Synthesis of TiO2 Hybrid Molecular Imprinted Nanospheres Linked by Silane Coupling Agent

This article presents work on designing TiO₂ hybrid MIP nanospheres via precipitation polymerization using methacrylic acid (MAA) as functional monomer and silane coupling agent 3-(trimethoxysilyl) propylmethacrylate (KH570) as organic–inorganic connective bridge. Hydrogen bond was proved to act between MAA and template bensulfuron-methyl (BSM) for pre- and post-polymerization as testified by infrared spectrometry (IR). Scanning electron microscope (SEM), transmission electron microscope (TEM) and the adsorption kinetics experiments as well as IR were employed for characterization. The results indicated that the TiO₂ hybrid MIP nanospheres revealed a more irregular shape and smaller average size compared to organic-only MIP nanospheres. Furthermore, faster adsorption kinetics was achieved, which made it promising in chemical sensor applications.     

红霉素分子印迹聚合物纳米微球的制备及其吸附特性

以红霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,采用沉淀聚合法制备了粒径均一的红霉素纳米分子印迹聚合物微球,优化了分子印迹聚合物的合成条件,确定了模板分子与功能单体的最佳摩尔比为1:3,对其进行了表征. 结果表明,所制聚合物对红霉素的实际最大吸附量可达202.12 mg/g,吸附约200 min达到平衡,对红霉素具有良好的选择性吸附能力.     

Selective adsorption and degradation of rhodamine B with modified titanium dioxide photocatalyst

A new highly selective photocatalyst (RhB‐MIP/TiO₂) was successfully prepared by surface molecular imprinting technique using rhodamine B (RhB) as template molecule. The adsorption kinetics show RhB‐MIP/TiO₂ possessed fast adsorption rate, and adsorption behavior followed the pseudo‐second‐order kinetics. The static binding experiments revealed RhB‐MIP/TiO₂ displayed strong affinity and high adsorption capacity for RhB. Moreover, the equilibrium adsorption rate of RhB‐MIP/TiO₂ for RhB can be well fitted by the Langmuir isotherm model. The thermodynamics parameters indicated that the binding system of RhB‐MIP/TiO₂ was endothermic and spontaneous. Compared with non‐imprinted photocatalyst (NIP/TiO₂), RhB‐MIP/TiO₂ exhibited excellent selectivity toward RhB, whose selectivity coefficient for RhB relative to rhodamine 6G (Rh6G) was 2.99. Selective photocatalytic degradation experiments indicated that the apparent rate constant for the photodegradation of RhB over RhB‐MIP/TiO₂ is 0.0212 min^?1, being 216% of that over NIP/TiO₂ (0.0098 min^?1). Therefore, RhB‐MIP/TiO₂ exhibited higher photocatalytic selectivity toward RhB. The prepared photocatalyst RhB‐MIP/TiO₂ has a promising perspective in industrial wastewater treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40890.     

Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of polymer morphology on the adsorption behaviors of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin

The influence of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin (MIP(MAA‐β‐CD)) morphology on the adsorption behavior studies towards benzylparaben (BzP) was explored. The effects of time, concentration, and temperature towards BzP uptake were extensively evaluated. The adsorption performance of MIP(MAA‐β‐CD) was compared with that on the molecularly imprinted polymer‐methacrylic acid (MIP(MAA)) synthesized without β‐CD. The MIP(MAA‐β‐CD) was synthesized to obtain a spherical and spongy‐porous texture with a broad pore size distribution. The MIP(MAA‐β‐CD) showed fast kinetic and the intra‐particle diffusion model demonstrated a three step (surface and pore) adsorption process. The Koble‐Corrigan isotherm was the most suitable model for data fitting, which indicated that MIP(MAA‐β‐CD) had homogeneous and heterogeneous surfaces. This finding clearly demonstrated that the large uptake and strong affinity of MIP(MAA‐β‐CD) did not only probably result from the monomer‐template interactions, but also due to the morphological MIP(MAA‐β‐CD) structure. In contrary to MIP(MAA‐β‐CD), MIP(MAA) synthesized with uniform morphology and narrow pore size distribution had lower adsorption capacities and its kinetic data fitted the pseudo‐second order diffusion model, indicating a two‐step (surface only) adsorption process. The MIP(MAA) adsorption process followed the Langmuir isotherm model referred to solely homogeneous uptake. The calculated thermodynamic parameters showed that the BzP uptake was exothermic, spontaneous, and physisorption process onto MIPs, which supported the results of kinetics and isotherm adsorption data. This study clearly revealed that the presence of β‐CD improved the morphology of synthesized MIP, and automatically enhanced the adsorption behavior of MIP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42720.     

Preparation of TiO<Subscript>2</Subscript> nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells

Efficiency of dye-sensitized solar cells [DSSCs] was enhanced by combining the use of TiO₂ nanotubes [TNTs] and nanoparticles. TNTs were fabricated by a sol-gel method, and TiO₂ powders were produced through an alkali hydrothermal transformation. DSSCs were constructed using TNTs and TiO₂ nanoparticles at various weight percentages. TNTs and TiO₂ nanoparticles were coated onto FTO glass by the screen printing method. The DSSCs were fabricated using ruthenium(II) (N-719) and electrolyte (I₃/I₃ ^-) dyes. The crystalline structure and morphology were characterized by X-ray diffraction and using a scanning electron microscope. The absorption spectra were measured using an UV-Vis spectrometer. The incident photocurrent conversion efficiency was measured using a solar simulator (100 mW/cm²). The DSSCs based on TNT/TiO₂ nanoparticle hybrids showed better photovoltaic performance than cells made purely of TiO₂ nanoparticles.     

Electrospun silk fibroin/PAN double-layer nanofibrous membranes containing polyaniline/TiO<Subscript>2</Subscript> nanoparticles for anionic dye removal

In the present study, novel silk fibroin (SF)/polyacrylonitrile (PAN) double-layer nanofilters defined by a variable composition of polyaniline (PANI)/TiO₂ nanoparticles were prepared using an electrospinning technique, and their application for dye removal was investigated. Scanning electron microscopy (SEM) showed that fibrous mats characterized by nanoscale diameters (70–120 nm) and random ultrafine fiber orientations without beads were successfully obtained. Tensile test results revealed that the strength and Young’s modulus were markedly enhanced in the hybrid double-layer SF-PAN membranes relative to single-layer polymers. In addition, the incorporation of PANI/TiO₂ nanoparticles within the hybrid samples resulted in a notable increase in strength and modulus. The adsorption-assisted nanofiltration performance of the membranes in removing anionic reactive black (HFGR) dye from aqueous solution was investigated using a dead-end stirred cell filtration device. The effect of several variables, including PANI/TiO₂ nanoparticle content, pH and dye concentration, were evaluated. Hybrid nanofilters containing 7.5 wt% PANI/TiO₂ nanoparticles demonstrated excellent dye removal efficiency of up to ~92% in acidic solution.     

Structure‐specific sorbent based on nanostructures for selective recognition of cimetidine from its structural analogues

Synthetic molecular units for cimetidine recognition (MWCNT‐MIP) were fabricated at the vinyl functionalized surface of MWCNT (MWCNT‐CH=CH₂). The products and intermediates were characterized using Fourier‐transform infrared spectroscopy, PXRD, thermogravimetric analysis, scanning electron microscope, and tunneling electron microscope techniques. The well fit curve of Langmuir adsorption isotherm clearly indicated the increased homogeneity of MWCNT‐MIP (R² = 0.998) as compared to the bulk MIP (R² = 0.966). The rebinding process was found to follow a second‐order kinetics with a rapid adsorption rate and decreased time period which suggested the enhancement of recognition sites on the surface of MWCNT‐MIP. The maximum saturated binding capacity (Q_max) showed a 31.73% increase after the incorporation of MWCNT on MIPs. The relative selectivity coefficient (k^') of MWCNT‐MIP (6.82) was higher than that of the bulk MIP (4.23). In addition, reusability of bulk and MWCNT‐MIPs was demonstrated. It was found that MWCNT‐MIP showed five repeated cycles without any loss in performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40947.     

Surface molecularly imprinted polymer microspheres based on nano‐TiO2 for selective recognition of kaempferol

The molecular imprinting technique is a new method for preparing molecularly imprinted polymers (MIPs) with specific molecular recognition sites for certain target molecules. In this study, a novel, facile preparation method was presented, called “seed precipitation polymerization,” for the synthesis of MIPs via surface imprinting and a support matrix. In the polymerization process, kaempferol was used as the template molecule, methacrylic acid as the functional monomer, nano‐TiO₂ as the support, azodiisobutyronitrile as the initiator, and ethylene glycol dimethacrylate as the crosslinker in acetonitrile solvent. The synthesized T‐MIP and MIP were analyzed by infrared spectroscopy and scanning electron microscopy. In addition, the obtained polymers were evaluated by adsorption isotherms and dynamic curves for their selective recognition properties for kaempferol. The results show that T‐MIP shows regular spherical particles; the adsorption dynamic curves of T‐MIP show that the adsorption capacity increases with time and reaches a maximum value and then finally reaches equilibrium, and the T‐MIP exhibits a higher affinity for kaempferol than does the MIP. The adsorption follows pseudo‐second‐order kinetics, the Freundlich adsorption equation fits the experimental data well, and there is strong evidence for multiple‐layer adsorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44888.     

Photocatalytic activity of metal-decorated SiO<Subscript>2</Subscript>@TiO<Subscript>2</Subscript> hybrid photocatalysts under water splitting

We report the fabrication of a metal-decorated hybrid nanocomposite with TiO₂ encapsulation (Metal/SiO₂@TiO₂, Metal=Pt or Ru) using a simple surface-modification chemical process. Metal nanoparticles capped with polyvinylpyrrolidone were successfully assembled on functionalized SiO₂ via electrostatic interactions, after which a thin layer of TiO₂ was coated on the surface by the sol-gel process to avoid agglomeration of the coated silica spheres. Transmission electron microscopy studies confirmed that the metal nanoparticles were uniformly distributed throughout the surface of the SiO₂ with a thin layer of TiO₂. In addition, X-ray diffraction was employed to ensure the crystal structure of the uniformly coated thin TiO₂ layer. Even after calcination at 500 °C, the structure remained intact, confirming high thermal stability. The photocatalytic activity of the metal-decorated SiO₂/TiO₂ nanocomposites was evaluated using the H₂ evolution reaction. The Metal/SiO₂@TiO₂ catalysts show the photocatalytic water splitting efficiency for H₂ generation (i.e., 0.14% for Pt/SiO₂@TiO₂ and 0.12% for Ru/SiO₂@TiO₂), while there is no generation of H₂ on the Metal/SiO₂ without a coating layer. These results indicate that the anatase crystalline coating layer has good thermal and chemical stability and plays a significant role in photocatalytic H₂ production.     

Hydrophilicity and crystallization behavior of PVDF/PMMA/TiO<Subscript>2</Subscript>(SiO<Subscript>2</Subscript>) composites prepared by in situ polymerization

Composites with enhanced hydrophilicity were prepared by adding TiO₂ or SiO₂ nanoparticles during the in situ polymerization of methyl methacrylate (MMA) in poly(vinylidene fluoride) (PVDF). The hydrophilicities of the PVDF/PMMA/TiO₂(SiO₂) composites generated in this manner were characterized by contact angle measurements and atomic force microscopy (AFM). The hydrophilicity was dependent on nanoparticle content; it gradually increased with increasing TiO₂ (or SiO₂) content when the TiO₂ (or SiO₂) content was no more than 4 wt% of PVDF. A homogeneous dispersion of the TiO₂ (or SiO₂) nanoparticles in the composite matrix was observed in scanning electron microscope (SEM) images. Based on Fourier transform infrared (FTIR) spectra and wide angle X-ray diffraction (WAXD) analyses, the crystalline phase composition of PVDF was not influenced by the addition of TiO₂ (or SiO₂); PVDF crystallized predominantly in the α phase after in situ polymerization. Nevertheless, the nanoparticles can promote the formation of the β phase of PVDF in composites; the β-phase content increased with increasing TiO₂ content, while it was almost independent of SiO₂ content.     

Enhancement of UV-aging resistance of UV-curable polyurethane acrylate coatings via incorporation of hindered amine light stabilizers-functionalized TiO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> nanoparticles

In this study, polymeric hindered amine light stabilizers (HALS)-functionalized silica coated rutile titanium dioxide (TiO₂-SiO₂) nanoparticles were prepared by encapsulating commercially available TiO₂-SiO₂ nanoparticles with methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers via miniemulsion polymerization. The obtained functional (TiO₂-SiO₂/P(MMA-co-PMPM)) fillers have been added to polyurethane acrylate (PUA) oligomers to get UV-curable nanocomposite coatings. The functionalization of the TiO₂-SiO₂ nanoparticles with polymeric HALS has been confirmed by infrared spectra (IR), thermogravimetric (TG), and X-ray photoelectron spectroscopy (XPS) analyses. The scanning electron microscope (SEM) micrographs indicated that homogeneous dispersion of TiO₂-SiO₂/P(MMA-co-PMPM) composite nanoparticles resulted in improved transparency and mechanical properties of the UV-curable PUA coatings. Rhodamine B (Rh.B) photodegradation measurement confirmed the excellent UV-shielding performance of PUA nanocomposite coatings containing TiO₂-SiO₂/P(MMA-co-PMPM). The addition of TiO₂-SiO₂/P(MMA-co-PMPM) composite nanoparticles reduced the UV-curable PUA coatings degradation rate dramatically. The UV-aging resistance of PUA coatings was improved significantly. Over all, the combination of TiO₂-SiO₂ nanoparticles and polymeric HALS offers an attractive way to fabricate the multi-functional fillers, which can be used to improve the mechanical properties and UV-aging resistance of PUA coatings simultaneously.     

In situ solvothermal synthesis and characterization of transparent epoxy/TiO2 nanocomposites

A solvothermal process was developed to in situ prepare epoxy (EP)/TiO₂ hybrid precursors. The chemical structure of samples was confirmed by X-ray and Fourier transformed infrared spectroscopy. Field emission scanning electron microscope micrographs of cured EP/TiO₂ hybrid composites showed that well-dispersed TiO₂ nanoparticles were successfully in situ formed in epoxy matrix through the solvothermal process. The thermogravimetic analysis, DSC, and gel content measurements showed that EP/TiO₂ hybrid precursors were fully cured with the glass transition temperature decreasing gradually. The effect of TiO₂ contents on optical and surface properties was investigated in detail. The results indicated that epoxy/TiO₂ nanocomposites exhibited excellent UV shielding effect and high visible light transparency. The contact angle of EP/TiO₂ nanocomposites, when the content of silane-coupling agent (KH560) was 5 g and the content of tetrabutyl titanate (TBT) was 3 g, can reach as high as 101°, which was 36° higher than that of pure EP, representing for the increase of hydrophobicity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Durable UV-protective cotton fabric by deposition of multilayer TiO<Subscript>2</Subscript> nanoparticles films on the surface

Durable ultraviolet (UV)-protective cotton fabric has great application potential in outdoor cotton clothing. In this study, oppositely charged TiO₂ nanoparticles were deposited onto cotton fabric through the layer-by-layer self-assembly technique, resulting in multilayer films with UV-protective properties. The mechanism of the technology has been investigated through characterization of the structure and properties using different techniques including FTIR, UV–Vis spectroscopy, and a scanning electron microscope with an energy-dispersive X-ray spectrum. The results showed that TiO₂ nanoparticles distributed uniformly on the surface of cotton fibers. The TGA results indicated that the TiO₂ nanoparticles deposit on cotton fabrics had little effect on the thermal stability of cotton fabrics. The tensile strength and air permeability of the cotton samples were tested by a universal material testing machine and automatic ventilation instrument. The UV protection property of cotton fabric after assembled multilayer films was measured by an ultraviolet transmittance analyzer, and the laundering experiments were carried out to determine the durability of TiO₂ nanoparticles on cotton fabric. The results showed that the UV protection property of cotton fabrics after assembled TiO₂ nanoparticles was still maintained at a high level after five launderings.     

Preparation of hydrophobic SiO<Subscript>2</Subscript>@(TiO<Subscript>2</Subscript>/MoS<Subscript>2</Subscript>) composite film and its self-cleaning properties

TiO₂/MoS₂ composite was encapsulated by hydrophobic SiO₂ nanoparticles using a sol–gel hydrothermal method with methyltriethoxysilane (MTES), titanium tetrachloride (TiCl₄), and molybdenum disulfide (MoS₂) as raw materials. Then, a novel dual functional composite film with hydrophobicity and photocatalytic activity was fabricated on a glass substrates via the combination of polydimethylsiloxane adhesives and hydrophobic SiO₂@(TiO₂/MoS₂) composite particles. The influence of the mole ratios of MTES to TiO₂/MoS₂ (M:T) on the wettability and photocatalytic activity of the composite film was discussed. The surface morphology, chemical compositions, and hydrophobicity of the composite film on the glass substrate were investigated by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and water contact angle (water CA) measurements. The results indicated that the composite film exhibited stable superhydrophobicity and excellent photocatalytic activity for degradation of methyl orange (MO) even after five continuous cycles of photocatalytic reaction when M/T was 7:1. The water CA and degradation efficiency for MO remained at 154° and 94%, respectively. Further, the composite film showed a good non-sticking characteristic with the water sliding angle (SA) at about 4°. The SiO₂@(TiO₂/MoS₂) composite consisting of hydrophobic SiO₂ nanoparticles and TiO₂/MoS₂ heterostructure could provide synergistic effects for maintaining long-term self-cleaning performance.     

Application of ZnO and TiO<Subscript>2</Subscript> nanoparticles coated onto montmorillonite in the presence of H<Subscript>2</Subscript>O<Subscript>2</Subscript> for efficient removal of cephalexin from aqueous solutions

This study considers the feasibility of uptake of cephalexin, an emerging contaminant, from aqueous solutions by using green local montmorillonite (GLM), montmorillonite coated with ZnO (ZnO/GLM) and montmorillonite coated with TiO₂ (TiO₂/GLM) in the presence of H₂O₂. Batch adsorption experiments were carried out as a function of pH, initial concentration of the cephalexin, adsorbent dosage, contact time, and temperature. Finally, the adsorbents were characterized by XRD, SEM and FTIR analyses. XRD patterns showed dramatic changes in the adsorbents after loading with the nanoparticles, confirming successful placing of the nanoparticles onto GLM. The GLM mineral surface after nanoparticle loading appears to be fully exposed and more porous with irregular shapes in particles diameters of 1-50 microns. FTIR analyses also confirmed dramatic changes in surface functional groups after modification with these nanoparticles. The results showed that the removal efficiency of cephalexin was better at lower pH values. Totally, the removal efficiency increased with increase in adsorbent dosage and contact time and decreased with concentration and temperature increase. The thermodynamics values of ΔG ^o and ΔH ^o revealed that the adsorption process was spontaneous and exothermic. In isotherm study, the maximum adsorption capacities (qm) were obtained to be 7.82, 17.09 and 49.26 mg/g for GLM, ZnO/GLM and TiO₂/GLM, respectively. Temkin constant (B _T ) showed that adsorption of cephalexin from solution was exothermic for all three adsorbents.     

The influence of the acidic scouring treatment on the wastewater treatment of TiO<Subscript>2</Subscript> loaded activated carbon electrode

Activated carbon (AC) electrodes were loaded with TiO₂ by using sol–gel method after a pretreatment process, the effect of the acidic pretreatment of the TiO₂ loaded electrode on its deionization efficiency of the wastewater containing NaCl solutions was studied; the physical, chemical and electrochemical properties of the electrode were characterized. The physical and chemical properties of the activated carbon before and after loaded with TiO₂ nanoparticles are characterized by using scanning electron microscopy, energy dispersion spectrum analyzer, Brunauer–Emmett–Teller gas adsorption method, thermal gravimetric analysis, Fourier transform infrared spectroscopy respectively. Electrochemical properties were characterized by employing electrochemical workstation and electrical adsorption deionization test. It was found that both the specific capacitance and the ions removal efficiency of the activated carbon loaded with TiO₂ had an increase of 16.4 and 49.8 % respectively in comparison with original activated carbon electrode. It was believed that this is due to the presence of crystal anatase TiO₂ nanoparticles (the mass content of titanium element in the TiO₂/AC complex is about 24.91 %) on the surface and pores in the activated carbon; while Ti–O–C bonds was found on the surface of the activated carbon, its surface wetting properties was significantly improved. However, it was also noticed that and the specific surface area of the activated carbon was decreased from 680.5 to 523.35 m² g^?1. This might lead to the decrease of the physical adsorption properties of the activated carbon electrodes, but its Electrical double-layer capacitance increases, electrical adsorption efficiency was improved.     

Location of functionalized-TiO<Subscript>2</Subscript> nanoparticle in an immiscible PP/PA6 blends and its effect on the compatibility of the components

Nanocomposites based on 70/30 (w/w) polypropylene (PP)/polyamide 6 (PA6) immiscible blends and functionalized-TiO₂ nanoparticles were prepared via melt compounding. The influences of TiO₂ on the morphology of nanocomposites were investigated. Scanning electron microscopy results revealed the domain size of the dispersed PA6 phase decreased in presence of functionalized-TiO₂ and the TiO₂ nanoparticles were preferentially located at the PA6 phase and at the interfacial region between PP and PA6, which were ascertained by differential scanning calorimetry. The functionalized-TiO₂ nanoparticles played the compatibilizer for the immiscible PP/PA6 blends, increasing the interaction of the two phases in certain extent. Therefore, a clear compatibiliting effect was induced by the TiO₂ in the immiscible PP/PA6 blends.     

ZSM-5/TiO<Subscript>2</Subscript> Hybrid Photocatalysts: Influence of the Preparation Method and Synergistic Effect

In this work, the influence of the preparation method of ZSM-5/TiO₂ hybrids on the photocatalytic performance for removal of formaldehyde (HCHO) or trichloroethylene (C₂HCl₃) in gas phase was analyzed. For this purpose, two methods for the synthesis of the hybrids, the incipient wetness impregnation (I) and the mechanical mixing method (M), were selected. The photocatalysts were characterized by N₂ adsorption–desorption, TEM, UV–Vis spectroscopy, XRD and electrophoretic migration. Also, the adsorption ability of the individual materials and hybrids was analyzed. ZSM-5/TiO₂ hybrids showed higher photocatalytic activity than bare TiO₂, independently of the preparation method selected. Mechanical mixing is a simple and easily scalable method to prepare highly active photocatalyst with high amounts of titania. The internal diffusion processes of the reactants to the active sites could be improved due to the micro–mesoporous structure developed on these hybrids. Incipient wetness impregnation method leads to photocatalysts with higher photodegradation rates per active site. The hybrids synthetized by this method show TiO₂ nanoparticles homogeneously dispersed on the ZSM-5 phase. The fraction of TiO₂ exposed on the surface ca. 75 mol% was similar for materials prepared by both methods, explaining the similar adsorption and photocatalytic properties, independently of the TiO₂ content. The nature of the pollutant has an important role in the adsorption and photocatalytic properties of the composites. Finally, the effect of the incorporation of the zeolite in the photocatalytic system was analyzed. For this purpose, the influence of the zeolite and titania arrangement in the sample holder on the photodegradation rate was analyzed. Although the incorporation of the zeolite induces a positive effect on the photocatalytic performance, independently of the position on the sample holder, a clear synergistic effect when both phases were in intimate contact such as in the ZSM-5/TiO₂ hybrid was observed.     

Biosynthesized Au/TiO<Subscript>2</Subscript>@SBA-15 catalysts for selective oxidation of cyclohexane with O<Subscript>2</Subscript>

A variety of TiO₂@SBA-15 supporters with various TiO₂ loadings were synthesized using a facile sol-gel method. Gold (Au)-based catalysts were prepared with an environmentally benign and economical bioreduction method via Cacumen Platycladi (CP) leaf extract and immobilized on various TiO₂@SBA-15 supporters with different TiO₂ loadings. The as-prepared biosynthesized Au catalysts were applied in the liquid-phase cyclohexane oxidation. The results showed that the Au nanoparticles were well-dispersed on TiO₂@SBA-15, and the Au existed as Au⁰. These biosynthesized Au catalysts are promising for cyclohexane oxidation, achieving a turnover frequency up to 3,426 h^?1 with a 14.1% cyclohexane conversion rate.