential (ESP) analysis showed that the asymmetric hydroxyl modification increased the dipole moment and may be more beneficial for electron transfer. The larger the dipole moment, the more negative the ESP. Theoretical results show that the introduction of hydroxyl groups is significantly superior in terms of light absorption, dipole moment and exciton binding energy as well as excitation energy. As the number of hydroxyl groups increases, they show more potential in increasing the excitation energy and light absorption and decreasing the exciton binding energy. This study provides new insights into the design and development of high-performance non-fused ring acceptors.

Introducing hydroxyl groups to tailor the d-band center of Ir atom through side anchoring for boosted ORR and HER

Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts. Herein, iridium (Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne (HsGDY), and coordinated with OH as an Ir atomic catalyst (Ir1-N-HsGDY). The electron structures, especially the d-band center of Ir atom, are optimized by these specific coordination atoms. Thus, the as-synthesized Ir1-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media. Benefiting from the unique structure of HsGDY, IrN2(OH)3 has been developed and demonstrated to act as the active site in these electrochemical reactions. All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity, showing a new strategy to design novel electrochemical catalysts.

Epoxy SQ-based amine functionalized superhydrophilic hybrid network for Ag+ adsorption and catalytic degradation of Rhodamine B

Most epoxy substituted silsesquioxane (SQ)-based materials are hydrophobic, it is of great interest to develop hydrophilic epoxy SQ-based materials for special applications. In this work, epoxy functionalized SQ with T10 (G-SQ) as main product was obtained by the hydrolytic condensation of 3-(glycidoxypropyl)trimethoxysilane; then the hybrid network of G-SQ-TAEA was produced by the amine-epoxy click reaction of G-SQ with tris(2-aminoethyl)amine (TAEA). The introduction of hydroxyl groups and the amine groups by the amine-epoxy click reaction greatly enhances the hydrophilicity of the hybrid network and facilitates the dispersion of G-SQ-TAEA in water. Interestingly, G-SQ-TAEA can adsorb Ag+ ions with a saturation capacity of 86.4 mg/g and the Ag-loaded G-SQ-TAEA (G-SQ-TAEA-Ag) can efficiently catalyze degradation of Rhodamine B (RhB) to colourless. This work offers a new strategy for removing contamination in water.

Hydroxyl-Decorated Pt as a Robust Water-Resistant Catalyst for Catalytic Benzene Oxidation.

In catalytic oxidation reactions, the presence of environmental water poses challenges to the performance of Pt catalysts. This study aims to overcome this challenge by introducing hydroxyl groups onto the surface of Pt catalysts using the pyrolysis reduction method. Two silica supports were employed to investigate the impact of hydroxyl groups: SiO2-OH with hydroxyl groups and SiO2-C without hydroxyl groups. Structural characterization confirmed the presence of Pt-Ox, Pt-OHx, and Pt0 species in the Pt/SiO2-OH catalysts, while only Pt-Ox and Pt0 species were observed in the Pt/SiO2-C catalysts. Catalytic performance tests demonstrated the remarkable capacity of the 0.5 wt % Pt/SiO2-OH catalyst, achieving complete conversion of benzene at 160 °C under a high space velocity of 60,000 h-1. Notably, the catalytic oxidation capacity of the Pt/SiO2-OH catalyst remained largely unaffected even in the presence of 10 vol % water vapor. Moreover, the catalyst exhibited exceptional recyclability and stability, maintaining its performance over 16 repeated cycles and a continuous operation time of 70 h. Theoretical calculations revealed that the construction of Pt-OHx sites on the catalyst surface was beneficial for modulating the d-band structure, which in turn enhanced the adsorption and activation of reactants. This finding highlights the efficacy of decorating the Pt surface with hydroxyl groups as an effective strategy for improving the water resistance, catalytic activity, and long-term stability of Pt catalysts.

Piranha Solution-Assisted Surface Engineering Enables Silicon Nanocrystals with Superior Wettability and Lithium Storage

Silicon anodes with a high theoretical capacity possess great potential applications in power batteries for electric vehicles, while their volume expansion always leads to crystal pulverization and electrode polarization. An ideal solution to alleviate such pulverization and polarization of silicon crystals is to simultaneously use nano-sized silicon crystals and introduce high viscosity and elasticity polymer binders. This work has achieved the adjustable introduction of hydroxyl groups to silicon nanocrystals under the optimal reaction temperature (e.g., 80 °C) and appropriate piranha solution composition (e.g., H2SO4/H2O2 = 3:1 v/v), ultimately forming an amorphous coating layer of ~1.3 nm on the silicon surface. The optimized silicon anode exhibits superior electrochemical performance (with an initial Coulombic efficiency of 85.5%; 1121.4 mA h g−1 at 1 A g−1 after 200 cycles) and improved hydrophilicity. The introduced hydroxyl groups significantly enhance the hydrophilicity of silicon in the electrolyte and the electrochemical activity of the silicon anodes. The hydroxyl groups achieve stronger bonding between silicon and polymer binders, ultimately improving the mechanical strength and stability of the electrode. The introduction of hydrophily functional groups on the surface of silicon crystals can be explored as an active strategy to solve the above issues. This surface engineering method could be extended to more fields of infiltrating silicon-based functional materials.

Preparation of High-k Polymeric Composites Based on Low-k Boron Nitride Nanosheets with High-Connectivity Lamellar Structure.

Typically, the basic method to enhance the dielectric response of polymer-based composites is to fill giant dielectric ceramic fillers, such as BaTiO3 and CaCu3Ti4O12, into the polymer matrix. Here, by using low-k boron nitride (BN) with well-controlled microstructure and surface, we successfully prepared a high-k polymeric composite, where the improvement in the dielectric constant of the composite even exceeds that of composites containing BaTiO3 and CaCu3Ti4O12 particles at the same weight percent. First, a lamellar boron nitride nanosheet (BNNS) aerogel was prepared by bidirectional freezing and freeze drying, respectively, and then the aerogel was calcined at 1000 °C to obtain the lamellar BNNS skeleton with some hydroxyl groups. Finally, the epoxy resin (EP) was vacuum impregnated into the BNNS skeleton and cured inside to prepare the lamellar-structured BNNSs/EP (LBE) composites. Interestingly, the dielectric constants of LBE with a 10 wt % BNNS content reached 8.5 at 103 Hz, which was higher by 2.7 times than that of pure EP. The experimental data and the finite element simulations suggested that the increased dielectric constants of LBE resulted from the combination of two factors, namely, the lamellar microstructure and the hydroxyl groups. The stacking of the BNNS phase into a highly connected lamellar skeleton significantly increased the internal electric field and the polarization intensity, while the introduction of hydroxyl groups on the BNNS surface further improved the polarization of the composite, resulting in a significant increase in the dielectric constant of the LBE. This work provides a new strategy for improving the dielectric constant through the microstructure design of composites.

Synthesis and flotation performance of a novel low-foam viscous cationic collector based on hematite reverse flotation desilication system

Traditional cationic collectors generally exist some disadvantages, such as high foam viscosity and difficulty in defoaming, which worsening the flotation separation effect. Herein, a novel cationic collector-dodecyl trihydroxyethyl ammonium bromide (DTDAB) with low-foam viscous was synthesized to optimize the reverse flotation system of hematite ore, which was achieved by introducing three hydroxyethyl groups into the nitrogen atoms of dodecyl trimethyl ammonium bromide (DTAB). The analysis of foam collapse performance indicated that the introduction of hydroxyl groups into hydrophilic head groups of DTAB reduced the interface surface tension and bubble coalescence, which were consistent with the design expectations. Meanwhile, flotation behaviors were systematically studied, and the results showed that the concentrates with 63.89 % total iron (TFe) grade and 89.27 % total iron recovery was obtained at pH 6.81, when the concentration of DTDAB and starch was 20 mg/L and 5 mg/L, respectively. Besides, the possible flotation mechanism was further studied by means of contact angle, Atomic force microscope (AFM), Fourier transforming infrared spectra (FT-IR), X ray photoelectron spectroscopy (XPS), and Density functional theory (DFT) calculation. The results comfirmed that the adsorption between DTDAB and quartz was caused by electrostatic force and hydrogen bonding affinity. In conclusion, it can be confirmed that the novel cationic collector DTDAB with low-foam viscous has the potential for the hematite reverse flotation desilication.

Fabrication of ultrafiltration membranes with improved antifouling and antibacterial capability by surface modification of quaternary ammonium

To minimize the organic/biological contamination, polymeric membranes with tertiary amine groups were synthesized and its surface was modified to obtain three types of quaternary ammonium modified ultrafilters. The antifouling and antibacterial properties of all prepared ultrafilters were studied. The performances differences of ultrafiltration membranes with different alkyl chain lengths of quaternary ammonium salts were explored. The results show that the increase of alkyl chain length of quaternary ammonium salts and the introduction of hydroxyl groups can effectively improve the permeability and anti-pollution performance of ultrafiltration membranes. After one cycle of Bovine serum albumin solution filtration test, the flux recovery ratio of the modified membrane is twice as much as that of the initial membrane, while the flux recovery ratio of the initial ultrafiltration membrane is only 36.6%. At the same time, the modified membrane has excellent antibacterial properties and water flux stability, which is conducive to the long-term use of the membrane.

A smartphone-available colorimetric and near-infrared fluorescence sensor for trace amounts of water detection in highly polar organic solvents

In this work, we aimed to construct a sensitive and convenient sensor for trace amounts of water detection in highly polar organic solvents. We designed and synthesized four D-π-A structure sensors DTA-2QA-OH, TPA-2QA, TPA-2QA-OH, and TPA-4QA-OH by adjusting the electron donor and the linking site of the electron acceptor. The TPA-2QA-OH synthesized by connecting hydroxylated triphenylamine and quinolinium at position 2C can be used as a sensitivity sensor for trace amounts of water detection in highly polar organic solvents by using Na2HPO4 as a deprotonation reagent. TPA-2QA-OH can detect trace amounts of water in DMSO, MeOH, and EtOH in both colorimetric and near-infrared fluorescence modes. The significant color change of the sensing systems was captured by a smartphone and analyzed by using the PhotoMetrix APP to construct a standard curve between RGB values and water content in solvents. The detection limit of the sensor TPA-2QA-OH for trace amounts of water by using colorimetric, fluorescent, or smartphone methods were calculated as low as 0.0009% vol in DMSO, 0.0064% vol in MeOH, and 0.0014% vol in EtOH, respectively. For the first time, the influence of the connection site of quinolinium on the photophysical properties and detection performance of the sensor was found. The conjugation of the electron donor groups as well as the introduction of hydroxyl groups on the electron donor are important for the construction of D-π-A structure colorimetric and fluorescence ICT sensors for trace water detection in highly polar organic solvents.

The evolution of surface species by steam pre-treatment on CrOx/Al2O3 catalysts for propane dehydrogenation

Propane dehydrogenation (PDH) has emerged as an efficient complementary process for producing propylene. The fundamental understanding of reaction mechanism of traditional CrOx-based catalysts is important for designing novel PDH catalysts. Here, the evolution of surface Cr species was investigated by means of steam pre-treatment to introduce a certain amount of hydroxyl groups on deeply reductive Cr2O3/Al2O3 catalysts without influencing the valence states and aggregated states. The surface structural features of CrOx/Al2O3 catalysts were investigated by FT-IR, TGA, XPS, NH3-TPD, and Py-IR characterization techniques. It demonstrated that more hydroxyls were produced on the surface of catalysts under steam treatment. Subsequently, hydroxyl groups were mostly removed during the H2 thermal treatment and abundant oxygen defect sites were generated. These defect sites showed an increasing number of acidic sites, thus exhibiting a relatively high PDH activity. This strategy of introducing hydroxyl groups to construct oxygen defect sites is also applicable to other oxide materials, which offers a novel perspective for rational catalyst design.

Tuning the structure characteristic of the flexible covalent organic framework (COF) meets a high performance for lithium-sulfur batteries

Rigid-based covalent organic frameworks (COFs) are always employed as sulfur-redox/confined host for adapting its varied states upon cycling of highly effective Li-S batteries. Restricted by the unalterable structure frameworks of rigid COFs, flexible COFs are considered to reserve greater capability in coping with active sulfur to meet higher energy demands, while no flexible COF host has been employed currently. In this work, flexible-based COFs with triazine-ring organic macromolecule blocks (COF-TPT(OH) and COF-TPT) are designed and developed as the host materials of Li-S batteries. The structural diversity of flexible-based COF could provoke the phenomenon of capacity increase, which endows the COF-TPT(OH)@S electrode with a high reversible capacity of 1100 mAh g-1 after 80 cycles at 0.1 C. Even after 1000 cycles at 0.5 C, it can still deliver 732 mAh g−1 with a low decay rate of 0.045 % per cycle. Moreover, the introduction of hydroxyl groups (-OH) equips COF-TPT(OH) with the characteristics of both rigid- and flexible- COFs, contributing to the enhanced abilities of the polysulfides conversion and limitation. Our findings will provide a new idea for the selection of host materials for Li-S batteries.

Nature-inspired construction of poly (vinylidene fluoride) membranes through the coordination coating of tannic acid with copper ions for oil-in-water emulsions separation

Construction of the separation membranes with underwater super-oleophobic property proposes a promising pathway in the field of oily wastewater treatment, but it is still plagued with the bottlenecks of the time-consuming preparation and the unsatisfied stability of resultant membranes. Herein, the alkali induced hydroxylation and the nature-inspired construction through the coordination coating of copper ions with tannic acid (Cu2+/TA) were performed on the poly (vinylidene fluoride) (PVDF) membrane substrate prepared by the thermally induced phase separation (TIPS). The introduced hydroxyl groups resulted from the membrane hydroxylation is beneficial for the subsequent construction of the Cu2+/TA coordination coating layer. The excellent hydrophilicity and the specifically hierarchical roughness of the immobilized coating layer endow the modified membranes with the hydrophilic/underwater super-oleophobic property. The optimized membrane correspondingly showed the improved flux of around 2000 L m−2•h−1 accompanied with the oil rejection of above 97.0% in treating two simulated oil-in-water emulsions (toluene and n-hexane). Besides, the flux recovery ratio increased from 72.4% of the pristine membrane to 93.3% of the modified membrane after the BSA fouling and regeneration test, which is also indicative of the improved antifouling behavior as a result of the hydrophilic coordination coating. The membrane stability was further demonstrated by the results of the sandpaper abrasion-resisting test and the long-term (up to 6 months) air-exposure treatment. This work might provide a straightforward strategy for designing advanced membrane for the large-scale applications of oil/water separation.

Bivalent dopamine agonists with co-operative binding and functional activities at dopamine D2 receptors, modulate aggregation and toxicity of alpha synuclein protein

To follow up on our previous report on bivalent compounds exhibiting potent co-operative binding at dopamine D2 receptors, we modified the structure of the linker in our earlier bivalent molecules (S)-6-((9-(((R)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)nonyl)-(propyl)amino)-5,6,7,8-tetrahydronaphthalen-1-ol (Ia) and (S)-6-((10-(((R)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)decyl)(propyl)amino)-5,6,7,8-tetrahydronaphthalen-1-ol (Ib) (Fig. 1) connecting the two pharmaophoric moieties to observe any tolerance in maintaining similar affinities and potencies. Specifically, we introduced aromatic and piperazine moieties in the linker to explore their effect. Overall, similar activities at D2 receptors as observed in our earlier study was maintained in the new molecules e.g. (6S,6′S)-6,6′-((1,4-phenylenebis(ethane-2,1-diyl))bis(propylazanediyl))bis(5,6,7,8-tetrahydronaphthalen-1-ol) (D-382) (Ki, D2 = 3.88 nM). The aromatic moiety in D-382 was next functionalized by introducing hydroxyl groups to mimic polyhydroxy natural products which are known to interact with amyloidogenic proteins. Such a transformation resulted in development of compounds like 2,5-bis(2-(((S)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)ethyl)benzene-1,4-diol (D-666) (Ki, D2 = 7.62 nM) which retained similar affinity and potency at D2 receptors. Such dihydroxyl compounds turned out to be potent inhibitors against aggregation and toxicity of recombinant alpha synuclein protein. The work reported here is in line with our overall goal to develop multifunctional dopamine agonist for symptomatic and disease modifying treatment of Parkinson’s disease.

Crystal Structure and Biochemical Analysis of a Cytochrome P450 Steroid Hydroxylase (BaCYP106A6) from Bacillus Species.

Cytochrome P450 (CYP) is a heme-containing enzyme that catalyzes hydroxylation reactions with various substrate molecules. Steroid hydroxylases are particularly useful for effectively introducing hydroxyl groups into a wide range of steroids in the pharmaceutical industry. This study reports a newly identified CYP steroid hydroxylase (BaCYP106A6) from the bacterium Bacillus sp. and characterizes it using an in vitro enzyme assay and structural investigation. Bioconversion assays indicated that BaCYP106A1 catalyzes the hydroxylation of progesterone and androstenedione, whereas no or low conversion was observed with 11β-hydroxysteroids such as cortisol, corticosterone, dexamethasone, and prednisolone. In addition, the crystal structure of BaCYP106A6 was determined at a resolution of 2.8 Å to investigate the configuration of the substrate-binding site and understand substrate preference. This structural characterization and comparison with other bacterial steroid hydroxylase CYPs allowed us to identify a unique Arg295 residue that may serve as the key residue for substrate specificity and regioselectivity in BaCYP106A6. This observation provides valuable background for further protein engineering to design commercially useful CYP steroid hydroxylases with different substrate specificities.

Chalcone derivatives as xanthine oxidase inhibitors: synthesis, binding mode investigation, biological evaluation, and ADMET prediction

Xanthine oxidase (XO) is a crucial target for the treatment of hyperuricemia and gout. A series of derivatives based on natural 3,4-dihydroxychalcone, obtained from Carthamus tinctorious and Licorice, were designed and synthesized. Nine derivatives (9a-e, 10b,c, and 15a,b) exhibited apparent XO inhibitory activity in vitro (IC50 values varied from 0.121 to 7.086 μM), 15b presented the most potent inhibitory activity (IC50 = 0.121 µM), which was 27.47-fold higher than that of allopurinol (IC50 = 3.324 µM). The SAR analysis indicated that introducing hydroxyl groups at 3′/4′/5′-position on ring A was more beneficial to the inhibition of XO than at 2′/6′-position; the removal of 3‑hydroxyl group on ring B could weaken the inhibitory potency of hydroxychalcones on XO, but it was beneficial to the XO inhibitory potency of methoxychalcones. Molecule modeling studies afforded insights into the binding mode of 15b with XO and supported the findings of SAR analysis. Additionally, kinetics studies demonstrated that 15b presented a reversible and competitive XO inhibitor, which spontaneously combined with XO through hydrophobic force, and finally changed the secondary conformation of XO. Furthermore, the acute hyperuricemia model was employed to investigate the hypouricemic effect of 15b, which could effectively reduce the serum uric acid levels of rats at an oral dose of 10 mg/kg. ADMET prediction suggested that compound 15b possessed good pharmacokinetic properties. Briefly, compound 15b emerges as an interesting XO inhibitor for the treatment of hyperuricemia and gout with beneficial effects on serum uric acid levels regulating. Meanwhile, the XO inhibitors with chalcone skeleton will deserve further attention and discussion.

Effect of the number of hydroxyl groups of CO2-triggered surfactants on capability and performance in CO2-stimulated response

This paper reports the synthesis and characterization of three CO2-triggered surfactants (S-0, S-2, S-4) containing different number of hydroxyl groups. The impact of the hydroxyl groups on S-0, S-2, and S-4 was investigated by observing the morphological appearance, conductivity, and pH after CO2 bubbling. The surface tension of the three CO2-triggered surfactants decreased from S-0 to S-2 then to S-4, meaning surface tension decreasing with increasing the number of hydroxyl groups. The interfacial tension results showed that surfactants with more hydroxyl groups can better reduce the interfacial tension at a given pH. The pKa and micromorphology results revealed different degree of protonation of the CO2-triggered surfactants by CO2 in water, causing variations in their aggregation patterns. Molecular simulations revealed that increasing the number of hydroxyl groups increases the thickness of the hydration layer. And S-4 with a thicker hydration layer will more likely form a complex network structure than S-0 and S-2 with a thinner hydration layer. The new surfactants utilize a simple and mild approach to synthesis; solving problems such as insolubility and phase separation through the introduction of hydroxyl groups. The study serves as a guide to the application of CO2-trigger surfactant solutions.

Structure-activity relationships of oxime compounds as flotation collectors by DFT calculations

The relationships between the structure of oxime compounds (R1R2C=NOH, R1/R2=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory (DFT) calculations illustrated that the introduced phenyl group at the R1 position could enhance the acidity, while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile, the introduced amino group at the R2 position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.