The comparative study of photocatalytic self‐cleaning properties of synthesized nanoscale titania and zirconia onto polyacrylonitrile fibers

The photocatalytic activity of TiO₂ and ZrO₂‐coated polyacrylonitrile (PAN) fibers was compared through the self‐cleaning of methylene blue and eosin yellowish. TiO₂ and ZrO₂ nanocrystals were successfully synthesized and deposited onto PAN fibers with photocatalytic self‐cleaning activity using the sol‐gel process at low temperature. The pristine and treated samples have been characterized by several techniques, such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The TiO₂ nanoparticles with 10–20 nm in size, and ZrO₂ with 20–40 nm have been synthesized to form dispersed particles on the fiber surface, which shows photocatalytic properties when exposed to UV–Vis light. The photocatalytic activity, tested by measuring the degradation of adsorbed methylene blue and Eosin Y. Photocatalytic activity of TiO₂‐coated fibers toward dyes degradation was higher than that of ZrO₂‐coated fibers. This preparation technique can be also applied to new fabrics to create self‐cleaning and UV irradiation protection properties in them. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Sonochemical deposition of silver nanoparticles on wool fibers

Silver nanoparticles were deposited on the surface of natural wool with the aid of powered ultrasound. The average particle size was 5–10 nm, but larger aggregates of 50–100 nm were also observed. The sonochemical irradiation of a slurry containing wool fibers, silver nitrate, and ammonia in an aqueous medium for 120 min under an argon atmosphere yielded a silver–wool nanocomposite. By varying the gas and reaction conditions, we could achieve control over the deposition of the metallic silver particles on the surface of the wool fibers. The resulting silver‐deposited wool samples were characterized with X‐ray diffraction, transmission electron microscopy, high‐resolution transmission electron microscopy, high‐resolution scanning electron microscopy, electron‐dispersive X‐ray analysis, Brunauer, Emmett, and Teller physical adsorption method, X‐ray photoelectron spectroscopy, and Raman and diffused reflection optical spectroscopy. The results showed that the strong adhesion of the silver to the wool was a result of the adsorption and interaction of silver with sulfur moieties related to the cysteine group. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1732–1737, 2007     

Photoactive behavior of polyacrylonitrile fibers based on silver and zirconium co‐doped titania nanocomposites: Synthesis,characterization, and comparative study of solid‐phase photocatalytic self‐cleaning

Silver and zirconium co‐doped and mono‐doped titania nanocomposites were synthesized and deposited onto polyacrylonitrile fibers via sol–gel dip‐coating method. The resulted coated‐fibers were characterized by X‐ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, thermogravimetric analysis, and BET surface area measurement. Photocatalytic activity of the TiO₂‐coated and TiO₂‐doped coated fibers were determined by photomineralization of methylene blue and Eosin Y under UV–vis light. The progress of photodegradation of dyes was monitored by diffuse reflectance spectroscopy. The XRD results of samples indicate that the TiO₂, Ag‐TiO₂, Zr‐TiO₂, and Ag‐Zr‐TiO₂ consist of anatase phase. All samples demonstrated photo‐assisted self‐cleaning properties when exposed to UV–vis irradiation. Evaluated by decomposing dyes, photocatalytic activity of Ag–Zr co‐doped TiO₂ coated fiber was obviously higher than that of pure TiO₂ and mono‐doped TiO₂. Our results showed that the synergistic action between the silver and zirconium species in the Ag‐Zr TiO₂ nanocomposite is due to both the structural and electronic properties of the photoactive anatase phase. These results clearly indicate that modification of semiconductor photocatalyst by co‐doping process is an effective method for increasing the photocatalytic activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Assembly of TiO2 Nanoparticles into Micrometer‐Sized Structures,Photocatalytically Active Under UV and Vis Light

Micrometer‐sized structures consisting of TiO₂ nanoparticles were prepared using the sol–gel technique in combination with the structure‐directing agent triethanolamine (TEA). The interaction of the TEA with the hydrolyzed sol–gel products led to the formation of TEA titanate complexes, which then enabled the assembly of sol–gel‐precipitated nanosized powders. A subsequent thermal treatment of these powders resulted in the formation of micrometer‐sized structures consisting of TiO₂ anatase and rutile nanoparticles. To characterize the prepared powders, FTIR spectroscopy, XRD analysis, the Brunauer‐Emmett‐Teller method (s_BET), UV–Vis spectrometry and electron microscopy (FE‐SEM, and TEM) were employed. The photocatalytic degradation of the azo dye known as methylene blue was monitored under UV and Vis irradiation and showed that the micrometer‐sized structures consisting of TiO₂ nanoparticles exhibited a similar photocatalytic activity to submicrometer‐sized structures consisting of TiO₂ nanoparticles prepared without TEA.     

Effect of wettability and silicone surface modification on the self‐cleaning functionalization of wool

Self‐cleaning wool has been realized by treatment with a colloidal sol of anatase nanocrystals. However, the mechanical properties of wool have been significantly deteriorated following the self‐cleaning functionalization treatment. To minimize the undesirable side‐effects induced by the nanocoating, a silicone surface modification post‐treatment has been introduced. The change in mechanical properties of TiO₂‐coated wool after modification with silicone was examined, and the effect of this process on the photocatalytic activity and its stability was assessed by a degradation test of food stains. Moreover, the wettability of wool has been modified using different nonionic wetting agents, in an attempt to shorten the wetting time during dip‐coating and the absorption rate was compared. The effect of wetting agents on the functionalization process and the photocatalytic activity was examined. The synchronized effect of wettability and silicone surface modification on the self‐cleaning functionalization of wool was also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of surface‐modified zinc oxide as cure activator on the properties of a rubber compound based on NR/SBR

Zinc oxide (ZnO) and nano‐zinc oxide (nZnO) were surface modified by polyethylene glycol (PEG) and poly propylene glycol (PPG). Modification of particles were controlled by transmission electron microscopy, Brunauer, Emmett, Teller specific surface area measurement, infrared (IR) spectroscopy, and differential scanning calorimetry. IR spectra were shown that the interactions between surface modifiers and particles are hydrogen bonding. Modified particles were applied as an activator in vulcanization of natural rubber/styrene butadiene rubber (NR/SBR) blend. Dispersion of modified particles in rubber matrix was investigated by scanning electron microscopy and shown good results. Blend properties were improved by using modified particles. These improvements were due to the better hydrophobicity of modified particles, which were more compatible with nonpolar rubber matrix and caused better participation in curing process. Modification by PEG and PPG were shown better compound properties for ZnO and nZnO, respectively. Application of ZnO‐modified particles were presented better compound properties in comparison with nZnO‐modified particles. It has confirmed more effective mixing of ZnO‐modified particles in rubber matrix by using ordinary mixers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Nitrogen‐ and Oxygen‐Enriched Carbon With Square Tubular Structure Prepared From Polyaniline as Electrode for Supercapacitors

Square tubular carbon with a large number of surface functional groups are prepared by carbonizing and activating polyaniline, which are synthesized by polymerization of aniline with a template‐free self‐assembly method in aqueous media. The physicochemical properties of the square tubular carbon is characterized by scanning and transmission electron microscopy, Brunauer–Emmett–Teller surface area measurements, Raman spectroscopy, and X‐ray photoelectron spectroscopy measurements. When used as an electrode, the square tubular carbon exhibit a specific capacitance of 223 F g^–1 at a scan rate of 2 mV s^–1, which could still stay over 90% when the scan rate increased by 10 times. The specific capacitance even hardly decrease at a current density of 3 A g^–1 after 10,000 cycles, which indicates that the square tubular carbon have good cycle durability and may be a promising candidate as an electrode for supercapacitors.     

Simultaneous coloration and functional finishing of cotton fabric using Ag/ZnO nanocomposite

In this study, colored cotton fabric with special functions, including self‐cleaning, anti‐bacterial, and ultraviolet (UV) blocking were prepared by applying zinc oxide as a photocatalyst and using silver nanoparticles as both a novel class of colorant for coloration and an agent capable of modifying the zinc oxide nanoparticles. The homogenous distribution of Ag/ZnO nanocomposite on the fibre surface was confirmed by field emission scanning electron microscopy (FE‐SEM), Energy‐dispersive X‐ray spectroscopy (EDS) and X‐ray mapping. X‐ray diffraction patterns showed the presence of the nanocomposite on the treated cotton fabric. The results indicated that adding silver nanoparticles to zinc oxide led to better self‐cleaning properties, even the photocatalytic activity of ZnO had no negative effect on fabric colour. Moreover, this process imparted proper anti‐bacterial properties and UV‐blocking activity to cotton fabrics.     

Preparation of nano‐ZIF‐8 in methanol with high yield

This article systematically presented analysis results of factors affecting the preparation of nano‐ZIF‐8 in methanol for high yield. Samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Brunauer‐Emmett‐Teller (BET) adsorption, and thermogravimetry‐differential thermal analysis (TG/DTA). Synthesized nano‐ZIF‐8 had advantages over commercial ZIF‐8 (Basolite^® Z1200 from Sigma‐Aldrich) such as a higher surface area, consisting of not only micropores like Basolite^® Z1200 but also subordinate mesopores, formed by an assembly of nano‐ZIF‐8 crystals, which was 30 nm. Specifically, for the first time, nano‐ZIF‐8 was prepared in methanol with the yield of 61.2 %.

     

Highly Efficient Room Temperature Synthesis of Silver‐Doped Zinc Oxide (ZnO:Ag) Nanoparticles: Structural,Optical, and Photocatalytic Properties

Synthesis of silver‐doped zinc oxide (ZnO:Ag) nanoparticles through precipitation method has been reported. The synthesis was conducted at room temperature and no subsequent thermal treatment was applied. ZnO nanoparticles were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), fourier transmission infrared spectroscopy (FTIR), and ultraviolet‐visible (UV–Vis) spectroscopy. Detailed crystallographic investigation was accomplished through Rietveld refinement. The effect of silver content on structural and optical properties of resultant ZnO nanoparticles has been reported. It was found that silver doping results in positional shifts for the XRD peaks and the absorption band edge of ZnO. These were attributed to the substitutional incorporation of Ag⁺ ions into Zn²⁺ sites within the ZnO crystal. In addition, higher silver incorporation resulted in smaller size for ZnO nanoparticles. The photocatalytic activity of the ZnO:Ag nanoparticles was also determined by methylene orange (MO) degradation studies and compared to that of undoped ZnO. Improved photocatalytic activity was obtained for ZnO:Ag nanoparticles. It has been shown that an optimum amount of silver dopant is required to obtain maximum photocatalytic activity.     

Promoted Fe2O3‐Al2O3‐CuO Chromium‐Free Catalysts for High‐Temperature Water‐Gas Shift Reaction

Promoted Fe₂O₃‐Al₂O₃‐CuO (FAC) chromium‐free catalysts were prepared for high‐temperature water‐gas shift reactions and characterized by X‐ray diffraction (XRD), Brunauer‐Emmett‐Teller method (BET), temperature‐programmed reduction (TPR), and transmission electron microscopy (TEM) techniques. The catalytic results revealed that among the investigated promoted catalysts with Ce, La, Zn, Y, and Mn as promoters, the Mn‐promoted sample showed higher activity compared to the other promoted catalysts. Increasing the Mn content improved the surface area and catalytic activity. The FAC catalyst promoted with a high Mn content exhibited maximum activity and relatively high stability in high‐temperature water‐gas shift reaction.     

Nano‐hydroxyapatite (HAp) and hydroxyapatite/platinum (HAp/Pt) core shell nanorods: Development,structural study,and their catalytic activity

The development of a new kind of material that is a nanostructured catalytic material with an environmentally benign nature that can be used for alternative energy has acquired significance in recent years. In this context, the use of heterogeneous catalysts for the transesterification of vegetable oils has gained prominence due to their eco‐friendly and reusable nature. Hence in the present study, pure hydroxyapatite (HAp) and hydroxyapatite/platinum (HAp/Pt) nanostructured particles have been prepared successfully through a facile chemical method without templates and surfactants and their catalytic activity investigated for transesterification of natural vegetable oil to bioenergy (biodiesel). The textural and structural features of pure HAp and HAp/Pt were investigated using various characterization techniques such as x‐ray diffraction, Fourier transform infrared (FTIR) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The elements present in the prepared nanostructures were confirmed through energy dispersive spectroscopy (EDS) and x‐ray photoelectron spectroscopy (XPS) techniques. The XPS analysis also confirms the metallic nature of the platinum in HAp/Pt. The specific surface area and porous nature of the prepared nanostructured catalysts were studied using the N₂ physisorption Brunauer‐Emmett‐Teller‐Barrett‐Joyner‐Halenda (BET‐BJH) method. The catalytic activity of the pure HAp nanoparticles and HAp/Pt core shell nanorods with the Simarouba glauca plant seed oil was investigated. The obtained results indicate that the pristine HAp nanoparticles and HAp/Pt core shell nanorods (NRs) show 91.4% and 87.1% fatty acid methyl ester (FAME) conversion, respectively, potentially offering environmental benign biocatalysts for biofuel production from natural feed stock.     

Seed‐Free Synthesis and Characterization of Zeolite Faujasite Aluminosilicate Coating on α‐Alumina Supports

NaY zeolite was synthesized by a simple sol–gel technique. NaY zeolite membrane was formed on the alumina substrate using optimized solution composition and synthesis conditions. The formation of the NaY zeolite was ascertained by X‐ray powder diffraction, which showed that the crystallinity improved with annealing. The high‐resolution transmission electron microscopy images of samples annealed at 300°C showed the formation of cubic structure corresponding to NaY zeolite. Brunauer–Emmett–Teller analysis revealed that the synthesized zeolite is a well crystallized NaY zeolite. The SEM images revealed the formation of fine structure NaY zeolite membrane on α‐alumina substrate.     

Optimization of Process Variables for Biodiesel Production Using the Nanomagnetic Catalyst CaO/NaY‐Fe3O4

Due to decreasing oil resources, alternative fuels such as biodiesel are required. The nanomagnetic catalyst CaO/NaY‐Fe₃O₄ was synthesized and used for biodiesel production from canola oil. The structure of the catalysts was characterized by X‐ray diffraction, field emission scanning electron microscopy, Brunauer‐Emmett‐Teller method, Fourier transform infrared spectroscopy, and vibrating sample magnetometer method. To optimize the influence of the operating variables, such as the methanol/canola oil molar ratio, the amount of catalyst, and the reaction time, on the yield of transesterification reaction, an experimental design was applied based on the Box‐Behnken method. The optimum values of these variables were predicted by the cubic model and were in excellent agreement with the experimental results.     

Facile Ion‐Exchange Synthesis and Visible Light Photocatalytic Studies of Cu2+, Sn2+, and Ag+‐Substituted LiMg0.5Ti0.5O2

A novel series of visible light‐sensitive Cu²⁺, Sn²⁺, and Ag⁺‐substituted LiMg_0.5Ti_0.5O₂ photocatalysts were synthesized by a facile ion‐exchange method and characterized by XRD, UV‐Vis diffuse reflectance spectra, scanning electron microscopy equipped with an X‐ray energy‐dispersive spectroscopy, Brunauer‐Emmett‐Teller surface area, inductively coupled plasma mass spectrometry, and thermal gravimetric analysis. The characterization results showed that morphology, crystallite size, and surface areas of the ion‐exchange products were almost similar to the parent compound. Absorption edges of Ag⁺‐doped (AMT), Cu²⁺‐doped (CMT), and Sn²⁺‐doped (SMT) samples were red shifted remarkably into the visible light region while parent LiMg_0.5Ti_0.5O₂ (LMT) was UV active. Photocatalytic activity of these samples was evaluated by studying the degradation of methylene blue and nitro benzene under visible light irradiation and the stability of all samples during photocatalytic experiment was also investigated. The activity of all photocatalysts was ranked accordingly as SMT ≥ AMT > CMT > LMT. The correlation between photocatalytic properties, band gap energy, rate of recombination of the charge carriers, and amount of ^●OH radicals generated during photocatalysis and the underlying reasons were discussed.     

Direct formation of “artificial wool” nanofiber via two‐spinneret electrospinning

To reproduce the excellent characteristics of natural fibers like wool and proteins, a novel two‐spinneret electrospinning technology was demonstrated in this communication, which can generate three‐dimensional self‐crimp fibers of HSPET/PTT, HSPET/PAN and PU/PAN directly. In the apparatus, two spinnerets were used to prevent gel formation or precipitation of the polymer, and the voltages of opposite polarities were applied to the spinnerets respectively. And the elecctrospun fibers morphology was observed by using scanning electron microscopy (SEM). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Self‐Assembled PMMA Porous Membranes Decorated with In Situ Synthesized ZnO Nanoparticles with UV‐Tunable Wettability

This study reports a simple approach to fabricate porous poly(methyl methacrylate) (PMMA) membranes homogeneously decorated with exposed zinc oxide (ZnO) nanoparticles (NPs). This fabrication method significantly overcomes the disadvantages of both conventional foaming processes and incorporation of inorganic NPs in polymeric matrices. In particular, the porous structure is simply self‐assembled by slowly evaporating a suitable solvent. The ZnO NPs are in situ formed by a thermally activated conversion of the zinc acetate precursor, previously embedded in the polymeric matrix. Scanning and transmission electron microscopy investigations show the formation of the desired self‐assembled highly porous structure and ZnO NPs with branched morphology, respectively. The wetting behavior of the membranes surface is studied as a function of the ZnO content and UV irradiation, exploiting the switchable wettability of ZnO. The obtained unexpected results are then tentatively rationalized taking into account the surface chemistry and the roughness that arises from both porous structure and the different NPs dimensions and content.     

A facile approach to fabricate porous nylon 6 nanofibers using silica nanotemplate

Porous Nylon 6 nanofibers were prepared using silica nanoparticles as the template. Firstly, Nylon 6/silica composite nanofibers were prepared as precursors by electrospinning Nylon 6 solutions containing different contents of silica nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and the inner structure of composite nanofibers; where it was found that silica nanoparticles were distributed both inside and on the surface of nanofibers. Analytical techniques [Fourier transform infrared (FTIR), differential scanning calorimetry, thermal gravimetric analysis (TGA), and wide‐angle X‐ray diffraction) were used to study the structure and properties of these composite nanofibers. The glass transition, melting, and crystallization processes of the fibers were affected by the addition of silica nanoparticles. Secondly, porous Nylon 6 nanofibers were obtained by removing silica nanoparticles via hydrofluoric acid treatment. The removal of silica nanoparticles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of the porous structure in these nanofibers. After the formation of the porous structure, Brunauer–Emmett–Teller specific surface areas of nanofibers were increased as compared to solid Nylon 6 and composite nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of zinc oxide and carbon nanotube composites by CVD method: photocatalytic studies

The present work describes the synthesis of multiwall carbon nanotubes (CNT), zinc oxide (ZnO) and their photocatalytic evolutions. Nickel doped fumed SiO₂ used as substrate for the synthesis of CNT by in chemical vapour deposition method. In-situ synthesis of ZnO:CNT composites was achieved in alkaline ethanolic medium with zinc chloride and CNT. The prepared composites were investigated by the Fourier Transform Infrared spectroscopy, confocal Raman spectroscopy, diffuse reflectance UV–visible spectrophotometer (DRS), X-ray diffraction, X-ray Photoelectron Spectroscopy (XPS), Brunaur–Emmett–Teller surface area and field emission scanning/transmission electron microscopy. The composites were employed in the degradation methylene blue and Reactive red-198 under visible light irradiation. The photocatalytic activity was determined by the spectrophotometric technique. The percentage of degradation was more for ZnO:CNT composites and shows higher capacitance, when compared to that of ZnO and CNTs. The recovered and reused catalysts catalytic activity was compared with that of fresh catalyst.