Hydroxyl Groups Of Glycerol Research Articles

Improved glyceraldehyde generation through FeOOH co-catalysts-modified BiVO4 featuring Bi-O-Fe active sites for photoelectrocatalytic glycerol oxidation

Heterojunction engineering is crucial for converting glycerol into valuable organic compounds via photoelectrochemistry, but controlling the structure precisely to enhance conversion efficiency remains challenging. In this study, we effectively created a compound photoanode with unique active regions by growing amorphous FeOOH co-catalysts on BiVO4. The results revealed that the Fe2+ ions located on the surface of the co-catalyst FeOOH facilitate the glycerol transformation process, whereas the electron-rich Bi-O-Fe sites contribute significantly to the preferential transformation of glycerol into glyceraldehyde. These sites not only serve as primary reactive centers, catalyzing the adsorption and conversion of glycerol hydroxyl clusters, but also act as repositories for trapping holes. This dual function accelerates the breaking of CH bonds to generate glycerol aldehyde and exhibits excellent desorption capacity, ensuring exceptional product selectivity. This led to exceptional glyceraldehyde production (709mmol m-2 h−1) compared to pristine BiVO4, showcasing a 14.98-fold increase.

Solar-driven highly selective conversion of glycerol to dihydroxyacetone using surface atom engineered BiVO4 photoanodes

Dihydroxyacetone is the most desired product in glycerol oxidation reaction because of its highest added value and large market demand among all possible oxidation products. However, selectively oxidative secondary hydroxyl groups of glycerol for highly efficient dihydroxyacetone production still poses a challenge. In this study, we engineer the surface of BiVO4 by introducing bismuth-rich domains and oxygen vacancies (Bi-rich BiVO4-x) to systematically modulate the surface adsorption of secondary hydroxyl groups and enhance photo-induced charge separation for photoelectrochemical glycerol oxidation into dihydroxyacetone conversion. As a result, the Bi-rich BiVO4-x increases the glycerol oxidation photocurrent density of BiVO4 from 1.42 to 4.26 mA cm−2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G illumination, as well as the dihydroxyacetone selectivity from 54.0% to 80.3%, finally achieving a dihydroxyacetone production rate of 361.9 mmol m−2 h−1 that outperforms all reported values. The surface atom customization opens a way to regulate the solar-driven organic transformation pathway toward a carbon chain-balanced product.

Environmental Stability Stretchable Organic Hydrogel Humidity Sensor for Respiratory Monitoring with Ultrahigh Sensitivity

AbstractReal‐time monitoring of respiration plays a very important role in human health assessment, especially in monitoring and analyzing respiration during exercise and sleep. However, traditional humidity sensors still have problems in flexibility, sensitivity, and durability, so there is an urgent need to develop humidity sensors with high sensitivity, stretchability, and environmental resistance as respiratory monitoring applications. Here, based on the double network hydrogel structure of polyvinyl alcohol and polyacrylamide, a highly sensitive, highly stretchable, and environmentally stable organic hydrogel humidity sensor has been manufactured by using the synergistic effect of lithium chloride and MXene. The hydrogel humidity sensor shows rapid response in the humidity range of 40–85% RH, and has a high sensitivity of −103.4%/% RH. In addition, it exhibits more than 3000% mechanical strain and excellent environmental resistance, which is attributed to the chemical cross‐linking in the hydrogel network and the synergistic effect of multiple hydroxyl groups in glycerol forming rich hydrogen bonds with water and polymer chains. The hydrogel humidity sensor is used for real‐time monitoring of breathing and sleep processes. This work provides a new strategy for preparing high‐performance, extensibility, and environmental stability hydrogel‐based sensors for respiratory monitoring.

Hydrogen Bond-Mediated Strong Plasticization for High-Performance Alginate Plastics.

The increasingly severe plastic pollution has urged an inevitable trend to develop biodegradable plastic products that can take over synthetic plastics. As one of the most abundant natural polymers, polysaccharides are an ideal candidate to substitute synthetic plastics. The rigidity of polysaccharide chains principally allows for high strength and stiffness of their materials, however, challenges the facile orientation in material processing. Here, a general hydrogen bond-mediated plasticization strategy to regulate isotropic sodium alginate (SA) chains to a highly ordered state is developed, and alginate plastics with high performances are fabricated. It is revealed that hydroxyl groups in glycerol modulate the viscoelasticity of SA solids by forming strong hydrogen bonds with SA chains, achieving a large stretchability at a high solid content. Highly orientated alginate films exhibit a superior tensile strength of 575MPa and toughness of 60.7MJ m-3, outperforming most regenerated biomass films. The high solid content and large stretchability mediated by strong hydrogen bonding ensure plastic molding of solid-like SA with high fidelity. This hydrogen bond-mediated plasticity provides a facile but effective method to justify the high performances of polysaccharide-based plastics.

Construction of a permeable metal-support interface for glycerol oxidation by the topological transformation of 2D precursor

Aiming at achieving a trade-off of electronic-interacted and permeable metal-support interfaces, we developed a feasible approach for constructing semi-continuous TiOx/Pt structure through the topological transformation of ultrathin PtCl62−/TiMgAl-layered double hydroxides (LDHs) to limit the migration degree of metal ions perpendicular to the lamellar direction. Structural characterization revealed that most Pt sites are permeable to the reactants in the ultrathin TiOx/Pt/TiMgAlOx-U catalyst. Despite that, there is still electron transfer to form abundant Pt0-oxygen vacancy(Vo)-Ti3+sites in the interfacial structure. In the glycerol oxidation reaction, the TiOx/Pt/TiMgAlOx-U exhibited a much higher reaction rate(289 molglycrol·molPt−1·h−1), which is 1.7 times of the bulk TiOx/Pt/TiMgAlOx-B and 5.2 times of the TiOx/Pt/TiO2 reference, and simultaneously maintained a decent glyceric acid selectivity. Mechanism study revealed that the Pt0-Vo-Ti3+interfacial structure could promote the activation and fluxion of active oxygen species, and was favorable for the activation of primary hydroxyl groups of glycerol and the aldehyde intermediate.

Mesoporous silicon-carbon composites: Novel supports of platinum nanoparticles for highly efficient selective oxidation of glycerol

Selective oxidation of glycerol is an extremely challenging reaction because of that three hydroxyl groups in glycerol are prone to randomly oxidize, resulting in unsatisfactory selectivity. In this work, silicon-carbon composites (Si-C-n) were designed and prepared as novel supports for nano Pt catalyst to boost the activity and selectivity in oxidation of glycerol to glyceric acid (GLYA). By the tannic acid/silicic acid self-assembly and carbonization process, mesoporous Si-C-n microspheres with high surface area. After the Pt loading, the as-prepared catalysts Pt/Si-C-3 exhibited significantly enhanced glycerol conversion (74.4%) and exceptional GLYA selectivity (86.7%). It also showed excellent stability, experiencing no obvious performance loss after six cycles. Characterizations and theoretical calculations verify that the introduction of Si species in the carbon framework provides preferred weak acid sites in Pt/Si-C-n, which could promote the desorption of product GLYA, enhance the electronic interaction between Pt and the support, and reduce the activation energy of rate-determining step, thus contributing to a high activity and selectivity to GLYA.

Unveiling the role of hydroxyl groups in glycerol as a critical descriptor for efficient electrocatalytic reforming of biomass molecules using PtCu alloy nanoparticle catalysts

Glycerol, one of the main byproducts of biodiesel production, has recently attracted attention since it can co-generate electricity and valuable chemicals via electrochemical glycerol oxidation reaction (EGOR). Due to the complexity of EGOR, there have been many arguments about its pathways to find the environmental conditions for producing targeted chemicals. The studies to find the representative descriptor that affects EGOR were performed, using a combination of ab-initio computational and experimental approaches. A novel porous carbon (PC) was employed as an effective support material to synthesize PtCu/PC catalysts, and then various electrochemical analyses were carried out. The adsorption energies of hydroxide and the binding strength of the hydroxyl groups in the glycerol on the catalysts were compared using a crystal orbital Hamilton population (COHP) analysis. Consequently, we found the tendency in the binding strength of hydroxyl group as a critical descriptor, rationalizing why the PtCu3/PC catalyst revealed the highest mass activity for EGOR.

Selective Valorization of Glycerol to Formic Acid on a BiVO4 Photoanode through NiFe Phenolic Networks.

The integration of the glycerol oxidation reaction (GOR) with the hydrogen evolution reaction in photoelectrochemical (PEC) cells is a desirable alternative to PEC water splitting since a large quantity of glycerol is easily accessible as the byproduct from the biodiesel industry. However, the PEC valorization of glycerol to the value-added products suffers from low Faradaic efficiency and selectivity, especially in acidic conditions, which is beneficial for hydrogen production. Herein, by loading bismuth vanadate (BVO) with a robust catalyst composed of phenolic ligands (tannic acid) coordinated with Ni and Fe ions (TANF), we demonstrate a modified BVO/TANF photoanode for the GOR with a remarkable Faradaic efficiency of over 94% to value-added molecules in a 0.1 M Na2SO4/H2SO4 (pH = 2) electrolyte. The BVO/TANF photoanode achieved a high photocurrent of 5.26 mA·cm-2 at 1.23 V versus reversible hydrogen electrode under 100 mW/cm2 white light irradiation for formic acid production with 85% selectivity, equivalent to 573 mmol/(m2·h). Transient photocurrent and transient photovoltage techniques and electrochemical impedance spectroscopy along with intensity-modulated photocurrent spectroscopy indicated that the TANF catalyst could accelerate hole transfer kinetics and suppress charge recombination. Comprehensive mechanistic investigations reveal that the GOR is initiated by the photogenerated holes of BVO, while the high selectivity to formic acid is attributed to the selective adsorption of primary hydroxyl groups in glycerol on TANF. This study provides a promising avenue for highly efficient and selective formic acid generation from biomass in acid media via PEC cells.

Insight into the selective oxidation mechanism of glycerol to 1,3‐dihydroxyacetoneoverAuCu–ZnOinterface

AbstractDirectional regulation of polyol oxidation selectivity by constructing active sites with specific structure is a critical yet challenging problem. Herein, the specific Au‐based catalyst with efficient Au–Cu–ZnO interfacial active sites was successfully designed to promote selective oxidation of glycerol to 1,3‐dihydroxyacetone under mild conditions. X‐ray absorption spectroscopy revealed that the increased electron transfer between Au and Cu increases the content of Au+, resulting in the higher catalytic activity (turnover frequency: 402.5 h−1). Meanwhile, small AuCu alloy nanoparticles (ca., 2.7 nm) could be inserted into the ZnO lattice with the formation of Au(Cu)–O–Zn linkages, resulting in the enrichment of interfacial oxygen vacancies. These interfacial oxygen vacancies induce the activation and adsorption of the secondary hydroxyl group of glycerol on the interfacial active sites, improving the selectivity of 1,3‐dihydroxyacetone (83.4%). Furthermore,in situFourier transform infrared, structure‐dependent kinetics and density functional theory calculation demonstrated that Au–Cu–ZnO interfacial active sites could enhance the participation of OH* and oxygen vacancies in activating the OH and CH bonds, respectively, promoting the improvement of the catalytic performance. The outcome of this work offers new insights for the rational design of high effective catalyst for the selective oxidation of polyol.

Indirect Substitution Constructing Halogen-Vacancy BiOCl1–xIn Solid Solution with a Suitable Surface Structure for Enhanced Photoredox Performance

Photocatalytic technology has made a series of breakthroughs in environmental remediation, but the degradation performance of persistent heavy metal ions and organic pollutants is not particularly excellent. In addition, the layered structure of bismuth oxyhalides (BiOX, X = I, Br, and Cl) has been a popular material for photodegradation and photoelectrochemistry. Accordingly, with a view to construct a suitable band structure and control the surface structure, it is necessary to develop a strategy to synthesize a BiOCl1-xIn solid solution with halogen vacancies. In this study, halogen vacancies are in situ introduced into the BiOCl1-xIn solid solution through constructing chemical bonds between the hydroxyl groups in glycerol and the I ions during the growth process. The band of the halogen-vacancy BiOCl1-xIn solid solution is widened and active sites centered at halogen vacancies are formed in the direction favorable for the photocatalytic reaction, resulting in enhanced performance in the reduction of Cr(VI) and the oxidation of phenol. The results obtained can provide a new idea for the design of efficient photocatalysts by controlling the formation of halogen vacancies.

DEVELOPMENT OF A BIODEGRADABLE COMPOSITE FILM FROM CHITOSAN, AGAR AND GLYCEROL BASED ON OPTIMIZATION PROCESS BY RESPONSE SURFACE METHODOLOGY

The aim of the study has been to develop a biodegradable film from marine polysaccharides. The optimization of polysaccharides quantity for the composite film was sought by empirical response surface methodology. The Box–Behnken Model Design was applied to optimize the concentration of chitosan (1.0-2.0% (w/v), agar (1.0-2.0% (w/v) and glycerol (0.1-0.5% (w/v) as independent variables to achieve the goal. The overall desirability function fits with the quadratic model (0.862043) at a significant level (p < 0.05) for the optimum concentration of chitosan (1.5% (w/v), agar (2.0% (w/v) and glycerol (0.41% (w/v) to obtain the minimum water vapor permeability (7.25 10-10g m m-2 Pa-1 s-1) and maximum tensile strength (12.21 Ma P), elongation at break (7.32%) and puncture resistance (16.18 N) in the optimized composite film. The absolute residual errors of experimental and predicted responses were between 1.24 and 3.56% acceptable levels. Attenuated total reflection–Fourier transform infrared spectroscopy confirmed the intermolecular non-covalent hydrogen bond between the hydroxyl groups of agar and glycerol with the amino group of chitosan. 3D atomic force microscopy images revealed that the chitosan, agar and glycerol film has layer-by-layer smooth surface properties due to homogenous interaction among the polysaccharides; this provides the film with good mechanical properties and with functional application. Chitosan was found to be responsible for the lower level of water vapor permeability and higher puncture resistance of the film. Tensile strength and elongation at break were influenced by agar and glycerol. The whiteness of the film was negatively affected with the concentration of chitosan.

Effects of nanocellulose fiber and thymol on mechanical, thermal, and barrier properties of corn starch films

This study explores the preparation of corn starch (CS) films incorporated with nanocellulose fiber (NCF) and different concentrations of thymol (0.1, 0.3, and 0.5% weight of thymol/volume of solution (% w/v)) via the solvent casting method. The resulting films were characterized by the functional chemistry, crystallinity, morphology, mechanical, thermal, and barrier properties. The Fourier transform infrared spectroscopy analysis confirmed the presence of intermolecular hydrogen bonding between the thymol and starch, as well as the thymol and glycerol, via hydroxyl groups of glycerol, starch, and thymol. The film crystallinity decreased with increasing concentration of thymol. The addition of NCF at 1.5% weight of starch increased the tensile strength (TS) and Young's Modulus (YM), but decreased the elongation at break (EAB), oxygen permeability, and water vapor permeability of the CS films. The thermal stability of the CS films was also improved with the addition of NCF. The addition of thymol to the CS/NCF bio-nanocomposite films decreased the TS and YM, respectively but increased the EAB due to the plasticizing effect of thymol. The addition of thymol also improved the thermal stability but reduced the barrier properties of the films. The effects on the mechanical, thermal, and barrier properties were more pronounced at higher concentrations of thymol. In conclusion, the inclusion of both NCF and thymol led to the improvement of the flexibility and thermal stability of the CS films.

Insights into the synergetic mechanism of basic active site and oxygen vacancy on thermally activated MOFs for the colophony esterification: Experiments and DFT calculations

Investigating an feasible catalytic mechanism on Zn-MOF and its derivative amphoteric oxides is of great importance for esterification. Herein, activated Fe3O4-functionalized IRMOF-1 that was well retained the porosity was fabricated by encapsulating magnetic Fe3O4 in IRMOF-1 and activating thermally at 298−1273 K, which was evaluated for the esterification of colophony with glycerol. Results demonstrate that the catalytic performance of catalysts could be effectively enhance by thermal activation due to the additional basic sites and oxygen vacancies created. FT-IR and several thermal analyses reveal the unique adsorption of glycerol instead of the traditional carboxylic acids. Density functional theory (DFT) calculations suggest that the basic sites of catalysts are the crucial active sites for the glycerol hydroxyl dissociation and the formation of nucleophilic glyceroxide, and the presence of oxygen vacancy could significantly destabilize the surface proton and glyceroxide anions. A synergetic esterification mechanism of basic active site and oxygen vacancy was proposed.

Biobased Hyperbranched Poly(ester)s of Precise Structure for the Release of Therapeutics

Hyperbrached poly(ester)s derived from naturally-occurring biomonomers may serve as excellent platforms for the sustained-release of therapeutics. Those generated from glycerol are particularly attractive. Traditionally, the difference in reactivity of the hydroxyl groups of glycerol has precluded the formation of well-defined polymers at high monomer conversion without gelation. Using the Martin-Smith model to select appropriate monomer ratios (ratios of functional groups), polymerization may be carried out to high conversion while avoiding gelation and with the assurance of a single type of endgroup. Various agents may be attached via esterification, amide formation or other process. Sustained release of the active agent may be readily achieved by enzyme-catalyzed hydrolysis.

Combined theoretical and experimental studies on CO2 capture by amine-activated glycerol

Although CO2 capture by alkanolamine aqueous solutions is a well-established technology, it demands high energy penalties and water consumption. Therefore, the development of new methods for CO2 removal is still a challenge. Herein, we employed the Density Functional Theory (DFT) to explore the potential of different mixtures composed of glycerol and nitrogen-containing bases to capture CO2. By combining glycerol, CO2 and the bases, it was possible to show that aliphatic amines are able to form intermolecular hydrogen bonds with the primary hydroxyl groups of glycerol, increasing their nucleophilicity and assisting the reaction with CO2 to form glycerol carbonate as the most stable product. To confirm that glycerol carbonate would be experimentally obtained from the given mixture, we selected triethylamine (TEA) to assist glycerol (Gly) in its reaction with CO2. The resulting product was characterized by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), 1D and 2D Nuclear Magnetic Resonance spectroscopy (1H and 13C NMR) and Thermogravimetric Analysis (TGA). The ATR-FTIR results showed that TEA is protonated after bubbling CO2 in the glycerol/TEA mixture, suggesting that the reaction with CO2 occurs after deprotonation of glycerol, forming organic carbonates, as also indicated in the NMR spectra. The combined theoretical and experimental results indicate that TEA is able to activate glycerol in its reaction with CO2 to form organic carbonates, being an alternative procedure for CO2 capture.

Chemical Exchange of Hydroxyl Groups in Lipidic Cubic Phases Characterized by NMR.

Proton transportation in proximity to the lipid bilayer membrane surface, where chemical exchange represents a primary pathway, is of significant interest in many applications including cellular energy turnover underlying ATP synthesis, transmembrane mobility, and transport. Lipidic inverse bicontinuous cubic phases (LCPs) are unique membrane structures formed via the spontaneous self-assembly of certain lipids in an aqueous environment. They feature two networks of water channels, separated by a single lipid bilayer which approximates the geometry of a triply periodic minimal surface. When composed of monoolein, the LCP bilayer features two glycerol hydroxyl groups at the lipid-water interface which undergo exchange with water. Depending on the conditions of the aqueous solution used in the formation of LCPs, both resonances of the glycerol hydroxyl groups may be observed by solution 1H NMR. In this study, PFG-NMR and 1D EXSY were employed to gain insight into chemical exchange between the monoolein hydroxyl groups and water in LCPs. Results including the relative population of hydroxyl protons in exchange with water for a number of LCPs at different hydration levels and the exchange rate constants at 35 wt % hydration are reported. Several technical aspects of PFG-NMR and EXSY-NMR for the characterization of chemical exchange in LCPs are discussed, including an alternative way to analyze PFG-NMR data of exchange systems which overcomes the inherent low sensitivity at high diffusion encoding.

Sulphuric acid-functionalized siliceous zirconia as an efficient and reusable catalyst for the synthesis of glycerol triacetate

In the present study, a sulphated siliceous zirconia catalyst (SSZ-550) has been prepared and characterized by XRD and FTIR analysis to indicate the incorporation of sulphate group over the matrix. X-ray photoelectron spectroscopy also revealed that sulphur group was incorporated over the matrix to impart the Bronsted acidity to the catalyst which is vital for the acetylation activity. To optimize the reaction parameters, viz. reagent molar ratios (3–12; glycerol/acetic acid), catalyst amount (1–5 wt%; catalyst/glycerol), reaction duration (20–50 min) and reaction temperature (30–100 °C) have been varied to obtain the optimum catalyst activity for the maximum glycerol triacetate yield. Finally, under the optimized reaction parameters of 9:1 glycerol/acetic acid molar ratio, 3 wt% catalyst, 80 °C reaction temperature and 40 min of reaction duration, a 93% glycerol triacetate yield was obtained. The catalyst was recovered from the reaction mixture and reused during six consecutive reaction runs while retaining 50% glycerol triacetate selectivity in the last cycle. A plausible mechanism suggests the heterogeneous catalyst-assisted protonation of carbonyl group of acetic acid to initiate the stepwise esterification of the hydroxyl groups of glycerol.

Pine Resin Derivatives as Sustainable Additives to Improve the Mechanical and Thermal Properties of Injected Moulded Thermoplastic Starch

Fully bio-based materials based on thermoplastic starch (TPS) were developed starting from corn starch plasticized with glycerol. The obtained TPS was further blended with five pine resin derivatives: gum rosin (GR), disproportionated gum rosin (dehydroabietic acid, RD), maleic anhydride modified gum rosin (CM), pentaerythritol ester of gum rosin (LF), and glycerol ester of gum rosin (UG). The TPS–resin blend formulations were processed by melt extrusion and further by injection moulding to simulate the industrial conditions. The obtained materials were characterized in terms of mechanical, thermal and structural properties. The results showed that all gum rosin-based additives were able to improve the thermal stability of TPS, increasing the degradation onset temperature. The carbonyl groups of gum rosin derivatives were able to interact with the hydroxyl groups of starch and glycerol by means of hydrogen bond interactions producing a significant increase of the glass transition temperature with a consequent stiffening effect, which in turn improve the overall mechanical performance of the TPS-resin injected moulded blends. The developed TPS–resin blends are of interest for rigid packaging applications.

Glycerol's generalized two-dimensional correlation IR/NIR spectroscopy and its principal component analysis.

In this manuscript, the fundamental vibration, the combination vibration and the first overtone vibration of the glycerol hydroxyl were studied by near-infrared and infrared spectroscopy. The composition and variation of hydrogen bond were analyzed by two-dimensional correlation spectroscopy and principal component analysis. The analysis revealed five types of hydroxyl and verified the existence of independent, intramolecular, as well as intermolecular, hydrogen bond hydroxyl. The principal component analysis showed that there were three main forms of glycerol association: the first and second principal components explained the majority of the spectral features, and the third was mainly the independent hydroxyl. The results provided insight into the structure of glycerol and illustrated the potential for using these tools in analyzing bonding in even more complex systems.

Synthesis and performance evaluation of silica-supported copper chromite catalyst for glycerol dehydration to acetol

Sol-gel technique was used to prepare silica-supported copper chromite catalyst from acid hydrolysis of sodium silicate. The catalyst was characterized by BET surface area, FESEM, XRD, H2-TPR and pyridine adsorption by FTIR. The catalyst was activated in a hydrogen atmosphere based on H2-TPR result. The surface acidity of the catalyst was evaluated by NH3-TPD and pyridine adsorption. XRD result of reduced catalyst showed the presence of Cu0, Cu1+ and Cr2O3 in the catalyst. Glycerol dehydration was carried out at different temperature (180 °C to 240 °C) from aqueous glycerol solution with the reduced catalyst in a batch reactor. The glycerol conversion was reached 100% with maximum acetol selectivity of 70% for highest Copper chromite loaded (40 wt%) on silica at 220 °C in atmospheric pressure. The distilled liquid product was analyzed by high-performance liquid chromatography. Oxidized catalyst and spent catalyst showed lower glycerol conversion with low acetol selectivity than the reduced form of the catalyst. This is due to the cuprous ion in the reduced form of the catalyst, which acts as Lewis acid sites in glycerol dehydration. Glycerol dehydration to acetol with reduced form of silica-supported copper chromite catalyst is reported. The reduced form of copper chromite (cuprous oxide) on silica surface acts as a lewis acid in glycerol dehydration. Cuprous oxide coordinates with terminal hydroxyl group of glycerol and forms low energy six-membered transition state in the dehydration reactions.