Integrated UV-based photo microreactor-distillation technology toward process intensification of continuous ultra-high-purity electronic-grade silicon tetrachloride manufacture

Ultra-high-purity silicon tetrachloride (SiCl₄) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl₄ has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl₄ was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm^-1 and 2160 cm^-1 indicating that characteristic vibrational modes of Si—H bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl₄ manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products.     

Optical transition properties,internal quantum efficiencies,and temperature sensing of Er3+ doped BaGd2O4 phosphor with low maximum phonon energy

The hosts with low maximum phonon energy (MPE) are preferred since the nonradiative consumption of the luminescence centers in them are low. Among the low MPE hosts, the oxide ones are more favored owing to their excellent stability and easy synthesis. In this work, the optical and spectroscopic properties of BaGd₂O₄:Er³⁺ phosphor were studied. The MPE of BaGd₂O₄ host was observed from Eu³⁺ phonon sideband (PSB) spectrum and Raman spectrum to be 477 cm⁻¹ which does not second to the fluoride hosts. The refractive index, which is indispensable for Judd–Ofelt calculation, was confirmed from the both approaches of the Eu³⁺-probe and the band gap energy, and the similar refractive indices were confirmed, therefore the average refractive index 2.01 was used in the Judd–Ofelt calculation. The Judd–Ofelt parameters of Er³⁺ in BaGd₂O₄ host was confirmed to be = 7.91 × 10⁻²¹ cm², = 2.36 × 10⁻²¹ cm², and = 9.00 × 10⁻²² cm². Furthermore, the internal quantum efficiencies for ⁴F_9/2 and ⁴I_J (J = 9/2, 11/2, and 13/2) levels were determined. Finally, the optical temperature sensing properties were studied in detail, and the temperature calibration curve was experimentally derived, meanwhile the maximum absolute sensitivity was confirmed to be 0.0028 K⁻¹.     

Synthesis and properties of unsaturated polyoxyethylene and its graft copolymers with styrene

The unsaturated polyoxyethylene (PEO) was synthesized by copolymerization of ethylene oxide with allyl glycidyl ether in toluene using bimetallic-oxo-alkoxide as a catalyst. The effects of polymerization conditions on conversion and intrinsic viscosity of the copolymer were studied. The unsaturated copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction. The relationship between crystallinity of the copolymers and conductivity of their LiClO₄ complexes were investigated. The copolymer with ∼ 65 wt % PEO content exhibits a room temperature conductivity of 1 × 10⁻⁴ S cm⁻¹ at a molar ratio of EO/Li = 20. The unsaturated PEO was graft-copolymerized with styrene using 2,2′-azobis(isobutyronitrile) as initiator in toluene, with grafting efficiency ∼ 50%. The purified graft copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction, and was shown to have good emulsifying properties and a phase-transfer catalytic property. LiClO₄ complex of the graft copolymer with 70 wt % PEO content exhibits a room temperature conductivity approaching 1 × 10⁻⁴ S cm⁻¹ at molar ratio of EO/Li = 20/1. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2417–2425, 1998     

Heterogeneous Photocatalysis in Microreactors for Efficient Reduction of Nitrobenzene to Aniline: Mechanisms and Energy Efficiency

Aniline was synthesized from nitrobenzene through photo‐induced reduction in microreactors under UV irradiation. Nitrobenzene solution and the nanofluid prepared by a TiO₂ nanocatalyst, PEG‐400, and deionized water were mixed in a capillary microreactor. The effects of catalyst composition, residence time, and substrate concentration on the reaction performance were systematically investigated. The conversion of nitrobenzene and the yield of aniline reached high values under optimized conditions. The excellent reusability of the photocatalyst was realized for four runs. A mechanism was proposed for this photocatalytic reduction process based on reaction kinetics. Both photo‐induced electrons and ^?CO₂^? could reduce nitrobenzene to aniline. The photonic efficiency in the microreactor was still much higher than that obtained in batch reactors, which was mainly attributed to the much larger effective radiation area of the microreactor.     

Structural,dielectric and magnetic properties of (ZnFe2O4/Polystyrene) nanocomposites synthesized by micro-emuslion technique

This work aims to study the effect of polymer on the structure, magnetic and dielectric properties of spinel ferrite composite. Nanocomposites based on polystyrene (PST)/ZnFe₂O₄ were synthesized by using the micro-emulsion method. The novel composites with PST to ZnFe₂O₄ ratios (4:0, 4:1, 4:2, 4:3, 4:4, 0:4) were analyzed by X-ray diffractometer (XRD) which confirms the spinel structure of ZnFe₂O₄ with an average crystallite size of 15.3 nm for pure ZnFe₂O₄ and decreases by increasing the polystyrene concentration. Field Emission Scanning Electron Microscopy (FESEM) gave the optimized results of surface morphology and the crystallite size which are in accordance with XRD data. Fourier Transform Infrared (FTIR) spectra show two main broad metal–oxygen bands corresponding to the intrinsic stretching vibrations of the metal at the tetrahedral site (observed between 837.9 and 1034.3 cm⁻¹) and traces of organic materials were observed at 1499.2 and 1766.4 cm⁻¹, which are associated with CO and CC stretching vibration respectively. O–H stretch of COOH weak acid of the carboxyl group was found at 2978.7 cm^-1. The composite with equal ZnFe₂O₄ to PST ratio (4:4) shows that real part of dielectric constant is independent of frequency at lower frequencies of an applied electric field. The resonance type behaviour was observed at higher frequency (2.5 GHz) which shows the material is excellent for dispersion of electric part of microwaves. The magnetization for pure ferrite (ZnFe₂O₄) at 15000 Oe was found to be 1.49 emu/g which decreases to 0.54 emu/g for the composite with the equal ferrite to polystyrene ratio. Based on their dielectric and magnetic characterization, these composites are considered suitable candidates to employ as microwave absorbing materials.     

Degradation of red lead pigment in the oil painting during UV aging

The degradation product and mechanism of red lead pigment (Pb₃O₄, minium) in pure powder and in modeled oil painting are dynamically tracked during ultraviolet light aging by the change of color, crystal structure, chemical composition, and surface morphology. After UV aging, the color of pure minium pigment gradually darkens from bright orange‐red into black, but the color of model paint samples made by minium and tung oil binder changes into brownish and whitish color (ΔE^* = 56.60). After aging, the crystal structure of Pb₃O₄ powder is proved to transfer into plattnerite (β‐PbO₂) by X‐ray diffraction (XRD) pattern, but the degradation product of Pb₃O₄ in model paint samples is identified as 2PbCO₃·Pb(OH)₂ by the noticeable peaks at 24.8°, 27.4°, and 34.3° in XRD pattern, and two new Fourier transform infrared peaks at 1393 cm^?1 and 682 cm^?1 attributed to the presence of , and a new peak at 1051 cm^?1 in Raman spectroscopy. During UV aging, the model paint samples' surface is verified gradually from wrinkled surface into nanoscale sheet‐like structure and finally a regular hexagonal plate‐like crystal structure, showing hexagonal crystals of hydrocerussit 2PbCO₃·Pb(OH)₂. This reveals the interaction between organic tung oil binder and inorganic minium to accelerate the degradation of Pb₃O₄ pigment. Therefore, the degradation mechanism is deduced as that CO₂ and H⁺ formed by oxidizing ester/carboxyl groups in tung oil reacts with Pb²⁺ to yield the white product of 2PbCO₃·Pb(OH)₂. It is believed that this study will contribute much to the complete understanding of the degradation of minium pigment in oil paintings.     

Photo Assisted Fenton in a Batch and a Membrane Reactor for Degradation of Drugs in Water

Abstract

Some advanced oxidation processes (AOP's) such as Fenton H₂O₂/Fe²⁺, photo assisted Fenton UV/H₂O₂/Fe²⁺, UV photolysis, and photo assisted Fenton—like UV/O₂/Fe²⁺ have been tested for the degradation of Gemfibrozil in aqueous solution in a batch system and then in a membrane reactor. A nanofiltration/reverse osmosis type cross‐linked polyamide, UTC‐60 (Toray) membrane (19 cm²) was used. In the batch degradation tests, the gemfibrozil, used at 5 mg/L, was degraded by employing the four AOP's but numerous peaks of intermediates were observed at the HPLC. Indeed DOC analyses showed poor mineralization in the case of photolysis (3.1%) and UV/O₂/Fe (10%), while it was 62% using the photo assisted Fenton and 24% using the Fenton. Thus in the membrane reactor only the Fenton and the photo assisted Fenton were tested. Obtained results showed a drug degradation higher than 92%, a mineralization higher than 55%, and a membrane retention of the catalyst in solution higher than 95%.     

[Ca24Al28O64]4+(4e−) are directly and quickly synthesized by self-reduction of C12H10Ca3O14 + Al2O3 without any reducing agent

C₁₂H₁₀Ca₃O₁₄ + Al₂O₃ powders are used as precursors, and the dense [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) (C12A7:e⁻) ceramic block with high electron density is quickly synthesized in one step under a spark plasma sintering (SPS) process with a temperature of 1000°C and a time of 5 minutes. The microstructure and composition analysis results show that the synthesized C12A7:e⁻ is dense (99.7%), has no defects, and no impurities are introduced. The electronic structure analysis results show that the electron concentration of the sample is 2 × 10²¹ cm⁻³. This method realizes the self-reduction of the sample through the CO gas generated during the sintering process, avoids the introduction of impurities, and dramatically simplifies the process. These results provide a potential path for the rapid fabrication of a large number of C12A7:e⁻ with high electron concentration and provide a basis for its practical applications such as cold cathode fluorescent lamp and catalyst carrier.     

NIR-responsive Fe3O4@PPy nanocomposite for efficient potential use in photothermal therapy

In this work, superparamagnetic Fe₃O₄@PPy nanocomposite with core-shell structure having strong near-infrared (NIR) absorption is synthesized via a facile two-step modified procedure. The prepared nanocomposite samples are characterized by UV–vis, FTIR, SEM, TEM, VSM, and XRD. The effects of laser power density (1.5–2.5 W cm⁻²) and aqueous concentration (0.01–0.2 mg ml⁻¹) of the nanocomposite on the photothermal performance are investigated in the NIR region (808 nm). At 0.1 mg ml⁻¹ concentration, the temperature reaches up to 50.1°C, 64.1°C, and 78.4°C within 10 min, under 1.5 W cm⁻², 2.0 W cm⁻², and 2.5 W cm⁻² NIR laser power density values, respectively. Photothermal conservation efficiency is calculated as 43.9% and the nanocomposite exhibits excellent photothermal stability. In summary, the core-shell Fe₃O₄@PPy nanocomposite is a promising candidate for photothermal therapy and simultaneous magnetic field-guided treatments.     

Synthesis and characterization of polypyrrole using TiO2 nanotube@poly(sodium styrene sulfonate) as dopant and template

A polypyrrole (PPy) using TiO₂ nanotube@poly(sodium styrene sulfonate) (TiO₂@PSS) as dopant and template was synthesized by chemical oxidation polymerization. The template TiO₂@PSS consisting of a TiO₂ nanotube core and PSS on the surface was prepared by a “grafting from” approach. PPy on the layer of TiO₂@PSS (TiO₂@PSS/PPy) was characterized by transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectrometry (FTIR), Raman spectroscopic analysis, UV‐visible (UV‐vis) spectroscopy, thermo gravimetric analysis, and electrical conductivity analysis. Results showed that TiO₂@PSS/PPy was successfully fabricated. The electrical conductivity of the TiO₂@PSS/PPy nanocomposites at room temperature was 11.6 S cm⁻¹, which was higher than that of the PPy (4.2 S cm⁻¹). This result was consistent with those based on FTIR, UV‐vis spectroscopy, and XPS analyses. The nanocomposites have nanoparticle size and controllable morphology and thus potential applications in photoelectrochemical devices, photocatalytic devices, conductive inks, electronic printing sensors, and electrodes. POLYM. COMPOS., 37:462–467, 2016. © 2014 Society of Plastics Engineers     

Elucidation of Interactions between l-Ascorbic Acid and Mixed Micellar Aggregates of Catanionic {Sodium Dodecylsulfate + Cetyltrimethylammonium Bromide} Surfactants via Physicochemical and Spectroscopic Studies

Surfactant micelles mimic the microenvironment present in biological systems and can act as a medium for antioxidant studies. Moreover, the thermodynamic profile of micellization and spectroscopic studies provides very good information about interactions in these systems. Thus, the mixed micellar behavior of sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) at varying mole fractions of SDS was studied in (0.01, 0.02, and 0.03) mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions with the aid of various techniques viz., conductivity, density and sound velocity, and spectroscopy. From the CMC values of the mixed surfactants, the degree of ionization (β) and thermodynamic parameters (, , and ) were evaluated at 298.15, 308.15, and 318.15 K. The UV absorption spectra were recorded in (1–3) × 10⁻⁴ mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions at various mole fractions of SDS. The proton (¹H) NMR spectra of mixed (SDS + CTAB) surfactants were studied in (0.01–0.03) mol kg⁻¹ ʟ-ascorbic acid solutions. Hydrodynamic diameters (D_h) of mixed micellar aggregates were obtained from the dynamic light scattering (DLS) studies. The present studies suggest the predominance of ionic-hydrophilic interactions between the ionic head groups {O-SO₃⁻ or N⁺ (CH₃)₃} of surfactants and the polar (–OH, –C=O and –O–) sites of ʟ-ascorbic acid.     

Novel approach in synthesizing ternary GO-Fe3O4-PPy nanocomposites for high Photothermal performance

In this study, graphene oxide-iron oxide-polypyrrole (GO-Fe₃O₄-PPy) ternary nanocomposites having high photothermal activity and stability are synthesized and analyzed using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and magnetic hysteresis measurement (VSM). The effect of power density (1.5–2.5 W cm⁻²), concentration (0.01–0.2 mg mL⁻¹), and component composition of nanocomposites on the photothermal properties in the near-infrared (NIR) region (808 nm) is examined. The results show that superparamagnetic GO-Fe₃O₄-PPy ternary nanocomposite exhibits excellent photothermal performance. The temperature reaches to 55.5, 72.3, and 83.1 °C under the irradiation of the 808 nm NIR laser at 1.5, 2.0^—, and 2.5 W cm⁻² of power density for 10 min at 0.1 mg mL⁻¹ photothermal therapy (PTT) agent, respectively, and moreover it has excellent photothermal stability. In summary, it is concluded that synthesized nanocomposites potentially may be used in simultaneous magnetic field-guided treatments. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48837.     

Effect of Fe3+ substitution on the structural modification and band structure modulated UV absorption of hydroxyapatite

The effect of Fe³⁺ ionic substitution in hydroxyapatite (Ca_10-xFe_x(PO₄)₆(OH)₂) was studied using structural modifications, resulting in an improvement in UV absorption through a tailored optical band structure. Ca²⁺ of HA being larger compared to Fe³⁺ contributes to the shrinkage of the lattice. Undoped HA has a peak at 1085 cm⁻¹ (ʋ₃ PO₄³⁻) which is shifted to 1033 cm⁻¹ for Fe-HA, because of the perturbation in HA structure. An improvement of UV absorption in the entire UVA and UVB range with an increase in Fe content because of a decrease in bandgap from 5.9 eV to 2.1 eV with undoped and doped HA. Theoretically obtained band gap and optical behaviour of the systems are well correlated with the experimental findings. Moreover, the use of marine biowaste from cuttlefish bone, as the source of HA; low cost and promising UV absorption can have a potential application as UV protective sunscreen filters.     

Viscoelastic Behavior of Synthesized Liquid Soaps and Surface Activity Properties of Surfactants

In the present work, a rheological study of liquid soaps prepared from different mixture of surfactants as a function of surfactant type and concentration was performed. The curves of shear stress vs. shear rate and viscosity vs. shear rate were recorded at constant temperature, 294 ± 0.1 K. The surface activity properties were also studied. The results of the study showed that values of surface tension, γ, were in the range 31–40 mN m⁻¹ and the critical micelle concentration (CMC), was of the order 10⁻⁴ mol L⁻¹. The calculated maximum surface excess, Γ_max, varied from 2.40 to 3.66 μmol m⁻², while minimum area per molecule, A_min, varied from 41.1 (for amphoterics) to 81.4 Ų (for nonionic surfactants). The standard free energy of micellization, −29.8 and −29.3 kJ mol⁻¹ for anionic and amphoteric surfactants, respectively, were while values for nonionic surfactants varied between −31.8 and − 30.3 kJ mol⁻¹. The free energy of adsorption, was the lowest for amphoteric surfactants (−37.9 kJ mol⁻¹), followed by anionics (−40.4 kJ mol⁻¹) and nonionics (−43.34 to −46.84 kJ mol⁻¹), indicating that micellization process is spontaneous in the examined medium. The synthetized liquid soaps show pseudoplastic behavior and they achieved pipe flow. The results of this research indicate that flow behavior was affected significantly by the ionic charge of the surfactant and the ionic strength of the formulation, suggesting that the flow behavior could be changed by manipulating the choice of the surfactant and salinity. The pH value of all liquid soaps examined were weakly acidic, in the range of 5.0–6.4.     

High-Performance All-Solid-State Supercapacitor Electrode Materials Using Freestanding Electrospun Carbon Nanofiber Mats of Polyacrylonitrile and Novolac Blends

Herein, this paper reports a facile method to prepare electrospun carbon nanofiber mats (ECNFMs) with high specific surface area and interconnected structure using polyacrylonitrile (PAN) as a precursor and novolac resin (NOC) as a polymer sacrificial pore-making agent. Without additional treatment, the prepared ECNFMs have a highly porous structure because NOC decomposes in a wider temperature range than most polymer activators. The NOC content in the PAN nanofibers shows important effects on porosity. The BET specific surface area of ECNFMs reaches a maximum of 1468 m² g⁻¹ when the precursor nanofibers contained 30 wt% NOC (ECNFM-3) after carbonization at 1000 °C. The supercapacitor device from ECNFM-3 electrode and all-solid-state electrolyte shows excellent cycling durability and high specific capacitance: ≈99.72% capacitance retention after 10 000 charge/discharge cycles and ≈320 mF cm⁻² at 0.25 mA cm⁻². Furthermore, it shows a large energy density of ≈11.1 $\mu$Wh cm⁻² under the power density of 500 mW m⁻². Activation of carbon nanofibers simply by the addition of NOC into precursor nanofibers can offer a handy way to prepare ECNFMs for high-performance all-solid-state supercapacitors and other potential applications.     

Effect of pro‐oxidants on biodegradation of polyethylene (LDPE) by indigenous fungal isolate,Aspergillus oryzae

Proxidant additives represent a promising solution to the problem of the environment contamination with polyethylene film litter. Pro‐oxidants accelerate photo‐ and thermo‐oxidation and consequent polymer chain cleavage rendering the product apparently more susceptible to biodegradation. In the present study, fungal strain, Aspergillus oryzae isolated from HDPE film (buried in soil for 3 months) utilized abiotically treated polyethylene (LDPE) as a sole carbon source and degraded it. Treatment with pro‐oxidant, manganese stearate followed by UV irradiation and incubation with A. oryzae resulted in maximum decrease in percentage of elongation and tensile strength by 62 and 51%, respectively, compared with other pro‐oxidant treated LDPE films which showed 45% (titanium stearate), 40% (iron stearate), and 39% (cobalt stearate) decrease in tensile strength. Fourier transform infrared (FTIR) analysis of proxidant treated LDPE films revealed generation of more number of carbonyl and carboxylic groups (1630–1840 cm⁻¹ and 1220–1340 cm⁻¹) compared with UV treated film. When these films were incubated with A. oryzae for 3 months complete degradation of carbonyl and carboxylic groups was achieved. Scanning electron microscopy of untreated and treated LDPE films also revealed that polymer has undergone degradation after abiotic and biotic treatments. This concludes proxidant treatment before UV irradiation accelerated photo‐oxidation of LDPE, caused functional groups to be generated in the polyethylene film and this resulted in biodegradation due to the consumption of carbonyl and carboxylic groups by A. oryzae which was evident by reduction in carbonyl peaks. Among the pro‐oxidants, manganese stearate treatment caused maximum degradation of polyethylene. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A Shock Tube Study of the Reactions of H Atoms with COS,CS2, and H2S

Reactions of H atoms with COS, CS₂, and H₂S were studied behind reflected shock waves at temperatures between 1170 K and 1830 K and pressures around 1.0 bar by applying atomic resonance absorption spectroscopy (ARAS) for time-resolved measurements of H atoms at L_α. The thermal decomposition of a few ppm ethyl iodide (C₂H₅I) was used as a H-atom source. In the presence of a large excess of the molecular reactant COS, CS₂, or H₂S, a consumption of H was observed which follows a pseudo first-order rate law. Rate coefficients for the reactions: were determined to be: k₁ = 2.4 × 10¹⁴exp(–3415 K/T) cm³mol⁻¹s⁻¹ k₂ = 1.4 × 10¹⁵exp(–9250 K/T) cm³mol⁻¹s⁻¹ k₃ = 2.5 × 10¹⁴exp(–2890 K/T) cm³mol⁻¹s⁻¹     

Microwave and terahertz properties of porous Ba4(Sm,Nd,Bi)28/3Ti18O54 ceramics obtained by sacrificial template method

Microwave and terahertz communications are increasingly significant, however, the lack of material information in terahertz band limits their development. Moreover, few lightweight materials with a high relative dielectric constant () are found suited for satellite communication and wearable devices. In this study, we developed lightweight porous Ba₄[(Sm_0.1Nd_0.9)_0.9Bi_0.1]_28/3Ti₁₈O₅₄ (BSNBT) ceramics exhibiting a total porosity ranging from 6.3% to 26.5% (bulk density ranging from 5.47 to 4.29 g/cm³) and relatively high ranging from 85.6 to 56.8, which were obtained by sacrificial template method using polymethyl methacrylate spheres (PMMAs) of varying average particle sizes, from 9 to 34 μm, as sacrificial materials. A high refractive index ranging between 7.5 and 8.9 and a low absorption coefficient of approximately 17 cm⁻¹ at 0.3 THz were obtained for the porous ceramics with different total porosities derived from PMMAs with average particle sizes of 9 and 19 μm. Furthermore, effective medium and Mie scattering theories were applied to understand the effects of porous structure on the dielectric properties in microwave and terahertz frequency ranges, respectively, owing to the different wavelengths in the BSNBT matrix. The results of this study suggest that introducing a porous structure can effectively exploit lightweight microwave dielectric ceramic materials and provide valuable information on their terahertz response mechanism.