Lower Band Gap Energy Research Articles

Comprehensive study of the molecular structure and nonlinear optical response of two novel halogenated pyrenyl-chalcones

Herein, two novel pyrenyl-chalcone derivatives named PCh-1 and PCh-2 were synthesized by the Claisen-Schmidt reaction and successfully recrystallized in acetone to get single crystals. The crystals were spectroscopically characterized via SCXRD and UV–Vis absorption. Quantum computational studies including NBO, MEP, FMO, and polarity were performed using DFT at B3LYP/6–311++G (d,p). Intermolecular interactions were investigated using Hirshfield analysis while intramolecular interactions were discussed experimentally (UV–Vis absorption spectroscopy) and theoretically using TD-DFT at CAM- B3LYP/6–311++G (d,p). The presence of the intermolecular interactions of CH…O, CH…F, CH…π, and π-π interactions stabilize both crystals in head-tail (PCh-1), zig-zag fashion (PCh-2), and face to face stacking. The hyper conjugative interactions extracted from NBO analysis confirmed the high stability of both crystals. The UV–Vis and FMO studies show low bandgap energy of 3.012 eV (PCh-1) and 3.047 eV (PCh-2) and opaque in the visible range revealing strong ICT. The nonlinear behavior of the compounds was investigated using the Z-scan technique via CW laser working at 637 nm. An excellent NLO response in order of 10−5 esu (PCh-1) & 10−6 esu (PCh-2) and fast response in limiting optical signal at 1245.5 mW (PCh-1) & 1431.9 mW (PCh-2) are observed. The structure-property findings suggest the higher inter/intramolecular charge transfer in PCh-1 compared to PCh-2 is due to the strength of the EDG, planarity of the bone structure, and polarizability. The high NLO performance of the crystals suggests a promising application to use them as NLO material.

The role of nanoparticles inclusion in monitoring the physical properties of PVDF

In this work, the effects of CoxZn1-x Fe2O4 (x= 0, 0.5, 1) nanofillers on the PVDF polymer were scientifically studied. The structure and magnetic and optical properties were studied. XRD confirms the synthesis of nanofiller in a single phase. FTIR confirms the formation of nanoferrites. HRTEM shows that the prepared nanoferrites have a cubic-like shape. Also, the size and agglomeration increase with Co-Zn Fe2O4 nanoferrites compared to the other singles one. The effect of adding nanoferrites into PVDF matrix was studied using XRD, FTIR, FESEM, VSM, and UV-Vis. XRD and FTIR approved the complexation between PVDF polymer and nanoferrites. Also, addition of nanoferrites into PVDF leads to decrease the semi-crystalline nature of PVDF. FESEM showed that embedding nanoferrites into PVDF polymers creates pores and PVDF/Co-Zn Fe2O4 increases the pore size on the PVDF surface. The magnetic properties of PVDF were enhanced by adding the nanofiller. For example, saturation magnetization was increased from 269.31E−6 to 62.052E−3 by adding CoFe2O4 to PVDF polymer. Band gap calculation showed that PVDF/Co-Zn Fe2O4 has the lowest band gap energy which makes it useful in photochemical and electronic applications.

Real-Time Degradation of Indoor Formaldehyde Released from Actual Particle Board by Heterostructured g-C3N4/TiO2 Photocatalysts under Visible Light

Indoor formaldehyde pollution causes a serious threat to human health since it is uninterruptedly released from wooden furniture. Herein, we prepared a g-C3N4-modified TiO2 composite photocatalyst and coated it on the surface of a commercial artificial particle board with the assistance of melamine formaldehyde adhesive. The g-C3N4/ TiO2 coating was then used to degrade formaldehyde which was released in real-time from the particle board under the irradiation of visible light. The results showed that compared with pure TiO2, the g-C3N4/ TiO2 composite with a heterojunction structure had a lower band gap energy (~2.6 eV), which could effectively capture luminous energy from the visible light region. Under continuous irradiation, the g-C3N4/ TiO2 photocatalytic coating was capable of degrading more than 50% of formaldehyde constantly released from the particle board. In the meantime, the photocatalytic coating also exhibited promising catalytic stability towards various formaldehyde release speeds, air flow velocities and environmental humidities. The hydroxyl radical and superoxide radical were found to be the predominant active species which triggered formaldehyde degradation. This study provides a feasible and practical approach for the improvement in indoor air quality through photocatalyst surface engineering.

Experimental Study on Kinetics and Mechanism of Ciprofloxacin Degradation in Aqueous Phase Using Ag-TiO2/rGO/Halloysite Photocatalyst

In this study, Ag-TiO2/rGO/halloysite nanotubes were synthesised from natural sources using a simple method. The material was characterised by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman spectroscopy, BET, scanning electron microscopy (SEM) and UV-vis DRS techniques. The as-synthesised material has a sandwich-like shape, with the active phase distributed evenly over the rGO/HNT support. Compared to pure TiO2, the material has a lower band gap energy (~2.7 eV) and a suitable specific surface area (~80 m2/g), making it able to participate effectively in the photochemical degradation of pollutants. The catalyst showed exceptional activity in the degradation of CIP antibiotics in water, achieving a conversion of about 90% after 5 h of irradiation at an initial CIP concentration of 20 ppm. This efficiency was significantly higher than that of pure TiO2 and Ag-TiO2, which could prove the important effect of the support and silver doping. The results of the experiments show that the process follows a pseudo-first-order kinetic model in the case of (1%)Ag wt. and pseudo-second-order in the case of (3%)Ag wt., which could be explained by the aggregation of silver and the increasing role of chemisorption. Tests with radical scavengers showed that the •OH radical had the greatest effect on CIP decomposition, while •O2− had the least. The neutral pH value and the high degree of mineralisation (approx. 80%) confirm the potential of the material for use in wastewater treatment.

Biopolymer templated strategized greener protocols for fabrication of ZnO nanostructures and their application in photocatalytic technology for phasing out priority pollutants.

Zinc oxide (ZnO) nanostructures have been successfully synthesized via template-assisted and template-free route using three different synthetic methods, i.e., sonochemical, mechanochemical, and hydrothermal. Biopolymer xanthan gum (XG) served as sacrificial template for ZnO synthesis as provided the surface for the growth of nanostructures in a controlled manner. The employment of multifarious synthetic techniques resulted in fabrication of ZnO nanoparticles with diverse morphologies such as needle shaped, hexagonal, and spherical particles. Further, the template-assisted protocols generated thermally stable highly crystalline nanostructures along with high surface area, larger pore size, and low band gap energies in contrast to template-free protocol. The structural and other physicochemical studies were manifested by XRD, N2 adsorption desorption, FESEM, TGA, and UV-Vis spectral analysis. The template-assisted ZnO nanostructures were explored as a potential photocatalyst for the catalytic degradation of emerging pollutants, i.e., triclosan (TCS) and imidacloprid (IMD) under the exposure of UV light. The products formed during the photocatalytic reaction were monitored by UV-Vis spectroscopy and HPLC. The results obtained revealed the high catalytic efficiency of ZnO synthesized via template-assisted sonochemical method for TCS (99.60%) and IMD (96.09%) which is attributed to the high surface area and lower band gap energy of the catalyst. The high catalytic potential of the sonochemically synthesized ZnO also substantiated from the kinetic data as high-rate constant was obtained. Thus, the template-assisted protocols developed led to preparation of nanostructures having tailored properties for efficient photocatalysis and can rapidly degrade selected emerging contaminants such as personal care products and organophosphate pesticides. Hence, environment-friendly synthesized photocatalyst can be appropriately employed to wastewater treatment contaminated with emerging pollutants.

Fabrication of g-C3N4 nanosheets immobilized Bi2S3/Ag2WO4 nanorods for photocatalytic disinfection of Staphylococcus aureus cells in wastewater: Dual S-scheme charge separation pathway

In this work, graphitic carbon nitride (g-C3N4) immobilized Bi2S3/Ag2WO4 (BS/AW/CN) heterojunction was successfully fabricated using a facile multi-step approach. The fabricated nanomaterials were characterized using different sophisticated technologies. The morphological investigations revealed the existence of g-C3N4 nanosheets loaded with Ag2WO4 and Bi2S3 in a nanorod-like structure. The BS/AW/CN nanocomposite exhibited improved surface area, which was attributed to the regular deposition of Bi2S3/Ag2WO4 on the surface of g-C3N4 nanosheets. The obtained BS/AW/CN heterojunction displayed excellent light absorption ability with promoted photoelectrochemical properties, which was attributed to the lower band gap energy of Bi2S3 species. The BS/AW/CN (0.25 g/L) showed superior photocatalytic antimicrobial activity against Staphylococcus aureus cells (∼1 × 107 CFU/mL) under 140 W of visible-light illumination, where complete inactivation activity was observed in 90 min. The disinfection kinetics verified the faster photoreaction process over BS/AW/CN compared with single and binary catalysts. The inactivated bacterial cells were further elucidated by fluorescence spectroscopy and electron microscopy techniques. The photocatalytic disinfection activity was also investigated under different operating conditions like pH, catalyst loading, and bacterial density. The stability studies verified the high photostability of the obtained heterojunction in five photoreaction runs, suggesting its potential applicability in wastewater disinfection systems. The electronic characteristics and radical trapping results were considered in justifying the dual-S-scheme heterojunction mechanism in the presence of BS/AW/CN. In conclusion, this work demonstrates the feasibility of an efficient visible-light responsive photocatalyst for Staphylococcus aureus cells disinfection in wastewater treatment systems.

Removal of ceftriaxone sodium antibiotic from pharmaceutical wastewater using an activated carbon based TiO2 composite: Adsorption and photocatalytic degradation evaluation

The water pollution becomes a serious concern for the sustainability of ecosystems due to the existence of pharmaceutical products (ceftriaxone (CEF) antibiotic). Even in low concentration of CEF has lethal effects on ecosystem and human health. To remove CEF, TiO2 is considered as an effective and efficient nanoparticles, however its performance is reduced due to wider energy gap and rapid recombination of charge carriers. In this study, activated carbon based TiO2 (ACT-X) heterogeneous nanocomposites were synthesized to improve the intrinsic properties of TiO2 and their adsorption-photocatalytic performance for the removal of CEF. The characterization results revealed that ACT-X composites have slower recombination of charge carriers, lower energy band gap (3.05 eV), and better light absorption under visible region of light. From ACT-X composites, the ACT-4 photocatalyst has achieved highest photocatalytic degradation (99.6%) and COD removal up (99.2%). The results of radical scavengers showed that photocatalytic degradation of CEF is mainly occurred due to superoxide and hydroxyl radicals. Meanwhile, the reusability of ACT-4 up to five cycles shows more than 80% photocatalytic degradation, which make the process more economical. The highest experimental adsorption capacity is achieved up to 844.8 mg g−1 using ACT-4. The favorable and multilayer heterogeneous adsorption is carried out according to the well-fitted data with pseudo-second-order and Freundlich models, respectively. These results indicate that the carbon-based TiO2 composites can be used as a green, stable, efficient, effective, reusable, renewable, and sustainable photocatalyst to eliminate the pharmaceutical pollutants (antibiotics) via adsorption and photocatalytic degradation processes.

Green-engineered synthesis of Bi2Zr2O7 NPs: excellent performance on electrochemical sensor and sunlight-driven photocatalytic studies.

In this rapid growing eco-friendly research world, synthesis of non-toxic, highly effective photocatalyst for potential applications is necessary. Herein, a strong ability Bi2Zr2O7 nanoparticle (BZO NP) with pyrochlore structure was fabricated by solution combustion synthesis using green (Mentha spicata) and chemical (Glycine) fuels. The X-ray diffraction analysis confirms the formation of pure phase for synthesized BZO NP using pudina extract (BZOP NP) compared to BZO NP using Glycine fuel (BZOG NP). The lower energy band gap of synthesized BZOP NP was observed than BZOG NP and its values were found to be 2.26 and 2.49eV measured by UV-visible absorbance spectral technique. The morphological analysis of pores and voids formation as examined by scanning electron microscopy (SEM) technique. The synthesized BZOP NP shows excellent photocatalytic activity for degradation of three different dyes under sunlight irradiation for about 150min with 97.9% for Rose Bengal (RB) dye with lower charge transfer resistance (Rct) value. For the very first time, the synthesized NPs can be utilized as supercapacitor with good specific capacitance (SPCcv) value of 14.3 F/g and SPCGD (12.5 F/g) for BZOP compared to BZOG indicating pseudocapacitance nature. The synthesized nanoparticles (NPs) can sense lead nitrate and dextrose at concentration 1-5mM in the potential range of - 1.0 to + 1.0V. Accordingly, the reduction potential peak at - 0.25V and oxidation potential peak found at - 0.82V confirms the presence of lead content and presence of additional potential peaks at - 0.37V and - 0.71V for detection of dextrose biochemical. Recyclability experiment showed the retainment of photocatalytic activity up to five cycles indicating the photostability.

Super capacitor, electrochemical measurement and sun light driven photocatalytic applications of CuFe2O4 NPs synthesized from bio-resource extract

The CuFe2O4 nanoparticle has been successfully synthesized from bio-mediated (Aloe-Vera) combustion process. The structural characterization of synthesized nanoparticle was achieved by spectral-characterizations viz; XRD, SEM, FT-IR and optical examinations. The XRD studies displays a spinel cubic phase development of nanoparticle and its average-particle size (19.3 ​nm). Low band gap energy of synthesized nanoparticle has been recorded to be 2.84 ​eV using UV–Visible absorption spectroscopy, which impacts to higher photodegradation efficiency. The potential photocatalytic activity of synthesized nanoparticle was examined using Malachite Green (MG) organic dye as a model, which is performed under specific quantities of stock solution (60 ​ppm) and obtained nanoparticle (50 ​mg). The photodegradation efficiency of synthesized material was evaluated for MG dye degradation achieved with 87.5% at 140 ​min under Sun-light. The excellent oxidation-reduction peak potentials were observed for synthesized spinel ferrite nanoparticle modified with carbon paste investigated by electrochemical analysis using 0.1 ​M KCl in the different scan rates 0.01–0.05 ​V/s. The charge-discharge studies of CuFe2O4-graphite electrode at current density (0.4 A/g) was discussed which is well correspondence to pseudo-capacitive behaviour. The synthesized NPs through bio-resources extract has become a potential new insight into multiple practical applications.

ZnO recovered from spent alkaline batteries as antimicrobial additive for waterborne paints.

Biocides are employed to prevent biodeterioration in waterborne paints. In the present study, we used zinc oxide nanoparticles (obtained from spent alkaline batteries) as biocide for indoor waterborne paint at 1.5% of the total solid content in paint. Two different zinc oxides synthesized from spent alkaline batteries, which showed photocatalyst activity, were employed as an antimicrobial agents. After leaching the anode of alkaline batteries, zinc was precipitated from the leachate liquor by introducing oxalic acid (O-ZnO) or sodium carbonate (C-ZnO). The antimicrobial properties of the prepared oxides were tested against Staphylococcus aureus (bacteria), Chaetomium globosum, and Aspergillus fumigatus (fungi) using agar well diffusion method. C-ZnO inhibited the growth of all the strains studied and presented enhanced activity than O-ZnO. The better performance as antimicrobial agent of C-ZnO compared to O-ZnO was attributed to its lower crystallite size, higher amount of oxygen monovacancies, and to its lower band gap energy. The oxide with the best performance in antimicrobial activity, C-ZnO, was employed for the formulation of waterborne acrylic paints. It was observed that 1.5% C-ZnO improved the antifungal properties and antibacterial properties compared to the control sample.

FTO Thin Films: Outcome of Substrate Temperature on the Structural and Optical Properties

In this work, Fluorine doped Tin Oxide (FTO) thin films are effectively deposited by JNSP technique using ammonium fluoride and tin chloride as solution composition. The influence of Substrate Temperature (ST) on the structural and optical properties of FTO thin films is investigated. XRD pattern authenticates the presence of single phase polycrystalline orthorhombic structure with favored orientation along (230) and (200) directions. The sharp band obtained between 475 and 700 cm-1 originated from asymmetric stretching vibrations of metal oxide (SnO2:F). The highest band gap energy was obtained as 3.57 eV at 425°C and lowest band gap energy was obtained as 3.49 eV at 450°C obtained from UV-Vis spectra.

Efficient NiO/F–TiO2 nanocomposites for 4-chlorophenol photodegradation

This work aimed to study NiO/F–TiO2 composites in the photocatalytic degradation of 4-chlorophenol. F–TiO2 support was prepared by in-situ fluorination of TiO2 using the sol-gel method. The heterostructured materials were prepared by wet impregnation method, varying NiO content (0.5, 1.0, and 2.0% wt). The solids were characterized by X-ray fluorescence, X-ray diffraction, nitrogen physisorption, diffuse reflectance UV–Vis spectrophotometry, infrared spectroscopy, and X-ray photoelectron spectroscopy. The characterization studies showed that the coupling of TiO2 with fluoride ions promoted the generation of ≡Ti–F surface species that could be responsible for the decrease in the recombination frequency of charge carriers and the increased photoactivity. In addition, it was found that the coupling of NiO/F–TiO2 semiconductors improved the photocatalytic properties of the fluorinated support, obtaining higher percentages of degradation and mineralization of the phenolic contaminant. These results are possibly a consequence of factors such as the formation of larger crystallites, lower band gap energies, and the generation of p-n type interfacial heterojunctions that potentiate the proper separation of electron-hole pairs. An effect of NiO content on photoactivity was observed, being a percentage of 1.0% wt the optimum in this photocatalytic treatment.

A novel nitrogenous core-shell MIL-101(Fe)-based nanocomposite for enhanced adsorption and photo-degradation of organic pollutant under visible light

Iron-based metal-organic frameworks are popular in the field of photocatalysis for their excellent visible light responsiveness. However, the rapid recombination of hole-electron pairs always limits its application. In this paper, a poly-nitrogen conjugated molecule, 1,1,2,2-Tetrakis(4-(pyridin-4-yl) phenyl) ethylene (TPPE) was simply modified on the surface of MIL-101(Fe) by alcohol-thermal method to tune its photocatalysis properties, and a novel nitrogenous core-shell MIL-101(Fe)-based nanocomposite (MIL-101(Fe)@TPPE) was prepared. The results showed that the hybrid material had a higher electron-hole separation rate and lower bandgap energy, along with a faster and stronger response to visible light compared with pure MIL-101(Fe). Batch studies showed that the optimized nanocomposite (MT-5) could efficiently photo-degrade TC, and the total removal rate was up to about 95% under visible light at pH 6 Additionally, MT-5 had very high adsorption capacity for tetracycline hydrochloride (TC), and the maximum adsorption capacity could reach 576.13 mg∙g−1. The studies on degradation mechanism proved that h+ and O2- played an important role during the photodegradation process. The degradation intermediates were analyzed, and QSAR was employed to evaluate the toxicity of TC and the intermediates. Furthermore, MT-5 exhibited good cycle stability, practical application, and environmental friendliness, which indicates its excellent applicable potential for organic pollutants removal.

Photocatalytic study of TiO2 thin films modified with Anderson-type polyoxometalates (Cr, Co and Ni): Experimental and DFT study

In this work, three Anderson-type polyoxomolybdates (POMs) with general formula (NH4)6-n[XMo6O24H6]−6+n where X = Co3+, Cr3+, and Ni2+ were deposited on TiO2 thin films Furthermore, the methylene blue (MB) dye adsorption capacity and photocatalytic degradation were studied. Morphological results show that the POMs/TiO2 films have a more heterogeneous surface in terms of particle size and distribution than bare TiO2 films. Optical characterization indicated that the CrMo6/TiO2 material had the lowest band gap energy with a value of 2.8 eV. The adsorption results show that the maximum percentage of MB adsorption was 37 % for NiMo6/TiO2 while bare TiO2 has only 9.2 %. The MB adsorption on POMs-TiO2 was modeled using and the Freundlich model showed the best fit in all studied films for MB removal. The MB photodegradation values shows this tendency 12 % for bare TiO2, 55 % for NiMo6/TiO2, 73 % for NiMo6/TiO2 and, 83 % for CrMo6/TiO2. Finally, DFT calculations were performed to characterize the geometry and electronic structure of the all compounds studied in this work, with the aim to explain the observed experimental results.

Photodegradation of tetracycline antibiotic by ternary recyclable Z-scheme g-C3N4/Fe3O4/Bi2WO6/Bi2S3 photocatalyst with improved charge separation efficiency: Characterization and mechanism studies

This article argues the design of the recyclable Z-scheme g-C3N4/Fe3O4/Bi2WO6/Bi2S3 (CNFBB) photocatalyst as an efficient concept to obtain photogenerated charge carriers with high redox potential. A cost-effective magnetic CNFBB nanocomposite was fabricated via a multistep method by decorating Fe3O4, Bi2WO6, and Bi2S3 on the surface of pure g-C3N4 nanosheets. The photocatalytic capability was demonstrated for the visible-light degradation of tetracycline antibiotic (TC) in an aqueous solution. Sophisticated analytical techniques such as XRD, FTIR, elemental mapping, EDS, SEM, AFM, TEM, VSM, DRS, PL, and BET were employed for the characterization of synthesized nanomaterials. The CNFBB catalyst showed improved TC degradation activity (98 % in 105 min) under LED illumination with a remarkable degradation rate of 0.0341 min−1, which is 2.27 times higher than that of ternary CNFB. The improved photocatalytic ability was ascribed to the synergistic impacts of g-C3N4, Fe3O4, Bi2WO6, and Bi2S3 by developing a quaternary CNFBB nanostructure with a high surface area, lower band gap energy, high stability, easily recycled, excellent redox potential, and an efficient charge separation mechanism. Interestingly, the CNFBB hybrid displayed good reusability and high stability after six cycles of experiments. The photodegradation mechanism was charge migration pathways, and band locations were systematically explained by the Z-scheme heterojunction system verified by radical quenching experiments, ESR results, and band structure calculation. This work can open new horizons in designing other Bi-based systems supported by g-C3N4 nanosheets for wastewater purification.

Electronic, thermodynamic, optical and photocatalytic properties of GaAgO2 and AlAgO2 compounds scrutinized via a systemic hybrid DFT

The crystal and electronic features, bonding nature, thermal, optical, and photocatalytic aspects of GaAgO2 and AlAgO2 crystals were simulated by applying density functional theory via CASTEP tools. The computed electronic band configuration confirms that both crystals are semiconductors with indirect bandgap energies of 2.34, 0.64, 3.34, and 1.259 eV for GaAgO2 and AlAgO2, respectively, using the B3LYP and GGA with PBE techniques. The thermal stability and thermal state were obtained from thermos-physical properties. Our predicted materials show excellent conduction of electrons, oxidation ability, and charge carriers transfer to the surface rapidly due to low bandgap energy and lighter effective mass. Both the GaAgO2 and AlAgO2 crystals possess tunable band edge potential. Electron holes are generated, which are extremely capable of organic pollutant degradation and generate hydrogen and oxygen from water. It was observed that AlAgO2 crystals exhibit more robust oxidation and reduction abilities than GaAgO2 crystals. Furthermore, we found notable absorption of incident light in a visible and ultraviolet range for both GaAgO2 and AlAgO2 crystals. Finally, our theoretical outcomes demonstrated that both crystals display remarkable photocatalytic properties, making them viable candidates for visible light response photo-catalysts, such as hydrogen and oxygen production from water splitting for environmental pollutant breakdown.

Multi Stimuli Responsive Non‐Doped Red Emitting AIEE Active Phenothiazine‐Based Chalcones: Crystal Structure, Solvatochromism, Turn‐on Mechanofluorochromism and Acidochromism

AbstractWe report on a series of phenothiazine‐based D‐π‐A‐π‐D type cross‐conjugated non‐doped red‐emitting molecules synthesized by simple Claisen‐Schmidt condensation, which exhibit excellent AIEE phenomena through the formation of large‐sized nano‐aggregates. These thermally stable red fluorescent organic materials have low band gap energies (Eg=1.84–2.15 eV) and also display reversible mechanofluorochromism. The CIE chromaticity coordinates of red emissive ground powders were closer to the standard red‐light chromaticity coordinates. These chalcones also exhibited positive solvatochromism, and large Stokes shifts. Finally, these compounds were utilized as reversible volatile acid sensors to detect TFA in solution as well as in solid state, by virtue of the presence of electron withdrawing carbonyl oxygen, and they could detect TFA at a concentration as low as 15.8 ppm in the presence of C4.

Characterization of TiO2 nanofibers with enhanced photocatalytic properties prepared by plasma assisted calcination

In this article, we present a novel approach to produce titania (TiO 2 ) nanofibers with enhanced properties using plasma pre-treatment. Nanofibers were produced from electro-spun polyvinylpyrrolidone (PVP) based nanofibers with titanium(IV) isopropoxide (TTIP) as a precursor. PVP/TTIP fibers were plasma treated using diffuse coplanar surface barrier discharge (DCSBD) followed by thermal calcination at 500 °C, 600 °C and 700 °C. The morphology of nanostructures was characterized using SEM, BET and XRD, the chemical composition was analyzed by XPS, ATR-FTIR, the photocatalytic activity was evaluated by degradation of methylene blue and band gap was determined from diffuse reflectance spectra (DRS) using Tauc plot. Initial plasma treatment caused decomposition of polymer matrix, which led to faster oxidation and crystalline phase transition at lower temperature during the following thermal processing/calcination. The results showed enhanced photocatalytic properties of plasma pre-treated fibers despite the fact they possess higher proportion of rutile and lower specific surface area. UV–vis DRS measurements exhibit lower band gap energy at 700 °C, but difference between plasma treated (PT) and non-treated (NT) samples at the same temperature was not observed.

Intensification of autocatalytic methyl oleate synthesis in continuous flow rotating recycle reactor under hybrid radiation: Process optimization and Scale-up

Intensification of the autocatalytic esterification of methanol with oleic acid for producing methyl oleate (biodiesel) was accomplished using a continuous flow rotating reactor under recycle mode. To exaggerate the biodiesel yield, highly efficient hybrid electromagnetic radiation (near-infrared and microwave irradiation) was used as an energy source. Spherical-shaped nano-zinc-titanate photocatalyst (low band-gap energy: 2.01 eV and low recombination rate) was prepared and utilized in the aforementioned novel reactor. Box-Behnken statistical optimization technique was applied to attain the optimum condition (catalyst concentration 30 wt%, reaction temperature 333 K, methanol: oleic acid mole ratio 11:1, LHSV: 0.20 min−1) resulting in maximum biodiesel yield. Moreover, at optimum rotating speed (∼235 rpm), high external and internal mass transfer coefficients were achieved which rendered a remarkably augmented reaction rate under ideal reactor behavior (Dispersion number: 6.42 × 10−7). A geometric-based COMSOL model was simulated which confirmed uniformity of hybrid irradiation and temperature distribution within the rotating catalytic packed bed; which was applied for the development of a parallel-autocatalytic reaction kinetic model. Langmuir Hinshelwood kinetics of the parallel autocatalytic esterification is well represented in the experimental data (RSSQ=1.52×10-7). Without recycle stream, the reaction exhibited a non-autocatalytic reaction with a lower yield of 79.04 % biodiesel within 0.20 min−1 LHSV, whereas, under recycle mode, the biodiesel yield was increased up to 93.55 % even at a higher LHSV of 0.25 min−1. For larger-scale production of the methyl oleate, the ASPEN PLUS simulator has been deployed for a throughput scale-up factor of 1000 (geometric similarity), which corroborates well with lab-scale yield/reactor performance.

Synthesis, characterization and band gap energy of new water soluble fluorescent diethanolamine-boron-subphthalocyanine dye using B nanoparticles and SiB6 microparticles

In the present work, the novel synthesis methods were developed for the preparation of a new water soluble and fluorescent diethanolamine-boron-subphthalocyanine (Dea-B-SubPc) dye. The boron nanoparticles and SiB6 were utilized as the boron sources for the Dea-B-SubPc synthesis. In order to obtain the boron nanoparticles, the powder mixture of boron microparticles, phthalonitrile (Pn) and KCl was encapsulated into a Cu pipe and then mechanically roll-milled at room-temperature. The Dea-B-SubPc dye was synthesized via the reaction of the roll-milled boron nanoparticles and Pn in 50 % Dea-toluene solution at 120 °C. The Dea-B-SubPc was also synthesized by the reaction of Pn and SiB6 microparticles using similar experimental conditions. The prepared Dea-B-SubPc was characterized by using the SEM, FT-IR, NMR, HR-ESI-MS, cyclic voltammetry (CV), UV–vis. absorption and fluorescence (FL) emission spectroscopy. The Dea-B-SubPc is soluble in H2O, DMSO, MeOH and EtOH solvents. The optical band gap energy of the Dea-B-SubPc was found as 2.15 eV in MeOH and H2O, and 2.10 eV in DMSO. The Dea-B-SubPc solutions exhibited FL emissions at 592.2 nm in DMSO, 575.2 nm in MeOH and 577.8 nm in H2O with the excitation at 450 nm. The EHOMO and ELUMO energy levels of the Dea-B-SubPc were calculated as −5.82 eV and −4.08 eV, respectively and then the electrochemical band gap energy was found as 1.74 eV using the CV measurements. In summary, both the B nanoparticles and SiB6 microparticles were used successfully for the synthesis of the Dea-B-SubPc as a new fluorescent and low band gap energy dye material.