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1.
J Chromatogr A ; 1722: 464890, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38598892

RESUMO

The rapidly growing market of monoclonal antibodies (mAbs) within the biopharmaceutical industry has incentivised numerous works on the design of more efficient production processes. Protein A affinity chromatography is regarded as one of the best processes for the capture of mAbs. Although the screening of Protein A resins has been previously examined, process flexibility has not been considered to date. Examining performance alongside flexibility is crucial for the design of processes that can handle disturbances arising from the feed stream. In this work, we present a model-based approach for the identification of design spaces, enhanced by machine learning. We demonstrate its capabilities on the design of a Protein A chromatography unit, screening five industrially relevant resins. The computational results favourably compare to experimental data and a resin performance comparison is presented. An improvement on the computational time by a factor of 300,000 is achieved using the machine learning aided methodology. This allowed for the identification of 5,120 different design spaces in only 19 h.


Assuntos
Anticorpos Monoclonais , Cromatografia de Afinidade , Desenho Assistido por Computador , Aprendizado de Máquina , Proteína Estafilocócica A , Cromatografia de Afinidade/métodos , Anticorpos Monoclonais/química , Proteína Estafilocócica A/química
2.
ChemSusChem ; : e202301730, 2024 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-38523408

RESUMO

Artificial ammonia synthesis via the Haber-Bosch process is environmentally problematic due to the high energy consumption and corresponding CO2 emissions, produced during the reaction and before hand in hydrogen production upon methane steam reforming. Photocatalytic nitrogen fixation as a greener alternative to the conventional Haber-Bosch process enables us to perform nitrogen reduction reaction (NRR) under mild conditions, harnessing light as the energy source. Herein, we systematically review first-principles calculations used to determine the electronic/optical properties of photocatalysts, N2 adsorption and to expound possible NRR mechanisms. The most commonly studied photocatalysts for nitrogen fixation are usually modified with dopants, defects, co-catalysts and Z-scheme heterojunctions to prevent charge carrier recombination, improve charge separation efficiency and adjust a band gap to for utilizing a broader light spectrum. Most studies at the atomistic level of modeling are grounded upon DFT calculations, wholly foregoing excitation effects paramount in photocatalysis. Hence, there is a dire need to consider methods beyond DFT to study the excited state properties more accurately. Furthermore, a few studies have been examined, which include higher level kinetics and macroscale simulations. Ultimately, we show there is still ample room for improvement with regard to first principles calculations and their integration in multiscale models.

3.
ACS Omega ; 9(6): 6027-6035, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38371759

RESUMO

The development of efficient, chemical hydrogen-storage materials is one of the greatest technical challenges for the coming hydrogen-based economy. Analyzed liquid organic hydrogen carriers (LOHCs), which bond, store, and release the H2 molecules through catalytic hydrogenation, cracking, and dehydrogenation cycles, are being considered as an alternative, functional option. The search for a highly industrialized reactive production process, coupled with the use of renewable electrical energy, has encouraged the consideration of characteristic stand-alone methods (such as microwave-assisted surface reactions, an increase in the rates by magnetic heating systems, electrocatalysis, variable photochemical manufacturing, and plasma). This mini review aims to highlight, assess, and critically evaluate these recent advances in the electrification of LOHC-related plant technologies. Besides base storing vectors, such as methanol, formaldehyde, and formic acid derivatives, reversible cycling compounds, i.e., benzene, toluene, polycyclic dibenzyl toluene (DBT), carbazole, and indole, are given an overview. These all compete with, for example, ammonia. Specific design methodologies, such as density functional theory (DFT), kinetics, mass-transfer phenomena, etc., are discussed, whether these were studied or the subject of modeling. Lastly, quantitative structure-performance relationships are correlated for activity, selectivity, and stability, where the latter was possible.

4.
Chimia (Aarau) ; 77(12): 816-826, 2023 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-38131404

RESUMO

The article discusses the production of platform chemicals from various biological sources, including glycerol, lignin, cellulose, bio-oils, and sea products. It presents the results of catalytic and downstream processes involved in the conversion of these biomass-derived feedstocks. The experimental approaches are complemented by numerical descriptions, ranging from density functional theory (DFT) calculations to kinetic modellingof the experimental data. This multi-scale modelling approach helps to understand the underlying mechanisms and optimize the production of platform chemicals from renewable resources.

5.
J Biomater Sci Polym Ed ; 34(18): 2537-2550, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37768315

RESUMO

To conquer the low water solubility and bioavailability of curcumin (CUR), to corroborate its functional qualities and to broaden its applicability in the pharmaceutical sector, numerous nanoscale methods have been widely exploited for its administration. Because of its polycystic, biodegradable, biocompatibility, non-toxicity, and non-allergenic properties, bovine serum albumin (BSA) and glycine (Gly) have been actively investigated as natural biopolymers for decades. Various BSA and Gly-based nanocarriers with unique features for CUR delivery, such as magnetic ferrite nanoparticles, are being developed (MNPs). In this work, magnesium ferrite (MgFe2O4)/BSA and nickel ferrite (NiFe2O4)/Gly nanocomposites loaded with CUR (drug model) were manufactured for the first time using a chemical co-precipitation approach to create biocompatible drug nanocarriers. It was found that the synthesized MgFe2O4/BSA and NiFe2O4/Gly nanoparticles have a uniform particle distribution and their size is much less than 100 nm. Saturation magnetization in MgFe2O4 and NiFe2O4 reaches 13.07 and 33.4 emu/g the remarkable peak of magnetization decreases to 10.99 and 32.36 emu/g after the addition of polymers. These analyses also showed the presence of chemical bonds in the structure of the nanocomposite. The curcumin diffusion process in NPs were determined using a mathematical modeling. The yielding of the product for MgFe2O4/BSA and NiFe2O4/Gly in 200 h is about 72 and 63%, respectively. Also, regressed relative diffusivities (D/R2), including effective steric hindrance, were determined as 5.75 × 10-4 and 2.72 × 10-4 h-1 for MgFe2O4/BSA and NiFe2O4/Gly, respectively. It shows that there is a significant steric barrier that significantly deviates from the molecular diffusion of the liquid. As a result, the low effective release of curcumin in the particles is more noticeable. Our study demonstrated the effective relationship between the polymer architecture and the biophysical properties of the resulting nanoparticles and shed light on new approaches for the design of efficient NP-based drug carriers.


Assuntos
Curcumina , Nanopartículas , Curcumina/química , Soroalbumina Bovina/química , Polímeros , Preparações de Ação Retardada , Nanopartículas/química , Portadores de Fármacos/química , Fenômenos Magnéticos , Tamanho da Partícula
6.
Int J Biol Macromol ; 252: 126433, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37604416

RESUMO

Biocomposite films from renewable sources are seen to be viable candidates as sustainable, zero-waste packaging materials. In this study, biocomposites films using chitosan and alginate as matrices, and pristine or acetylated cellulose nanocrystals (CNCs) as reinforcement agents, were fabricated, thoroughly characterized in terms of structure (with ATR-FTIR and XRD), morphology (SEM), thermal stability (TGA coupled with FTIR), water content and solubility and mechanical properties and subjected to controlled biological degradation in aqueous environment with added activated sludge. Biodegradation activity was followed through respirometry by measurement of change in partial O2 pressure using OxiTop® system. While the initial rate of biodegradation is higher in chitosan-based films with incorporated CNCs (both pristine and modified) compared to any other tested biocomposites, it was observed that chitosan-based films are not completely degradable in activated sludge medium, whereas alginate-based films reached complete biodegradation in 107 h to 112 h. Additional study of the aqueous medium with in situ FTIR during biodegradation offered an insight into biodegradation mechanisms. Use of advanced statistical methods indicated that selection of material (ALG vs CH) has the highest influence on biodegradability, followed by solubility of the material and its thermal stability.


Assuntos
Quitosana , Nanopartículas , Celulose/química , Quitosana/química , Alginatos , Esgotos , Água , Nanopartículas/química
7.
Energy Fuels ; 37(11): 7577-7602, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-37283706

RESUMO

Photocatalytic carbon dioxide reduction (PCCR) for methanol synthesis (CH3OH) targeting renewable energy resources is an attractive way to create a sustainable environment and also balance the carbon-neutral series. The application of PCCR to methanol enables the generation of solar energy while reducing CO2, killing two birds with one stone in terms of energy and the environment. In recent years, research on CO2 utilization has focused on hydrogenation of CO2 to methanol due to global warming. This article mainly focuses on selective carbonaceous materials such as graphene, mesoporous carbon, and carbon nanotubes (CNTs) as catalysts for heterogeneous photocatalytic CO2 reduction to methanol. In addition, special emphasis will be placed on the state of the art of PCCR catalysts as this type of research will be of great benefit for further development in this field. The main features of the reaction kinetics, techno-economic study, and current technological developments in PCCR are covered in detail.

8.
Angew Chem Int Ed Engl ; 62(31): e202305804, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37226934

RESUMO

Ethylene epoxidation is industrially and commercially one of the most important selective oxidations. Silver catalysts have been state-of-the-art for decades, their efficiency steadily improving with empirical discoveries of dopants and co-catalysts. Herein, we perform a computational screening of the metals in the periodic table, identify prospective superior catalysts and experimentally demonstrate that Ag/CuPb, Ag/CuCd and Ag/CuTl outperform the pure-Ag catalysts, while they still confer an easily scalable synthesis protocol. Furthermore, we show that to harness the potential of computationally-led discovery of catalysts fully, it is essential to include the relevant in situ conditions e.g., surface oxidation, parasitic side reactions and ethylene epoxide decomposition, as neglecting such effects leads to erroneous predictions. We combine ab initio calculations, scaling relations, and rigorous reactor microkinetic modelling, which goes beyond conventional simplified steady-state or rate-determining modelling on immutable catalyst surfaces. The modelling insights have enabled us to both synthesise novel catalysts and theoretically understand experimental findings, thus, bridging the gap between first-principles simulations and industrial applications. We show that the computational catalyst design can be easily extended to include larger reaction networks and other effects, such as surface oxidations. The feasibility was confirmed by experimental agreement.

9.
Polymers (Basel) ; 15(7)2023 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-37050280

RESUMO

Cellulose nanocrystals (CNCs) were acetylated to the various parametrised degrees of substitution (DS), determined through attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and incorporated into alginate (ALG) and chitosan (CH) film-forming solutions. An investigation of morphology with scanning electron microscopy (SEM) revealed increased chemical compatibility with the CH matrix after acetylation, producing a smooth surface layer, while ALG mixed better with pristine CNCs. The ATR-FTIR analysis of films demonstrated inter-diffusional structural changes upon the integration of pristine/modified CNCs. Films were evaluated in terms of water contact angle (WCA), which decreased upon CNC addition in either of the biocomposite types. The H2O barrier assessed through applicative vapour transmission (WVT) rate increased with the CNC esterification in CH, but was not influenced in ALG. To evaluate the relationship between environmental humidity and mechanical properties, conditioning was applied for 48 h under controlled relative humidity (33%, 54% and 75%) prior to the evaluation of the mechanical properties and moisture content. It was observed that tensile strength was highest upon specimens being dry (25 ± 3 MPa for ALG, reinforced with neat CNCs, or 16 ± 2 MPa in the CH with CNCs, reacting to the highest DS), lowering with dewing, and the elongation at break exhibited the opposite. It is worth noting that the modification of CNCs improved the best base benchmark stress-strain performance. Lastly, (thermal) stability was assessed by means of the thermogravimetric analysis (TGA) technique, suggesting a slight improvement.

10.
Mikrochim Acta ; 190(5): 184, 2023 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-37069457

RESUMO

In recent years, various types of radiosensitizers have been developed to address the challenges of cancer radiotherapy. Here, platinum-functionalized oxygenated single-walled carbon nanotubes (O-SWCNTs-Pt) coated with folic acid (FA) and bovine serum albumin (BSA) (O-SWCNTs-Pt-BSA-FA) were synthesized, characterized, and used as radiosensitizers to improve the therapeutic efficacy of X-rays in a mouse model of breast cancer (4T1) in vitro. The nanosensitizer was characterized by different techniques, such as transmission electron microscopy (TEM), selected area electron diffraction (SAED), dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), ultraviolet-visible (UV-visible), and Fourier transform infrared (FTIR) spectrometry. The evaluation of cell viability with nanocarriers O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, Pt-BSA-FA, and O-SWCNTs-Pt-BSA-FA is reported at the concentrations of 10, 30, and 90 µg/mL by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence and absence of X-rays at 4 and 8 Gy. The results showed that administration of O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, Pt-BSA-FA, and O-SWCNTs-Pt-BSA-FA + 8 Gy at a concentration of 90 µg/mL reduced survival by 75.31, 65.32, 67.35, and 60.35%, respectively. O-SWCNTs-Pt-BSA-FA has a hydrodynamic size of 88.57 nm and a surface charge of -29 mV, which indicates special stability. Compared with O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, and Pt-BSA-FA, it has very strong cell-killing activity in the 4T1 cell line. It is also noteworthy that SWCNTs can act as a controlled release and delivery system for PtNPs due to their unique properties and easy penetration into biological membranes. As a result, the  new nanosensitizer may play a role in cancer treatment in conjunction with radiotherapy technology. Graphical abstract.


Assuntos
Nanopartículas Metálicas , Nanotubos de Carbono , Neoplasias , Animais , Camundongos , Nanotubos de Carbono/química , Platina , Raios X , Linhagem Celular , Soroalbumina Bovina/química , Neoplasias/tratamento farmacológico
11.
ChemSusChem ; 16(14): e202300142, 2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-36972065

RESUMO

Polyethylene terephthalate (PET) is a non-degradable single-use plastic and a major component of plastic waste in landfills. Chemical recycling is one of the most widely adopted methods to transform post-consumer PET into PET's building block chemicals. Non-catalytic depolymerization of PET is very slow and requires high temperatures and/or pressures. Recent advancements in the field of material science and catalysis have delivered several innovative strategies to promote PET depolymerization under mild reaction conditions. Particularly, heterogeneous catalysts assisted depolymerization of post-consumer PET to monomers and other value-added chemicals is the most industrially compatible method. This review includes current progresses on the heterogeneously catalyzed chemical recycling of PET. It describes four key pathways for PET depolymerization including, glycolysis, pyrolysis, alcoholysis, and reductive depolymerization. The catalyst function, active sites and structure-activity correlations are briefly outlined in each section. An outlook for future development is also presented.

12.
Biotechnol Adv ; 61: 108055, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36374851

RESUMO

Biotechnology has revolutionized science and health care by providing new biomolecules with biological and medical applications. However, the low stability of several life-saving bioproducts still hinders their transport, storage, and application. Hence, protein-based bioproducts instability and high costs are the main bottlenecks limiting access to biopharmaceuticals in low-income countries and communities. Aiming to improve the stability of protein-based products, researchers have studied ionic liquids (ILs) as protein stabilizers due to their unique properties and ability to enhance the solubility and stability of a wide range of biomolecules. Although different classes of ILs have the potential to improve protein stability, their effects are dependent on several variables, such as the complex and intrinsic properties of proteins, the nature and concentration of ILs, and environmental conditions (e.g., temperature, pH). For medical applications, the biocompatibility of ILs can also limit their biological use. Therefore, the current state-of-the-art on ILs applications for non-enzymatic protein stabilization was carefully analyzed and discussed, considering protein properties, ILs classes, and IL solutions concentrations. Lastly, a critical perspective regarding ILs applications as protein stabilizers was presented, highlighting the current lacunas in the field while guiding future studies to answer the existing paradigms.


Assuntos
Líquidos Iônicos , Solubilidade , Biotecnologia , Temperatura
13.
ACS Appl Mater Interfaces ; 14(28): 31862-31878, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35801412

RESUMO

Dry reforming of methane (DRM) is a promising way to convert methane and carbon dioxide into H2 and CO (syngas). CeO2 nanorods, nanocubes, and nanospheres were decorated with 1-4 wt % Ni. The materials were structurally characterized using TEM and in situ XANES/EXAFS. The CO2 activation was analyzed by DFT and temperature-programmed techniques combined with MS-DRIFTS. Synthesized CeO2 morphologies expose {111} and {100} terminating facets, varying the strength of the CO2 interaction and redox properties, which influence the CO2 activation. Temperature-programmed CO2 DRIFTS analysis revealed that under hydrogen-lean conditions mono- and bidentate carbonates are hydrogenated to formate intermediates, which decompose to H2O and CO. In excess hydrogen, methane is the preferred reaction product. The CeO2 cubes favor the formation of a polydentate carbonate species, which is an inert spectator during DRM at 500 °C. Polydentate covers a considerable fraction of ceria's surface, resulting in less-abundant surface sites for CO2 dissociation.

14.
Sci Rep ; 12(1): 11786, 2022 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-35821518

RESUMO

Plastic waste has become a major global environmental concern. The utilization of solid waste-derived porous carbon for energy storage has received widespread attention in recent times. Herein, we report the comparison of electrochemical performance of porous carbon foams (CFs) produced from waste polyurethane (PU) elastomer templates via two different activation pathways. Electric double-layer capacitors (EDLCs) fabricated from the carbon foam exhibited a gravimetric capacitance of 74.4 F/g at 0.1 A/g. High packing density due to the presence of carbon spheres in the hierarchical structure offered excellent volumetric capacitance of 134.7 F/cm3 at 0.1 A/g. Besides, the CF-based EDLCs exhibited Coulombic efficiency close to 100% and showed stable cyclic performance for 5000 charge-discharge cycles with good capacitance retention of 97.7% at 3 A/g. Low equivalent series resistance (1.05 Ω) and charge transfer resistance (0.23 Ω) due to the extensive presence of hydroxyl functional groups contributed to attaining high power (48.89 kW/kg). Based on the preferred properties such as high specific surface area, hierarchical pore structure, surface functionalities, low metallic impurities, high conductivity and desirable capacitive behaviour, the CF prepared from waste PU elastomers have shown potential to be adopted as electrodes in EDLCs.

15.
Antioxidants (Basel) ; 11(6)2022 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-35740097

RESUMO

A 70% ethanol(aq) extract of the rhizome bark of the invasive alien plant species Japanese knotweed (JKRB) with potent (in the range of vitamin C) and stable antioxidant activity was incorporated in 1% w/v into a chitosan biofoil, which was then characterized on a lab-scale. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay confirmed the antioxidant activity of the JKRB biofoil upon contact with the food simulants A, B, C, and D1 (measured half-maximal inhibitory concentrations-IC50) and supported the Folin-Ciocalteu assay result. The migration of the antioxidant marker, (-)-epicatechin, into all food simulants (A, B, C, D1, D2, and E) was quantified using liquid chromatography hyphenated to mass spectrometry (LC-MS). Calculations showed that 1 cm2 of JKRB biofoil provided antioxidant activity to ~0.5 L of liquid food upon 1 h of contact. The JKRB biofoil demonstrated antimicrobial activity against Gram-positive bacteria. The incorporation of JKRB into the chitosan biofoil resulted in improved tensile strength from 0.75 MPa to 1.81 MPa, while elongation decreased to 28%. JKRB biofoil's lower moisture content compared to chitosan biofoil was attributed to the formation of hydrogen bonds between chitosan biofoil and JKRB compounds, further confirmed with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The JKRB biofoil completely degraded in compost in 11 days. The future upscaled production of JKRB biofoil from biowastes for active packaging may support the fights against plastic waste, food waste, and the invasiveness of Japanese knotweed, while greatly contributing to the so-called 'zero-waste' strategy and the reduction in greenhouse gas emissions.

16.
ACS Appl Mater Interfaces ; 14(27): 30796-30801, 2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35713305

RESUMO

Metal nanoparticles are potent reaction catalysts, but they tend to aggregate, thereby limiting their catalytic efficiency. Their coordination with specific functional groups within a porous structure prevents their aggregation and facilitates the mass flow of catalytic starting materials and products. Herein, we use a thiacalix[4]arene-based polymer as a porous support with abundant docking sites for Au nanoparticles. The sulfur atoms bridging the phenolic subunits of thiacalix[4]arene serve as Lewis basic sites that coordinate Au atoms. Therefore, this approach takes advantage of the functional groups inherent in the monomer and avoids laborious postsynthetic modifications of the polymer. The presented system was tested for visible-light-driven photocatalytic CO2 reduction, where it showed adequate ability to generate 6.74 µmol g-1 CO over the course of 4 h, while producing small amounts of the CH4 product. This study aims to stimulate interest in the design and development of synthetically simpler porous polymer supports for various metal nanoparticles in catalytic and other applications.

17.
Eur J Pharm Biopharm ; 177: 107-112, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35764219

RESUMO

PURPOSE: Large-scale freezing and thawing experiments of monoclonal antibody (mAb) solutions are time and material consuming. Computational Fluid Dynamic (CFD) modeling of temperature, solute composition as well as the stress time, defined as the time between start of freezing and reaching Tg' at any point in the container, could be a promising approach to ease and speed up process development. METHODS: Temperature profiles at six positions were recorded during freezing and thawing of a 2L rectangular bottle and compared to CFD simulations via OpenFOAM. Furthermore, cryoconcentration upon freezing and concentration gradients upon thawing of a mAb solution were predicted and the stress time calculated. RESULTS: Temperature profiles during freezing were accurately matched by the CFD simulation. Thawing time was only 45 min to 60 min longer in the model. The macroscopic cryoconcentration of the mAb was also matched by the simulation; only a highly concentrated region in the top and a diluted core in the geometrical centre of the 2 L bottle were not well reflected in the simulation. The concentration gradient after thawing obtained by simulation as well agreed with the experimental result. In addition, CFD simulations allowed to extract the global temperature distribution, the formation of ice, and thus the distribution of stress in the freezing liquid. CONCLUSION: CFD simulations via OpenFOAM are a promising tool to describe large-scale freezing and thawing of mAb solutions and can help to generate a deeper understanding and to improve testing of the robustness of the processes.


Assuntos
Anticorpos Monoclonais , Biodiversidade , Congelamento , Hidrodinâmica , Temperatura
18.
Sci Rep ; 11(1): 23810, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34893654

RESUMO

Selective photochemical oxidation of styrene was performed in an active acetonitrile medium, using H2O2 with or without ultraviolet (UV) light radiation. Pyrithione metal complexes (M-Pth: M = Cu(II), Ni(II), Ru(II); Pth = 2-mercaptopyridine-N-oxide) were used as catalysts. Catalytic testing measurements were done by varying the time, chemical reaction temperature and H2O2 concentration with or without UV energy. Epoxide styrene oxide (SO), benzaldehyde and acetophenone were the major synthesized products. A high batch rate, conversion and selectivity towards SO was shown in the presence of UV. A minor constant formation of CO2 was observed in the stream. Coordinated Ru-based compounds demonstrated the highest process productivity of SO at 60 °C. The effect of the functional alkyl substituent on the ligand Pth, attached to the specific ruthenium(II) centre, decreased the activity of the substance. Ni-Pth selectively yielded benzaldehyde. The stability of the catalysts was examined by applying nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis coupled with mass spectrometry. Tested metal complexes with pyrithione (M-Pth) exhibited excellent reuse recyclability up to 3 cycles.

19.
Polymers (Basel) ; 13(24)2021 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-34960994

RESUMO

The aim of the study was to isolate lignin from organosolv, beech tree (Fagus sylvatica), and Japanese knotweed (Reynoutria japonica), to use it for paper surface and to replace part of the non-renewable product resources with bio-based ones. A total of nine coated samples with different lignin formulations and starch were compounded, prepared, and evaluated. The basic (grammage, thickness, specific density), mechanical (elongation at break, tensile, burst and tear indices), and barrier properties (contact angle, water penetration, water vapour permeability, kit test) of the coated papers were investigated. The analysis showed no significant difference in tensile properties between uncoated and coated samples. Furthermore, the decrease in water vapour transmission rate and the lower contact angle for coated samples were nevertheless confirmed. The novel coating materials show promising products with very good barrier properties. Finally, the correlation between structural, morphological, and (other) natural lignin-based factors was revealed, highlighting the importance of parameters such as the equivalence ratio of aliphatic and phenolic hydroxyl groups or the average molecular weight. Tuning functionality by design could optimise performance in the future.

20.
Polymers (Basel) ; 13(22)2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34833178

RESUMO

A bio-epoxy surface adhesive for adherence of the metal component species to glass substrate with desirable adhesion strength, converted controlled removal upon request, and bio-based resource inclusion was developed. For the development of resin, three different lignin-based aromatic monophenols, guaiacol, cresol, and vanillin, were used in the chemical epoxidation reaction with epichlorohydrin. The forming transformation process was studied by viscoelasticity, in situ FTIR monitoring, and Raman. Unlike other hydroxyl phenyls, guaiacol showed successful epoxide production, and stability at room temperature. Optimization of epoxide synthesis was conducted by varying NaOH concentration or reaction time. The obtained product was characterized by nuclear magnetic resonance and viscosity measurements. For the production of adhesive, environmentally problematic bisphenol A (BPA) epoxy was partially substituted with the environmentally acceptable, optimized guaiacol-based epoxy at 20, 50, and 80 wt.%. Mechanics, rheological properties, and the possibility of adhered phase de-application were assessed on the bio-substitutes and compared to commercially available polyepoxides or polyurethanes. Considering our aim, the sample composed of 80 wt.% bio-based epoxy/20 wt.% BPA thermoset was demonstrated to be the most suitable among those analyzed, as it was characterized by low BPA, desired boundary area and recoverability using a 10 wt.% acetic acid solution under ultrasound.

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