Iodine-doped Titanium Dioxide Research Articles

Enhanced removal of sulfamethoxazole via adsorption and photodegradation using biochar-modified iodine-doped TiO2 photocatalysts under simulated sunlight

This study aimed to prepare a biochar-modified iodine-doped titanium dioxide composite photocatalyst (B/I-TiO2) via hydrothermal reaction and evaluate its performance in sulfamethoxazole (SMX) degradation under simulated sunlight. Biochar was prepared from four agricultural wastes using hydrothermal and pyrolysis technologies, resulting in 3–30 graphite layers with a d-spacing of 0.35 nm. Hydrothermal activation transformed the disordered structure into a graphite microcrystalline structure, producing biochar with a quasi-three-dimensional graphene structure. Doping with 1–15 wt% of this biochar shifted the characteristic wavelength of B/I-TiO2 to 423–426 nm and increased the specific surface area by 1.25–1.94 times. The 5LB700H2I1T composite photocatalyst found the highest SMX removal efficiency of 40 %, and the 5WB900H2I1T composite photocatalyst found the highest SMX photodegradation efficiency of 30 %, respectively, irradiated with simulated sunlight of 3 hours. The wavelength redshift and degradation performance enhancement primarily resulted from iodine doping and the biochar's excellent crystallinity and high surface area. SMX removal was achieved through adsorption and photodegradation, with hydroxyl radicals and electron holes playing a significant role compared to superoxide radicals.

Efficient E/Z conversion of (all-E)-lycopene to Z-isomers with a high proportion of (5Z)-lycopene by food grade plant extracts

The conversion of lycopene from natural sources, mainly in all trans configurations, to cis configuration means a significant increase in bioavailability. However, the existing isomerization methods have problems with residual organic solvents, which limits the use of products. such as metal ion catalysis, electrocatalysis, and iodine-doped titanium dioxide (I–TiO2) catalysis. In this paper, the effects of common plant extracts on lycopene isomerization and its stability were investigated. Among them, sulforaphane and allicin showed significant catalytic effects, with sulforaphane being the most effective. Therefore, Broccoli sprouts were selected as a food component to investigate the catalytic isomerization of lycopene. After the optimization of pretreatment, the final content of sulforaphane was 5.81 mg/g. The cis-proportion of lycopene was elevated from 5% in the blank group to more than 60% when the treated broccoli sprout paste was added to the tomato paste. Also, the bioavailability of lycopene increased significantly with the increase in cis proportion. Compared with other isomerization methods, the method studied in this paper does not require any organic reagents and only uses food-grade materials such as allicin, sulforaphane, and broccoli sprouts to catalyze the cis-trans isomerization of lycopene.

Lycopene: Heterogeneous Catalytic E/Z Isomerization and In Vitro Bioaccessibility Assessment Using a Diffusion Model.

Highly efficient heterogeneous catalytic E/Z isomerization of lycopene was achieved using an iodine-doped titanium dioxide (I-TiO2 ) catalyst prepared by sol-gel method. The effects of reaction temperature and reaction time were investigated in detail. The maximum total Z-ratio of lycopene exceeded 78% after 2 h of refluxing at 75 °C in ethyl acetate. Moreover, lycopene samples with a series of total Z-ratios were prepared and the bioaccessibility of these samples was estimated using a diffusion model, the results showed that the bioaccessibility of lycopene markedly increased conforming to a linear regression model with increasing of the total Z-ratio of lycopene from 3.6% to 78.5%. Furthermore, the specific role of the microstructure and melting point of 3.6% and 78.5% total Z-ratio of lycopene was also investigated to understand the probable mechanism for the enhanced bioaccessbility of (Z)-lycopenes.

Gas circulating fluidized beds photocatalytic regeneration of I-TiO2 modified activated carbons saturated with toluene

This paper demonstrated a new regeneration method of modified activated carbon saturated with toluene using gas circulating fluidized beds photocatalysis (GCFBP). The AC was impregnated with a photocatalyst to yield light regenerable composite, namely iodine-doped titanium dioxide (IT/AC). IT/AC samples were characterized by XRD, FESEM, BET and adsorption valves of methylene blue. The results showed that loaded limited amount of I-TiO2 had little influence on the structure and adsorption properties of activated carbon. The adsorption kinetics of toluene on IT/AC composites showed best agreement with Yoon–Nelson model. Gas circulating fluidized bed reaction system was beneficial to migration of toluene on composites. The rate-limiting process was toluene adsorption from the cycle gas and photochemical oxidation of toluene. In addition, experimental results showed that IT/AC composites exhibited good recycling stability, reusability, and in situ renewability. The regenerated efficiency of composites saturated with toluene with light irradiation of 60min and gas flow of 4L/min was 95.98% (particle size 40–60 mesh) and 85.15% (particle size 20–40 mesh), respectively. The regenerated efficiency after three times regeneration can reach 87.09% (40–60 mesh) and 77.85% (20–40 mesh). The regenerated efficiency of GCFBP increased 80% more than that of gas circulating fluidized bed (GCFB) and 20% more than that of acyclic gas-phase photocatalysis. The removal efficiency of toluene in recycle gas reached 88.3% after 150min reaction. The regeneration kinetics of GCFBP were consistent with the improved Langmuir–Hinshelwood model.

Highly efficient trans–cis isomerization of lycopene catalyzed by iodine-doped TiO2nanoparticles

Highly efficienttrans–cisisomerization of lycopene was achieved in the presence of a novel iodine-doped titanium dioxide (I-TiO2) catalyst.

Photocatalytic reduction of carbon dioxide using iodine-doped titanium dioxide with high exposed {001} facets under visible light

Iodine-doped titanium dioxide nanosheets with high exposed {001} facets (IFTO) were synthesized by a two-step hydrothermal treatment followed by calcination at 350 °C.

Preparation of iodine doped titanium dioxide to photodegrade aqueous bisphenol A under visible light

Highly photoactive iodine-doped titanium dioxide (I-doped TiO2) photocatalysts were synthesized to degrade aqueous bisphenol A (BPA) under irradiation by visible light and sunlight. The band gap energies of TiO2 and I-doped TiO2 (I/Ti mole ratio=0.5%) were 3.01 and 3.04, and the BPA photodegradation rate constants were 1.61, and 5.11h−1, respectively. The most probable reaction mechanism was proposed to involve IO4− and IO3− as electron acceptors that generate an inductive effect, increasing the photocatalytic efficiency of TiO2. Results indicated that I-doped TiO2 not only acted favorably as a photocatalyst, but also exhibited considerable mineralization effects. In addition, a recycling test after ten experiments demonstrated the stability and reusability of the photocatalyst.

Preparation of Iodine Doped Titanium Dioxide to Degrade Aqueous Bisphenol A

Degradation of aqueous bisphenol A (BPA) using photocatalysts of granular iodine doped titanium dioxide (I-doped TiO2) under various irradiations (365 or 410 nm) was investigated. The degradation effect of aqueous BPA using I-doped TiO2 photocatalysts (iodine/titanium = 0.5 mole %) were 93 and 100 % under two irradiations of visible and UV light. This result indicated that I-doped TiO2 photocatalysts of were achieving energy-saving. In addition, the BPA removal rate satisfies pseudo-first-order kinetics and the degradation of BPA was evident after five cycles, indicating the stability and reusability.

Highly efficient bacteria inactivation and phenol degradation by visible light irradiated iodine doped TiO2

In this study visible light active iodine doped titanium dioxide samples prepared by sol–gel method were investigated. Photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence spectroscopy (XFS), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and by Brunauer–Emmett–Teller (BET) surface area technique.Different iodine/titanium ratios (nI/nTi=0.0–2.6) were applied during the synthesis and the optimum value was determined by phenol degradation under UV and VIS irradiations. The photocatalytic efficiency towards phenol degradation and the inactivation of Escherichia coli (E. coli) contaminated water under visible light illumination (conventional 24W energy-saving compact fluorescence lamps) of the most active iodine-doped TiO2 (nI/nTi=0.5; 79.5m2/g; 98wt% anatase) was compared with well known reference photocatalysts, that are Aeroxide P25 and Aldrich anatase (>85nm primary crystallite size). Results showed that our iodine doped TiO2 was far more efficient at inactivating the E. coli and decomposing the phenol than Aeroxide P25. Electron spin resonance (ESR) measurements confirmed the formation of highly reactive OH radicals by the iodine doped titania under VIS irradiation. In contrast, singlet oxygen and superoxide radical ions were not detected. The performed experiments also proved that dissolved iodine was produced in very low concentrations (about 0.01–0.025mg/L) from the irradiated titanium dioxide. The dissolved iodine could have some contribution to the phenol oxidation and the disinfection effects. This study demonstrated this property of iodine-doped titanias for the first time.

A magnetic TiO2 photocatalyst doped with iodine for organic pollutant degradation

A series of iodine-doped titanium dioxide (I-TiO2) photocatalysts was synthesized by using silica-coated Fe3O4 (SF) as the magnetic core (abbreviated here as ITSF), in order to facilitate the efficient recovery of these photocatalysts. Transmission electron microscopy and X-ray diffraction results indicated that the ITSF nanoparticles had a ternary structure with a core of Fe3O4, a SiO2 mesosphere and an I-TiO2 crust with a mixture of anatase and rutile phases. Magnetic measurements with a vibrating sample magnetometer showed that the ITSF core–shell structures exhibited favorable superparamagnetic behaviors and the magnetic saturation value decreased after coating with the non-magnetic I-TiO2 layer. The photocatalytic activity of the particles was tested by degrading an aqueous phenol solution under visible-light illumination. The photocatalytic activity of the multi-functional hybrid magnetite nanoparticles was enhanced with increasing content of TiO2, while the magnetism of the composite particles decreased. Moreover, an optimum molar ratio of 1:10 I/TiO2 was determined for the efficient degradation of phenol. The study showed that the presence of SF magnetic core would be helpful in the separation and recovery of I-TiO2 photocatalysts.

Synthesis, characterization and application of iodine modified titanium dioxide in phototcatalytical reactions under visible light irradiation

Iodine doped titanium dioxide has been successfully prepared by simple hydrolysis of tetrabutyl titanate in the presence of iodic acid. The adopted method allowed for the production of spherical iodine doped titaniun dioxide nanoparticles with varied amount of iodine content. Analysis by X-ray diffraction, Raman, transmission electron microscopy as well as UV–vis DRS revealed that titanium dioxide nanostructures were doped with iodine which existed in two different valence states I5+ and I−. The iodine in the form of I5+ is believed to have doped into the lattice whereas I− was well dispersed on the surface of TiO2 probably as iodine adducts hence rendering it to be highly absorbing in visible light region. The I-TiO2 exhibited improved photocatalytic activity toward degradation of acid orange 7 (AO7), methyl orange (MO) and 2,4-dichlorophenol (2,4-DCP) under visible light over the pristine TiO2 prepared by the same method. High catalytic properties are attributed to iodine doping which led to high specific surface area, absorption in visible region as well as alleviation of charge carrier recombination. The most probable route undertaken in the degradation of AO7 is through indirect oxidation by the hydroxyl radicals.

Increasing the catalytic activities of iodine doped titanium dioxide by modifying with tin dioxide for the photodegradation of 2-chlorophenol under visible light irradiation

The photocatalytic degradation of 2-chlorophenol (2-CP) irradiated with visible light over iodine doped TiO 2 (IT) modified with SnO 2 (SIT) nanoparticles has been investigated in this study. The structure and optical properties of the SIT catalysts have been well characterized by X-ray diffraction, the Brunauer–Emmett–Teller method, transmission electron microscopy, UV–visible absorption spectra and X-ray photoelectron spectroscopy. The effects of preparation conditions, such as SnO 2 content and calcination temperature, on the photocatalytic degradation efficiency have been surveyed in detail. The improved photocatalytic activity of SIT is derived from the synergistic effect between the SnO 2 and IT, which promoted the efficiency of migration of the photogenerated carriers at the interface of the catalysts and thereby enhanced the efficiency of photon harvesting in the visible region. The action of scavengers (fluoride ion, iodide ion, tert-butyl alcohol, and persulfate ion), as well as N 2 purging on the photodegradation rate reveal that the valence band hole is mainly responsible for the effective photocatalytic removal of 2-CP and the corresponding TOC reduction.

A visible light-responsive iodine-doped titanium dioxide nanosphere

I-doped titanium dioxide nanospheres (I-TNSs) were synthesized via a two-step hydrothermal synthesis route, their potential for the efficient utilization of visible light was evaluated. The prepared anatase-phase I-TNSs had a bimodal porous size distribution with a Brunauer-Emmett-Teller surface area of 76 m 2/g, a crystallite size of approximately 14 nm calculated from X-ray diffraction data, and a remarkable absorption in the visible light region at wavelengths > 400 nm. The photocatalytic activity of the samples was evaluated by decoloration of Methyl Orange in aqueous solution under visible light irradiation in comparison to the iodine-doped TiO 2 (I-TiO 2). The I-TNSs showed higher photocatalytic efficiency compared with I-TiO 2 after irradiation for 180 min even though the latter had a much greater surface area (115 m 2/g). It was concluded that the surface area was not the predominant factor determining photocatalytic activity, and that the good crystallization and bimodal porous nanosphere structure were favourable for photocatalysis.

Visible-light-response iodine-doped titanium dioxide nanocrystals for dye-sensitized solar cells

We report on the synthesis of visible-light-response iodine-doped TiO2 nanocrystals (I-TNCs), and their implementation as photoanodes of dye-sensitized solar cells (DSSCs). The preparation of I-TNCs starts with hydrolysis of titanium isopropoxide in iodine-based aqueous system, followed by hydrothermal treatment and annealing process to achieve anatase structure. The I-TNCs were characterized by TEM, SEM, XRD, EDS and XPS. Under an optimized I/Ti doping ratio of 20 mol%, the photovoltaic performance of the cell based on I-TNCs is significantly better, with an energy-conversion efficiency of 7.0% under 100 mW cm−2 illumination, which is 42.9% higher than that of the cell based on undoped TNCs. Interestingly, the I-TNCs-based cell shows a higher conversion efficiency of 10.0% under 30 mW cm−2 illumination. The improved performance is explained by the expanded visible-light harvesting (characterized by incident photon to current conversion efficiency and UV-vis absorption spectra), lowered recombination resistance (characterized by electrochemical impedance spectroscopy, Rrec) together with prolonged electron lifetime τe. These results suggest substantial potential of TiO2 nanocrystals with controlled doping in DSSC application.

Visible light-driven iodine-doped titanium dioxide nanotubes prepared by hydrothermal process and post-calcination

A novel class of iodine-doped TiO 2 nanotubes (I-TNTs) has been synthesized via a hydrothermal route using Degussa P25 as a precursor and subsequent calcination. The photocatalytic ability of the products was evaluated in terms of phenol degradation in an aqueous solution under visible light irradiation. The structural properties of the catalysts were characterized by X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra. According to the XRD data, I-TNTs are pure anatase, revealing a shift of crystallite phase for P25 from rutile to anatase. The surface area of I-TNTs is significantly larger than that of I-doped TiO 2 (I-TiO 2) nanoparticles, which is an important advantage of the photocatalysts formed with a hydrothermal procedure. XPS and UV–vis spectroscopy show that iodine was incorporated into the TiO 2 lattice, and such incorporation extends the photoresponse of TiO 2 from UV to the visible light region. As far as phenol degradation is concerned, the I-TNTs are clearly superior to I-TiO 2 nanoparticles, pure TNTs and P25. The photocatalytic activity of I-TNTs hydrothermally synthesized at 150 °C had a significantly higher level than that synthesized at 200 °C. This is attributed to the increase of reactive sites and the enhancement of mass transfer that result from the large surface areas associated with the tubular morphology. Additionally, the increase of Ti 3+ content also contributes to the improvement of photocatalytic activity of I-TNTs.

Visible Light-Induced Degradation of Phenol over Iodine-Doped Titanium Dioxide Modified with Platinum: Role of Platinum and the Reaction Mechanism

The role of platinum deposited on iodine-doped titanium dioxide (Pt/I-TiO2) catalyst during photodegradation of phenol under irradiation with visible light was investigated. The results of this study demonstrate that the Pt/I-TiO2 photocatalyst enhanced the phototransformation of phenol, with a negligible increase upon photomineralization. The results of the phototransformation of para substiuted phenols (p-methylphenol, phenol, p-chlorophenol, and p-nitrophenol) show that the phenol−TiO2 interaction, influenced by the Hammett constants, has the principal role in photodegradation. Furthermore, the action of scavengers (iodide ion, tert-butyl alcohol, fluoride ion, and persulfate ion), as well as N2 purge on the photodegradation of phenol prove that the phototransformation of phenol occurs on the surface of the photocatalyst and is initiated mostly by a valence band hole (hvb+), and the degradation process is limited by the keto−enol tautomeric equilibrium between hydroquinone and quinone. On the basis of ...