Effect of Nano TiO2 on Self-cleaning Property of Cross-linking Cotton Fabric with Succinic Acid Under UV Irradiation

Optimization of curing cotton textiles through self-cleaning property constructs the main goal of the present study. Cotton fabrics with 0.1, 0.3, 0.5, 1 and 1.5 on weight of bath percent were cured by nano titanium dioxide (P25 Degussa) with cross-link and non cross-link methods. In this study, succinic acid was used as a cross-link agent to attach TiO₂ to the cotton. The amount of loaded titania particles to cotton fabrics and the thermal behavior of cured samples were studied by the burning method and thermogravimetric analysis, respectively. Self-cleaning degree of cured samples, stained with natural and synthesized dyes under irradiation of 20 and 400 W UV lamps was investigated by a reflectance spectrophotometer. The structure and morphology of treated cotton fabrics were investigated using scanning electron microscopy and crystallinity of titania coatings by X-ray diffraction spectroscopy. The tearing strengths of titania-coated cotton fabrics before and after light irradiation were measured. Results showed that the stability of nano TiO₂ coating and self-cleaning degree of treated samples with cross-link method were much higher than those of non cross-link method, and cotton cellulosic chains were not decomposed by the photocatalytic activity of titania.     

Photocatalytic disinfection of bacterial pollutants using suspended and immobilized TiO2 powders

The photocatalytic disinfection of Enterobacter cloacae and Enterobacter coli using microwave (MW), convection hydrothermal (HT) and Degussa P25 titania was investigated in suspension and immobilized reactors. In suspension reactors, MW‐treated TiO₂ was the most efficient catalyst (per unit weight of catalyst) for the disinfection of E. cloacae. However, HT‐treated TiO₂ was approximately 10 times more efficient than MW or P25 titania for the disinfection of E. coli suspensions in surface water using the immobilized reactor. In immobilized experiments, using surface water a significant amount of photolysis was observed using the MW‐ and HT‐treated films; however, disinfection on P25 films was primarily attributed to photocatalysis. Competitive action of inorganic ions and humic substances for hydroxyl radicals during photocatalytic experiments, as well as humic substances physically screening the cells from UV and hydroxyl radical attack resulted in low rates of disinfection. A decrease in colony size (from 1.5 to 0.3 mm) was noted during photocatalytic experiments. The smaller than average colonies were thought to occur during sublethal ^?OH and O₂^?? attack. Catalyst fouling was observed following experiments in surface water and the ability to regenerate the surface was demonstrated using photocatalytic degradation of oxalic acid as a model test system.     

Photocatalytic Activity of Microwave Plasma-Synthesized TiO2 Nanopowder

Nanocrystalline TiO₂ was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV–vis spectroscopy and BET surface area analyzer. The synthesized TiO₂ powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO₂ catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO₂ as compared to that over commercial Degussa P-25 TiO₂.     

Dipole‐Induced Band‐Gap Reduction in an Inorganic Cage

Metal‐doped polyoxotitanium cages are a developing class of inorganic compounds which can be regarded as nano‐ and sub‐nano sized molecular relatives of metal‐doped titania nanoparticles. These species can serve as models for the ways in which dopant metal ions can be incorporated into metal‐doped titania (TiO₂), a technologically important class of photocatalytic materials with broad applications in devices and pollution control. In this study a series of cobalt(II)‐containing cages in the size range ca. 0.7–1.3 nm have been synthesized and structurally characterized, allowing a coherent study of the factors affecting the band gaps in well‐defined metal‐doped model systems. Band structure calculations are consistent with experimental UV/Vis measurements of the Ti_xO_y absorption edges in these species and reveal that molecular dipole moment can have a profound effect on the band gap. The observation of a dipole‐induced band‐gap decrease mechanism provides a potentially general design strategy for the formation of low band‐gap inorganic cages.     

硼铈共掺杂纳米TiO2光催化降解三氯杀螨醇和菊酯类农药

采用溶胶-凝胶法在钛酸丁酯水解过程引入硼酸、硝酸铈,制备具有光催化活性的硼铈共掺杂纳米二氧化钛（TiO2）,经XRD、TEM、FT-IR、UV-Vis-DRS表征晶体结构,在日光灯照射下,光催化降解三氯杀螨醇、高氟氯氰菊酯、氟戊菊酯农药。结果表明：硼铈共掺杂的TiO2只有锐钛矿型,而纯的或掺铈的TiO2有含有锐钛矿型、金红石相和少量板钛矿型,UV-Vis-DRS测定结果表明硼铈共掺杂的TiO2禁带宽度变小,硼铈共掺杂的TiO2在可见光区吸光度高于掺杂铈和不掺杂的TiO2,在420nm~850nm有强的吸收;在同样光照下对三氯杀螨醇、高氟氯氰菊酯、氟戊菊酯的降解试验证明硼铈共掺杂纳米TiO2的光催化活性高于不掺杂或只掺杂铈的TiO2。     

晶相组成可调的高活性可见光应答型二氧化钛纳米复合光催化材料的制备

采用新的化学溶液法,通过不同体积的钛酸四异丙酯的2-乙二醇单乙醚溶液与一定浓度的H₂O₂水溶液直接反应并对生成的钛过氧化配合物进行焙烧,制备了一系列TiO₂光催化剂. 表征发现,所得TiO₂样品为金红石和锐钛矿的纳米复合晶体,改变2-乙二醇单乙醚的体积可实现金红石相比例在0~96%广范围的调变.与商业二氧化钛P-25相比,所得的TiO₂紫外-可见光吸收谱出现明显红移,间隙能降低, 在可见光照射下,该样品对亚甲基蓝有良好的降解活性. 当2-乙二醇单乙醚的添加量为5 ml时,所得样品体相中金红石相比例接近50%,其光催化活性和吸附性能最好,可分别是P-25的3倍和5倍. 拉曼光谱结合X射线衍射等表征结果表明,该样品的表面仅含少量的金红石相. TiO₂纳米复合晶表面晶相的组成和分布对其光催化降解亚甲基蓝的活性及其吸附能力有直接的影响. 另外,TiO₂纳米复合晶的缺陷浓度也是增强其光吸收能力,提高其可见光光催化活性的原因之一.     

Efficient Decomposition of Organic Pollutants Over In2O3/TiO2 Nanocomposite Photocatalyst Under Visible Light Irradiation

The heterojunction structures of In₂O₃/TiO₂, exhibiting visible light photocatalytic efficiency, has been synthesized by utilizing maleic acid as an organic linker to combine In₂O₃ and Degussa P25 (TiO₂) nanoparticles. The prepared nanocomposite has been characterized by FESEM, TEM, XRD and UV?CVisible reflectance spectra. The photocatalytic efficiency of the composite photocatalyst has been investigated based on the decomposition of 2-propanol (IP) in gas phase and 1,4-dichlorobenzene (DCB) in aqueous phase under visible light (??????420?nm) irradiation. The results reveal that the In₂O₃/TiO₂ composite photocatalyst with 7?wt% In₂O₃ demonstrated 6.3 times of efficiency in evolving CO₂ from gaseous IP and 8.7 times of efficiency in removing aqueous DCB in compare with Degussa P25. In this In₂O₃/TiO₂ composite system, TiO₂ seems to be the principal photocatalyst whereas the function of In₂O₃ is to sensitize TiO₂ by absorbing visible light (??????420?nm). The extraordinary high photocatalytic efficiency of this composite In₂O₃/TiO₂ under visible light has been explained on the basis of relative energy band positions of the component semiconductors.     

Phosphorous,nitrogen, and molybdenum ternary co-doped TiO2: preparation and photocatalytic activities under visible light

P, N, and Mo ternary co-doped nano TiO₂ photocatalysts ((P, N, Mo)-TiO₂) were prepared by a single step sol–gel method, which show much enhanced photocatalytic activities over Mo-TiO₂, (P, N)-TiO₂, un-doped TiO₂ and Degussa P25 under visible light irradiation. The degradation rate of 0.72Mo–P-TiO₂ is as high as 65.3%, which is about 6.7 times of that of Degussa P25. Possible reasons for the improvement of photocatalytic activities were analyzed.     

Comparison of photocatalysis degradation of 4-nitrophenol using N,S co-doped TiO2 nanoparticles synthesized by two different routes

The photocatalytic degradation of 4-nitrophenol as pollutant in aqueous solutions was investigated under visible light irradiation over two different N?CS-codoped anatase TiO₂ catalysts prepared by sol?Cgel methods using titanium isopropoxide and titanium tetrachloride as two different precursors. The catalysts were characterized by XRD, SEM, DRS, EDAX and FT-IR. The effects of various operating parameters including the initial concentration of 4-nitrophenol (2?C14?ppm), solution pH (5?C8) and kinetic reactions were studied. The optimum solution pH was at around 6. For comparison purpose, the photodegradation activity of the commercial Degussa P-25 TiO₂ catalyst has also been studied. The results indicated that photocatalytic activity of N?CS-codoped TiO₂ with titanium isopropoxide as precursor was higher than N?CS-codoped TiO₂ with titanium tetrachloride as precursor and Degussa P-25.     

Carbon‐Dot‐Sensitized,Nitrogen‐Doped TiO2 in Mesoporous Silica for Water Decontamination through Nonhydrophobic Enrichment–Degradation Mode

Mesoporous silica synthesized from the cocondensation of tetraethoxysilane and silylated carbon dots containing an amide group has been adopted as the carrier for the in situ growth of TiO₂ through an impregnation–hydrothermal crystallization process. Benefitting from initial complexation between the titania precursor and carbon dot, highly dispersed anatase TiO₂ nanoparticles can be formed inside the mesoporous channel. The hybrid material possesses an ordered hexagonal mesostructure with p6mm symmetry, a high specific surface area (446.27 m² g^?1), large pore volume (0.57 cm³ g^?1), uniform pore size (5.11 nm), and a wide absorption band between λ=300 and 550 nm. TiO₂ nanocrystals are anchored to the carbon dot through Ti?O?N and Ti?O?C bonds, as revealed by X‐ray photoelectron spectroscopy. Moreover, the nitrogen doping of TiO₂ is also verified by the formation of the Ti?N bond. This composite shows excellent adsorption capabilities for 2,4‐dichlorophenol and acid orange 7, with an electron‐deficient aromatic ring, through electron donor–acceptor interactions between the carbon dot and organic compounds instead of the hydrophobic effect, as analyzed by the contact angle analysis. The composite can be photocatalytically recycled through visible‐light irradiation after adsorption. The narrowed band gap, as a result of nitrogen doping, and the photosensitization effect of carbon dots are revealed to be coresponsible for the visible‐light activity of TiO₂. The adsorption capacity does not suffer any clear losses after being recycled three times.     

Novel type of SO3H–functionalized nano‐titanium dioxide as a highly efficient and recyclable heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyrans

n ‐Butylsulfonated nano‐titania (n‐TiO₂‐NH‐(CH₂)₄‐SO₃H) as a highly efficient and reusable nanocatalyst was prepared by grafting 2,4‐toluene diisocyanate as a bi‐functional covalent linker onto a nano‐titania support, followed by reduction and then ring opening‐reaction of the synthesized amine with 1,4‐butanesultone. Fourier transform infrared spectroscopy, X‐ray diffraction, field‐emission scanning electron microscopy and thermogravimetric analysis were used to characterize the catalyst. The catalytic activity of n‐TiO₂‐NH‐(CH₂)₄‐SO₃H was evaluated in the synthesis of tetrahydrobenzo[b ]pyrans, which affords high yields. Statistical experimental design was applied as an efficient and powerful method to achieve the optimal conditions for this catalytic reaction leading to high yield. Moreover, the catalyst was recovered and reused at least six times without a significant decrease in catalytic activity.     

A Blinking Mesoporous TiO2−x Composed of Nanosized Anatase with Unusually Long‐Lived Trapped Charge Carriers

A mesoporous TiO_2?x material comprised of small, crystalline, vacancy‐rich anatase nanoparticles (NPs) shows unique optical, thermal, and electronic properties. It is synthesized using polymer‐derived mesoporous carbon (PDMC) as a template. The PDMC pores serve as physical barriers during the condensation and pyrolysis of a titania precursor, preventing the titania NPs from growing beyond 10 nm in size. Unlike most titania nanomaterials, during pyrolysis the NPs undergo no transition from the anatase to rutile phase and they become catalytically active reduced TiO_2?x. When exposed to a slow electron beam, the NPs exhibit a charge/discharge behavior, lighting up and fading away for an average period of 15 s for an extended period of time. The NPs also show a 50 nm red‐shift in their UV/Vis absorption and long‐lived charge carriers (electrons and holes) at room temperature in the dark, even long after UV irradiation. The NPs as photocatalysts show a good activity for CO₂ reduction.     

A Blinking Mesoporous TiO2−x Composed of Nanosized Anatase with Unusually Long-Lived Trapped Charge Carriers

A mesoporous TiO_2−x material comprised of small, crystalline, vacancy-rich anatase nanoparticles (NPs) shows unique optical, thermal, and electronic properties. It is synthesized using polymer-derived mesoporous carbon (PDMC) as a template. The PDMC pores serve as physical barriers during the condensation and pyrolysis of a titania precursor, preventing the titania NPs from growing beyond 10 nm in size. Unlike most titania nanomaterials, during pyrolysis the NPs undergo no transition from the anatase to rutile phase and they become catalytically active reduced TiO_2−x. When exposed to a slow electron beam, the NPs exhibit a charge/discharge behavior, lighting up and fading away for an average period of 15 s for an extended period of time. The NPs also show a 50 nm red-shift in their UV/Vis absorption and long-lived charge carriers (electrons and holes) at room temperature in the dark, even long after UV irradiation. The NPs as photocatalysts show a good activity for CO₂ reduction.     

Characteristics of microwaves on second generation nitrogen-doped TiO2 nanoparticles and their effect on photoassisted processes

Characteristics of 2.45-GHz microwave radiation were examined on two second generation nitrogen-doped TiO₂ nanomaterials prepared by annealing Degussa P-25 TiO₂ and Ishihara ST-01 TiO₂ at 400 °C and 500 °C, respectively, in air in the presence of urea, and for comparison on the undoped pristine samples. Band gaps of all four samples were determined by diffuse reflectance spectroscopy. Both the sizes and the BET specific surface areas of the TiO₂ particles were determined, together with dielectric constants and dielectric loss factors. Nitrogen doping caused the size to increase and surface area to decrease. Temperature–time profiles showed that the heating efficiency of the N-doped specimens by the microwaves was greater, particularly significant for the N-doped P25 sample, but rather small for the N-ST01 sample. The effect of microwaves on the surface optical phonons of the samples, with and without UV–vis irradiation, was examined by an in situ Raman spectroscopic technique; for the undoped P-25 and nitrogen-doped N-P25 TiO₂ systems the effect was negligible. By contrast, microwave irradiation of Ishihara ST-01 and nitrogen-doped N-ST01 TiO₂ samples showed significant changes in the 144-cm^?1 optical phonons. Results infer a microwave thermal effect on the Ishihara ST-01 and N-ST01 specimens, whereas for the Degussa P-25 samples the microwaves also imparted a specific effect as the microwaves influenced the N-dopant sites in contrast to the ST-01 systems where the dopant sites were unaffected as evidenced by temperature–time profiles. The microwave-/photo-assisted degradation of 4-chlorophenol under various conditions of UV–vis irradiation and conventional heating, as opposed to microwave heating, confirms the specific microwave effect for the P-25 systems.     

Enhanced Bactericidal Activity of Modified Titania in Sunlight against Pseudomonas aeruginosa,a Water-Borne Pathogen

Photocatalyst-mediated inactivations generate reactive oxygen species and OH radicals, which induce oxidative destruction of membrane integrity, causing damage to membrane phospholipids of gram negative bacteria like Pseudomonas aeruginosa. Nanosized TiO₂ was synthesized by gel to crystalline conversion and Zr-doped TiO₂ was synthesized by pulverization using appropriate precursor. The doped nanocrystals retained the anatase phase with a marginal increase in crystallite size, averaging at 25 nm. SEM–EDX analysis of the doped sample depicts the substantial growth of grain size with 1.33 atomic weight % of zirconium. The created electron states in the doped sample act as charge carrier traps suppressing recombination which later detraps the same to the surface of the catalyst causing enhanced interfacial charge transfer. Zr-doped TiO₂ at the molecular scale exhibits better photocatalytic activity with lower bandgap energy that can respond to visible light. The redshift caused by the dopants in absorption spectra of TiO₂ facilitated the nonintrinsic sample to exhibit nearly 2-fold enhancement of photoinactivation in sunlight. Extent of photoinactivation of P. aeruginosa was observed to be complete (100%) within 150 min of sunlight exposure in the presence of modified TiO₂.     

Synthesis,characterization and photocatalytic application of TiO2/magnetic graphene for efficient photodegradation of crystal violet

A magnetized nano‐photocatalyst based on TiO₂/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO₂/magnetic graphene exhibited much higher photocatalytic performance than bare TiO₂. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO₂/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H₂O₂ amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH^? scavenger), p‐benzoquinone (O₂^?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated.     

Single step sol-gel made silver chloride on Titania xerogels to inhibit <Emphasis Type="Italic">E. coli</Emphasis> bacteria growth: effect of preparation and chloride ion on bactericidal activity

We report the antibacterial efficacies of silver and/or silver chloride containing titania xerogels synthesized with modified single step sol-gel methods against Escherichia coli bacteria. As the silver loading in TiO₂ increases, the amount of the xerogel required to inhibit the growth of the bacteria decreases and also we found that pure TiO₂ was not bactericidal. Among modified single step sol-gel methods used in this study, the additional HCl treatment sol-gel route III was very effective to obtain only AgCl crystallites in TiO₂. Based on viable cell count method, 0.125 g/L of 29%Ag/TiO₂ (made with HNO₃ sol-gel route I) was enough to inhibit the growth of E. coli whereas 0.6 g/L of 29%Ag/TiO₂ (made with the additional HCl treatment sol-gel route III) was required. However, antibacterial activity of 29%Ag/TiO₂ (made with HNO₃ sol-gel route I) after 6 usages was the same as 29%Ag/TiO₂ (made with the additional HCl treatment sol-gel route III).     

Sol-gel preparation and characterization of Co/TiO<Subscript>2</Subscript> nanoparticles: Application to the degradation of methyl orange

Cobalt doped titania nanoparticles were synthesized by sol-gel method using titanium(IV) isopropoxide and cobalt nitrate as precursors. X-Ray diffraction (XRD) results showed that titania and Co/TiO₂ nanoparticles only include anatase phase. The framework substitution of Co in TiO₂ nanoparticles was established by XRD, scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX) and Fourier transform infrared (FT-IR) techniques. Transmission electron microscopy (TEM) images confirmed the nanocrystalline nature of Co/TiO₂. The increase of cobalt doping enhanced “red-shift” in the UV-Vis absorption spectra. The dopant suppresses the growth of TiO₂ grains, agglomerates them and shifts the band absorption of TiO₂ from ultraviolet (UV) to visible region. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. Although the photocatalytic activity of undoped TiO₂ was found to be higher than that of Co/TiO₂ under UV irradiation, the presence of 0.5% Co dopant in TiO₂ resulted in a catalyst with the highest activity under visible irradiation.     

Synthesis of bimodal porous structured TiO2 microsphere with high photocatalytic activity for water treatment

In this work bimodal structured titanium dioxide (TiO₂) microsphere has been prepared from commercial TiO₂ powder and nano-sized titania gel via sol–gel spray-coating technique. Crystallization and transformation behavior of titania gel were investigated. The results revealed that the crystallization and transformation of anatase particles were substantially affected by the concentration of solvent and calcination temperature. Anatase crystallite size of 10 nm was obtained at mole ratio of solvent/precursor 50/1 and calcination temperature of 450 °C. The prepared nano-sized titania gel was embedded within the core (commercial TiO₂, P25) during the spraying process. The prepared TiO₂ microsphere was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), field emission electron microscope (FESEM) and micropore analysis. The photocatalytic activity was monitored by following the degradation of phenol with activity benchmarked against commercial P25 (Degussa). The increase of photocatalytic activity of TiO₂ microsphere was attributed to the nano-sized anatase crystallite which has been incorporated into the TiO₂ microsphere.     

Specific features of disposal of sulfuric acid solutions resulted from magnesium silicate decomposition

The photocatalytic activity of crystalline titania nanopowders synthesized in a stream of ultrahigh-frequency discharge oxygen-containing low-temperature plasma was assessed. To this end, oxidation of an organic dye was carried out in UV-irradiated aqueous suspensions of TiO₂ at different concentrations and varied irradiation times.