Fourier Transform Infrared Spectroscopy Results Research Articles

Formulation and In-Vitro Evaluation of Meloxicam Solid Dispersion using Natural Polymers.

Meloxicam (MLX) is non-steroidal anti -inflammatory, poorly water soluble, highly permeable drug and the rate of its oral absorption is often controlled by the dissolution rate in the gastrointestinal tract. Solid dispersion (SD) is an effective technique for enhancing the solubility and dissolution rate of such drug.
 The present study aims to enhance the solubility and the dissolution rate of MLX by SD technique by solvent evaporation method using sodium alginate (SA), hyaluronic acid (HA), collagen and xyloglucan (XG) as gastro-protective hydrophilic natural polymers.
 Twelve formulas were prepared in different drug: polymer ratios and evaluated for their, percentage yield, drug content, water solubility, dissolution, crystal lattice using powder X-ray diffraction (PXRD) and studies and Fourier Transform Infrared Spectroscopy (FTIR) for determination the drug-polymer interaction.
 All the prepared showed improvement of drug solubility except that prepared with HA. The best result was obtained with formula SD1 (MLX: SA 1:1) that showed a high percentage yield (97), high drug content (97.4±0.05) and increase in solubility compared to solubility of pure MLX with improved dissolution rate. the PXRD study revealed the conversion of the drug to amorphous form without chemical interaction according to FTIR results

Geochemistry and sedimentology of tropical mangrove sediments along the southwest coast of Sri Lanka: Fingerprints for development history of wetlands

Tropical wetlands are one of the major terrestrial carbon sinks during the Holocene. However, there is considerable uncertainty in the development history of tropical wetlands in different geographical regions. In this study, the main objective was to synthesize the formation history of mangrove wetlands along the southwest coast of Sri Lanka in terms of past sea-level records in the region. Sedimentological observations were determined using representative sediment cores at Telwatta. Geochemical characteristics of sediment cores were determined using δ13C and δ15N stable isotopes, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The chronology was obtained using accelerated mass spectrometry 14C data for fossil coral samples. Black color fine to medium-grained core sediments can be identified as H3/H4 levels of decomposition based on the modified Von Post classification. This study identified that organic-rich sediment accumulation was initiated over the basal/inland coral deposits, any time after middle Holocene sea-level highstands. In this study, paleo sea-level indicator (i.e., basal coral in present-day land area) suggests that sea-level was about 1–2 m higher than present during ca. 5500 Cal year B.P. Heavy rainfall on the southwestern slopes also promotes the preservation of organic-rich sediments with seasonal flooding. The temporal variations of organic matter and carbonate contents suggest that there are no clear facies variations in this sedimentary succession. XRD analysis identified clay minerals such as montmorillonite and illite, and it indicates the deposition of sediments from a near distance or in situ source materials due to reinforced physical erosion. Stable isotopic values (δ13C = –27.18‰ to –26.46‰ and δ15N = 6.64‰ to 8.01‰) reflect the mixing of freshwater sources (i.e., dissolved organic carbon and nitrate) to C3 terrestrial plants dominant sediments. The humification index based on FTIR results (aromatic C=C and asymmetric COO- group vibrations to polysaccharides (1630/1053 cm −1)) suggests a depleted level for decarboxylation below ∼30 cm. The ratio of carboxyl C=O and aromatic ester group vibrations to polysaccharides (1720/1053 cm −1) also shows similar variations with the humification index. Looking forward, the 1720/1053 cm −1 ratio can be proposed as a possible geochemical proxy for determining the degree of formation of humic acids in organic-rich sediments.

Performances of functional groups and KOH-transformation in corn stover waste through catalytic pyrolysis

Catalytic pyrolysis can enhance the value of corn stover waste (CSW) by converting it into the functionalized carbon-based material. Understanding of the performance of functional groups in the CSW via catalytic pyrolysis, including catalyst transformation, is essential for the productive utilization of biomass waste. In this research, the changes of surface functionalities on the CSW and catalyst behavior by pyrolysis temperature in the range of 400–700 °C under N2 atmosphere and the KOH-catalyst loading in the range of 0.5 to 3 M were investigated. The surface functional groups on carbon materials were analyzed by using Fourier-transform infrared spectroscopy (FTIR) technique whilst the KOH-transformation was examined for crystalline structures by using X-ray diffraction (XRD) technique. From the FTIR results, in case of without catalyst the increase of pyrolysis temperature led to the decrease of surface functional groups which were hydroxyl, alkyl, carboxyl, carbonyl, ketone, ester and especially ether groups. However, at high temperature of 700 °C the graphite structure could be formed due to high polymerization reaction and more condensed carbon structure. The increase in concentration of KOH-catalyst from 0.5 to 3 M resulted in the increase of band intensities of OH stretching, CO stretching and KO vibration which could confirm the deposition of KOH-catalyst on the CSW surface. The maximum intensity of the functional groups was derived from the catalytic pyrolysis at a temperature of 400 °C with the KOH-catalyst concentration of 1 M. After the catalyst removal, the functional group of carbonate ion (CO32−) disappeared which became carbonaceous material. In terms of analysis of KOH-transformation by XRD, the KOH-catalyst could transform to crystalline compounds such as K2O, KHCO3 and K2CO3. The catalytic pyrolysis at pyrolysis temperatures of both 400 and 700 °C with the KOH-catalyst concentration of 1 M was transformed into KHCO3 in contrast to KOH at the concentration of 3 M, which was transformed into K2CO3. The investigation illustrated that KOH-transformation at 1 M and 3 M similarly presented K2O crystallite. Overall, the FTIR spectra accorded with XRD result of carbon materials obtained showed the KOH-transformation pathways in this research. This research work lies in the fact that the pyrolysis temperature in cases of without/with KOH-catalyst used in pyrolysis process can impact upon the surface functional groups on the carbon-based material and KOH-transformation.

Porous biochar derived from tea saponin for supercapacitor electrode: Effect of preparation technique

Biochar is widely employed as an electrode of supercapacitor. In this work, one-step pyrolysis and chemical activation method were introduced to prepare porous biochars from tea saponin (TS). The performance differences of biochars prepared by two methods were studied. On this basis, further researches were carried out to explore the influence of the mass ratio of KOH/pre-carbonized precursor on the structure and electrochemical performance of the biochars. All samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman spectra, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results revealed that KOH could effectively increase the specific surface area of biochar. The specific area of ACTS-1.0 prepared with a KOH/pre-carbonized precursor mass ratio of 1:1, is up to 1550.03 cm2/g with a pore volume of 0.9076 cm3/g, and the structure was highly amorphous and disordered. The FT-IR and XPS results showed that there are various functional groups on the ACTS-1.0 biochar surface. These structural and compositional advantages lead to a higher specific capacitance (278 F/g) of ACTS-1.0 in an aqueous electrolyte and a high energy density of 27.01 Wh/kg at an organic electrolyte. Meanwhile, the as-prepared ACTS-1.0 has excellent cycling stability over 10,000 cycles in various electrolytes.

Selective depressive effect of pectin on sphalerite flotation and its mechanisms of adsorption onto galena and sphalerite surfaces

In this work, pectin was investigated as a non-toxic and eco-friendly sphalerite depressant in the flotation separation of galena and sphalerite. The selective adsorption of pectin on sphalerite surfaces was predicted by molecular dynamics simulations, and its depressive effect was evaluated by single- and mixed-mineral flotation tests. The relevant adsorption characteristics and associated interaction mechanisms were further investigated by electrokinetic studies, adsorption density analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The flotation results demonstrated that pectin exerts a selective depressive effect on sphalerite flotation and could achieve the separation of galena from sphalerite. Electrokinetic and adsorption studies confirmed that pectin is adsorbed on both mineral surfaces. However, pectin is adsorbed much less extensively on the galena surface than on the sphalerite surface and could be displaced by xanthate. FTIR and XPS results revealed that the interactions between pectin and galena are physical interactions, the most likely of which is hydrophobic interactions based on the “salting-out” effect. The strong adsorption of pectin on the sphalerite surface was attributed to chemical complexation, and it could not be displaced by xanthate through competitive adsorption. Specifically, pectin is chemisorbed on the sphalerite surface through the O atoms of its –OH and –COOH groups, while Zn atoms on the sphalerite crystals function as adsorption sites.

Inclusion Complex of Gedunin-2-Hydroxypropyl-Β-Cyclodextrin Prepared by Kneading and Freeze-Drying Methods: Synthesis and Structural Characterization

Abstract The potential application of gedunin, a pharmacologically active limonoid, is limited in medicine because it has poor aqueous solubility. This study was aimed at preparation and characterization of an inclusion complex of gedunin and 2-hydroxypropyl-β-cyclodextrin (HBD) to increase the solubility in aqueous solvents and thus enhance the possibility of pharmaceutical formulation and oral administration of gedunin. Inclusion complex of gedunin isolated from Entandrophragma angolense heartwood with 2-hydroxypropyl-β-cyclodextrin (HBD) was prepared using freeze-drying and kneading methods. The gedunin-2-hydroxypropyl-β-cyclodextrin complex (GCD) was characterized using elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H-NMR) and X-ray diffraction analysis (XRD). Elemental analysis indicated that gedunin and HBD formed 1:1 stoichiometric inclusion complex. Results of FT-IR indicated that gedunin was stabilized in HBD cavity by intra-molecular hydrogen bonds and van der Waals forces. 1H-NMR revealed that the entire gedunin molecule was not trapped into the core of the HBD. Nevertheless, the fraction trapped may be sufficient to enhance the apparent solubility of gedunin. XRD results showed the formation of new solid crystalline phase. The results obtained by different characterization techniques clearly indicated that both kneading and freeze-drying methods led to inclusion complex formation which may enhance oral administration of gedunin.

Study on the cytocompatibility, mechanical and antimicrobial properties of 3D printed composite scaffolds based on PVA/ Gold nanoparticles (AuNP)/ Ampicillin (AMP) for bone tissue engineering

Over the years, gold nanoparticles (AuNP) have been widely used in several biomedical applications related to the diagnosis, drug delivery, bio-imaging, photo-thermal therapy and regenerative medicine, owing to their unique features such as surface plasmon resonance, fluorescence and easy surface functionality. Recent studies showed that gold nanoparticles display positive effect on osteogenic differentiation. In line with this effect, 3-Dimesional (3D) scaffolds that can be used in bone tissue were produced by exploiting the properties of gold nanoparticles that increase biocompatibility and support bone tissue development. In addition, ampicillin was added to the scaffolds containing gold nanoparticles as a model drug to improve its antimicrobial properties. The scaffolds were produced as composites of polyvinyl alcohol (PVA) main matrix as PVA, PVA/AuNP, PVA/Ampicillin (AMP) and PVA/AuNP/AMP. Scanning Electron Microscopy (SEM) Fourier Transform Infrared Spectroscopy (FTIR), tensile measurement tests, and in vitro applications of 3D scaffolds were performed. As depicted by SEM, scaffolds were produced at pore sizes appropriate for bone tissue regeneration. According to FTIR results, there was no modification observed in the AMP, PVA and gold nanoparticles due to mixing in the resultant scaffolds. In vitro results show that 3D printed composite scaffold based on PVA/AuNP/AMP are biocompatible, osteo-inductive and exhibit antimicrobial properties, compared to PVA scaffolds. This study has implications for addressing infections during orthopedic surgeries. The PVA-based gold nanoparticle 3D tissue scaffold study containing ampicillin covers a new study compared to other articles based on gold nanoparticles.

NovelN,N‐dimethylacrylamidecopolymer containing multiple rigid comonomers as a filtrate reducer inwater‐baseddrilling fluids and mechanism study

AbstractUltra‐high temperature dramatically deteriorates rheological properties and filtration performance of water‐based drilling fluids (WBDFs), especially for a salt‐gypsum formation that greatly restricts the application of WBDFs in ultra‐deep well drilling operations. Hence, the research in this article used an anionic copolymer (DANS) prepared byN,N‐dimethylacrylamide, 2‐acrylamide‐2‐methylpropanesulfonic acid,N‐vinylpyrrolidone, and sodium 4‐styrenesulfonate as an anti‐ultra‐high temperature and anti‐salt contamination filtrate reducer. Due to its multiple bulky cyclic structures in the side chain, DANS exhibits excellent thermal stability in the thermal gravimetric, rheological, and filtration tests. By adding 1.0 wt% DANS, the American Petroleum Institute (API) filtration volume of sodium bentonite‐based fluids (SBT‐BFs) decreased from 56.0 to 9.2 ml after aging at 240°C. Even under both 20 wt% NaCl contamination and 240°C aging, SBT‐BFs with 2.0 wt% DANS could maintain a filtration volume of 9.4 ml, whereas SBT‐BFs without DANS reached a filtration volume of 203.0 ml. The possible filtration control mechanism of DANS was further investigated via the Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), ζ potential, particle size distribution, filter cake micro‐morphology, and transmission electron microscopy (TEM). Confirmed by FTIR and AFM results, the effective adsorption was formed between DANS and bentonite even under a high‐salinity environment. Thus, a firm “dot net” structure formed by bentonite/DANS was observed by TEM, significantly improving the colloidal stability, dispersibility, and filter cake compactness of SBT‐BFs. Finally, by utilizing DANS as the core treatment agent, a high‐density WBDFs system with a temperature resistance of 240°C and a salt‐tolerance of 20 wt% has been successfully prepared.

Characterization, in vitro bioactivity and biological studies of sol‐gel‐derived TiO2 substituted 58S bioactive glass

AbstractBioactive glasses (BGs) have been used for bone formation and bone repair processes in recent years. This study investigated the titanium substitution effect on 58S BGs (Ti‐BGs) 60SiO2‐(36 − X)CaO‐4P2O5‐XTiO2 (X = 0, 3, and 5 mol.%) prepared by the sol‐gel technique, and the main goal was to find the optimum amount of titanium in Ti‐BGs. Synthesized BGs, which were investigated after immersion in simulated body fluid (SBF), were tested by X‐ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy. Moreover alkaline phosphate (ALP) activity, 3‐(4,5dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, and antibacterial studies were employed to investigate the biological properties of Ti‐BGs. According to the FTIR and XRD test results, hydroxyapatite (HA) formation on Ti‐BGs surfaces was confirmed. Meanwhile, the presence of 5 mol.% compared to 3 mol.% increased the HA grain distribution and their size on the Ti‐BGs surface. Additionally, MTT and ALP results confirmed that the optimal amount of titanium substitution in BG was 5 mol.%. Since 5 mol.% Ti incorporated BG (BG‐5) had the highest biocompatibility level, antibacterial properties, maximum cell proliferation, and ALP activity among the synthesized Ti‐BGs, it is presented as the best candidate for further in vivo investigations.

Incorporation of thyme essential oil into the β-cyclodextrin nanosponges: Preparation, characterization and antibacterial activity

Thyme essential oil (TEO) is a natural phenolic compound and has high antimicrobial and antioxidant activity. However, essential oils are very sensitive to environmental conditions and have high volatility and poor solubility that limit their applications. In this study, the incorporation of TEO into the β-cyclodextrin nanosponges was investigated. Diphenyl carbonate was used as cross-linker. The characterization of the obtained nanosponges was done by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), andthermogravimetric analyzer(TGA). Encapsulation efficiency, loading capacity, solubility, and antibacterial properties of the TEO-nanosponges were analyzed. The TEO-nanosponges showed porous structures with an average size lower than 326 nm. The results of FTIR and XRD confirmed the incorporation of TEO into the nanosponges. Thermogravimetric analysis indicated that the inclusion complex of TEO and nanosponges enhanced the thermal stability of TEO significantly. The inclusion complex of TEO into the nanospongesincreased its antibacterial activity. The aqueous solubility of TEO was enhanced by 15-folds after encapsulation within nanosponges. Minimum inhibitory concentration of TEO was decreased up to 29.4 folds after encapsulation into the nanosponges. The results suggest that β-cyclodextrin nanosponges can potentially be used as a delivery system for hydrophobic and sensitive compounds to increase their usage in the pharmaceutical and food industries.

Facile synthesis of novel tremella-like Mn0@Mn2O3 and its exceptional performance on removal of phosphate

Phosphorus is an essential nutrient for biological growth, but its excessive presence in water can lead to eutrophication. Reducing phosphorus concentrations is an important way to prevent eutrophication of surface water bodies. In this study, a novel zero-valent manganese (ZVM) Mn0@Mn2O3 sorbent was synthesized via a facile one-step reduction method at ambient temperature. The morphology and surface properties of the Mn0@Mn2O3 were analyzed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Zeta potential analyzer, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The obtained amorphous sample consists of many small tremella-like particles. The as-prepared sorbent shows exceptional phosphate removal performance and has a maximum adsorption capacity of 113.7 mg-P/g at pH 7.0, superior to many reported adsorbents. The removal of phosphate is obviously pH-dependent and is favorable under near-neutral and weak-alkaline conditions (pH 6.5–8.5). The kinetics data fit well to the pseudo-second-order model. The coexisting SO42-, CO32- and Cl- have no great influence on phosphate sorption, whereas, the SiO32- shows negative effect at high concentration. The sorbent is effective for phosphate removal from real municipal wastewater. The results of ionic strength effect experiment, SEM, XRD, FTIR and XPS analyses reveal that the phosphate was mainly removed through surface precipitation and formation of inner-sphere surface complexes. The Mn0@Mn2O3 is a promising sorbent for phosphate removal from surface water and wastewater, owning to its exceptional performance, high selectivity, environmental friendliness and easy preparation.

Efficient removal of tetracycline by a hierarchically porous ZIF-8 metal organic framework

Most reported metal organic frameworks (MOFs) have microporous structures and defective active sites, limiting their practical application to macromolecular substances. A hierarchical porous zeolitic imidazolate framework-8 (ZIF-8) was prepared using poly(diallyldimethylammonium chloride) (PDDA) as a structure-directing agent under facile “aqueous room-temperature” conditions to increase the mass transfer and adsorption capacity tetracycline hydrochloride (TCH). The ZIF-8 pore structure and morphology were synchronously tuned by controlling the PDDA molecular weight and dosage. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Bruner-Emmett-Teller (BET), scanning electron microscopy (SEM), NH3-temperature-programmed desorption (NH3-TPD) and adsorption results revealed abundant pore structures and open metal sites in the prepared materials, along with excellent TCH adsorption performance compared with ZIF-8, despite decreased BET surface areas. Initial screens revealed large adsorption capacities of hierarchical porous ZIF-8P3(4) (976.8 mg g−1) due to the presence of more abundant unsaturated metal sites than ZIF-8 and novel hierarchical porous structures. Therefore, TCH adsorption on ZIF-8 and ZIF-8P3(4), including the kinetics, isotherms, thermodynamics and pH effect, was studied. The adsorption process follows pseudo-second-order kinetics and the Freundlich models better, indicating multilayer adsorption of TCH on the surface of the two absorbents. Adsorption behavior test, FTIR, XPS, BET and XRD results show that TCH adsorption on ZIF-8 and ZIF-8P3(4) most likely involves coordination bonds, electrostatic and π-π interactions, hydrogen bonds, and pore-filling effects. This study provides new insights into the template preparation of MOFs with high adsorption performance as potentially economical adsorbents to remove organic matter from contaminated water.

Preparation and performance of microcapsules for asphalt pavements using interfacial polymerization

Microcapsules for asphalt pavement containing asphalt rejuvenator as the core material were prepared via interfacial polymerization using high-speed shearing. Isophorone di-isocyanate (IPDI) and distilled water were used as the reaction monomers of the oil and water phases, respectively. Polyvinyl alcohol (PVA) was used as an emulsifier. The preparation process was optimized based on the type and concentration of the emulsifier, shearing speed, shell-core ratio, and reaction temperature. The technical properties of the asphalt pavement microcapsules prepared via the optimal preparation process were evaluated by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), laser particle size analyzer, and Thermogravimetric analysis (TGA) from the aspects of micromorphology, particle size, shell thickness, and thermal stability. Results showed that PVA possesses satisfactory emulsifying and shell-forming properties, which made it a suitable emulsifier in the oil phase. The optimized conditions of the microcapsule preparation are as follows: the concentration of the emulsifier solution was 0.4%, the shearing speed was 5000 RPM, the shell-core ratio was 0.6, and the range of reaction temperature was 60–70 °C. The diameter of the optimal microcapsules was primarily distributed between 10 and 17 µm. Furthermore, the average particle size was 14.26 µm; the microcapsule shell thickness was relatively uniform (2–3 µm). The results of FT-IR and TGA demonstrated that the asphalt pavement microcapsules maintain good chemical and quality stability at high temperature, indicating that the microcapsules can withstand the high temperature during the asphalt-mixture production process. The results of salt tolerance test showed that microcapsules have certain salt tolerance. The mean elastic modulus and hardness of microcapsules were 466.86 MPa and 56.27 MPa, respectively obtained by nano indentation test.

Thermogravimetric Kinetics Study of Scrap Tires Pyrolysis Using Silica Embedded With NiO and/or MgO Nanocatalysts

Abstract In this study, a set of three new silica-based embedded with NiO and/or MgO nanocatalysts (SBNs) have been prepared and tested for the pyrolysis of scrap tires (STs). The intent is to identify and optimize the best nanocatalyst that decreases the operating temperature and speeds up the pyrolysis reaction rate. The influence of the three prepared SBNs nanocatalysts on STs was scrutinized using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The kinetic triplets were estimated utilizing the isoconversional method of the Ozawa–Flynn–Wall (OFW) corrected model. Experimental TGA and FT-IR results showed a thermal decomposition of all volatile organic additives alongside the polyvinyl compounds at a lower temperature in the presence of these SBNs. However, a competitive decomposition behavior appeared for each SBN nanocatalysts. The kinetic triplets’ findings showed different effective activation energy trends at two different conversion regions (low and high conversions), suggesting different reaction mechanisms confirmed by the reaction kinetic models. Interestingly, NiO-MgO-SBNs showed the highest reaction rate for this thermo-pyrolysis of STs, which could be because of synergetic interaction between NiO and MgO nanoparticles. Moreover, the results of the change in Gibbs free energy of activation (ΔG‡) indicated the promising catalytic activity for those SBNs by promoting the spontaneity of pyrolysis reaction. These proof-of-concept findings could promote the futuristic use of NiO-MgO-SBNs at the industrial level toward sustainable ST pyrolysis.

Flotation separation of molybdenite and talc by xanthan gum

In this study, the depressive effect of xanthan gum (XG) on molybdenite and talc flotation was studied using potassium butyl xanthate (PBX) as collector, and the mechanism through which molybdenite was separated from talc was investigated by Fourier transform infrared (FTIR) spectroscopy, Time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). The single mineral flotation experiments showed that both molybdenite and talc were depressed by XG in the absence of PBX. When PBX was used, molybdenite recovered its excellent floatability while talc was still depressed by XG. In artificial mixed minerals flotation experiment, the flotation recovery of molybdenite remained around 80% while that of talc was about 20% at pH 3–9. XPS analysis results showed that XG adsorbed on molybdenite “surface” by physical adsorption instead of chemical adsorption and hydrophobic interaction played a main role. The results of FTIR spectroscopy and TOF-SIMS indicated that the pre-adsorption of XG on molybdenite cannot hinder the further chemisorption of PBX on molybdenite “edge”, leading to the co-adsorption of depressant and collector on molybdenite surface. Because PBX has no collecting ability on talc, the flotation separation of molybdenite and talc was achieved through the collecting of molybdenite by PBX and the inhibiting of XG on talc.

Highly active and water tolerant Pt/MFe2O4 (M = Co and Ni) catalysts for low temperature CO oxidation

Pt supported on CoFe2O4 and NiFe2O4 spinel oxides were much more active for low temperature CO oxidation compared to those supported on monometallic oxides (i.e. Co3O4, Fe2O3 and NiO). The Pt/CoFe2O4 catalyst gave the best performance, with a turnover frequency of 0.27 s−1 at 50 ℃, which was three times as high as that on the Pt/Fe2O3. The interaction between Pt and the spinel oxide facilitated the activation of the oxygen species as evidenced by the H2 temperature programmed reduction results, and weakened the adsorption strength of CO on the Pt atoms as revealed by the in situ diffuse reflectance infrared Fourier transform spectroscopy results and kinetic investigation. These facts accounted for the enhanced reactivity. Moreover, the catalysts exhibited excellent water tolerance, which maintained activity even under 10 vol.% water vapor in the feed stock. Therefore, these catalysts are promising for practical applications.

Characterisation and stability of co-amorphous systems containing olanzapine and sulphonic acids

Introduction A large number of active pharmaceutical compounds currently under development are poorly water soluble, which can limit their bioavailability and results in formulation challenges [1]. Co-amorphous systems (CAMs) are known to increase the apparent solubility and dissolution rate of drugs [1,2]. To date, sulphonic acids have never investigated as possible co-formers for Olanzapine (OLZ; a BSC class II drug) and, thus, the aim of this work is to evaluate their potential on the formation of stable CAMs. Materials and methods OLZ was used as model drug. Saccharin (SAC), cyclamic acid (CA), acesulfame (ACE; obtained by neutralisation of potassium acesulfame) and their salts, sodium saccharin, sodium cyclamate and potassium acesulfame, respectively, were used as co-formers. Mixtures (2 g) of OLZ and each co-former, in molar ratios 1:1, were submitted to milling, solvent evaporation (SE) and quench cooling. Samples were characterised by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier-transform infra-red spectroscopy (FTIR) and cooling/heating stage microscopy. Solubility assessment, powder dissolution rate and stability studies were also performed. Results SAC, CA and ACE demonstrated to be successful co-formers in the production and stabilisation of OLZ-CAMs obtained by the three different techniques, presenting a single glass transition temperature (Tg) in thermograms and a typical halo in XRPD diffractograms. None of the salts were capable of forming a CAM, resulting in phase separation and absence of Tg events. Microscopical analysis supported DSC data and provided images of the CAMs recrystallization. Band shifts and broadening of the CAMs FTIR spectra suggest an intermolecular interaction between the N–H group in OLZ and the C = O group in SAC and ACE and the O-H group in CA. Solubility of OLZ was significantly increased (up to 199 times) when produced by SE with SAC. Dissolution rate was also increased for all the CAMs produced. SAC and CA successfully stabilised the CAMs produced, for more than 8 weeks at 25 °C/11, 53 and 75% RH and at 25 °C/11 and 53% RH, respectively. Discussion and conclusions In this study OLZ was successfully amorphized using the neutral forms of the sulphonic acids. The impossibility of the salts to form a CAM is in agreement with the FTIR results, since the groups responsible for the molecular interaction with OLZ are unavailable in these molecules due to their negative charge. SE proved to be the best technique to produce CAMs with the different co-formers, resulting in the highest increase in solubility. SAC has shown to be the best co-former, with the highest solubility and stability over time, under higher relative humidity. Moreover, the increased dissolution rate of the CAMs suggests improved bioavailability of OLZ, a feature with therapeutic impact, which should be confirmed in vivo.

Experimental Study on the Enhanced Thermal Performance of Two-Phase Closed Thermosyphon Using Mechanical and Chemical Treated MWCNTs Nanofluids

Nowadays the two-phase closed thermosyphon (TPCT) has been widely used as an important heat transfer medium for passive cooling systems. Since the enhancement of the performance of electronic device releases a considerable amount of heat, the development of working fluids which can improve thermal performance of the TPCT is necessary. In this experiment, two different type of MWCNT nanofluids were successfully made by using ball-mill process and alkaline treatment. The morphological and structural analysis were conducted by using transmission electron microscope (TEM), fourier-transform infrared spectroscopy (FT-IR). Also thermal conductivity of modified MWCNT nanofluids were investigated by introducing transient hot wire method. The results of TEM, FT-IR and thermal conductivity showed that the MWCNTs were successfully functionalized as well as had higher thermal conductivity. The TPCT was fabricated with copper tube and total length of the TPCT is 700mm, in which the evaporator section, the adiabatic section and the condenser section are 150mm, 400mm, and 150mm, respectively. The experiment of the thermal performance of the TPCT was evaluated by introducing RMS value of the temperature of the evaporation section, thermal resistance and heat transfer coefficient at five different filling ratios, 10%, 30%, 50% and 70% by ratcheting up heat loads in five levels, 5W, 8W, 10W, 13W and 15W. The overall results showed that the both of modified MWCNT nanofluids can decrease thermal resistance and increase the heat transfer coefficient, especially at 10% filling ratio with 8W. M-CNT nanofluid can even enhance the thermal performance of TPCT at 30% filling ratio with all heat loads.

Steam exploded wood cell walls reveals improved gas permeability and sound absorption capability

Steam explosion is a useful method to soften and dimensionally stabilizing wood. The effects of steam explosion at low pressure (6 bar) on wood cell walls are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), capillary flow porometry and two-microphone transfer function. The average sound absorption coefficient (SAC) of treated Chinaberry samples on the cross-sectional surface exhibited significant improvement of 79% relative to control specimens over a wide frequency range of 250–6400 Hz. Whereas, a little increment SAC of 5% was observed in the case of Ginkgo wood. Color of steam-exploded woods became black due to chemical reactions in wood cell walls during the steam explosion. The air permeability, SAC and color change are correlated with the results of FTIR and XRD. These results suggest that steam explosion could be used to manufacture wood-based sound absorption board to control the acoustical housing environment.

Assessing the Effects of Sunlight on the Photooxidation of Tropical Oils with Experimental and Computational Approaches

AbstractThis study aims to investigate the influence of high‐intensity sunlight radiation on the photooxidation of tropical oils (TO). Coconut oil (CNO), palm oil (PO), and palm kernel oil (PKO) were chosen for determining the indicators of photooxidation when exposed to and in the absence of sunlight for 7 weeks. The results showed a significant (P < 0.05) increase in free fatty acid (FFA) levels and peroxide value (PV) when the TO were exposed to sunlight. The iodine value and color content decreased significantly (P < 0.05) due to the decomposition of unsaturated FFA owing to the breaking down of the π‐bonds and the degradation of color pigments during photooxidation. Fourier transform infrared spectroscopy (FTIR) analysis showed strong vibrational absorptions at 1721 and 3505 cm−3, 1720 and 3560 cm−3, and 1721 and 3554 cm−3 for the CNO, PO, and PKO samples exposed to sunlight, respectively. These bands can be attributed to the presence of secondary oxidation products, which were absent in the TO that were not exposed to sunlight. A simulation was performed to support the FTIR results, which also indicated peaks from the secondary oxidation products at 1744 and 3660 cm−3. The study also revealed that the rate of photooxidation was different for each TO. The rate of oxidation followed the order PO > PKO > CNO. In contrast, no notable changes were observed in the TO kept away from sunlight. These results suggest that exposing TO to sunlight influences their oxidation stability and quality.