Agglomeration Of TiO2 Nanoparticles Research Articles

Study on the inhibitory behavior of high-voltage electric field on the agglomeration and sedimentation of nanoparticles in suspension

Nanoparticles can improve the heat transfer effect of fluids, however, they are difficult to dissolve in the base fluid and are prone to fouling, agglomeration and sedimentation during flow, which affects their efficient heat transfer characteristics. In this paper, the inhibitory effect of high-voltage electric field on the agglomeration and deposition of TiO2 nanoparticles in suspension was comparatively studied by comprehensive gravity sedimentation, spectrophotometer, particle size analysis, and zeta potential method. Studies have shown that the absorbance of suspensions is basically the same in neutral and acidic environments. However, in a highly alkaline environment, the agglomeration rate of nanoparticles increases significantly, resulting in a decrease in the absorbance of the suspension. The high-voltage non-uniform electric field generated by the active Cu rod electrode can effectively inhibit the agglomeration of TiO2 nanoparticles. However, the suppression effect of an external electric field is not necessarily the higher the voltage, the better. Different nanomaterials have different critical voltages. The high-voltage electric field of 1 kV has the best inhibitory effect on the agglomeration and deposition of TiO2 nanoparticles. An in-depth analysis of the mechanisms of the movement and agglomeration of TiO2 particles in suspension under high-voltage electric field excitation was conducted. The result shows that the agglomeration and sedimentation of particles in suspension depend on the Zeta potential of the nano particles. The higher the absolute value, the more stable the dispersion system is.

Enhancing fluidization quality of nanoparticle agglomerates by combining vibration, stirring and jet assistances

Gas fluidization is an efficient method to process nanoparticles. In this study, we employ 3D printing to fabricate a hollow stirring structure of blades with jet holes and position it in a vibrating fluidized bed to realize an integration of vibration, stirring and jetting assistance methods, without increasing structural complexity. The fluidization of SiO2, Al2O3 and TiO2 nanoparticle agglomerates with different primary particle sizes and surface properties are investigated. The combination of vibration and stirring improves the bed expansion obviously, while a further addition of the gas jets at a velocity of a few meters per second allows a further small improvement of bed expansion. The jets slightly reduce the agglomerate size in the dense bed, the agglomerate size at the bed outlet, and the elutriation rate. By combining vibration, stirring and jets, the fluidization is enhanced while the elutriation is kept low during fluidization lasting for a few hours.

Natural Rubber-TiO2 Nanocomposite Film for Triboelectric Nanogenerator Application.

In this research, natural rubber (NR)-TiO2 nanocomposites were developed for triboelectric nanogenerator (TENG) application to harvest mechanical energy into electrical energy. Rutile TiO2 nanoparticles were used as fillers in NR material to improve dielectric properties so as to enhance the energy conversion performance of the NR composite TENG. The effect of filler concentration on TENG performance of the NR-TiO2 composites was investigated. In addition, ball-milling method was employed to reduce the agglomeration of TiO2 nanoparticles in order to improve their dispersion in the NR film. It was found that the TENG performance was significantly enhanced due to the increased dielectric constant of the NR-TiO2 composite films fabricated from the ball-milled TiO2. The TENG, fabricated from the NR-TiO2 composite using 24 h ball-milled TiO2 at 0.5%wt, delivered the highest power density of 237 mW/m2, which was almost four times higher than that of pristine NR TENG. Furthermore, the applications of the fabricated NR-TiO2 TENG as a power source to operate portable electronics devices were also demonstrated.

Influence of restitution and friction coefficients on the velocity field of polydisperse TiO2 agglomerates in a conical fluidized bed by the adhesive CFD-DEM simulation

The hydrodynamic behavior of cohesive TiO2 nanoparticle agglomerates was studied in a conical fluidized bed. The effects of size, particle polydispersity, and airflow velocity were analyzed in the transition regime from heterogeneous to homogeneous and turbulent fluidization. The simple-agglomerates size was ~25–75 μm with fractal dimensions of ~1.95–2.50. Adhesive CFD-DEM simulations were performed to study the interaction between the simple-agglomerates by combining Mindlin-Dersiewicz and Johnson-Kendall-Roberts (JKR) contact models. The effects of restitution and friction coefficients, probability density function, and coordination number of agglomerates were studied on the particle velocity profiles in the spout and annular zones. The error analysis results showed that bed dynamics is more sensitive to a change in the friction coefficient than in the restitution coefficient. A good agreement between the results was found for friction and restitution coefficients close to one, which is evidence of nearly elastic collisions between TiO2 agglomerates.

Optical and morphological studies of TiO2 nanoparticles prepared by sol–gel method

Titanium dioxide (TiO2) nanoparticles were prepared at room temperature by the sol–gel process using titanium butoxide (Ti(OBu)4) precursor. The synthesized nanoparticles were calcinated at 500 °C for 60 min. The optical and morphological properties were studied using scanning electron microscope (SEM), particle size analyzer (dynamic light scattering, DLS), Fourier transform infrared (FTIR), fluorescence (FL), and UV–Visible spectroscopy. UV–Visible absorption spectrum showed the absorbance peak in the ultraviolet region ~ 380 nm and FTIR spectrum confirmed the presence of anatase-TiO2 from 400 to 1000 cm−1. SEM micrograph depicted the agglomeration of TiO2 nanoparticles is due to the adhesion of nanoparticles to each other and diffused boundaries. The nanoparticles size was found 131 nm by DLS particle size analyzer. Further, FL spectroscopy revealed the emission spectrum at 360 nm with that the high excitation peak appeared at 644 nm which is indicating the strong red-shift in the spectral region.

The Influence of Bovine Serum Albumin Modified Titanium Dioxide Nanoparticles on Myoblast Cytotoxicity

Titanium dioxide nanoparticles (TiO2NPs) are utilised as a key constituent in many biopharmaceuticals and food products. This is mainly attributed to their favorable chemical properties which enhance their biocompatibility. However, alteration of the physicochemical properties in various matrices remains unexplored. The present study aims to determine if TiO2NPs modified by bovine serum albumin (BSA) have the ability to influence cytotoxicity in C2C12 myoblast cells. The physicochemical properties of TiO2NPs were altered using BSA in a concentration range of 0.3 – 1.5 mg/mL and characterised using nanoparticle (NP) tracking analysis and transmission electron microscopy. Results show that cytotoxicity is enhanced at a BSA concentration of 0.8 mg/mL, which agrees with reduced particle agglomeration and favorable zeta potential. This proves that the state of TiO2 NPs agglomeration directly affects cytotoxicity which can be due to internalization of the smaller nanoparticle (NP) aggregates. These findings suggest that in vitro cytotoxicity assays incorporate the physicochemical characteristics of NPs in relation to the specific cell model used and colloidal state of the substance being tested.

Effect of CNT on the growth and agglomeration of TiO2 nanoparticles

Titanium dioxide nanoparticles (TiO2 -NPs) are agglomerated by inclusion of CNTs during the nucleation and growth process using the hydrothermal method at 160 ⁰C. The content of C-atoms was determined from EDAX-spectra and line scan. The XRD peak of TiO2 indicated the rutile phase R(210), while CNT- TiO2 showed the anatase phase A(004). Williamson-Hall (W-H) models showed the linear fitted negative slope, indicated the presence of compressive strain in TiO2 and CNT- TiO2 crystal lattice. Agglomeration of TiO2 nanoparticles was confirmed from the surface morphology and elemental analysis. The FTIR spectra showed the interfacial interaction between CNTs and TiO2 with vibrational frequency of Ti-O-C bonds at 1065 cm-1

Comparison of adolescent cortisol and testosterone measured by chemiluminescent immunoassay and liquid chromatography dual mass spectrometry

TiO2 has been widely used in the fields of environmental protection, energy conversion, plastics, coatings, cosmetics, and more. However, it has a wide band gap (3.2 eV) and the easy agglomeration of TiO2 nanoparticles hinders its application. This study adopts a one-step hydrothermal method to prepare urchin-like TiO2 photocatalyst and studies the morphology of TiO2 in relation to hydrothermal time, hydrothermal temperature and hydrogen peroxide (H2O2) amount. In addition, the urchin-like TiO2 is annealed in hydrogen atmosphere to discuss the influence of oxygen vacancies on the band gap and photocatalytic performance improvement.

Comparative effects of TiO2 and ZnO nanoparticles on growth and ultrastructure of ovarian antral follicles

Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NP) have been demonstrated to reach the ovary. However, the potential detrimental effects of these metal-based NP on ovarian antral follicles and whether they can be directly taken up by follicular cells are unknown. The aim of this study was to evaluate whether TiO2 and ZnO NP internalize into the antral follicle, and further compared any potential detrimental effects of either NP on growth, ultrastructure and viability of antral follicles. It has been described that TiO2 and ZnO NP induce oxidative stress, thus this study indirectly assessed whether oxidative stress was involved. Antral follicles were cultured with TiO2 (5, 25 and 50 μg/mL) or ZnO (5, 15 and 25 μg/mL) NP for 96 h. TiO2 NP were internalized and agglomerated into cells, increased follicle diameter and disrupted the cytoskeleton arrangement, effects that were partially prevented by a co-exposure with trolox. Moreover, ZnO NP partially dissolved into culture media, decreased follicle diameter, and disrupted cytoskeletal arrangement, and these effects were not prevented by trolox. Ultrastructural alterations induced by exposure to both NP were evidenced by impaired transzonal projections and swelling mitochondria. Oxidative stress mediates TiO2 NP-induced effects but not those from ZnO NP in antral follicle development. Our results suggest that both NP induced ovarian follicle toxicity through different toxic mechanisms, possibly due to a stimulation of ZnO NP solubility and agglomeration of TiO2 NP into the follicular cells.

Surface coating of titania and graphene oxide onto plasma-activated polymer membranes as efficient photocatalysts for organics removal from water

In this study, various weight ratios of titania (TiO2) and graphene oxide (GO) mixed powders were coated on the surface of microporous poly(vinylidene fluoride) (PVDF) membranes after the membranes were activated by argon plasma and immediately grafted with acrylic acid. Such composite membranes were first characterized by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and water contact angle measurements. These composite membranes were then applied to remove phenol and m-nitrophenol in the single and binary systems under UV irradiation. Results showed that the presence of GO enhanced the efficiency of TiO2 photocatalysis due to its ability to minimize the agglomeration of TiO2 nanoparticles and the recombination rate of electron-hole pairs. In contrast to traditional suspended catalyst systems, the as-prepared composite membranes were proven to be more economic and efficient materials for the removal of organic pollutants. Finally, the intermediates produced during UV photocatalysis of single and binary phenol/m-nitrophenol using the composite membranes were detected and identified by UPLC®-QTof/MS, and the degradation pathways were proposed accordingly.

Modification of the optical properties and nano-crystallinity of anatase TiO2nanoparticles thin film using low pressure O2 plasma treatment

TiO2 nanoparticles (NPs) thin films with a thickness of 50 nm and a core-shell nanostructure were prepared using the spin coating technique and were treated using an inductively coupled O2 plasma at low pressure. While no significant features were observed during pumping, two kinetics can be identified during plasma processing using in situ spectroscopic ellipsometry. For very short plasma treatment times, the removal of solvent-based organic moieties surrounding TiO2 nanoparticles produces a densification of the inorganic TiO2 films. Such mineralization effect by the O2 plasma treatment was confirmed by X-ray photoelectron microscopy. For larger time scales, the average size of TiO2 NPs rises and significant changes of the optical properties occur. While no significant changes in the film nanostructure were observed by Scanning Electron Microscopy, a rise in the crystallite size and an increase in the agglomeration of TiO2 nanoparticles were confirmed by Transmission Electron Microscopy and Atomic Force Microscopy, respectively. The mechanisms involved in such plasma-induced modification of nanostructured TiO2 thin films are discussed in line with the energy fluxes of plasma-generated species.

Influence of TiO2 nanoparticles (wt%) onto the physical and mechanical properties of the TiO2-geopolymer paste

The TiO2-geopolymer paste had been prepared by dry-mixing of the fly ash with various concentration (wt%) of TiO2 nanoparticles (2.5%, 5.0%, 10.0% and 15.0%). Those powder mixtures were then mixed with the alkali activator with the ratio of 2.5 and were cured at room temperature for 28 and 640 days. The phase and chemical bonding analysis revealed that the incorporation of TiO2 nanoparticles did not create any additional phase or functional group, but only physical interaction might have occurred in between the TiO2 and geopolymer matrix. However, the physical properties were depending on the TiO2 nanoparticles content where setting time of the geopolymer can be shortened by the addition of certain amount of TiO2 nanoparticles (up to 5.0 wt%). The water absorption also increased as a function of TiO2 content, due to the formation of the micro cracks as a result from the agglomeration of TiO2 nanoparticles. The compressive strength reaches its maximum value, 85.9 MPa with 5.0 wt% of TiO2 nanoparticles. Beyond 5wt%, the strength decreased almost half of the maximum value, where agglomeration becomes a main factor. While for 640 days of ageing, sample with 15.0 wt% shows triple increment from 30.6 MPa to 95.3 MPa.

Membrane distillation crystallization using PVDF membrane incorporated with TiO2 nanoparticles and nanocellulose

Abstract Polyvinylidene fluoride (PVDF) membrane was improved using TiO2 nanoparticles and nanocellulose for membrane distillation crystallization in this work. Besides the addition of TiO2 nanoparticles and nanocellulose, PVDF membrane was post-modified with octadecyltrichlorosilane after phase inversion using a dual coagulation bath. The addition of hydrophilic TiO2 nanoparticles and nanocellulose reduced membrane hydrophobicity, but the dispersed TiO2 nanoparticles assisted silane modification to improve surface hydrophobicity. Besides reducing the agglomeration of TiO2 nanoparticles, nanocellulose induced the formation of larger pore size and higher porosity as proven in SEM images and gravimetric measurement, respectively. The abundant moieties of nanocellulose accelerated the exchange between solvent and non-solvent during phase inversion for the formation of large pore size and porosity, but membrane thickness increased due to the thickening effects. The modified membrane showed higher water permeate flux in membrane distillation with salt rejection greater than 97%. Severe fouling in membrane distillation crystallization was not observed.

Pulsed Laser Ablation in Water Synthesis of Black TiO2-Graphene Oxide Nanocomposites and the Enhanced Photocatalytic Performance

Black TiO₂-graphene oxide (GO) nanocomposites are synthesized via the pulsed laser ablating TiO₂ powders and GO in deionized water. The simple process enables the preparation of black TiO₂ nanoparticles and anchors them onto the GO sheet in one step. The TiO₂-GO nanocomposites exhibit greatly enhancement for photocatalytic degradation of Rhodamine B (RB) dye in comparison with the pristine and the ablated black TiO₂. The heterojunction structure plays an important role in efficient charge separation, which reduces the recombination of photogenerated electrons and holes. The unique two-dimensional structure of GO enables the composite to have a large specific surface area, and prevents the agglomeration of TiO₂ nanoparticles, which are beneficial to the photocatalytic performance of the composite.

Watermelon-like TiO2 nanoparticle (P25)@microporous amorphous carbon sphere with excellent rate capability and cycling performance for lithium-ion batteries

To overcome the inferior rate capability and cycling performance of TiO2 nanomaterials as an anode material of lithium-ion batteries, we encapsulate TiO2 nanoparticles (P25) in carbon spheres through a facile pyrrole polymerization and carbonization. Material characterization demonstrates TiO2 nanoparticles are uniformly embedded in microporous amorphous carbon spheres, forming a watermelon-like structure. P25@C exhibits excellent high rate capability with average discharge capacity of 496, 416, 297, 240, 180, 99, 49 and 25 mAh g−1 at current rate of 0.5C, 1C, 5C, 10C, 20C, 50C, 100C and 200C, which shows superior long-term cycling performance with discharge capacity of 106.9 mAh g−1 at 20C after 5000 cycles. The capacity loss rate is only 0.008% per cycle. The outstanding lithium storage performance is ascribed to the watermelon-like composite structure, which remarkably improves electronic conductivity and structure stability of TiO2 nanoparticles. More importantly, the agglomeration of TiO2 nanoparticles is eliminated, and the entire surface of every TiO2 nanoparticle participates in the electrochemical reaction, which brings about an intense capacitive Li storage effect and leads to the high specific capacity and excellent rate capability of P25@C. This is confirmed through qualitative and quantitative analysis of the contributions from surface capacitive storage and bulk intercalation storage to the total capacity of the composite.

Enhancing the High Voltage XLPE Cable Insulation Characteristics Using Functionalized TiO<sub>2</sub> Nanoparticles

The current research aims to study the influence of loading Titanium Dioxide (TiO2) nanoparticles on the dielectric, thermal and mechanical properties of the commercial Cross-Linked Polyethylene (XLPE) used as the main insulation in power cables. Using the concept of composite, XLPE/TiO2 nanocomposites samples were prepared by the melt blending method with different ratios of nanoparticles (0.5, 2, 3.5 and 5% wt/wt). The surface treatment of TiO2 nanoparticles was carried out to reduce the agglomeration of TiO2 nanoparticles inside the XLPE. The morphology of the prepared samples was studied by X-ray Diffraction (XRD) and the dispersion of nanoparticles in the XLPE polymer matrix is checked using Field Emission Scanning Electron Microscopy (FE-SEM). Thermal analysis test for all samples have been investigated. The dielectric properties, such as dielectric constant (er) and loss tangent (tan δ) for XLPE/TiO2 nanocomposites were measured under frequencies ranging from 1 Hz to 1 MHz. AC Breakdown Voltage (AC-BDV) was also measured using a controlled high voltage testing transformer (50 Hz) under sphere-to-sphere field. The mechanical properties were evaluated by performing the tensile test and tensile strength and elongation values were measured. It was found that nanocomposites with functionalized TiO2 exhibited better dielectric, thermal and mechanical properties compared to nanocomposites with nonfunctionalized TiO2.

The mutual effects between the interparticle forces and mechanical properties on fluidization of TiO2 nanoparticle agglomerates in a conical fluidized bed: nanoindentation and pressure fluctuation analysis

Understanding the agglomeration process of nanoparticles (NPs) can help to decrease their adhesion during fluidization. Herein, the mutual effects between the mechanical properties and interparticle cohesive forces of the TiO2 NPs as well as the fluidization regimes were studied in a conical fluidized bed. Young’s modulus and hardness of the agglomerates were determined by nanoindentation test. The size range of NPs, porous simple-agglomerates, and dense complex-agglomerates were 23 ± 3 nm, ~ 40–80 μm, and ~ 170–270 μm, respectively. Pressure fluctuation analysis exhibited a transition flow regime from a particulate phase to bubbling, slugging, turbulent fluidization, and spouting regime. The ratio of hydrodynamic to interparticle force was applied to describe the bed characteristics, while the granular Bond number obtained from settling experiments was used to find the agglomerates fractal dimension. The laser images showed the size, structure, and number of agglomerates depends on the type of fluidizing gas and fluidization regime. The dependency of the hardness on the fluidization regime showed the interparticle force diminishes with decreasing the asperity radius of agglomerates. The results showed full fluidization takes place, where the primary complex-agglomerates breakdown into simple-agglomerates and re-agglomerate into secondary complex-agglomerates with the fragile structures and irregular shape that simply fluidized at the spouting regime.

Dispersion of Titanium(IV) Oxide Nanoparticles in Mixed Matrix Membrane Using Octaisobutyl Polyhedral Oligomeric Silsesquioxane for Enhanced CO2/CH4 Separation Performance

Titanium(IV) oxide (TiO2) nanoparticles have been incorporated into mixed matrix membranes (MMMs) to improve gas separation performance. However, TiO2 nanoparticles tend to agglomerate due to high surface energy and van der Waals forces. This leads to precipitation which causes the formation of non-homogeneous MMM morphology. In this study, the effect of octaisobutyl polyhedral oligomeric silsesquioxane (POSS) addition on TiO2/polysulfone MMM was investigated. The aims are to enhance gas separation performance whilst preventing agglomeration of TiO2 nanoparticles. The results demonstrated that inclusion of POSS as dispersant increases MMMs’ CO2/CH4 selectivity and permeance, possibly due to less void formation and more evenly distributed pore structure. For example, synergistic addition of 5 wt% TiO2 and 5 wt% POSS increased the CO2/CH4 selectivity up to 390% compared to MMM without POSS. This is supported by elemental mapping of titanium which revealed that POSS successfully dispersed TiO2 nanoparticles and prevented aggregation. TiO2-POSS/PSf MMMs also retained their favorable thermal stability.

Preparation and properties of duplex NI-P-TIO2/NI nanocomposite coatings

Duplex Ni-P-TiO2/Ni coatings were deposited on the brass substrate by using two baths. Ni-P-TiO2nanocomposite coatings were electroplated as the outer layer on the Ni-plated brass substrate by adding transparent TiO2sol (0–50 mL/L) into the Ni-P plating solution. The microstructure, mechanical property and corrosion resistance of the duplex Ni-P-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the interface of duplex coating was uniform and the adhesion between two layers was extremely good. The microhardness of duplex Ni-P-12.5 mL/L TiO2/Ni coating was [Formula: see text]616 HV[Formula: see text] compared to [Formula: see text]539 HV[Formula: see text] of Ni-P /Ni coating and [Formula: see text]307 HV[Formula: see text] of single Ni coating. Meanwhile, the wear resistance and the corrosion resistance of the duplex nanocomposite coating have also been improved remarkably compared with single Ni coating. However, adding excessive TiO2sol (more than 12.5 mL/L) caused the agglomeration of TiO2nanoparticles and led to a porous structure in the outer layer, resulting in the deterioration of coating properties.

Effect of thermal processing on the tribology of nanocrystalline Ni/TiO2 coatings

The tribological performance of a nanocrystalline coating is heavily influenced by its composition, morphology, and microstructural characteristics. This research work describes the effect of heat treatment temperature on the microstructural, morphological, and mechanical behavior of nanocrystalline Ni/TiO2 coatings produced by electrophoresis. The surface morphology and coating cross section were characterized by scanning electron microscopy (SEM). The composition of coatings and the percentage of TiO2 nanoparticles incorporated in the Ni matrix were studied and estimated by using an energy-dispersive spectroscopic (EDS) analysis, while x-ray diffractometry (XRD) was used to investigate the effect of heat treatment temperature on phase structure. The results showed agglomeration of TiO2 nanoparticles on the surface of the coating. The high hardness and wear resistance recorded for the as-deposited coating was attributed to the uniform distribution of TiO2 nanoparticle clusters throughout the cross section of the coating. Heat treatment of the Ni/TiO2 coatings to temperatures above 200 °C led to significant grain growth that changed the surface morphology of the coating and reduced the strengthening effects of the nanoparticles, thus causing a reduction in the hardness and wear resistance of the coatings.