Effect of pressure on TiO2 crystallization kinetics using in‐situ high‐temperature synchrotron radiation diffraction

The phase transformation behavior of TiO₂ sol‐gel synthesized nanopowder heated in a sealed quartz capillary from room temperature to 800°C was studied using in‐situ synchrotron radiation diffraction (SRD). Sealing of the capillary resulted in an increase in capillary gas pressure with temperature. The pressures inside the sealed capillary were calculated using Gay‐Lussac's Law, and they reached 0.36 MPa at 800°C. The as‐synthesized material was entirely amorphous at room temperature, with crystalline anatase first appearing by 200°C (24 wt% absolute), then increasing rapidly in concentration to 89 wt% by 300°C and then increasing more slowly to 97 wt% by 800°C, with there being no indication of the anatase‐to‐rutile transformation up to 800°C. The best estimate of activation energy for the amorphous‐to‐anatase transformation from the SRD data was 10(2) kJ/mol, which is much lower than that observed when heating the material under atmospheric pressure in a laboratory XRD experiment, 38(5) kJ/mol. For the experiment under atmospheric pressure, the anatase crystallization temperature was delayed by ~200°C, first appearing after heating the sample to 400°C, after which crystalline rutile was first observed after heating to 600°C. The estimated activation energy for the anatase‐to‐rutile transformation was 120(18) kJ/mol, which agrees with estimates for titania nanofibers heated under atmospheric pressure. Thus, heating the nanopowders material under pressure promoted the amorphous‐to‐anatase transformation, but retarded the anatase‐to‐rutile transformation. This behavior is believed to occur in an oxygen‐rich environment and interstitial titanium is also expected to form when the material is heated under high gas pressure. This suggests that atmospheric oxygen appears to accelerate the amorphous‐to‐anatase transformation, whereas interstitial titanium inhibits TiO₂ structure relaxation, which is required for the anatase‐to‐rutile transformation.     

Extractive Separation of Lithium Isotopes by Crown Ethers

Abstract

Separative abilities of crown ethers to lithium isotopes were investigated for the number of oxygen atoms composing crown rings and for the substituted groups to 15-crown-5. The separation factors at 0°C were 1.057 for 12-crown-4, 1.042 for benzo-15-crown-5, 1.041 for lauryloxymethyl-15-crown-5, 1.043 for tolyloxymethyl-15-crown-5, and 1.024 for dicyclohexano-18-crown-6. The enthalpy change of the isotopic equilibrium in the absolute value was the greatest for 12-crown-4; ΔH° = ?0.78 kJ/mol. In the substituted 15-crown-5s the separation factor was greatest for tolyloxymethyl-15-crown-5, and ΔH° values decreased in the order: benzo- > tolyloxymethyl- > lauryloxymethyl-15-crown-5. For enthalpy changes, benzo-15-crown-5 has the possibility of giving a larger separation factor than the present one, α = 1.042, by choosing more suitable conditions. In spite of its large distribution coefficient, dicyclohexano-18-crown-6 is not superior for isotopic separation of lithium in regard to the small enthalpy change of isotopic equilibrium; ΔH° = ?0.15 kJ/mol. The addition of DMSO to the initial solution of LiI caused a remarkable increase in the distribution coefficient without changing the isotopic separation factors.     

Comparison of free energy surfaces calculations from ab initio molecular dynamic simulations at the example of two transition metal catalyzed reactions

We carried out ab initio molecular dynamic simulations in order to determine the free energy surfaces of two selected reactions including solvents, namely a rearrangement of a ruthenium oxoester in water and a carbon dioxide addition to a palladium complex in carbon dioxide. For the latter reaction we also investigated the gas phase reaction in order to take solvent effects into account. We used two techniques to reconstruct the free energy surfaces: thermodynamic integration and metadynamics. Furthermore, we gave a reasonable error estimation of the computed free energy surface. We calculated a reaction barrier of ΔF = 59.5 ± 8.5 kJ mol(-1) for the rearrangement of a ruthenium oxoester in water from thermodynamic integration. For the carbon dioxide addition to the palladium complex in carbon dioxide we found a ΔF = 44.9 ± 3.3 kJ mol(-1) from metadynamics simulations with one collective variable. The investigation of the same reactions in the gas phase resulted in ΔF = 24.9 ± 6.7 kJ mol(-1) from thermodynamic integration, in ΔF = 26.7 ± 2.3 kJ mol(-1) from metadynamics simulations with one collective variable, and in ΔF = 27.1 ± 5.9 kJ mol(-1) from metadynamics simulations with two collective variables.     

TiO2-PDVB Janus particles enhanced compatibility of titanium dioxide and recycled waste styrofoam

People are always puzzled by “white pollution” in recent decade. Recycling of waste styrofoam as a coating is a good sustainable solution to resolve this problem. However, the poor compatibility between inorganic additives and polymer hinders the application of recycled polystyrene. In this article, anisotropic Janus particles were used to increase the compatibility of titanium dioxide/waste styrofoam coatings. SEM results show that Janus particles can be anchored at the interface between styrofoam and titanium dioxide, increasing the dispersion of titanium dioxide, and improving the compatibility of inorganic particles and organic polymer. The glass-transition temperature of styrofoam coating increases from 77 °C to 89 °C in titanium dioxide/styrofoam contained 1 wt % of Janus particles, which certified that Janus particles have compatibilization on titanium dioxide/styrofoam coating. Attributing to this compatibilization, the tensile strength of titanium dioxide/styrofoam with 1 wt % of Janus particles rises about 45% compared with titanium dioxide/styrofoam. The yield stress, storage modulus, and viscosity of titanium dioxide/styrofoam contained 1 wt % of Janus particles are the smallest and the closest to Newtonian fluid. Janus particles used in the recycled styrofoam coating is benefit to expand the application of waste styrofoam and the new anisotropic Janus compatibilizer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48691.     

Removal of strontium from aqueous solutions by adsorption onto activated carbon: kinetic and thermodynamic studies

This work reports the adsorption of strontium from aqueous solutions onto activated carbon. Various factors such as pH, initial concentration of strontium, particle size and temperature were considered. The optimum conditions obtained were: pH value = 4.0, contact time = 8 h, initial concentration of Sr(II) = 100 mg/l, particle size = 270 μm and temperature of 293.15 K. The adsorption of strontium(II) on activated carbon follows pseudo-first order kinetics and the energy of activation E_a calculated using the Arrehenius equation was found to be 3.042 kJ/mol.The adsorption isotherms could be fitted by the Langmuir model with the maximum adsorption capacity Q_o being 5.07×10^–4 mol/g at 293.15 K. A dimensionless separation factor R_L was used to judge the favourable adsorption. The values of the mass transfer coefficient β_L (cm/s) at different temperatures indicated that the velocity of mass transfer of Sr(II) ions onto activated carbon was slow. The intraparticle diffusion mechanism is of great importance in determining the overall rate of removal and the negative entropy of activation ΔS^# value 145.13 J/mol K, reflects that no significant change occurs in the internal structure of activated carbon during adsorption of strontium(II). The Gibbs free energy ΔG°_ads values range from –36.61 kJ/mol to –41.75 kJ/mol at 293.15–333.15 K, which show the physical adsorption properties of activated carbon and indicate the feasibility of the process.     

Isothermal and nonisothermal melt‐crystallization kinetics of syndiotactic polystyrene

Analyses of the isothermal and nonisothermal melt kinetics for syndiotactic polystyrene have been performed with differential scanning calorimetry, and several kinetic analyses have been used to describe the crystallization process. The regime II→III transition, at a crystallization temperature of 239°, is found. The values of the nucleation parameter K_g for regimes II and III are estimated. The lateral‐surface free energy, σ = 3.24 erg cm^?2, the fold‐surface free energy, σ_e = 52.3 ± 4.2 erg cm^?2, and the average work of chain folding, q = 4.49 ± 0.38 kcal/mol, are determined with the (040) plane assumed to be the growth plane. The observed crystallization characteristics of syndiotactic polystyrene are compared with those of isotactic polystyrene. The activation energies of isothermal and nonisothermal melt crystallization are determined to be ΔE = ?830.7 kJ/mol and ΔE = ?315.9 kJ/mol, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2528–2538, 2002     

A novel synthesis route of titanium dioxide with (NH4)0.3TiO1.1F2.1 as by-product

This work explores a new route for the synthesis of titanium dioxide using scraps and titanium chips, which are typically discarded as waste, as the precursor materials. The band-gap energy of the synthesised materials was determined using diffuse reflectance spectroscopy. The morphology, elemental analysis, crystallinity, and chemical structure of the synthesised materials were determined by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, and infrared and Raman spectroscopies, respectively. The X-ray and Raman analyses confirmed the formation of titanium dioxide in its tetragonal (anatase) crystalline form after heat treatment (400 °C, 2 h). Moreover, a mixture of (NH₄)_0,3TiO_1,1F_2,1 and anatase TiO₂ was obtained as a by-product. After heat treatment, this by-product was converted into fluorine-doped titanium dioxide, also in anatase crystalline form. The apparent crystallite size (L_c) of anhydrous titanium dioxide was found to be smaller than that of the calcined by-product. The diffuse reflectance spectroscopy analysis revealed that the calcined by-product has a significantly higher absorption capacity at higher wavelengths, as well as a lower band-gap energy value. The scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) analyses showed large particulates on which smaller particles are deposited and good dispersion of the elemental components. The anhydrous titanium dioxide sample presents a smaller particle size than the calcined by-product.     

Enantiomerization Kinetics of 2,2′-Disubstituted Biphenyls: A Dynamic Chiral HPLC Investigation

The enantiomers of eight axially chiral biaryls were separated by chiral HPLC. On-column enantiomerization of 1-(o-tolyl)naphthalene and 2-cyclohexyl-2′-dimethylaminobiphenyl was observed between 10 °C and 35 °C, generating characteristic HPLC elution profiles with a plateau between the resolved enantiomer peaks. Computer simulation of the experimentally obtained chromatograms allowed determination of the Gibbs free energies of activation, ΔG^≠, as 93.2 kJ/mol and 88.4 kJ/mol, respectively.     

Formation and reactivity of oxides and basic salts. III. Titanium dioxides and basic titanic salts

Methods of production and application of titanium dioxides and basic titanic salts have been summarised and the appropriate physical properties of the products have been studied. Variations in phase composition, surface area and crystallite and aggregate sizes have been correlated with experimental conditions. When titanic sulphate or chloride is hydrolysed by sodium hydroxide, the basic salts initially formed are decomposed subsequently to hydrous titanium dioxide as the pH becomes stabilised at higher values. The specific surface of the basic sulphate increases considerably when it hydrolyses to anatase. On calcination at temperatures up to about 750°, the anatase crystallites can grow from about 0·006 μm to the requisite 0·1–0·5 μm range, but the aggregate sizes vary widely. Shock-heating at temperatures between 600° and 900° removes the remaining water and breaks up the larger aggregates. At higher temperatures, the anatase is transformed to rutile which subsequently sinters. The rutile produced by shorter calcinations at 1100°–1150° is similar in crystallite size to that obtained by complete oxidation (‘burning’) of titanic chloride vapour at the same temperatures. Results emphasise the need for close control of residence time in the high-temperature zone in the production of pigmentary titanium dioxide.     

The Removal of Hg (II) Ions from Laboratory Wastewater onto Phosphorylated Haloxylon ammodendron: Kinetic and Equilibrium Studies

Haloxylon ammodendron (HA), a desert plant residue, has been utilized as adsorbent material for the removal of Hg (II) ions from laboratory wastewater after treatment with phosphoric acid to form Haloxylon ammodendron cellulose phosphate (HACP). Three levels of HACP having different phosphorous content were prepared. The HACP samples were characterized by estimating the phosphorous content as well as FT-IR spectra. Using the batch experimental systems, the removal of Hg (II) on the HACP particles was investigated. The data of the adsorption isotherm was tested by the Langmuir, Freundlich and Temkin models. The removal processes of Hg (II) onto HACP particles could be well described by pseudo-second order model. The adsorption rate of mercury was affected by the initial heavy metal concentration, initial pH, adsorbent dose and agitation time and temperature as well as extent of modification. The adsorption experiments indicated that the HACP particles have great potential for the removal of Hg (II) from laboratory wastewater. The maximum adsorption capacity (Q_max) of the HACP towards Hg (II) ions was found to be 384.6 and 416.7 and 476.2 mg/g at 30, 40 and 50°C, respectively. Similarly, the Freundlich constant, n values were found to be 6.6, 4.4 and 3.8 at 30, 40 and 50°C, respectively. The thermodynamics constants of the adsorption process: ΔH°, ΔS° and ΔG° were evaluated.     

A comparative study of removal of Cu(II) from aqueous solutions by locally low-cost materials: marine macroalgae and agricultural by-products

In this study, adsorption of Cu(II) onto the five locally abundantly low-cost biosorbents (Laminaria japonica, P. yezoensis Ueda, rice bran, wheat bran and walnut hull) was investigated depending on initial solution pH, contact time, adsorbent concentration and reaction temperature. Cu(II) removal was pH-dependent for various biosorbents investigated. For P. yezoensis Ueda, rice bran, wheat bran and walnut hull, the batch equilibrium data were correlated to Langmuir and Freundlich isotherms and the data fitted better to the Langmuir isotherm equation and yielded Langmuir monolayer capacity of 5.04, 10.41, 6.85 and 3.52 mg/g at the temperature of 20°C, respectively. In the case of Laminaria japonica, the equilibrium data obeyed the Hill-der Boer equation for the whole initial concentration ranges of 0–200 mg/L examined, but only to Langmuir and Freundlich equations for the initial concentration less than 120 mg/L at various temperatures. The apparent thermodynamic parameters were calculated for each of the five biosorbents (ΔH = 9.25–40.04 kJ/mol; ΔG = –17.60 to –24.16 kJ/mol and ΔS = 85.81–228 J/mol K). The numerical values obtained showed that Cu(II) adsorption is a spontaneous, entropy-driven and endothermic process. The batch kinetic data were correlated to the pseudo-first order and pseudo-second order models and the data fitted better to the pseudo-second order equation (the pseudo-second order rate constants, k_2,e = 0.1059–0.9453 g/(mg min); the correlation coefficients, r = 0.9816–0.9993).     

二氧化钛光触媒在金属镀膜与金属防护技术中的应用第一部分光触媒分散技术

介绍了二氧化钛的晶体类型和基本性质、典型的锐钛型二氧化钛的XRD图谱。对纳米粒子的团聚现象进行了解释。对纳米粒子的分散原理——高分子分散剂／界面活性剂分散和电解质分散进行了说明。分别介绍了水溶液中二氧化钛以及改性后的锐钛型纳米二氧化钛的Zeta电位与pH的关系。研究了锐钛型纳米二氧化钛在聚丙烯酸盐分散介质中的粒径分布。结果表明,在此分散介质中,纳米颗粒的分布比较集中,粒径小于50．7 nm的粒子占60％,其平均粒径远低于传统的涂料级和颜料级分散的粒子;该溶液呈现明显的丁达尔现象,光触媒活性高,在实验室存放24个月后质量稳定;将此溶胶涂至玻璃表面,所得涂膜透明度高。     

Equilibrium,kinetics, and thermodynamics of Pd(II) adsorption onto poly(m‐aminobenzoic acid) chelating polymer

This study describes the equilibrium, kinetics, and thermodynamics of the palladium(II) (Pd(II)) adsorption onto poly(m‐aminobenzoic acid) (p‐mABA) chelating polymer. The p‐mABA was synthesized by the oxidation reaction of m‐aminobenzoic acid monomer with ammonium peroxydisulfate (APS). The synthesized p‐mABA chelating polymer was characterized by FTIR spectroscopy, gel permeation chromatography (GPC), thermal analysis, potentiometric titration, and scanning electron microscopy (SEM) analysis methods. The effects of the acidity, temperature, and initial Pd(II) concentration on the adsorption were examined by using batch adsorption technique. The optimum acidity for the Pd(II) adsorption was determined as pH 2. In the equilibrium studies, it was found that the Pd(II) adsorption capacity of the polymer was to be 24.21 mg/g and the adsorption data fitted better to the Langmuir isotherm than the Freundlich isotherm. The kinetics of the adsorption fitted to pseudo‐second‐order kinetic model. In the thermodynamic evaluation of the adsorption, the ΔG° values were calculated as ?16.98 and ?22.26 kJ/mol at 25–55°C temperatures. The enthalpy (ΔH°), entropy (ΔS°), and the activation energy (E_a) were found as 35.40 kJ/mol, 176.05 J/mol K, and 61.71 kJ/mol, respectively. The adsorption of Pd(II) ions onto p‐mABA was a spontaneous, endothermic, and chemical adsorption process which is governed by both ionic interaction and chelating mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42533.     

Applicability of Activated Carbon to Treatment of Waste Containing Iodine-Labeled Compounds

Abstract

A timber industry waste was transformed to activated carbon by a one-step chemical activation process using H₃PO₄ (H). The used activated carbon (SDH) was characterized by N₂ adsorption, FTIR, density, pH, point of zero charge pH_pzc, moisture and ash content. Methylene blue (MB) and the iodine number were calculated by adsorption from the solution. The applicability of the different activated carbon produced was carried out to treatment of aqueous waste contaminated with iodine-labeled prolactin (I-PRL) Treatment processes were performed under the varying conditions; contact time, temperature, carbon type, carbon dosage, and different particle size of the activated carbon (SDH). The results indicated that 5 hours are sufficient to reach a plateau, and the amount of I-PRL adsorbed on SDH activated carbons increase with the solution temperature with thermodynamic parameter of ΔG° = ?7.962 (kJ/mol), ΔH° = 28.869 (kJ/mol) and ΔS° = 109.94 (J/mol K). The optimum adsorption results were reached using carbon dose of 0.1 gm with particle size of <0.25 mm, and a batch factor (V/M) of 7.14 mlg^?1. First- and second-order equations, intraparticle diffusion equation, and the Elovich equation have been used to test experimental data. The experimental data was found to fit the second-order model and a chemisorptions mechanism. 0.7 M NaOH can be used for regeneration of spent SDH activated carbon with the efficiency of 99.6% and the regenerated carbon can be reused for five cycles effectively.     

Kinetics of anatase transition to rutile TiO2 from titanium dioxide precursor powders synthesized by a sol-gel process

Kinetics of anatase transition to rutile TiO₂ from titanium dioxide precursor powders synthesized by a sol-gel process have been studied using differential thermal analysis (DTA), X-ray diffraction, transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED) and high resolution TEM (HRTEM). The DTA result shows residual organic matter decomposed at 436 K. The transition temperature for amorphous precursor powders converted to anatase TiO₂ occurred at 739 K. Moreover, the full anatase transition to rutile TiO₂ occurred at 1001 K. The activation energy of anatase TiO₂ formation was 128.9 kJ/mol. On the other hand, the activation energy of anatase transition to rutile TiO₂ was 328.4 kJ/mol. Mesoporous structures can be observed in the TEM image.     

Effect of Germanium Oxide (GeO2) Additive on the Anatase-to-Rutile Phase Transition

The effect of germanium oxide (GeO₂) addition on the anatase-to-rutile phase transition was investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). TiO₂ xerogels containing up to 20 mol% GeO₂ were prepared by refluxing and hydrolyzing titanium tetraisopropoxide (TTIP) and germanium butoxide (GB) using nitric acid as a catalyst. The following occurred with increasing amounts of GeO₂ in the xerogels: (i) the crystallization temperature of anatase increased from 410° to 565°C and the DTA temperature of the anatase-to-rutile phase transition increased from 676° to 977°C in 20 mol% GeO₂-containing xerogel; (ii) the crystallite size of anatase became smaller; (iii) the lattice a-parameter of the anatase showed little change, but the c-parameter decreased up to 20 mol% GeO₂; (iv) both the lattice a- and c-parameters of the rutile decreased monotonically. From these results, the added GeO₂ is considered to become incorporated into the anatase structure. The following occurred with increasing anatase heating temperature: (i) the lattice c-parameter of the anatase increased gradually and approached the value of pure anatase; and (ii) the chemical composition of the xerogel surfaces, measured by XPS, showed an increase in GeO₂ content, indicating the expulsion of GeO₂ from the anatase to form an amorphous surface layer. The formation of this amorphous GeO₂ surface layer is thought to play an important role in retarding the anatase-to-rutile phase transition by suppressing diffusion between the anatase particles in direct contact, and limiting their ability to act as surface nucleation sites for rutile, as in the case of SiO₂ additions. However, GeO₂ addition is less effective than SiO₂ in retarding the phase transition.     

Thermoplastic elastomeric hydrogenated styrene-butadiene elastomer: Optimization of reaction conditions,thermodynamics, and kinetics

Thermoplastic elastomeric hydrogenated styrene—butadiene (HSBR) elastomer was prepared by diimide reduction of styrene-butadiene rubber in the latex stage. The products were characterized by infrared, ¹H-NMR, ¹³C-NMR spectroscopy, and differential scanning calorimetry (DSC). The standard free energy change, ΔG⁰ at 298°K is −44.7 × 10⁴ kJ/mol, indicating that the formation of HSBR is thermodynamically feasible. The value of heat change of the reaction at constant volume, ΔU_T is −41.6 × 10⁴ kJ/mol. The effect of different reaction parameters on the level of hydrogenation, calculated from nuclear magnetic resonance spectroscopy, was also investigated. The degree of hydrogenation increases with the increase in reaction time, temperature, the concentration of reactants and catalyst. A maximum of 94% hydrogenation was obtained under the following conditions: time, 4 h; temperature, 45 ± 2°C; pH, 9.36; cupric sulphate (CuSO₄ · 5H₂O) catalyst concentration, 0.0064 mmol; hydrazine concentration, 0.20 mol; and hydrogen peroxide concentration, 0.26 mol. The diimide reduction of SBR is first-order with respect to olefinic substrate, and the apparent activation energy is 9.5 kJ/mol. The glass transition temperature increases with the increase in saturation level due to development of crystalline segments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1151–1162, 1997     

Studies on the kinetics of in situ epoxidation of vegetable oils

In the present work, the kinetics of the epoxidation of soybean oil (SBO) by peroxyacetic acid (PAA) generated in situ in the presence of sulfuric acid as the catalyst was studied at various temperatures (45, 65 and 75 °C). It was found that epoxidation with almost complete conversion of unsaturated carbon and negligible oxirane cleavage can be attained by the in situ technique. The rate constant for epoxidation of SBO was found to be of the order of 10^–6 mol^–1s^–1 and the activation energy of epoxidation is 43.11 kJ/mol. Some thermodynamic parameters: enthalpy, entropy and free activation energy of 40.63 kJ/mol, –208.80 J/mol and 102.88 kJ/mol, respectively, were obtained for the epoxidation of SBO. The kinetic and thermodynamic parameters of epoxidation obtained from this study indicate that an increase in the process temperature would increase the rate of epoxide formation. The epoxidation of corn oil and sunflower oil were also investigated under the same conditions. The results show that the reaction rate is in the order of soybean oil > corn oil > sunflower oil.     

Synthesis of Oleyl Oleate with Immobilized Lipase from Mucor miehei

The synthesis of oleyl oleate with immobilized 1,3-specific lipase from Mucor miehei is presented in this article. Oleyl alcohol was esterified with oleic acid in the presence of a Mucor miehei lipase (lipozyme^IM) to obtain oleyl oleate. The effects of various temperatures and various enzyme/substrate ratios have been investigated to determine optimal conditions for the esterification process. The highest conversion of oleic acid 86.9 % was obtained at 50°C. The optimal addition of lipase to substrates was determined to be 0.1 g per gram of reaction mixture. The esterification can be modeled successfully as a reverse second-order reaction. Thermodynamic properties of the reaction system at 50°C were also determined. Activation energy was 14.65 kJ/mol, entropy of activation –0.8 J/mol·K and free energy of activation was 98.568 kJ/mol.     

Synthesis of conducting polyaniline/TiO2 composite nanofibres by one‐step in situ polymerization method

Conducting polyaniline (PANI)/titanium dioxide (TiO₂) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO₂ particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO₂ composite nanofibres was also discussed. This composite contained ～ 65% conducting PANI by mass, with a conductivity of 1.42 S cm^?1 at 25°C, and the conductivity of control PANI was 2.4 S cm^?1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007