Immobilization Of TiO2 Nanoparticles Research Articles

Immobilization of TiO2 nanoparticles on PES substrate via dopamine and poly (vinyl alcohol) for long-term oil/water purification

In this paper, a facile procedure is presented to prepare a membrane with antifouling properties based on Tio2 and polyvinyl alcohol hydrophilicity and the high adhesion of dopamine. First, vapor-induced phase separation was used to prepare the PES substrate, and then TiO2 nanoparticles were anchored on the membrane surface with the assistance of dopamine and PVA. The nanoparticles were uniformly immobilized on membrane surface, significantly advancing the performance of the PES membrane. Results of contact angle measurements revealed an outstanding improvement in the surface hydrophilicity. The fabricated membranes had higher water permeation during oil/water separation and also greater oil rejection with approximately 50% improvement compared with the pristine membrane. Moreover, a FRR of 81% after fouling with oil droplets, increasing in subsequent cycles to 87%, showing a good regeneration capability during long-term performance was achieved by the modified membrane, which confirms the low fouling tendency. Stability of NPs was investigated through a cross-flow water flux, followed by weight measurements, FE-SEM and EDX analysis prior and after the flux. The results proved the stability of modifiers on the membrane surface.

A Graphene Acid - TiO2 Nanohybrid as Multifunctional Heterogeneous Photocatalyst for the Synthesis of 1,3,4-Oxadiazoles.

The immobilization of TiO2 nanoparticles on graphene acid (GA), a conductive graphene derivative densely functionalized with COOH groups, is presented. The interaction between the carboxyl groups of the surface and the titanium precursor leads to a controlled TiO2 heterogenization on the nanosheet according to microscopic and spectroscopic characterizations. Electronic communication shared among graphene and semiconductor nanoparticles shifts the hybrid material optical features toward less energetic radiation but maintaining the conductivity. Therefore, GA-TiO2 is employed as heterogeneous photocatalyst for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles using ketoacids and hydrazides as substrates. The material presented enhanced photoactivity compared to bare TiO2, being able to yield a large structural variety of oxadiazoles in reaction times as fast as 1 h with full recyclability and stability. The carbocatalytic character of GA is the responsible for the substrates condensation and the GA-TiO2 light interaction ability is able to photocatalyze the cyclization to the final 1,3,4-oxadiazoles, demonstrating the optimal performance of this multifunctional photocatalytic material.

Immobilization of TiO2 Nanoparticles in Cement for Improved Photocatalytic Reactivity and Treatment of Organic Pollutants

Non-point organic pollutants in stormwater are a growing problem in the urban environment which lack effective and efficient treatment technologies. Incorporation of conventional wastewater techniques within stormwater management practices could fundamentally change how stormwater quality is managed because contaminants can be degraded during stormwater transport or storage. This study investigated the photocatalytic reactivity of titanium dioxide functionalized with maleic anhydride (Ti-MAH) within cement pastes when compared to ordinary Portland cement. Preparation of Ti-MAH was performed by permanently bonding maleic anhydride to titanium in methanol, drying and powdering the residual material, and then inter-grinding the preparation with cement during mixing. When compared with OPC, the Ti-MAH cured cement paste is more reactive under a wider range of light wavelengths, possesses a higher band gap, sustains this heightened reactivity over multiple testing iterations, and treats organics effectively (>95% methylene blue removal). Amorphous silica within calcium-silica-hydrate, C-S-H, is theorized to bond to the powdered Ti-MAH during curing. Verification of silicon bonding to the titanium by way of MAH was demonstrated by FTIR spectra, SEM imagery, and XRD. Creating a sustainable and passive photocatalytic cement that precisely bonds silica to Ti-MAH is useful for organic contaminants in urban stormwater, but use can translate to other applications because Ti-MAH bonds readily with any amorphous silica such as glass materials, paints and coatings, optics, and LEDS, among many others.

A promising nanocatalyst: Upgraded Kraft lignin by titania and palladium nanoparticles for organic dyes reduction

The evaluation of dye degradation was adorned a great interest due to scarcity of water, courtesy of industrialization. Here, Kraft lignin was upgraded by immobilization of TiO2 nanoparticles (NPs) by the reflux method (KL-T). Palladium (Pd) NPs were produced in a promising way by laser ablation in liquid (LAL) and loaded on KL-T to prepare an efficient nanocatalyst (KL-T/Pd). The synthesized KL-T/Pd is characterized by X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectrometry (EDX), and Transmission electron microscope (TEM) analyses. The KL-T/Pd nanocomposite was applied as an efficient and novel nanocatalyst for the reduction of methylene blue (MB) and methyl orange (MO) by NaBH4 as a reducing agent in aqueous media at ambient temperature. Our experimental results displayed that the 1 mg of KL-T/Pd catalyst can be reduced MB and MO organic dyes within 23 and 8 s, respectively at room temperature. The KL-T/Pd nanocatalyst can be recycled and reused four times with no considerable loss of performance. Having different advantages such as high catalytic performance, safe synthesis method, and high stability, lignin was suggested as a natural substrate.

Immobilization of TiO2 Nanoparticles in Hydrogels Based on Poly(Methyl Acrylate) and Succinamide Acid for the Photodegradation of Organic Dyes

Hydrogels have excellent properties that make them ideally suited as host matrices for the immobilization of photoreactive materials such as TiO2 nanoparticles that serve as catalysts in the photodegradation of organic dyes, which is of great importance in practical water pollution treatment applications. However, the application of hydrogels for this purpose remains poorly studied. The present study addresses this issue by developing two types of hydrogels based on poly(methyl acrylate) and succinamide acid with embedded TiO2 nanoparticles for use as photocatalysts in the photodegradation of organic dyes. The results of the analysis demonstrate that the TiO2 nanoparticles are distributed uniformly in the hydrogel matrices, and the hydrogels maintain their original structures after use. The photodegradation efficiencies of the developed TiO2-hydrogels are demonstrated to be reasonably close to that of freely distributed TiO2 nanoparticles in solution for four different organic dyes. In addition, the results of degradation-regeneration cycling tests demonstrate that immobilizing the TiO2 nanoparticles into the hydrogels greatly reduces their loss during utilization, and the photocatalysts can be easily reused. In fact, the two TiO2-hydrogels retain reasonably high photocatalytic degradation performance after four degradation-regeneration cycles.

Funkcionalizacija PLA aerogelova pomoću TiO2 nanočestica

This study was aimed to prepare material with high porosity and photocatalytic activity by immobilization of TiO2 nanoparticles (NPs) onto poly(lactic acid) (PLA) aerogels. PLA aerogels were prepared in three steps: (1) dissolution of polymer in chloroform at 22 °C, (2) chloroform replacement with ethanol, and (3) supercritical CO2-drying at pressure 19 MPa and temperature 39 ºC. Immobilization of TiO2 NPs was performed by in situ and ex situ methods. Obtained samples were characterized using SEM, EDX, and FTIR analysis. Photocatalytic activity of developed material was tested by following decolorization of dye C.I. Acid Orange 7 in water solution. It was shown that the morphology of PLA aerogels was slightly affected by TiO2 NPs immobilization. PLA aerogels with TiO2 NPs immobilized by ex situ method sustained floatability during test period and provided a complete decolorization of dye solution after 330 minutes of illumination. High photocatalytic activity of the sample was preserved within three repeated cycles of dye decolorization.

Enhancement of photodegradation efficiency of PVA/TiO2 nanofiber composites via plasma treatment

Anatase titanium dioxide (TiO2) nanoparticles (NPs) embedded in poly(vinyl alcohol) (PVA) nanofibers were fabricated for the photodegradation of methylene blue (MB) as the test analyte. 1 wt% TiO2 NPs were dispersed in 12 wt% PVA solution prior to electrospinning to form the nanofibers. Raman spectroscopy implied the incorporation of the NPs into the nanofibers without significant change in the chemical structure of either TiO2 or PVA. Scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmission electron microscopy revealed smooth, bead-free, and continuous nanofibers, uniform NP distribution, and negligible NP agglomeration, respectively. The effect of oxygen plasma treatment on the photodegradation efficiency of the PVA/TiO2 was also investigated. Photodegradation of MB exhibited up to 30% increase in degradation efficiency using the plasma-treated PVA/TiO2 nanofiber mats. The partially exposed immobilized TiO2 NPs became more photocatalytically active while being supported by PVA nanofibers. Immobilization of TiO2 NPs would allow reusability thereby extending its service life ideal for environmental applications.

Efficient Immobilised TiO2 in Polyvinylidene fluoride (PVDF) Membrane for Photocatalytic Degradation of Methylene Blue

Immobilised titanium dioxide (TiO2) in membrane structures has recently become attractive. This is due to the elimination of the separation step after the process of photocatalytic degradation. The efficiency of the TiO2 surface area exposed to UV light as the main important parameter needs to be considered. The immobilisation of TiO2 nanoparticles in the polyvinylidene fluoride (PVDF) membrane structure with different particle sizes (6 nm and 30 nm) was prepared via various techniques including the tape casting and spin coating methods to study the distribution of TiO2 nanoparticles in the membrane structure. Besides, the effects of the spinning speed in spin coating methods on the membrane structure and photocatalytic performance were investigated. The morphological and physical characteristics were also explored by field emission scanning electron microscope (FESEM) energy dispersion of X-ray (EDX), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The prepared membranes were tested in a photocatalytic system using methylene blue (MB) as a model pollutant. The results showed that the immobilisation of TiO2 nanoparticles in membrane structure could enhance the rate of MB degradation. The aggregation of the 6 nm and 30 nm TiO2 particle sizes prepared by tape casting method shows similar performance in MB degradation rate but contradict the result of the spin coating method. The good distribution and uniformity of the 6 nm TiO2 particle size exhibit a higher MB degradation rate. The thickness of the membrane can be tailored using the spin coating method and UV penetration towards the photocatalytic membrane up to 55.64 μm of thickness, which could enhance the MB photocatalytic degradation rate.

Photosensitized TiO2 films on polymers – Titania-polymer interactions and visible light induced photoactivity

Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can be synthesized using a low temperature oxygen plasma treatment of the polymer (PP) followed by deposition of TiO2 nanoparticles and their sensitization with organic ligands. The whole process consists of three major steps: surface activation involving its partial oxidation, immobilization of TiO2 nanoparticles and photosensitization of titania film by impregnation with the solution of organic ligands forming surface Ti(IV) charge transfer complexes. XPS and IR analysis revealed the formation of oxygen-containing groups at the polymer surface upon plasma treatment. These groups participate in the formation of TiOC bonds which ensure a very good adhesion of titania films to polymeric surface. The dip-coating process using an aqueous colloidal solution of TiO2 nanoparticles allows to synthesize a compact coating with a thickness of 100–300 nm. Coordination of catechol-like ligands to surface Ti(IV) centers results in formation of colored charge transfer complexes responsible for absorption of visible light and an effective photoinduced charge separation. Photogenerated electrons and holes can take part in surface redox reactions responsible for degradation of pollutants. Tests with various organic ligands (catechol, 2,3-naphthalenediol, pyrogallol and rutin) revealed, that the titanium dioxide coating modified with catechol was the most photoactive one when visible light irradiation was applied. Presented photocatalytic coatings can be effectively used as self-sterilizing surfaces activated by visible light.

Modification of nanocrystalline TiO2 coatings with molecularly imprinted TiO2 for uric acid recognition.

Combining the surface modification and molecular imprinting technique, a novel piezoelectric sensing platform with excellent molecular recognition capability was established for the detection of uric acid (UA) based on the immobilization of TiO2 nanoparticles onto quartz crystal microbalance (QCM) electrode and modification of molecularly imprinted TiO2 (MIT) layer on TiO2 nanoparticles. The performance of the fabricated biosensor was evaluated, and the results indicated that the biosensor exhibited high sensitivity in UA detection, with a linear range from 0.04 to 45μM and a limit of detection of 0.01μM. Moreover, the biosensor presented high selectivity towards UA in comparison with other interferents. The analytical application of the UA biosensor confirmed the feasibility of UA detection in urine sample.

Enhanced photocatalytic activity of rGO/TiO2 for the decomposition of formaldehyde under visible light irradiation

Due to the low concentration of indoor air contaminants, photocatalytic technology shows low efficiency for indoor air purification. The application of TiO2 for photocatalytic removal of formaldehyde is limited, because TiO2 can only absorb ultraviolet (UV) light. Immobilization of TiO2 nanoparticles on the surface of graphene can improve the visible light photocatalytic activity and the adsorption capacity. In this study, rGO (reduced graphene oxide)/TiO2 was synthesized through a hydrothermal method using titanium tetrabutoxide and graphene oxide as precursors, and was used for the degradation of low concentration formaldehyde in indoor air under visible light illumination. Characterization of the crystalline structure and morphology of rGO/TiO2 revealed that most GO was reduced to rGO during the hydrothermal treatment, and anatase TiO2 nanoparticles (with particle size of 15–30nm) were dispersed well on the surface of the rGO sheets. rGO/TiO2 exhibited excellent photocatalytic activity for degradation of formaldehyde in indoor air and this can be attributed to the role of rGO, which can act as the electron sink and transporter for separating photo-generated electron–hole pairs through interfacial charge transfer. Furthermore, rGO could adsorb formaldehyde molecules from air to produce a high concentration of formaldehyde on the surface of rGO/TiO2. Under visible light irradiation for 240min, the concentration of formaldehyde could be reduced to 58.5ppbV. rGO/TiO2 showed excellent moisture-resistance behavior, and after five cycles, rGO/TiO2 maintained high photocatalytic activity for the removal of formaldehyde (84.6%). This work suggests that the synthesized rGO/TiO2 is a promising photocatalyst for indoor formaldehyde removal.

Development of photocatalytic titanium dioxide membranes for degradation of recalcitrant compounds

BACKGROUND Immobilization of TiO2 photoactive nanoparticles on a nanofiltration membrane without loss of permselectivity properties is currently a challenge. In this study, immobilization of TiO2 nanoparticles on a ceramic commercial membrane surface by direct current reactive magnetron sputtering was addressed. The best membrane was compared with an unmodified membrane and a membrane modified by a generic chemical–physical method in terms of membrane permselectivity and photocatalytic properties. RESULTS Magnetron sputtering was able to achieve similar photocatalytic activity to the chemical–physical method, where Evonik P25 TiO2 nanoparticles were used, while maintaining membrane rejection and permeability. The layer formed by magnetron sputtering exhibits uniformly distributed nanostructured columns, aligned perpendicularly to the membrane surface. Furthermore, the membrane hydrophilicity increase achieved is promising for fouling control. A shorter sputtering time and distance between the titanium target and the membrane were preferable to effectively degrade the pesticides diuron and chlorfenvinphos. Under optimum sputtering conditions, 95% and 78% increases were attained for the degradation of diuron and chlorfenvinphos, respectively, compared with the unmodified membrane. CONCLUSION The photocatalytic membranes developed are potential candidates for the simultaneous retention and photocatalytic degradation of recalcitrant micropollutants. However, if the purpose is to retain low molecular weight molecules, retentive properties should be improved. © 2016 Society of Chemical Industry

Immobilisation of TiO2-nanoparticles on sewage sludge and their adsorption for cadmium removal from aqueous solutions

In this study, pure TiO2-nanoparticles and TiO2/sewage sludge (TS) as biomass material were synthesised via a sol–gel method. The adsorption potential of nanosized TiO2 and TS for removal of Cd(II) was investigated in a batch system. The prepared adsorbents were characterised using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The XRD analysis showed that pure TiO2 is in amorphous phase before calcination and in anatase phase at annealing temperature of 400 °C. TiO2/sewage sludge that calcined at 400 °C (TS400) was found to be the best adsorbent for cadmium removal from aqueous solution. Kinetic and isotherm studies were carried out by considering the parameters, pH, initial concentration and contact time. The optimum pH value for Cd(II) adsorption onto TS400 was found to be 6. Langmuir isotherm showed better fit than Freundlich isotherm and the maximum adsorption capacity was found to be 29.28 mg/g which is higher than that of many other adsorbents reported in literature. The sorption kinetic data were well fitted with a pseudo-second-order model. These results demonstrated that TS400 was readily prepared and is the promising and effective solid material for the removal of Cd(II) from aqueous solutions.

Immobilization of TiO2 nanoparticles on montmorillonite clay and its effect on the morphology of natural rubber nanocomposites

Natural rubber/organoclay/titanium dioxide nanocomposites were obtained via mechanical blending using rubber latex, organically modified montmorillonite clay (cloisite 30B) and titanium dioxide (TiO2). Glycerol was utilized as a dispersant for the inorganic components. Scanning electron microscopy analysis shows that TiO2 nanoparticles were deposited on the clay surface and that the clay–TiO2 combination was homogeneously dispersed on the natural rubber. The high aspect ratio and the polar character of the clay layers allowed interactions with individual nanoparticles of TiO2. The X-ray diffraction patterns reveal an increment of the crystalline character of the NR/C30B/TiO2 nanocomposites as a consequence of the nanoscale dispersion of the TiO2 particles. Infrared Spectroscopy spectra indicate compatibility between natural rubber and glycerol due to the formation of hydrogen bonds. A mechanism in particle–natural rubber compatibility, in which glycerol is involved, is proposed. However, nanoscale dispersion was largely dependent on the clay–TiO2 interactions. This work proposes an easy method to immobilize TiO2 nanoparticles on clay layers, which allows their dispersion in polymers. Nanocomposites obtained by this method can be used for supports of photocatalyst molecules.

Immobilization of TiO2 nanoparticles on PET fabric modified with silane coupling agent by low temperature hydrothermal method

PET fabric was first modified with silane coupling agent KH-560, and then was loaded with a layer of nano-scaled TiO2 particles using tetrabutyl titanate as precursor by low temperature hydrothermal method, followed by dyeing with Disperse Blue 56. The morphology, crystalline phase, chemical modification, thermal stability and optical property of PET fiber before and after treatments were studied by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, thermal gravimetric and diffuse reflectance spectrum techniques. The properties of tensile, air permeability, luster, ultraviolet (UV) protection, photocatalytic activity, K/S value and color fastness were also measured. It was found that compared with the TiO2-coated fabric without modification with KH-560, the loading of TiO2 nanoparticles on the surface of the TiO2-coated fabric modified with KH-560 was obviously improved. The pure anatase TiO2 nanoparticle was grafted onto the fiber surface. The onset decomposition temperature increased. The absorbing capability to ultraviolet radiation was enhanced. The properties of tensile, air permeability, luster, K/S value and color fastness changed slightly. The UV protection ability and photodegradation of methyl orange under UV illumination were enhanced to some extent.

Immobilization of TiO2 nanoparticles on natural Luffa cylindrica fibers for photocatalytic applications

TiO2/Luffa composites have been successfully prepared via a sol–gel method from the hydrolysis of a precursor of TiO2. The possibility to use Luffa fibers as biotemplate to self-support hierarchical TiO2 macrostructures has also been tested with success. The photocatalysts and the TiO2/Luffa composites were characterized by X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis, FT-IR, and UV-visible spectroscopy. The photocatalytic activities have been investigated in the photodegradation of methanol, chosen as model molecules for VOCs in air. The reactions have been followed by IR-operando spectroscopy. TiO2/Luffa composites exhibited a good stability and photocatalytic activity under UV light irradiation, giving rise to a new generation of green photocatalysts, easy to shape and manufacture, for the photodegradation of organic pollutants.

Photocatalytic Composites of Silicone Nanofilaments and TiO2 Nanoparticles

AbstractNanoscale TiO2 photocatalysts are key materials for convenient wastewater treatment and other essential cleaning processes. Immobilization of TiO2 nanoparticles (NPs) is thus indispensable for the facile handling and separation of nanocatalysts as well as for minimizing their potential health and environmental hazards. Silicone nanofilaments are introduced as a new flexible carrier type for titania NPs because they are compatible with a wide range of substrates and they display high chemical stability. TiO2‐NPs are deposited on glass slides covered with thin carpets of silicone nanofilaments in a single reaction step starting from TiF4 and optimized ethanol/water ratios. The resulting composites are characterized using a wide range of electron microscopy and other analytical techniques, and their photocatalytic activity in the decomposition of methylene blue (MB) is superior to immobilized TiO2 references on plain substrates.

Immobilization of TiO2 nanoparticles in polymeric substrates by chemical bonding for multi-cycle photodegradation of organic pollutants

Nano titanium dioxide (TiO2) photocatalyst is generally immobilized onto the matrix through the physical absorption, hydrogen bonding or chemical bonding, which is utilized for the application of wastewater treatment. In this research, TiO2 nanoparticles were immobilized in polyvinyl alcohol (PVA) matrix via solution-casting combined with heat-treatment method. Structure characterization indicated that TiOC chemical bond formed via dehydration reaction between TiO2 and PVA during the heat treatment process, and TiO2 nanoparticles had been chemically immobilized in PVA matrix. Photodegradation results of methyl orange (MO) showed that the film with 10wt% TiO2 and treated at 140°C for 2h exhibited a remarkable ultraviolet (UV) photocatalytic activity, approximately close to the TiO2 slurry system. This was mainly attributed to the fixation effect by TiOC chemical bonds, which was indirectly confirmed by the slight loss of TiO2 photocatalysts even after 25-cycle use. In addition, the good swelling ability of PVA matrix provided the MO molecules with more opportunities to fully contact with TiO2, thus benefited the photocatalysis. This route to chemically immobilize TiO2 nanoparticles is simple and cheap to prepare polymer/TiO2 hybrid materials with high photocatalytic activity for multi-cycle use, which is of significance to the practical application of TiO2 catalysts.

TiO2 Immobilized in Cellulose Matrix for Photocatalytic Degradation of Phenol under Weak UV Light Irradiation

TiO2/cellulose composite films have been prepared via a sol−gel method from the hydrolysis of a precursor TiO2 sol solution in the regenerated cellulose films prepared on the basis of cellulose dissolution at low temperature. The structure and properties of the composite films were characterized by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, FT-IR, UV−visible spectroscopy, and photocatalytic degradation tests. The micronanoporous structure and hydroxyl groups in the regenerated cellulose films at the wet state provided cavities and affinity for the creation and the immobilization of TiO2 nanoparticles in the cellulose matrix through electrostatic and hydrogen bonding interactions. The TiO2/cellulose composite films exhibited a good photocatalytic activity for photodegradation of phenol under weak UV light irradiation, leading to an important application in photodegradation of organic pollutant. This was a portable photocatalyst, wh...

Immobilization of TiO2 nanoparticles onto paper modification through bioconjugation

TiO2 is commonly used as a brightening agent for paper, but may also be used on paper as a photocatalyst. The TiO2 aggregates that typically form in/on paper are inefficient both for brightening or photooxidation. We describe, for the first time, the preparation of homogeneously distributed, non-aggregated TiO2 particles on cellulose fibers using explicit bioconjugation with the fusion protein of CBM2a-Strep-tag II/streptavidin/biotinylated TiO2. The maximum absorption of proteins and nanoparticles onto paper were determined to be ca. 6.22 × 10−2 nm−2 for CBM2a-Strep-tag II, 1.93 × 10−2 nm−2 for streptavidin, and 58 µm−2 for TiO2nanoparticles, respectively. The efficiency of photocatalysis of the TiO2-containing paper prepared by this bioconjugation method was demonstrated by the decolorization of UV sensitive dye (reactive black dye 5). Immobilized TiO2 efficiently degraded the dye within about 10 hours. Only after extensive photolysis (12 hours) did sufficient degradation of the bioconjugating linkers occur such that free TiO2 particles and cellulose fibers were found in the supernatant. These experiments demonstrate that bioconjugation of TiO2 to paper leads to an effective, supported photocatalyst system.