Showing papers on "Fourier transform infrared spectroscopy published in 2018"

A Novel Synthesis Route of Mesoporous γ-Alumina from Polyoxohydroxide Aluminum

Abstract: Mesoporous gamma-aluminas (γ-Al2O3) were synthesized starting from an unusual precursor of polyoxohydroxide aluminum (POHA). This precursor was obtained from aluminum oxidation in alkaline water-ethanol solvent in the presence of d-glucose that induces the formation of a gel, which leads to the POAH powder after ethanolic treatment. Precipitated POHAs were calcined at different temperatures (300, 400, 700 and 900 °C) resulting in the metastable γ-Al2O3 phase. Whereas at 300 °C no γ-Al2O3 phase was formed, unexpectedly, mesoporous γ-Al2O3 was obtained at 400 oC having a high specific surface area (282 m2/g) and a narrow pore size distribution. At higher temperatures, the aluminas had the expected decrease in surface area: 166 m2/g (700 °C) and 129 m2/g (900 °C), respectively. The structural change from POHA to alumina calcined at 400 oC occurs directly without the need to isolate the hydroxide or oxyhydroxide aluminum precursors. Both POHA and transition aluminas were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), N2 sorption and Scanning Electron Microscopy (SEM). These findings show an alternative route to produce high standard aluminas.

Impacts of temperature and selected chemical digestion methods on microplastic particles.

Abstract: Alkaline and wet peroxide oxidation chemical digestion techniques used to extract microplastics from organic matrices were assessed for recoveries and for impacts on ability to identify polymer types. Methods using wet peroxide oxidation generated enough heat to result in the complete loss of some types of microplastic particles, and boiling tests confirmed that temperatures >70 °C were responsible for the losses. Fourier transform infrared spectroscopy (FT-IR) confirmed minimal alteration of the recovered polymers by the applied methods. Environ Toxicol Chem 2018;37:91-98. © 2017 SETAC.

Covalent organic frameworks: efficient, metal-free, heterogeneous organocatalysts for chemical fixation of CO2 under mild conditions

Abstract: The cycloaddition of CO2 to epoxides to form cyclic carbonates is very promising and does not generate any side products. Metal-free, heterogeneous organocatalysts offer an environmentally friendly alternative to traditional metal-based catalysts. Herein two triazine-based covalent organic frameworks (COF-JLU6 and COF-JLU7) were successfully synthesized under solvothermal conditions. The structural and chemical properties of COFs were fully characterized by using powder X-ray diffraction analysis, structural simulation, Fourier transform infrared spectroscopy, 13C solid-state NMR spectroscopy, electron microscopy, thermogravimetric analysis and nitrogen adsorption. The two COF materials combine mesopores, high crystallinity and good stability, as well as a large number of hydroxy groups in the pore walls. They possess a high Brunauer–Emmett–Teller (BET) specific surface area up to 1390 m2 g−1 and a large pore volume of 1.78 cm3 g−1. The COF-JLU7 displays a high CO2 uptake of 151 mg g−1 at 273 K and 1 bar. Importantly, COF-JLU7 was found to be a highly effective catalyst to convert CO2 into cyclic carbonate through the cycloaddition reaction with epoxides under mild conditions. The effect of reaction parameters, such as reaction temperature, reaction time and CO2 pressure, on the catalytic performance was also investigated in detail. Moreover, the new framework-based catalyst can be recovered and reused five times without a significant loss of catalytic efficiency.

Cellulose Nanofiber-Based Polyaniline Flexible Papers as Sustainable Microwave Absorbers in the X-Band.

Abstract: A series of flexible, lightweight, and highly conductive cellulose nanopapers were fabricated through in situ polymerization of aniline monomer on to cellulose nanofibers with a rationale for attenuating electromagnetic radiations within 8.2–12.4 GHz (X band). The demonstrated paper exhibits good conductivity due to the formation of a continuous coating of polyaniline (PANI) over the cellulose nanofibers (CNF) during in situ polymerization, which is evident from scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The free hydroxyl groups on the surface of nanocellulose fibers promptly form intermolecular hydrogen bonding with PANI, which plays a vital role in shielding electromagnetic radiations and makes the cellulose nanopapers even more robust. These composite nanopapers exhibited an average shielding effectiveness of ca. −23 dB (>99% attenuation) at 8.2 GHz with 1 mm paper thickness. The fabricated papers exhibited an effective attenuation of electrom...

Valorization of acid isolated high yield lignin nanoparticles as innovative antioxidant/antimicrobial organic materials

Abstract: In this study, dissolution of pristine alkali lignin into ethylene glycol, followed by addition of different acidic conditions (HCl, H2SO4, and H3PO4 at different pH) has been considered as a simple method to prepare high yield lignin nanoparticles (LNP). Field emission scanning electron microscopy (FESEM), Zeta potential, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA) have been utilized to determine the influence of the precipitation procedures on particle size, Zeta potential, molecular weight, and thermal stability of final obtained LNP. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) were also considered to investigate the influence of lignin chemical structures and composition on its antioxidative and antimicrobial behaviors. Results from DPPH (1,1-diphenyl-2-picryl-hydrazyl) activity revealed the antioxidant response of LNP aqueous solutions, whereas results from antimicrobial tests confirmed LNP ...

Green synthesis, characterization and catalytic degradation studies of gold nanoparticles against congo red and methyl orange.

Abstract: The present study reports, novel and greener method for synthesis of gold nanoparticles (AuNPs) using 5,7-dihydroxy-6-metoxy-3',4'methylenedioxyisoflavone (Dalspinin), isolated from the roots of Dalbergia coromandeliana was carried out for the first time. The synthesized gold nanoparticles were characterized by UV-Vis spectroscopy, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The observed surface plasmon resonance (SPR) at 532nm in the UV-Vis absorption spectrum indicates the formation of gold nanoparticles. The powder XRD and SAED pattern for synthesized gold nanoparticles confirms crystalline nature. The HR-TEM images showed that the AuNPs formed were small in size, highly monodispersed and spherical in shape. The average particle sizes of the AuNPs are found to be ~10.5nm. The prepared AuNPs were found to be stable for more than 5months without any aggregation. The catalytic degradation studies of the synthesized AuNPs towards degradation of congo red and methyl orange, showed good catalytic in the complete degradation of both the dyes. The reduction catalyzed by gold nanoparticles followed the pseudo-first order kinetics, with a rate constant of 4.5×10-3s-1 (R2=0.9959) and 1.7×10-3s-1 (R2=0.9918) for congo red (CR) and methyl orange (MO), respectively.

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4) magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

Abstract: Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV–visible (UV–vis) spectroscopy and N2 adsorption–desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590–619 cm−1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0–76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

Constructing bio-templated 3D porous microtubular C-doped g-C3N4 with tunable band structure and enhanced charge carrier separation

Abstract: For the first time, the bio-templated porous microtubular C-doped (BTPMC) g-C3N4 with tunable band structure was successfully prepared by simple thermal condensation approach using urea as precursors and kapok fibre which provides a dual function as a bio-templates and in-situ carbon dopant. Prior to the thermal condensation process, the impregnation strategies (i.e. direct wet and hydrothermal impregnation) of urea on the treated kapok fibre (t-KF) were compared to obtained well-constructed bio-templated porous microtubular C-doped g-C3N4. The details on a physicochemical characteristic of the fabricated samples were comprehensively analyze using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), N2 adsorption-desorption, Thermogravimetric (TGA), and UV–vis spectroscopy. Our finding indicated that the hydrothermal impregnation strategy resulted in well-constructed microtubular structure and more carbon substitution in sp2-hybridized nitrogen atoms of g-C3N4 as compared to the direct wet impregnation. Also, compared to pure g-C3N4, the fabricated BTPMC g-C3N4 exhibited extended photoresponse from the ultraviolet (UV) to visible and near-infrared regions and narrower bandgap. The bandgap easily tuned with the increased t-KF loading in urea precursor which responsible for in-situ carbon doping. Moreover, as compared to pristine g-C3N4, dramatic suppression of charge recombination of the BTPMC g-C3N4 was confirmed through photoluminescence, photocurrent response, and electrochemical impedance spectroscopy. The resultants BTPMC g-C3N4 possesses more stable structure, promoted charge separation, and suitable energy levels of conduction and valence bands for photocatalysis application.

Synthesis and characterization of TiO2/graphene oxide nanocomposites for photoreduction of heavy metal ions in reverse osmosis concentrate

Abstract: In this study, graphene oxide (GO), titanium dioxide (TiO2) and TiO2/GO nanocomposites were synthesized as the catalysts for photoreduction of endocrine disrupting heavy metal ions in reverse osmosis concentrates (ROC). The morphology, structure and chemical composition of these catalysts were characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Brunauer–Emmett–Teller analysis, Barrett–Joyner–Halenda, Fourier transform infrared spectroscopy and Raman spectroscopy. The photocatalytic experiments showed that TiO2/GO nanocomposites exhibit a higher photoreduction performance than pure TiO2 and GO. Under the optimal conditions, the removal rates of Cd2+ and Pb2+ can reach 66.32 and 88.96%, respectively, confirming the effectiveness of photoreduction to reduce the endocrine disrupting heavy metal ions in ROC resulted from the combined adsorption–reduction with TiO2/GO nanocomposites.

Fabrication of nanostructured flowerlike p-BiOI/p-NiO heterostructure and its efficient photocatalytic performance in water treatment under visible-light irradiation

Abstract: Bismuth-related nanomaterials have received intense attention as potential promising photocatalysts for environment remediation. BiOI is well-known due to efficient photocatalytic activity, high stability, low cost and nontoxicity. In this study, novel nanostructured high-yield visible-light-induced photocatalyst p-BiOI/p-NiO was synthesized by a facile solvothermal method. Several characterization methods, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Fourier Transform Infrared Spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET) surface area, photoluminescence (PL) spectroscopy and UV–vis diffuse reflectance spectroscopy (DRS) were employed to study the phase structures, morphologies and optical properties of the samples. The photocatalytic properties of the as-prepared products were measured with the degradation of acid orange 7 (AO7) at room temperature under visible light illumination. It was found that the NiO amount in the BiOI/NiO composites played an important role in the corresponding photocatalytic properties. The best performance was achieved at 10% content. Enhanced photocatalytic activity of the composites was due to the improved photogenerated carrier separation capacity due to suitable heterojunction formation. In addition the mechanism was proposed for the coupled semiconductors. The reusability of nanophotocatalyst and effects of pH, dye concentration and photocatalyst dosage were also investigated.

Synthesis of polyamide grafted carbon microspheres for removal of rhodamine B dye and heavy metals

Abstract: Polyamide branches grafted onto carbon microspheres (CMS) was successfully synthesized by interfacial polymerization of 1,3,5-trimesoyl chloride and 1,3-phenylene diamine in situ with CMS. The obtained CMS-polyamide was characterized by Fourier transform infrared spectroscopy, thermogravimetric analyzer, scanning electron microscopy and Energy-dispersive X-ray spectroscopy. The sorption efficiency of the CMS-polyamide was evaluated by using rhodamine B (RhB) dye-polluted solutions. It exhibited excellent adsorption performance for the removal of RhB with adsorption capacity of 19.9 mg/g. The pseudo-second-order equation and the Langmuir model exhibited a good correlation with the adsorption kinetics and isotherm data with R2 of >0.99. Tests of adsorption/desorption were performed, and the results showed that dye loaded CMS-polyamide could be regenerated (97%) using acetone. Possible adsorption mechanisms have been proposed, where electrostatic attraction, π-π stacking interactions and complexation interaction with metal dominate the adsorption of RhB. The excellent removal rate (≈100%) of RhB, even in the presence of heavy metals (Pb, Cd, Hg, Cr, Ni, and Cu) in single and binary systems, endowed the CMS-polyamide with the potential for applications in water treatment.

Synthesis of polyacrylamide immobilized molybdenum disulfide (MoS2@PDA@PAM) composites via mussel-inspired chemistry and surface-initiated atom transfer radical polymerization for removal of copper (II) ions

Abstract: In present work, novel polyacrylamide immobilized molybdenum disulfide (MoS2@PDA@PAM) composites were synthesized via the mussel-inspired chemistry and surface initiated atom transfer radical polymerization (SI-ATRP). The as-prepared MoS2@PDA@PAM composites were characterized by energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Characterization results provide sufficient evidences for the successful functionalization of MoS2 with PAM. The products were used as adsorbents for removing of copper (II) ions. Results show the introduction of PAM onto MoS2 could enhance the adsorption capacity of MoS2@PDA@PAM towards copper (II) ions. The amount of adsorbed copper (II) ions by MoS2@PDA@PAM composites is 2.5 times that of pristine MoS2. The effects of various experimental factors on the adsorption process, including contact time, initial copper (II) ion concentrations, solution pH and temperature, were also studied in this work. The batch experiments show that the adsorption of copper (II) ions onto MoS2@PDA@PAM is dependent on time, pH and temperature. The optimum solution pH is observed at pH 7 and the increase of temperature is favorable for the adsorption of MoS2@PDA@PAM towards copper (II). Based on the experiment data, the adsorption kinetics, isotherms and thermodynamics were also investigated. The kinetics and isotherm studies show that pseudo-second-order kinetic and Freundlich isotherm models could well fit with the adsorption data. The thermodynamic results show that the adsorption of copper (II) ions on MoS2@PDA@PAM is a spontaneous and endothermic process. The adsorption process is mainly governed by the chemisorption involving the electrostatic interaction and/or chemical chelation between copper (II) ions and amino groups on the surface of MoS2@PDA@PAM. Taken together, it is proven that the PAM can be immobilized onto the MoS2 nanosheets via the mussel-inspired chemistry and SI-ATRP, and it can enhance the adsorption performance of MoS2@PDA@PAM composites, which might be used as adsorbents to remove heavy metal ions in real environment treatment.

Facile One-Pot Synthesis of Graphene Oxide by Sonication Assisted Mechanochemical Approach and Its Surface Chemistry.

Abstract: Facile one pot synthesis of graphene oxide (GO) by sonication assisted mechanochemical approach has been reported here The amalgamation of ultrasonication and mechanical stirring has assisted the synthesis of GO in a short time duration of only 4 hours with good reaction yield The structural characterization of GO was performed by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Visible spectroscopy and Raman spectroscopy Atomic force microscopic (AFM) analysis manifested the flake like morphology of GO with average sheet thickness ~15 nm AFM also provides important information about the surface roughness Transmission electron microscope (TEM) analysis gave clear visualization of well exfoliated structure of GO in the form of thin flakes The field emission scanning electron microscope (FESEM) analysis revealed a crimpling surface morphology of GO The average size of GO flake as revealed through various morphological as well as light scattering techniques was around 3 μm Moreover, important surface chemistry of the synthesized GO was well ascertained through contact angle analysis, AFM analysis and zeta potential analysis

Highly Pure Silica Nanoparticles with High Adsorption Capacity Obtained from Sugarcane Waste Ash.

Abstract: Silica nanoparticles (SiO2NPs) from renewable sources can be used in very different materials, such as paints, membranes for fuel cells, Li-ion batteries, adsorbents, catalysts, and so on. Brazil is the world's largest producer of sugarcane and generates huge amounts of sugarcane waste ash (SWA), which is a Si-rich source. This study investigates a method to produce highly pure SiO2NPs from SWA. The SiO2NPs were characterized by inductively coupled plasma optical emission spectroscopy, scanning and transmission electron microscopy (TEM), X-ray diffraction analyses, specific surface area and pore distribution, UV and Fourier transform infrared spectroscopy, and thermogravimetric analyses and applied as an adsorbent material in the removal of acid orange 8 (AO8) dye from aqueous solution. The SiO2 content was 88.68 and 99.08 wt % for SWA and SiO2NPs, respectively. TEM images of SWA and SiO2NPs exhibit drastic alterations of the material size ranging from several micrometers to less than 20 nm. The SiO2NPs showed a specific surface area of 131 m2 g-1 and adsorption capacity of around 230 mg g-1 for acid orange 8 dye. Furthermore, the recycling of the SiO2NPs adsorbent after AO8 adsorption was very satisfactory, with reuse for up to five cycles being possible. The results indicate that it was possible to obtain highly pure silica in a nanosize from the waste material and produce an adsorbent with high adsorption capacity and the possibility of reuse.

Synthesis and characterization of ZnO–CuO nanocomposites powder by modified perfume spray pyrolysis method and its antimicrobial investigation

Abstract: Pure ZnO, ZnO–CuO nanocomposites can be synthesized by using a modified perfume spray pyrolysis method (MSP). The crystallite size of the nanoparticles (NPs) has been observed by X-ray diffraction pattern and is nearly 36 nm. Morphological studies have been analyzed by using Field Emission Scanning Electron Microscopy (FESEM) and its elemental analysis was reported by Elemental X-ray Analysis (EDX); these studies confirmed that ZnO and CuO have hexagonal structure and monoclinic structure respectively. Fourier Transform Infrared (FTIR) spectra revealed that the presence of functional frequencies of ZnO and CuO were observed at 443 and 616 cm−1. The average bandgap value at 3.25 eV using UV–vis spectra for the entitled composite has described a blue shift that has been observed here. The antibacterial study against both gram positive and negative bacteria has been studied by the disc diffusion method. To the best of our knowledge, it is the first report on ZnO–CuO nanocomposite synthesized by a modified perfume spray pyrolysis method.

Photocatalytic properties of BiOCl-TiO2 composites for phenol photodegradation

Abstract: BiOCl-TiO2 composites were synthesized by sol-gel method; using two commercial BiOCl (P2600 and SB) with different BiOCl-TiO2 weight ratios. They were characterized by different techniques such as X-ray diffraction (XRD), electron microscopy (SEM, HRTEM and TEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), time resolved micro-wave conductivity (TRMC) and UV–vis diffuse reflectance spectroscopy (UV-DRS). In addition, these composites (BiOCl-TiO2) were evaluated for the photodegradation of phenol (50 mgL−1) under visible irradiation (λ > 450 nm). The results showed effective phenol degradation with the PTi-75 composite, which has 75% by weight of TiO2, obtaining up to 40% of degradation during 6 h of reaction. The SEM analysis showed that micro-sheets of BiOCl are irregularly embedded on agglomerates of TiO2 nanoparticles. A mechanism was proposed, which considers the excitation by the overlap of the BiOCl-TiO2 bands; where the TiO2 has a conduction band more electronegative than that of BiOCl, allowing that TiO2 electron of the conduction band can be transferred to conduction band of BiOCl; while the holes present in the valence band of BiOCl can be moved to TiO2 valence band preventing the electron-holes recombination.

Fourier Transform Infrared (FTIR) Spectroscopy Analysis of Transformer Paper in Mineral Oil-Paper Composite Insulation under Accelerated Thermal Aging

Abstract: Mineral oil is the most popular insulating liquid for high voltage transformers due to its function as a cooling liquid and an electrical insulator Kraft paper has been widely used as transformer solid insulation for a long time already The degradation process of transformer paper due to thermal aging in mineral oil can change the physical and chemical structure of the cellulose paper Fourier transform infrared (FTIR) spectroscopy analysis was used to identify changes in the chemical structure of transformer paper aged in mineral oil FTIR results show that the intensity of the peak absorbance of the O–H functional group decreased with aging but the intensity of the peak absorbance of the C–H and C=O functional groups increased with aging Changes in the chemical structure of the cellulose paper during thermal aging in mineral oil can be analyzed by an oxidation process of the cellulose paper and the reaction process between the carboxylic acids in the mineral oil and the hydroxyl groups on the cellulose The correlation between the functional groups and the average number of chain scissions of transformer paper gives initial information that the transformer paper performance can be identified by using a spectroscopic technique as a non-destructive diagnostic technique

Green Synthesis of Zinc Oxide and Copper Oxide Nanoparticles Using Aqueous Extract of Oak Fruit Hull (Jaft) and Comparing Their Photocatalytic Degradation of Basic Violet 3

Abstract: Here we report green synthesis of highly crystalline ZnO and CuO nanoparticles (NPs) by oak fruit hull (Jaft) as reducing and stabilizing agent. This method is nontoxic, eco-friendly and low cost in comparison with chemical and/or physical techniques. The characterization of obtained particles was studied by using field emission scanning electron microscopy (FESEM), X-ray diffraction analysis and Fourier transform infrared spectroscopy. The results indicating that NPs synthesized by Jaft extract have high purity and the average particle size is 34 nm. The ZnO NPs exhibited photocatalytic activity higher than CuO NPs for degradation of basic violet 3 dye in water at room temperature. The amount of basic violet 3 dye degradation by metal oxide NPs were studied by employing UV–Vis spectroscopy. Furthermore, the degradation of basic violet 3 using metal oxide NPs followed pseudo-first-order kinetics.