Particle Size Of TiO2 Nanoparticles Research Articles

Green synthesis of SiO2 and TiO2 nanoparticles using safflower (Carthamus tinctorius L.) leaves and investigation of their usability as alternative fuel additives for diesel-safflower oil biodiesel blends

Research into alternative fuels for diesel engines is currently focusing on the utilization of nanoparticles (NPs) as a promising solid fuel additive. The basis of such studies is to investigate the possibilities of using solid–liquid mixtures in internal combustion engines (ICEs). In general, NPs are commercially sold and readily available. On the other hand, NPs that can be produced from biomass through green synthesis have recently been preferred because of their environmental-friendly, low cost, and low toxicity. In the present study, therefore, the influence of alternative fuels to be prepared by adding metal-based silicon dioxide (SiO2) and titanium dioxide (TiO2) NPs obtained by green synthesis using safflower (Carthamus tinctorius L.) leaves to diesel-safflower seed oil biodiesel (SSOB) blends (B10 and B20) at varying levels (50, 100, and 250 ppm) on the engine performance and emissions was extensively examined under laboratory conditions. While the particle size of the synthesized SiO2 NPs was calculated as approximately 41 nm, the particle size of TiO2 NPs was calculated as 47 nm. Additionally, it was observed that the obtained NPs generally had spherical and irregular particle structures. The presence of SiO2 (Si: 21.2 %, O 67.3 %) and TiO2 (Ti: 50.7 %, O: 45.8 %) was confirmed by EDX analysis. On the basis of the engine tests, the highest fuel consumption was calculated to be 2.132 kg/h for the B20Ti250 at the highest load. It was pointed out that the fuel blends including NPs descended CO and HC emissions whereas ascended NOx emissions. At 75 % load, the CO2 emissions for diesel fuel (DF), B20, and B20Ti250 were 0.468, 0.491, and 0.502 kg/kWh, respectively.

Exploring the bioactivity of reduced graphene oxide and TiO2 nanocomposite for the regenerative medicinal applications

Millions of people globally suffer from issues related to chronic wounds due to infection, burn, obesity, and diabetes. Nanocomposite with antibacterial and anti-inflammatory properties is a promising material to promote wound healing. This investigation primarily aims to synthesize reduced graphene oxide and titanium dioxide (rGO@TiO2) nanocomposite for wound healing applications. The rGO@TiO2 nanocomposite was synthesized by the one-step hydrothermal technique, and the physicochemical characterization of synthesized nanocomposite was performed by X-ray diffraction, Fourier transforms infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and dynamic light scattering. Further, the nanocomposite antibacterial, cytotoxicity, and wound-healing properties were analyzed by disc diffusion method, MTT assay, and in vitro scratch assay, respectively. Based on the TEM images, the average particle size of TiO2 nanoparticles was around 9.26 ± 1.83 nm. The characteristics peak of Ti–O–Ti bonds was observed between 500 and 850 cm−1 in the Fourier transforms infrared spectrum. The Raman spectrum of graphene oxide (GO) was obtained for bands D and G at 1354 cm−1 and at 1593 cm−1, respectively. This GO peak intensity was reduced in rGO, revealing the oxygen functional group reduction. Moreover, the rGO@TiO2 nanocomposite exhibited dose-dependent antibacterial properties against the positive and negative bacterium. The cytotoxicity for 5–100 µg/mL of rGO@TiO2 nanocomposite was above the half-maximal inhibitory concentration value. The in vitro scratch assay for rGO@TiO2 indicates that the nanocomposite promotes cell proliferation and migration. The nanocomposite recovered the wound within 48 h. The rGO@TiO2 nanocomposite shows potential materials for wound healing applications.

Effect of TiO2 nanoparticles on the mass transfer process of absorption of toluene: Experimental investigation and molecular dynamics simulation

Toluene is a typical representative of aromatic volatile organic compounds, and its elimination makes an important contribution to combating air pollution. In this work, the effect of TiO2 nanoparticles on the mass transfer process during the removal of toluene by deep eutectic solvent (tetraethylammonium chloride and oleic acid) was investigated experimentally and theoretically. First, the removal effect of different nanofluids was evaluated by dynamic bubble absorption experiments. The concentration and particle size of TiO2 nanoparticles have a significant effect on the toluene removal performance of nanofluids. Toluene removal performance was improved with the increase of TiO2 concentration until the concentration increased to 0.1 wt %. However, However, when the concentration of TiO2 nanoparticles increases further to 0.5 wt %, the toluene removal performance is weakened. It was also found that the mass transfer effect decreases as the size of the nanoparticles increases. In addition, the microscopic mechanism of mass transfer of toluene before and after the addition of TiO2 nanoparticles is investigated by molecular dynamics simulations. The interaction energy, radial and spatial distribution functions, and self-diffusion coefficient were calculated to provide molecular insights into the mass transfer mechanism. The results show that TiO2 nanoparticles improve the mass transfer performance of toluene without changing the mechanism of interaction between toluene and deep eutectic solvent. TiO2 nanoparticles increase the area of gas-liquid mass transfer or the diffusion rate of gas in the liquid phase to improve the mass transfer process.

Size optimization of nanoparticle and stability analysis of nanofluids for spectral beam splitting hybrid PV/T system

Spectral beam splitting hybrid PV/T system is a promising way to utilize effectively full spectrum solar energy for power and high-grade heat cogeneration. Heat medium liquid with nanoparticles (NPs) exhibits great potential in solar photothermal applications considering where using NPs to selectively absorb and transmit solar spectrum enables more efficient PV/T system. The paper begins with an introduction to the finite-difference-time-domain (FDTD) method system to analyze the full spectrum solar optical properties of SiO2 and TiO2 NPs. Moreover, taking spectral response of monocrystal silicon solar cells as example, the degree of appropriateness (DOA) was proposed to evaluate the response degree of NPs to specific bands of sunlight and optimize particle size. We suspend SiO2 and TiO2 NPs in Deionized water (DI) by two-step method to filter out the ideal spectrum for generating electricity from monocrystal silicon solar cells. The effects of ultrasonic time, ultrasonic power, and NPs/dispersants mass fraction ratios (MFR) on the stability of SiO2/water and TiO2/water nanofluids (NFs) were experimentally investigated based on static precipitation and absorbance methods. The results show that the optical properties are sensitive to the particle size of NPs and the extinction power increase with the increase of particle size. The particle size of TiO2 NPs in the range of 20-200 nm can regulate the position of extinction peak over a wide extent of 300-400 nm. The DOA of SiO2 and TiO2 NPs with particle size of 20 nm is the largest, which are 94.21% and 97.45%, respectively. The stability of SiO2/water and TiO2/water NFs is the best when Sodium Hexametaphosphate (SHMP) is added as dispersant. And the optimal MFR of NPs and SHMP is 1:1. The 0.05wt% SiO2/water NFs prepared has high stability at 250 W ultrasonic power and 50 min ultrasonic time. Moreover, the good stabilization of 0.01wt% TiO2/water NFs is achieved at 200 W ultrasonic power and 50 min ultrasonic time.

Antimicrobial edible materials via nano-modifications for food safety applications

Abstract Edible films from carboxymethyl cellulose (CMC)/starch incorporated with titanium dioxide (TiO2) nanoparticles were developed. The prepared films were characterized by Fourier transforms infrared, X-ray diffraction, transmission electron microscopy, dynamic light scattering, swelling behaviour, and thermal and mechanical properties. Results showed a decrease in the average particle size of TiO2 nanoparticles with increasing irradiation dose up to 30 kGy. The swelling capacity of CMC/starch blends is ordered in the sequence of composition ratio 2:1 > 1:1 > 1:2. The effect of different irradiation doses (2.5, 5, 10, 15, and 20 kGy) and different concentrations of TiO2 (0.5, 1, 1.5, 2, 2.5, and 3 wt%) on the film properties was evaluated. The tensile strength increased gradually, accompanied by a decline in elongation percentage with the increase in the irradiation dose and increase in the TiO2 contents up to 2.5 wt%. The irradiated CMC/starch/TiO2 film showed higher thermal stability than CMC/starch film. Furthermore, the unirradiated and irradiated CMC/starch/TiO2 edible films were applied to fresh strawberries by surface coating. The irradiated film showed a superior effect in prolonging the fruits’ shelf life. The antimicrobial activity of CMC/starch/TiO2 film against Escherichia coli and Staphylococcus aureus was increased by increasing the irradiation dose. In conclusion, CMC/starch/TiO2 edible film exhibited the prerequisite behaviour for potential application in active food packaging.

Characteristics of organic titanate modified titanium dioxide nanoparticles and its dispersibility in acrylic emulsion coating

AbstractThis work presents the characteristics of rutile TiO2 nanoparticles modified by isopropyl tri[di(octyl) phosphato] titanate (KR‐12) with the content of 3, 5 and 10 wt.% as compared to TiO2 nanoparticles weight. The infrared (IR) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), and thermal gravimetry analysis (TGA) methods were used to evaluate the surface modification efficiency of the TiO2 nanoparticles with KR‐12. The TGA and IR analysis results indicated that the organic coupling agent (KR‐12) was grafted to the surface of the nanoparticles. The TiO2 nanoparticles after modification could disperse stably in water easily. The modification caused the shift of surface charge of the TiO2 nanoparticles to more positive region. The average particle size of TiO2 nanoparticles modified with 0, 3, 5, and 10 wt.% of KR‐12 was 443.9 nm, 295.3 nm, 334.8 nm, and 392.3 nm, respectively. The hydrophobic ability of TiO2 nanoparticles was improved significantly after modification. The modified TiO2 nanoparticles could well disperse in acrylic emulsion coating with dispersed phase size of 200‐400 nm.

Evaluation of the dependence of methyl orange organic pollutant removal rate on the amount of titanium dioxide nanoparticles in MWCNTs-TiO2 photocatalyst using statistical methods and Duncan’s multiple range test

ABSTRACT Here, we prepared two kinds of nanocomposites (MCT#1 and MCT#2) involving MWCNTs and TiO2 nanoparticles. The characterisation of the samples is carried out based on FTIR spectroscopy and TEM. The Ti-O groups that is attributed to the TiO2 nanoparticles can be confirmed according to the FTIR analysis. TEM images show that the average particle size of TiO2 nanoparticles in prepare MCT#1 and MCT#2 is equal to 13 nm and 15 nm, respectively. The influences of nanocomposites weight fraction and illumination time are investigated on the decomposition rate of methyl orange (MO) as pollutant. The photocatalytic results exhibit that the decomposition rate of MO is increased with respect to the weight fraction and illumination time. Meanwhile, higher decomposition rate can be observed using MCT#2 compared to MCT#1. Statistical analysis of the results based on Duncan’s multiple range test at α = 0.05 reveals that all of the applied levels of the factors have a significant effect on the decomposition rate. The response surface results confirm that the effect of illumination time is high that that of weight fraction of MCT#1 and MCT#2.

Investigating the Effects of Particle Size on the Growth of Silkworm and Fiber Properties with Feeding TiO2 NPs

The production method of functional silk by feeding the various nanoparticles is simple, it has attracted the attention of many researchers. However, many researchers have studied the concentrate of nanoparticles (NPs), there are few studies on the particle size. This study is aimed to confirm the effects in silkworm growth, cocoon quality, and mechanical properties of silk with feeding TiO2 NPs of the various particle size. TiO2 10nm, 50nm, 100nm powers individually are fed to silkworm, investigated the mortality and proliferation rate, cocoon mass and cocoon shell mass, mechanical characteristic of silk fiber. The experiments demonstrated that the larger the particle size of TiO2 NPs, the greater the adverse impact on the growth and livability of silkworms. The stress of 523.35±42 MPa and strain of 19.73±1.8% of the TiO2-10nm added silk were increased 35.9% and 19.5% on average, respectively. By the analysis of the Fourier transform infrared (FTIR) spectra, it was confirmed that this resulted in a more random coil/?-helix structure. The nanoparticles are acted as knots, forming the cross-linked network, resulting in lower crystallinity and higher strain, but the larger the particle, the fewer the number of knots, at the same time, it has a great impact on protein synthesis, and then the strength may be decreased. The effect in the silkworm body of TiO2 NPs particle size has to be deeply studied, but this study has important significance to study in the production of the functional silk by feed additives.

TiO2 nanostructured coated functionally modified and composite electrospun chitosan nanofibers membrane for efficient photocatalytic degradation of organic pollutant in wastewater

In this study, we prepared chitosan (Cs_P) nanofibers (NFs) membrane by electrospinning. The Cs_P NFs membrane was then chemically functionalized (CsF) by a novel stepwise chemical process. The CsF NFs membrane was electrospray with TiO2 nanoparticles (NPs) to prepare the CsF_Coa NFs membrane. A second NFs membrane with embedded TiO2 NPs (Cs_Co) was also prepared by electrospinning. The TiO2 NPs, Cs_P, CsF s, CsF_Coa NFs, and Cs_Co NFs membranes were analyzed by standard spectroscopic, microscopic, X-ray, and thermal methods. Fourier transform infrared (FTIR) analysis confirmed the incorporation of the new functional group into the Cs structure. X-ray photoelectron spectroscopy (XPS) data confirmed the FTIR results and the fabrication of the CsF NFs membrane. Scanning electron microscope (SEM) micrographs showed a smooth morphology for the Cs_P NFs membrane and a denser morphology for the CsF NFs membrane (NFs swelled with functionalization). The SEM micrographs also showed a dense cloud of TiO2 NPs on the surface of the Cs_Coa NFs membrane. Transmission electron microscope (TEM) showed that the particle size of TiO2 NPs varied between 20 and 35 nm and tended to be spherical. The X-ray diffraction (XRD) pattern confirmed the existence of the anatase phase of the TiO2 NPs. The presence of TiO2 in the Cs_Coa and Cs_Co NFs membranes was also confirmed by energy-dispersive x-ray spectroscopy (EDX). Surface profilometry confirmed an increase in the surface roughness of the CsF and Cs_Coa NFs membranes. Brunauer–Emmett–Teller (BET) analysis revealed that the isotherms and hystereses for all NFs membranes were of the IV and H3 types, respectively, corresponding to mesopores and slit pores. The higher photocatalytic activity of the Cs_Coa NFs membrane (89%) compared to the Cs_Co NFs membrane (40%) was attributed to a balance between the short band gap, high surface roughness, and lower surface area.

An Ultrasound-Assisted Minireactor System for Continuous Production of TiO2 Nanoparticles in a Water-in-Oil Emulsion

In this work, ultrasound-assisted synthesis of TiO2 nanoparticles in a water-in-oil emulsion in a minireactor has been introduced. For this, a lab-scale ultrasound-assisted minireactor system was developed. Experiments were carried out at different precursor solution flow rates, precursor and surfactant concentrations, and minireactor geometries. Lowering the precursor concentration and flow rate significantly decreases the average particle size of TiO2 nanoparticles. However, increasing the surfactant concentration decreases the average particle size up to a certain extent after which it increases due to an increase in viscosity of the microemulsion. Also, the use of a spiral tube and straight tube minireactor leads to a lesser average particle size due to efficient mixing characteristics. Results show that these parameters influence the particle size of TiO2 nanoparticles. Moreover, ultrasound-assisted synthesis (at an ultrasound frequency of 22 kHz) is able to produce TiO2 nanoparticles of significantly reduced size compared to those produced without using ultrasound. This is achieved by intensified dispersion of aqueous droplets in the oil phase and prevention of droplet coalescence, nucleate grouping, and nanoparticle agglomeration due to the cavitational effect of ultrasonication. The lowest average particle size of 20.9 nm of TiO2 nanoparticles was obtained at a precursor concentration of 4 vol %, a precursor solution flow rate of 150 mL/h, and a surfactant concentration of 0.006 g/mL using the minireactor of spiral geometry.

Effect of food on orally-ingested titanium dioxide and zinc oxide nanoparticle behaviors in simulated digestive tract

Nanomaterials have been widely utilized in human daily life. The interaction between nanoparticles (NPs) and food matrices through oral ingestion is important for fate and potential toxicity of NPs. In this study, the interaction between NPs (i.e., titanium dioxide (TiO2) and zinc oxide (ZnO)) and food matrices (namely sucrose, protein powder, and corn oil) was investigated by use of an in vitro physiological model. Measurement using asymmetrical flow field-flow fractionation (AF4) showed that particle size of TiO2 NPs in saliva fluid decreased from 102 ± 6.21 nm (control) to 69.2 ± 6.90 and 81.9 ± 4.30 nm in protein powder and corn oil. Similar trend was also observed for ZnO. Compared with gastric fluid, micelles formed by corn oil in intestinal fluid further dispersed NPs, as indicated by approximately 11.1% and 13.2% decrease in particle size of TiO2 and ZnO NPs, respectively. Characterization of TEM, FTIR and AFM showed that a layer of biological corona was attached on surface of NPs in protein and oil. The XPS demonstrated that oil bound with NPs through forming covalent bonds, while protein bound with NPs through van der Waals force and electrostatic force for TiO2 and ZnO NPs, respectively. The result here demonstrated the importance of considering food effect when investigating the morphology and behavior of NPs after oral ingestion. This understanding was valuable in assessment of environmental fate and biological effects of NPs.

The effect of titanium (IV) chloride surface treatment to enhance charge transport and performance of dye-sensitized solar cell

In this study, the photovoltaic and electrochemical characteristics of the dye-sensitised solar cell (DSSC) after titanium (IV) chloride (TiCl4) treatment on a TiO2 photoelectrode were investigated. Photoelectrodes of untreated, pre-TiCl4 and post-TiCl4 treatment were prepared to form a complete DSSC. The photoelectrode was sensitised in 40 mM of TiCl4 solution at 80 °C for 30 min, and then it is sintered at 500 °C. The morphology of photoelectrodes has been studied using FESEM, and it was found that, after TiCl4 treatment, the particle necking and particle size of TiO2 nanoparticles were increased significantly. Therefore, it improved the electron transfer path on the TiO2 layer. Subsequently, the light absorption intensity after post-TiCl4 treatments was increased due to strong adhesion and homogeneity of the TiO2 layer on the FTO substrate, which results in higher current density and photon-conversion efficiency by 18.95 mAcm−2 and 8.03% when compared to an untreated electrode at 12.1 mAcm−2 and 4.08% (increment of 56.7% and 96.9%), respectively. Electrochemical impedance spectroscopy used to study the internal electrochemical characteristics of DSSC after the treatment. Thus, it proves that the treatment suppresses the charge recombination between TiO2 and the electrolyte interface by increasing charge transfer resistance after post-TiCl4 treatment by 24.06 Ω from 16.11 Ω for untreated photoelectrodes (increment of 49.39%). The electron lifetime also improved from 0.4 to 1.59 ms, which results in the enhancement of charge collection efficiency after post-treatment by 31.09% compared to the untreated electrode. Improvement of charge collection efficiency indicated that the TiCl4 treatment had played an important role in charge separation and charge collection on the TiO2 and electrolyte interface of DSSC.

Titanium Dioxide Nanoparticles: Synthesis, X-Ray Line Analysis and Chemical Composition Study

TiO2 nanoparticleshave been synthesized by the sol-gel method using titanium alkoxide and isopropanolas a precursor. The structural properties and chemical composition of the TiO2 nanoparticles were studied usingX-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy.The X-ray powder diffraction pattern confirms that the particles are mainly composed of the anatase phase with the preferential orientation along [101] direction.The physical parameters such as strain, stress and energy density were investigated from the Williamson- Hall (W-H) plot assuming a uniform deformation model (UDM), and uniform deformation energy density model (UDEDM). The W-H analysis shows an anisotropic nature of the strain in nanopowders. The scanning electron microscopy image shows clear TiO2 nanoparticles with particle sizes varying from 60 to 80nm. The results of mean particle size of TiO2 nanoparticles show an inter correlation with the W-H analysis and SEM results. Our X-ray photoelectron spectroscopy spectra show that nearly a complete amount of titanium has reacted to TiO2.

Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells.

Pulsed electric field assisted sol–gel preparation of TiO2 nanoparticles

This work studies the effect of a pulsed electric field (PEF) on the precipitation and properties of TiO2 nanoparticles. TiO2 nanoparticles were prepared using pulsed DC electric field assisted sol–gel method. The duration of the PEF treatment was varied to investigate its effect on the particle size of TiO2 nanoparticles. The nanoparticles were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, UV diffuse reflectance spectroscopy (UV-DRS) and transmission electron microscopy (TEM). It was found that TiO2 particles prepared with pulsed electric field assisted sol-gel method had enhanced average crystallite size due to the effect of the pulsed electric field on primary nucleation. The effect of electric field on nanoparticle preparation is interesting which can be used to control the grain and crystallite size of nanoparticle.

The use of TiO2 nanoparticles to enhance CO2 absorption

The enhancement of absorption of CO2 by propylene carbonate in the presence of TiO2 nanoparticles was investigated. The influences of solids loading and particle size of TiO2 nanoparticles on the absorption rate were studied experimentally. The results show that the gas absorption rate can be enhanced significantly in the presence of TiO2 nanoparticles. The CO2 absorption enhancement factor firstly increases and then decreases with the increases of solids loadings, which proves the existence of optimal solids loading. The particle size is also a main factor, which affects CO2 absorption enhancement factor. As the particle size increases, the optimal solids loading gradually increases. A three-dimensional instantaneous numerous-particle di-mechanism model based on the shuttle mechanism as well as a micro-convection mechanism was developed. The results calculated by the model are close to the experimental results, which showed the model can predict experimental data very well.

Synthesis and Crystallization Studies of Thermo-plastic Polyster/Titania Nanocomposites

The present work reports the non-isothermal crystallization kinetics of PET- TiO2 nanocomposites. The average particle size of TiO2 nanoparticles, prepared by chemical route, has been calculated 32 nm using Debay-Scherrer's formula in XRD peaks. PET-TiO2 nanocomposites have been synthesized using solution casting method. The investigation of non-isothermal crystallization behavior has been conducted by means of Differential Scanning Calorimeter (DSC). The crystallization temperature shift to lower temperature for both PET pristine and PET-TiO2 nanocomposites due to decrease in mobility of chain segments and heterogeneous nucleation. Also, the inclusion of TiO2 nanoparticles may accelerate nucleation rate in nanocomposites that causes the crystallization time and absolute crystallinity fraction. The thermal conductivity of inorganic filler TiO 2 nanoparticles may affect the crystallization temperature.

The effect of inorganic ions on the aggregation kinetics of lab-made TiO2 nanoparticles in water

Metal oxide nanoparticles released from nanotechnology-based industries have attracted more attention recently because of their potentially hazardous effect to humans and the ecosystem. The aggregation of nanoparticles has a great influence on their fate in the environment and is relevant to their potential toxicities. In this study, we synthesized stable TiO2 nanoparticle suspension and investigated their distinct aggregation kinetics in the presence of various inorganic ions. Different concentrations of salts (NaCl, CaCl2 and Na2SO4) were chosen to represent various environmental solutions. The particle size of TiO2 nanoparticles increased when ionic concentrations went up. The stability of TiO2 nanoparticles in water is also affected by combinations of salts and ionic strength. For our lab-made TiO2 nanoparticles, it was easier to form aggregates in the presence of anions than in the presence of cations. Furthermore, divalent ions were better than monovalent ions in promoting aggregation formation. The attachment efficiencies of TiO2 aggregates were constructed based upon the aggregation kinetics. The critical coagulation concentration values for our lab-made TiO2 nanoparticles were higher than previously reported. The aggregation kinetics fit the Derjaguin–Landau–Verwey–Overbeek theory well; that is, divalent anions neutralized the nanoparticle surface charge and promoted aggregate formation more efficiently than the monovalent ones did. Our results indicated that the ionic concentration and ionic type required for the aggregation of TiO2 NPs are critical. These factors should be taken into account for interpreting the behavior of NPs and for developing strategies to remove NPs from the aquatic environment.

Stability Analysis of Nano-Sized Titanium Dioxide in Aqueous Environment

Nano-sized titanium dioxide in aquatic environment poses potential impact on environment and human health. In this research, the impact of pH value, humic acid (HA) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles(NPs) in the aqueous enviorment was investigated using a batch test. The results showed that the particle size of TiO2 NPs was not sensitive to the pH value but presented inversely proportional to zeta potential. The TiO2 NPs become more stable along with surface zeta potential, accompany with small particle size and high dispersion. In the presence of HA, the particle size was smaller and TiO2 NPs could be stabilized. This might be synergistic effect of the ligand exchange and electrostatic force. Meanwhile, NPs particle size increased with the addition of Ca2+ and the stability of TiO2 NPs became decreased.

Synthesis of TiO2 Nanoparticles Using Chemical Vapor Condensation

AbstractNano-sized TiO2 particles are of interest for many applications, including use as photocatalysts and in heat transfer fluids (nanofluids). In the present study, TiO2 nanoparticles with controllable phase and particle size have been obtained through homogeneous gas-phase nucleation using chemical vapor condensation (CVC). The phase and particle size of TiO2 nanoparticles under various processing conditions have been characterized using x-ray diffraction and transmission electron microscopy. Chamber temperature and pressure were found to be two key parameters affecting particle phase and size. Pure anatase phase was observed for synthesis temperatures as low as 600 °C with chamber pressure varying from 20-50 Torr. When the furnace temperature was increased to 1000 °C at a pressure of 50 Torr, a mixture of anatase and rutile phases was observed, with the predominant phase being anatase. The average particle size under all the experimental conditions was observed to be less than 20 nm.