Surface Modification Of Titanium Dioxide Research Articles

Transparent and High-Refractive-Index Titanium Dioxide/Thermoplastic Polyurethane Nanocomposites.

Transparent nanocomposite films made of surface-modified titanium dioxide nanoparticles and thermoplastic polyurethane are prepared via film casting approach showing enhanced refractive indexes and mechanical properties. Two different sets of composites were prepared up to 37.5 wt % of inorganic nanoparticles with a diameter <15 nm, one set using particles capped only with oleic acid and a second one with a bimodal system layer made of oleic acid and mPEO-5000 as coating agents. All of the composites show significantly enhanced refractive index and mechanical properties than the neat polymeric matrix. The transparency of nanocomposite films shows the excellent dispersion of the inorganic nanoparticles in the polymeric matrix avoiding aggregation and precipitation phenomena. Our study provides a facile and feasible route to produce transparent nanocomposite films with tunable mechanical properties and high refractive indices for various applications.

4-(Triethoxysilyl)butanoic acid as a self-assembled monolayer for surface modification of titanium dioxide.

In this study, the carboxy silane 4-(triethoxysilyl)butanoic acid (TESBA) was used to modify titanium dioxide (TiO2) to create a self-assembled monolayer (SAM) and then directionally immobilize a capture antibody using protein A. We selected the amino silane (3-aminopropyl)triethoxysilane (APTES) to perform a comparative analysis with TESBA, and employed glutaraldehyde (GA) as the control. The modification and detection effects and the limit of detection (LOD) were evaluated by detecting human immunoglobulin G (IgG). The average normalized sensitivity of the dual-grating coupler waveguide biosensor was 49.63 ± 0.27 RIU-1 and the optimum resolution was 1.30 × 10-6 RIU. When the SAM was prepared using TESBA and APTES followed by GA, the LOD was 4.59 × 10-7 g mL-1 and 5.29 × 10-7 g mL-1, respectively. We analyzed the modification and detection effects by the t-test and concluded that the differences in the modification effects using TESBA and APTES followed by GA were significant and the differences in the detection effects using TESBA and APTES followed by GA were insignificant. The use of TESBA as the SAM led to the modification effect being superior to that obtained using APTES followed by GA. The detection effect using TESBA was as outstanding as that using APTES followed by GA. Our findings demonstrate the feasibility and effectiveness of using TESBA as the SAM to carboxylate the surface of TiO2, thereby enabling immobilization of biomolecules for human IgG detection.

Study on the Mechanical Characteristics, Heat Resistance, and Corrosion Resistance of Unsaturated Polyester Resin Composite

In this study, the researchers aimed to broaden the applications of unsaturated polyester resin (UPR) composites in the building field by incorporating surface-modified titanium dioxide (TiO2) nanoparticles and reinforced chopped glass fibers within the UPR matrix. Specifically, the composites containing 4 wt.% TiO2 nanoparticles and 30 wt.% chopped glass fiber exhibited remarkable properties of 46.1 kJ/m2 in impact strength, 90.1 MPa in flexural strength, 78.8 MPa in tensile strength, and 121.5 °C in heat deflection temperature, which improve 207.5%, 80.3%, 62.5%, and 73.6%, respectively, when compared with the blank sample. Furthermore, the results of the corrosion resistance test showed that the composites performed poorly against polar organic and alkaline solutions, presented good corrosion resistance against acidic media, and behaved relatively stable in the salt solution.

Аnti-corrosion coatings based on modified epoxy compositions

The influence of surface-modified titanium dioxide on the electrochemical features of epoxy compositions was researched. The raise of epoxy primer protective properties by the presence of surface-modified fillers in its composition was determined. It is shown that the mechanism of the modified filler protective effect in epoxy coating applied on the steel is similar to the effect of solid zinc phosphate which effectiveness corresponds to the level of the known inhibitory pigment.

Evaluation of the impact of alkyl silane entity (APTES) on photocatalyst (TiO2) and their photocatalytic degradation of organic compounds for environmental remediation.

Environmental pollution by diverse organic pollutants is a serious issue facing humanity, and the scientific community is working hard to find a solution to climatic change due to pollution. Along the same lines, we have tried to find a material/method which is economical and less laborious for achieving the same desired objectives. In this work, the surface modification of titanium dioxide to be used as a photocatalyst was carried out with different concentrations of alkyl silane agent APTES (3-aminopropyltriethoxysilane) and studied their impact on the degradation of representative compound, i.e., methylene blue. The surface-modified TiO2-APTES nanoparticles were obtained via the solvothermal process. The APTES in different molar (0.21-0.41M) concentrations was obtained by dissolving APTES in ethanol. The obtained samples were characterized through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy, and UV-visible spectroscopy. The photocatalytic activity was inferred from the degradation ability of functionalized nanoparticles for methylene blue and evaluated by UV-visible spectroscopy. Our results demonstrated a significant 70% degradation rate of methylene blue.

Preparation and Properties of New Thermal Reflective Coating for Asphalt Pavement.

This paper aims to study the applicability of an epoxy resin modification to improve its anti-aging properties, which are conducive to road performance. To achieve this goal, a wide range of laboratory activities were conducted, including an emulsion mixed with epoxy resin and liquid phenolic resin as the coating substrate; surface-modified titanium dioxide, silica, hollow glass beads and sericite powder as functional fillers; then adding pigments and various additives to prepare a new asphalt pavement heat-reflective coating. Secondly, the optimum brushing amount of the coating was obtained, and the cooling effect was clarified. Finally, the road performance was evaluated by testing the coating's skid resistance, wear resistance and impermeability. The results show that the skid resistance, abrasion resistance and impermeability of the heat reflection coating meet the specification requirements.

Impact of relative humidity on ethylene removal kinetics of different scavenging materials for fresh produce industry

Active ethylene scavenging in fresh produce involves the use of adsorbers and oxidizers, such as, potassium permanganate, activated carbon, clays and zeolites, often integrated as sachets, labels, liners, or films. Although many studies have been done to develop novel ethylene scavengers, only a few of them have analyzed the ethylene removal kinetics, especially under different humidity conditions. Kinetic studies can provide information on the ethylene removal rate and ethylene removal at equilibrium which can be highly useful in assessing the efficacy of the scavenger. The main objective of this study was to investigate the ethylene removal kinetics of different scavenging materials at various relative humidity (RH) conditions (0%, 50%, and 100%) at a fixed temperature (13 °C). The active scavenging materials investigated in this study included two commercially available, (potassium permanganate-based and basolite) and three chemically-modified ones (surface modified zeolite with potassium permanganate; surface modified zeolite with zinc, copper and silver; and plasma surface modified titanium dioxide with palladium). Kinetic experiments were conducted with the scavengers placed inside air tight glass jars (1 L) with an initial ethylene concentration of 10 µL L−1. The data obtained was fit to Lagergren pseudo first order kinetic model. Potassium permanganate-based scavengers displayed the highest ethylene removal (~ 8.7–10 mL kg−1) at all three RH conditions. Whereas basolite, zeolite modified with copper, zinc and silver and titanium dioxide modified with palladium were found to be efficient at 0% RH, however, at 50% and 100% RH, a prominent ethylene desorption was observed. Furthermore, a case study of packaging of blueberries with selected scavengers was performed. Blueberry packages containing potassium permanganate and zeolite modified with potassium permanganate had the minimum ethylene concentration of 0.012 ± 0.01 and 0.004 ± 0.00 µL L−1, respectively, at the end of 14 d storage.

Improving the stability of nanofluids via surface-modified titanium dioxide nanoparticles for wettability alteration of oil-wet carbonate reservoirs

The main challenge of the application of nanofluids for enhanced oil recovery (EOR) in oil-wet carbonate reservoirs is maintaining their stability under high-temperature and high-salinity which is normally seen in reservoir conditions. In this work, surface-modified TiO2 nanoparticles were synthesized by N-(2-Aminoethyl)−3-Aminopropyltrimethoxysilane (AEAPTMS) as a coupling agent for surface modification of nanoparticles. Zeta potential and dynamic light scattering analyses were used to evaluate the stability of the prepared nanofluids. Results indicated that nanofluids had high stability in 90 °C and 20 wt% salinity. The influence of nanofluids on wettability alteration of carbonate rocks was studied by measuring the contact angle value. Untreated rock samples were strongly oil-wet, with water advancing and receding contact angles of 165.1° and 166.2°, respectively. After treatment with 3wt% concentration of surface-modified TiO2 nanoparticles, the rock plate wettability changed to a water-wet state, with water advancing and receding contact angles of 37.6° and 48.2°, respectively. Suggested surface-modified TiO2 nanoparticles were more effective in wettability alteration of the rock surfaces compared to the un-modified TiO2 nanoparticles. Furthermore, higher concentration of nanoparticles, higher the ability of the nanoparticles on changing the rock wettability.

Impact of ascorbic acid on polydopamine modified amorphous TiO2-xNx nanosheets

Surface modification of titanium dioxide (TiO2) with enediol like dopamine improves its optoelectronic properties due to chelation of Ti atom by electron donating bidentate ligand. Introduction of N in TiO2 is expected to weaken the interaction between Ti atoms and bidentate ligand because of extra active acceptor sites. Hence, the chemistry of N doped TiO2 and dopamine is likely to display contradictory behavior in comparison to TiO2-dopamine. In this study, amorphous TiO2-xNx nanosheet were synthesized incorporating diethyl triamine (DETA) and acetonitrile (ACN) which plays significant role in obtaining desired morphology. Furthermore, the chemistry of interaction between TiO2-xNx and dopamine was explored, wherein dopamine self-polymerizes on the surface of nanosheets forming TiO2-xNx – Polydopamine (PD). Comparative study of TiO2-xNx–PD and TiO2-PD were investigated in presence of similar enediol ligand such as ascorbic acid (AA) along with weak and strong acid. It was observed that only in presence of AA, TiO2-xNx–PD bond gets weaken from the fluorescence recovery of PD. This behavior of AA was tested with a detection range of 10–100 nM and limit of detection of 2 pM in biological fluid. Our results could be helpful for tuning the optoelectronic properties of TiO2 based hybrid composites for future applications.

Surface modification of titanium dioxide with silver nanoparticles for application in photocatalysis

Silver nanoparticles (Ag NPs) have been deposited on powder TiO2 by a novel one-step method involving atmospheric pressure discharge cold plasma treatment without the use of any environmentally and biologically hazardous reducing agents. It was found that composite TiO2/AgNPs has structure like the core–shell constructed by the TiO2 sphere cores and Ag nanoparticles (NPs) shell, were obtained via Ag nanoseed mediated plasma chemical reduction. The prepared samples are characterized by using scanning electron microscopy, UV/Vis spectroscopy. The characterization results indicate that Ag NPs with an average size of about 10–25 nm are uniformly distributed on the surface of the Ag nanoseed modified TiO2 spheres. The effect of various operation parameters such as irradiation time, initial dye concentration and catalyst dose was studied. The results indicated that the catalytic efficiency of TiO2/Ag is higher than that of pure TiO2 and TiO2/Ag+ composites. The degradation of MB decreased from 78.0 to 37.0% during 20 min irradiation with the rise in startup MB concentration from 1.25 to 10 mg/L. An enhanced degradation of MB was noticed with the increment in the amount of composite from 1.2 to 2.4 g/L and afterwards an increase in catalyst mass to 7.2 g/L resulted decrease in the degradation of MB.

Surface modification of TiO2 particles with 12‐hydroxy stearic acid and the effect of particle size on the mechanical and thermal properties of thermoplastic polyurethane urea elastomers

AbstractThe efficient surface modification of titanium dioxide (TiO2) particles with different sizes was first carried out with “water only method” (Appl. Surf. Sci. 2018, 447, 664–672) developed in our group using 12‐hydroxy stearic acid (12‐HSA) as the modifier. The 12‐HSA‐modified TiO2 particles with different sizes were then used to explore their effect on the mechanical and thermal properties of a thermoplastic polyurethane urea (TPUU) elastomer with superior mechanical and thermal properties produced newly in our lab using nonsymmetric alicyclic diisocyanate and diamine. Orthogonal experimental results showed that the order of impact of each factor on the modification efficiency of TiO2 particles was: Temperature &gt; time &gt; modifier content. It was found that, in the nanometer (≤100 nm) range, smaller particles were more helpful to enhance the tensile strength of the TPUU elastomer, while larger ones to increase more significantly the elongation at break. Besides, the TiO2/polyurethane urea nanocomposites exhibited much better thermomechanical performance than the pristine TPUU elastomer, and the thermomechanical performance of the nanocomposites increased with decreasing particle size.

Effects of different surface-coated nTiO2 on full-grown carrot plants: Impacts on root splitting, essential elements, and Ti uptake

The production and environmental release of surface-modified titanium dioxide nanoparticles (nTiO2) have increased. Hence, crops may be directly exposed to the nTiO2 in soil. In this study, we grew carrots in soils amended with pristine, hydrophilic and hydrophobic surface-coated nTiO2 at 100, 200, and 400 mg kg−1 until full-plant maturity. The content of Ti in plant secondary roots treated with different nTiO2 at 400 mg kg−1 was in the order of hydrophobic > hydrophilic > pristine treatments, with values of 140.1, 100.5, and 64.3 mg kg−1, respectively. The fresh biomass of the taproot was significantly decreased by all nTiO2 forms at 400 mg kg−1 by up to 56 %, compared to control. Pristine nTiO2 at 100 mg kg−1 enhanced the fresh weight of leaves by 51 % with respect to control. Remarkably, an abnormal increase of taproot splitting was found in plants treated with all nTiO2 forms. In carrots treated with the surface-coated nTiO2, the accumulation of Ca, Mg, Fe, and Zn increased in leaves; but Mg, Mn, and Zn decreased in taproots. These results suggest that future regulation of nTiO2 release into soils should consider its surface coating properties since the phytotoxicity effects depend on nTiO2 outer structure.

Role of the chemical modification of titanium dioxide surface on the interaction with silver nanoparticles and the capability to enhance antimicrobial properties of poly(lactic acid) composites

In this work, the antimicrobial activity of neat and silanized titanium dioxide deposited with silver nanoparticles was evaluated when it was used as filler in a poly(lactic acid) matrix. The silanization and deposition processes were evaluated by scanning transmission electron microscopy and X-ray photoelectron spectroscopy confirming the chemical modification on the titanium dioxide surface by 3-aminopropyltriethoxy silane and the formation of silver nanoparticles. According to the elemental analysis conducted by energy-dispersive X-ray spectroscopy, more silver, 7.4% higher, was deposited on the oxide when this was previously silanized and when 30% w/w of silver nitrate was used as a precursor. The antimicrobial effect was confirmed for the nanoparticles through the disk diffusion method and for the composites by drop test, against Staphylococcus aureus and Escherichia coli bacteria; the results showed that the inhibition rate increased by 14.2% and 39.1% for nanoparticles and by 57.6% and 38.8% for composites against each bacteria, respectively, when deposition was performed on silanized titanium dioxide. Also, better mechanical properties were obtained in the composites filled with silanized oxide; the best results were obtained in the PLA/sTiO2–Ag 20% system with an improvement of 45.7% in tensile stress and of 38.73% for Young’s modulus. Finally, the toxicity of the composites was evaluated by seeding peripheral blood mononuclear cells; results show evidence that composites filled with these nanoparticles are non-toxic since these do not migrate from the polymeric matrix, which helps to enhance the prolonged surface antibacterial effect and to open a broad perspective of the commercial use of these composites.

Surface Modification of Titanium Dioxide under Ultrasonic Treatment

The surface modification of titanium dioxide in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymers by ultrasonic treatment was studied. The pigment surface modification by the above copolymers was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorption onto the pigment surface was quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymers as achieved by ultrasonic treatment and is a consequence of ultrasonically induced pigment surface activation.

Influence of the Support Modification Methods on the Chlorophenol Utilization by the Peroxidase Immobilized on Titanium Dioxide

In the current work, the synthesis of the effective multicomponent biocatalysts on the base of horseradish peroxidase immobilized on the modified titanium dioxide for the utilization of chlorophenolic water contaminants was performed. The influence of the support modification methods on the biocatalyst activity and stability was studied. The immobilization of horseradish peroxidase on the unmodified titanium dioxide was found to be ineffective due to the high losses in the enzyme amount during the reaction as well as the biocatalyst particles aggregation (the activity reduces more than 95 %). The titanium dioxide surface modification by the sodium alginate and carbodiimide (23.5 % activity in comparison with the native enzyme); hydrochloric acid, chitosan and glutaric dialdehyde (33.7 % activity in comparison with the native enzyme); and hydrochloric acid, chitosan, glutaric dialdehyde and aminopropyltriethoxysilane (42.5 % activity in comparison with the native enzyme) were found to be the most effective methods. Besides, the last two biocatalysts showed high stability in 10 consecutive cycles. The synthesized biocatalyst can be effectively used for the removal of chlorophenols from the wastewater until the concentrations of 10 ppm.

TiO2 and PEEK Reinforced 3D Printing PMMA Composite Resin for Dental Denture Base Applications.

The future of manufacturing applications in three-dimensional (3D) printing depends on the improvement and the development of materials suitable for 3D printing technology. This study aims to develop an applicable and convenient protocol for light-curing resin used in 3D industry, which could enhance antibacterial and mechanical properties of polymethyl methacrylate (PMMA) resin through the combination of nano-fillers of surface modified titanium dioxide (TiO2) and micro-fillers of polyetheretherketone (PEEK). PMMA-based composite resins with various additions of TiO2 and PEEK were prepared and submitted to characterizations including mechanical properties, distribution of the fillers (TiO2 or/and PEEK) on the fractured surface, cytotoxicity, antibacterial activity, and blood compatibility assessment. These results indicated that the reinforced composite resins of PMMA (TiO2-1%-PEEK-1%) possessed the most optimized properties compared to the other groups. In addition, we found the addition of 1% of TiO2 would be an effective amount to enhance both mechanical and antibacterial properties for PMMA composite resin. Furthermore, the model printed by PMMA (TiO2-1%-PEEK-1%) composite resin showed a smooth surface and a precise resolution, indicating this functional dental restoration material would be a suitable light-curing resin in 3D industry.

Ultrasonically-assisted surface modified TiO2/rGO/CeO2 heterojunction photocatalysts for conversion of CO2 to methanol and ethanol.

Converting CO2 to usable fuel may contribute to lowering of global warming, thus this study developed effective heterojunction photocatalysts for the photoreduction of CO2 with water into methanol and ethanol fuels. The photocatalysts were prepared from combining surface modified titanium dioxide (TiO2) nanoparticles with reduced graphene oxide (rGO) and cerium oxide (CeO2). The TiO2 surfaces were firstly modified via the sono-assisted exfoliation, with high intensity ultrasonic waves (ultrasonic horn, 20 kHz, 150 W/cm2) in 10 M NaOH for 1 h. Highly reactive nanosheets delaminated from outer surfaces of the primary TiO2 crystals leading to an increase in specific surface active area, light absorption and decrease in electron-hole recombination rate, which enhanced photocatalytic activity. Then, 0.75 wt% rGO and 1 wt% CeO2 were incorporated into the surface modified TiO2 to promote photogenerated charge separation, electron mobility and CO2 absorptivity. The modified TiO2/rGO/CeO2 photocatalysts exhibited superior photocatalytic performance by producing methanol at 641 μmol/gcath and ethanol at 271 μmol/gcath, almost 7 times higher than rates from pure TiO2. The significant improvement in CO2 photoconversion activity was mainly attributed to the high interfacial contact area and strong connection between the reactive delaminated TiO2 nanosheets, rGO and CeO2, which, in turn, facilitated the flow of large number of photogenerated charge carriers to react with the absorbed species, and the multi-step charge transportation due to the heterojunction effect that effectively retarded electron-hole recombination.

Surface modification of TiO2 with polydopamine and its effect on photocatalytic degradation mechanism

TiO2 presents a broad application prospect in the field of degradation of environmental pollutants. However, the development of TiO2 photocatalyst has been limited by two factors, namely, narrow spectral response range and low quantum efficiency. Surface coating can selectively change the physical and chemical properties of core particles, whereas the synergistic action between core and shell can optimize material performance. In this paper, surface modification of titanium dioxide (TiO2) by dopamine polymerization was used to improve its photocatalytic performance. Among polydopamine (PDA)-modified TiO2, TiO2@PDA-0.4 mg/mL-2 h showed the best degradation rate of Rhodamine B (RhB): the degradation rate reached 99.28% and 77.40% after 1.5 h of ultraviolet–visible (UV–vis) and visible (Vis) light irradiation, respectively. Compared with the uncoated TiO2, the degradation rate has shown improvement, especially under Vis light irradiation, with the photocatalytic performance improving by 35.04%. Absorption, emission, and impedance spectra showed that surface modification of TiO2 with suitable thickness of PDA effectively increased light absorption and promoted separation of photogenerated carriers. High-performance liquid chromatography–mass spectrometry revealed the differences in photocatalytic degradation mechanism of TiO2@PDA to RhB under UV–vis and Vis light irradiation. Compared with those under UV–vis light irradiation, the intermediate products under Vis light irradiation are relatively simple. TiO2@PDA generated more electrons, which interacted with H2O to produce large amounts of ·OH and holes under UV–vis light irradiation in comparison with that under Vis light irradiation. In addition to deacetylation, deamination, and decarboxylation by hydroxylation, excess ·OH in the photocatalytic process would attack benzene rings directly to produce N,N-diethylacetamide.

Study of nanostructure of polymer adsorption layers on the particles surface of titanium dioxide

The surface modification of titanium dioxide in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymers, poly(acrylic acid)/polystyrene graft copolymers, and hydrophobically modified polyethyleneoxide urethane by ultrasonic treatment was studied. The pigment surface modification by the above copolymers was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorption onto the pigment surface was quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymers as achieved by ultrasonic treatment varies with the copolymer architecture and is a consequence of ultrasonically induced pigment surface activation.

Fe Doped Titania Photocatalyst for Degradation of Methyl Orange

Abstract Surface modification of titanium dioxide (TiO2) by doping method is one of the ways to lower TiO2 band gap and thus increasing its absorption to the visible region. This study was conducted to demonstrate a feasible modification of TiO2 by using iron (Fe) metal as the doping agent. Fe-doped TiO2 photocatalyst with the ratio of 1:1 was prepared by using the wet-impregnation method. The prepared photocatalyst was applied for the degradation of methyl orange (MO) under ultraviolet (UV) and visible light irradiation. A 0.20 g/L of Fe-doped TiO2 efficiently degraded 82.8% and 74.4% of 5 ppm MO under UV light and visible light irradiation, respectively. MO removal up to 85% was attained using bare TiO2 in the presence of UV compared to only 11% under visible light. The UV-Vis Diffuse Reflectance spectroscopy confirmed the reduction of TiO2 band gap upon Fe doping.