Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterisation of silver‐ or copper‐doped TiO2 catalysts and their catalytic activity in dye degradation

In this study, silver‐ or copper‐doped TiO₂–Ce‐, TiO₂–La‐, and commercial TiO₂ (P25)‐supported catalysts were prepared. The catalysts and supports were characterised by powder X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption studies. UV‐light‐assisted heterogeneous Fenton‐like oxidation of two different‐structure dyes (anionic azo dye Orange II, CI Acid Orange 7 and cationic triphenylmethane dye Crystal Violet, CI Basic Violet 3) was investigated over the catalysts. Higher catalytic activity was observed in the oxidation of Orange II than in the oxidation of Crystal Violet. For both dyes, the TiO₂–Ce and TiO₂–La‐supported catalysts, which were in the form of anatase only, gave higher photocatalytic activity than the P25‐supported catalysts, which were in the form of anatase and rutile. Complete colour removal was observed during oxidation of Orange II over Cu/TiO₂–Ce and Cu/TiO₂–La catalysts, whereas the highest degree of decolorisation, 89.3%, was achieved by oxidation of Crystal Violet over Ag/TiO₂–Ce. The pH of the solution affected the surface state of the TiO₂, thus affecting the photocatalytic degradation of the dyes. The surface area of the catalysts is also a key parameter that influences their photocatalytic activity. It was observed that catalysts having higher surface areas brought about greater dye degradation.     

Solid‐state synthesis and characterization of polyaniline/nano‐TiO2 composite

Polyaniline/nano‐TiO₂ composites with the content of nano‐TiO₂ varying from 6.2 wt % to 24.1 wt % were prepared by using solid‐state synthesis method at room temperature. The structure and morphology of the composites were characterized by the Fourier transform infrared (FTIR) spectra, ultraviolet‐visible (UV–vis) absorption spectra, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge measurement, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results from FTIR and UV–vis spectra showed that the composites displayed higher oxidation and doping degree than pure PANI. The XRD and morphological studies revealed that the inclusion of nano‐TiO₂ particles hampered the crystallization of PANI chains in composites, and the composites exhibited mixed particles from free PANI particles and the nano‐TiO₂ entrapped PANI particles. The galvanostatic charge–discharge measurements indicated that the PANI/nano‐TiO₂ composites had higher specific capacitances than PANI. The composite with 6.2 wt % TiO₂ had the highest specific capacitance among the composites. The further electrochemical tests on the composite electrode with 6.2 wt % TiO₂ showed that the composite displayed an ideal capacitive behavior and good rate ability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Decomposition of gas‐phase aromatic hydrocarbons by applying an annular‐type reactor coated with sulfur‐doped photocatalyst under visible‐light irradiation

BACKGROUND: Unlike many water pollution applications, visible‐light‐driven photocatalysis of gas‐phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S‐doped visible‐light‐induced TiO₂ to treat gas‐phase aromatic hydrocarbons, using a continuous air‐flow annular‐type reactor. RESULTS: The prepared S‐enhanced TiO₂ powders, along with a commercially available TiO₂ powder (Degussa P‐25), were characterized using diffuse reflectance UV‐VIS‐NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p‐xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency. CONCLUSIONS: The S‐doped TiO₂ and undoped P25 TiO₂ powders exhibited different catalyst characteristics. The results demonstrate that an annular‐type reactor coated with visible‐light‐activated S‐doped TiO₂ can serve as an effective tool to treat gas‐phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry     

Degradation of 1‐amino‐4‐bromoanthraquinone‐2‐sulfonic acid using combined airlift bioreactor and TiO2‐photocatalytic ozonation

BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor (AILR) in combination with the TiO₂‐photocatalytic ozonation (TiO₂/UV/O₃) process was investigated for the degradaton of 1‐amino‐ 4‐bromoanthraquinone‐2‐ sulfonic acid (ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon (GAC) as biocarrier, could run steadily for 4 months at 1000 mg L^?1 of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand (COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO₂/UV/O₃ process more significantly improved the mineralization rate of ABAS bio‐decolorization products with over 90% TOC removal efficiency, compared with O₃, TiO₂/UV and UV/O₃ processes. Furthermore, the release efficiencies of Br^? and SO₄^2? could reach 84.5% and 80.2% during TiO₂/UV/O₃ treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO₂/UV/O₃ was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry     

Hydrophobic and tribological behaviors of a poly(p‐phenylene benzobisoxazole) fabric composite reinforced with nano‐TiO2

1H,1H,2H,2H‐Perfluorooctyl trichlorosilane (PFTS) was used to modify TiO₂ nanoparticles, and hydrophobic PFTS–TiO₂ nanoparticles were obtained by an ultrasonic reaction method. The PFTS–TiO₂ surface morphological and hydrophobic properties were analyzed with scanning electron microscopy (SEM), Fourier transform infrared spectrometry, and contact angle (CA) testing. Then, the poly(p‐phenylene benzobisoxazole) fabric–phenolic composite filled with PFTS–TiO₂ as a lubricant additive was fabricated by a dip‐coating process. The tribological properties of the composite were investigated, and the wear surface morphology was observed by SEM. The experimental results show that the water CA of the composite filled with PFTS–TiO₂ was 158°, and the composite containing 4 wt % PFTS–TiO₂ exhibited excellent antifriction and abrasion resistance. The hydrophobic surface of the composite showed excellent durable performance with a static water CA of 126.7° after abrasion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45077.     

Double‐functional characteristics of a surface molecular imprinted adsorbent with immobilization of nano‐TiO2

A new chitosan molecular imprinted adsorbent obtained by immobilization of nano‐TiO₂ on the adsorbent surface (surface‐imprinted adsorbent with nano‐TiO₂) was prepared. Based on photocatalytic reaction and the surface molecular imprinting technology, this new kind of surface‐imprinted adsorbent with immobilization of nano‐TiO₂ can not only adsorb template metal ions but can also degrade organic pollutants. The results showed that, after the nano‐TiO₂ was immobilized on the adsorbent surface, the adsorption ability for the imprinted ion (Ni²⁺) of this new imprinted adsorbent immobilized with nano‐TiO₂ was not affected, but the degradation ability for p‐nitrophenol (PNP) of the surface‐imprinted adsorbent with nano‐TiO₂ increased three‐fold compared with that of the surface‐imprinted adsorbent without nano‐TiO₂, from 23.8 to 76.1% (at an initial PNP concentration of 20 mg·dm^?3). The optimal TiO₂ concentration in the adsorbent preparation was 0.025 g·TiO₂ g^?1 adsorbent. The removal capacity for PNP reached 60.25 mg·g^?1 (at 400 mg·dm^?3 initial PNP concentration) under UV irradiation. The surface‐imprinted adsorbent with nano‐TiO₂ can be reused for at least five cycles without decreasing the removal ability for PNP and the imprinted ion (Ni²⁺). Copyright © 2006 Society of Chemical Industry     

Structural and ultraviolet‐protective properties of nano‐TiO2‐doped polypropylene filaments

Textiles, with appropriate light absorbers and suitable finishing methods, can be used as ultraviolet (UV) protection materials. In this study, we investigated the effects of nano‐TiO₂ particles on the UV‐protective and structural properties of polypropylene (PP) textile filaments. Master batches of PP/TiO₂ nanoparticles were prepared by melt compounding before spinning, and filaments incorporating 0.3, 1, and 3% TiO₂ nanoparticles were spun in a pilot melt‐spinning machine. The structural properties of the nanocomposite fibers were analyzed with scanning electron microscopy, X‐ray diffractometry, differential scanning calorimetry, and tensile tests. The UV‐protection factor was determined to evaluate the UV‐protective properties of the filaments. In conclusion, although the structure and mechanical properties of the nanocomposite filaments were slightly affected by the addition of nano‐TiO₂, the UV‐protective properties of the PP filaments improved after treatment with nano‐TiO₂, and the nanocomposite filaments exhibited excellent UV protection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Removal of 4‐chlorophenol from contaminated water using coconut shell waste pretreated with chemical agents

BACKGROUND: At concentrations higher than 1 mg L^?1, 4‐chlorophenol (4‐CP) is very toxic to living organisms, and if ingested beyond the permitted concentration it causes health disorders such as cancer and mutation. This laboratory study investigates treatment of contaminated water laden with 4‐CP using coconut shell charcoal (CSC) waste. Batch studies were conducted to study the effects of dose, pH, and equilibrium time on 4‐CP removal. To improve 4‐CP removal, surface modification of the adsorbent with TiO₂, HNO₃, and/or NaOH was undertaken. RESULTS: At an initial 4‐CP concentration of 25 mg L^?1 under optimized conditions (dose 13.5 g L^?1, pH 2.0; agitation speed 150 rpm and 50 min equilibrium time), the NaOH‐treated CSC demonstrated a greater removal of 4‐CP (71%) than those oxidized with HNO₃ (40%) and/or coated with TiO₂ (52%). The adsorption capacity of the NaOH‐treated CSC (54.65 mg g^?1) was higher than those treated with HNO₃ (23.13 mg g^?1) or coated with TiO₂ (48.42 mg g^?1). CONCLUSION: Although treatment results using the NaOH‐treated CSC alone were promising, the treated effluents were still unable to meet the required limit of less than 1 mg L^?1. Therefore, subsequent treatments are still required to complement the removal of 4‐CP from the wastewater. Copyright © 2010 Society of Chemical Industry     

Polyaniline modified mesoporous titanium dioxide that enhances oxo‐biodegradation of polyethylene films for agricultural plastic mulch application

Mesoporous titanium dioxide (M‐TiO₂) nanoparticles were successfully prepared followed by chemical modification with different contents of polyaniline (PANI/M‐TiO₂) and were used to accelerate the photo‐oxidation and biodegradation process of low‐density polyethylene (LDPE) film. The influence of these additives as a pro‐oxidant additive on the accelerated degradation of LDPE was investigated by photocatalytic oxidation under UV light irradiation and biodegradation with fungal strains. It was found that the as‐prepared PANI modified M‐TiO₂ particles exhibited an obvious light response from 400 to 800 nm which can improve the utilization of solar light. Compared with M‐TiO₂, PANI/M‐TiO₂ exhibited better photocatalytic performance when irradiated under UV light and the subsequent biodegradation efficiency was enhanced. Enhancement of the photocatalytic performance of PANI/M‐TiO₂ could be attributed to good dispersibility and compatibility of PANI/M‐TiO₂ in the LDPE matrix, a narrow band gap, effective separation of photogenerated electron–hole pairs and the chromophoric group of PANI which was used as a photosensitizer in the LDPE/PANI/M‐TiO₂ composite film. © 2019 Society of Chemical Industry     

Visible light photocatalytic activity of TiO2/heat‐treated PVC film

BACKGROUND: Semiconductor TiO₂ has been investigated extensively due to its chemical stability, nontoxicity and inexpensiveness. However, the wide band gap of anatase TiO₂ (about 3.2 eV) only allows it to absorb UV light. TiO₂ nanoparticles modified by conditional conjugated polymers show excellent photocatalytic activity under visible light. However, these conjugated polymers are not only expensive, but also difficult to process. Polyvinyl chloride (PVC) was heat‐treated at high temperature to remove HCl and a C?C conjugated chain structure was obtained. When TiO₂ nanoparticles were dispersed into the conjugated polymer film derived from PVC, this composites film exhibited high visible light photocatalytic activity. RESULTS: The photocatalytic activity of TiO₂/heat‐treated PVC (HTPVC) film was investigated by degrading Rhodamine B (RhB) under visible light irradiation. The photodegradation of RhB follows apparent first‐order kinetics. The rate constants of RhB photodegradation in the presence of the TiO₂/HTPVC films with different mass content of TiO₂ are 16–56 and 4–14 times that obtained in the presence of the pure HTPVC and TiO₂/polymethyl methacrylate (PMMA) composite film, respectively. The TiO₂/HTPVC film showed excellent photocatalytic activity and stability after 10 cycles under visible light irradiation. CONCLUSION: TiO₂/HTPVC film exhibits high visible light photocatalytic activity and stability. Copyright © 2012 Society of Chemical Industry     

Effect of titanium dioxide on the flame‐retardant finishing of cotton fabric

In this study, titanium dioxide (TiO₂) or nano titanium dioxide (nano‐TiO₂) was used as a cocatalyst in the flame‐retardant (FR) formulation of N‐methylol dimethylphosphonopropionamide (Pyrovatex CP New, FR), melamine resin [Knittex CHN, crosslinking agent (CL)], and phosphoric acid (PA) for cotton fabrics to improve the treatment effectiveness and minimize the side effects of the treatment. For FR‐treated cotton fabrics, the flame extinguished right after removal of the ignition source with no flame spreading. However, after neutralization and/or home laundering, FR–CL‐treated specimens failed the flammability test, whereas the opposite results were obtained from FR–CL–PA‐treated specimens. A noticeable result was that the TiO₂/nano‐TiO₂ cocatalyst had a significant effect on decreasing the flame‐spread rate. Thermal analysis found that the FR‐treated specimens without wet posttreatment showed two endothermic peaks representing the phosphorylation of cellulose and acid‐catalyzed dehydration. In addition, the treated fabrics showed some new characteristic peaks in their chemical structures; these were interpreted as carbonyl bands, CH₂ rocking bands, and CH₃ asymmetric and CH₂ symmetric stretching. The surface morphology of the FR–CL–PA‐treated cotton specimens showed a roughened and wrinkled fabric surface with a high deposition of the finishing agent that had a lower breaking load and tearing strength, which resulted from the side effects of the CL used. However, the addition of a TiO₂ or nano‐TiO₂ cocatalyst could compensate for the reduction in the tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Template‐free synthesis of single‐/double‐walled TiO2 nanovesicles: Potential photocatalysts for engineering application

Single‐ and double‐walled anatase TiO₂ nanovesicles have been, respectively, prepared by a template‐free hydrothermal treatment of Ti(SO₄)₂ with H₂O₂ and urea. Photocatalytic degradation of Rhodamine B indicates that double‐walled TiO₂ nanovesicles have an initial lower but a final higher photocatalytic efficiency than single‐walled ones. All nanovesicles have significantly lower performance than commercially available P25 TiO₂. The enhanced capacity for UV light absorption and· OH radicals production, large specific surface area, and unique hierarchical hollow architectures contribute to the enhanced photocatalytic activity and improved feasibility of anatase TiO₂ nanovesicles for engineering applications. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1478–1482, 2015     

Novel chitosan‐TiO2 nanohybrid: Preparation,characterization, antibacterial,and photocatalytic properties

In this report, chitosan (CS) encapsulated titanium dioxide (TiO₂) nanohybrid was prepared by chemical precipitation method. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD) confirmed the formation of nanohybrid. Transmission electron microscopy (TEM) analysis showed the immobilization of TiO₂ nanoparticles on the surface of CS. The nanohybrid was also characterized by thermogravimetric analysis (TGA) and zeta potential. The nanohybrid exhibited high photocatalytic activity as evident from the degradation of methylene blue (MB) dye. The result revealed substantial degradation of the MB dye (90%) under UV‐light illumination. The catalytic efficiency was unaltered even after five cycles of reuse. In addition, the nanohybrid exhibited a superior antibacterial activity of 100% within 24 h of treatment against Escherichia coli (E. coli) was measured by colony forming units (CFU). POLYM. COMPOS., 35:327–333, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of linear low‐density polyethylene/low‐density polyethylene/TiO2 membranes

Because of their special functions, the application of nanoscale powders has recently attracted both industrial and theoretical interest. In this study, nanoscale TiO₂, which exhibited a special UV absorption and consequent antibacterial function, was added to a low‐density polyethylene/linear low‐density polyethylene hybrid by melt compounding to yield functional composite membranes. TiO₂ exhibited an apparent induced nucleation effect on the crystallization of polyethylene, and the size of the crystallites decreased while the number increaed with the introduction of TiO₂; however, the crystallinity of polyethylene changed little. Also, TiO₂ exhibited an ideal dispersion in the membrane with an average size less than 100 nm, and this excellent dispersion provided the membranes extra UV absorption; moreover, the transparency of the membranes was maintained to satisfy common requirements. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 216–221, 2005     

Photostabilization of polypropylene by surface modified rutile‐type TiO2 nanorods

Rutile‐type titanium dioxide (TiO₂) nanorods were prepared, superficially modified and tested for the protection of polypropylene (PP) from the UVB and UVC irradiations. The silica coating blocked the active sites on the nanorods and the following calcination further reduced the amount of surface hydroxyl groups and thus, made the TiO₂ nanorods more efficient against the photodegradation. Compared with spherical TiO₂ nanoparticles, the calcined silica‐coated TiO₂ nanorods demonstrated good photostabilization efficiency due to the excellent shielding effect and the improved dispersion of the nanoparticles in PP matrix. When used in combination with the conventional hindered amine light stabilizer (HALS), CHIMASSORB^® 944, the surface modified TiO₂ nanorods revealed strong synergistic effect during the photo‐oxidation of the PP composites. The capacity of photostabilization was much higher than the combination with the commercial spherical TiO₂ nanoparticles and even higher than the typical HALS photostabilization system containing hindered phenol TINUVIN^® 328. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40601.     

Effect of the grain size of nanoparticle dye‐coated titanium dioxide on the short‐circuit current density and open‐circuit voltage of an indium tin oxide/titanium dioxide/poly(acrylonitrile)–propylene carbonate–lithium perchlorate/graphite solar cell

A dye‐sensitized indium tin oxide (ITO)/titanium dioxide (TiO₂)/polyacrylonitrile (PAN)–propylene carbonate (PC)–lithium perchlorate (LiClO₄)/graphite solar cell was fabricated, and its performance was tested in the dark and under the illumination of a 100 mW/cm² light. Three TiO₂ samples were used in the device, namely, uncoated TiO₂, a TiO₂ film coated with methyl red dye, and a TiO₂ film coated with coumarin dye. The films were deposited onto an ITO‐covered glass substrate by a controlled hydrolysis technique assisted with a spin‐coating technique. The films were characterized by scanning electron microscopy to determine their average grain size. The smallest grain size (48 nm) was obtained for the uncoated film. An electrolyte of PAN–LiClO₄ with PC plasticizer was prepared by a solution‐casting technique. A graphite electrode was prepared on a glass slide by an electron‐beam evaporation technique. The device showed rectification properties in the dark and showed a photovoltaic effect under illumination. The device with the uncoated TiO₂ film showed the highest short‐circuit current density (2.0 μA/cm²) and an open‐circuit voltage of 0.64 V because it possessed the smallest grain size. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of titanium dioxide/poly(methyl methacrylate‐co‐n‐butyl acrylate‐co‐methacrylic acid) hybrid composite particles via emulsion polymerization

Titanium dioxide core and polymer shell composite poly(methyl methacrylate‐co‐n‐butyl acrylate‐co‐methacrylic acid) [P(MMA‐BA‐MAA)] particles were prepared by emulsion copolymerization. The stability of dispersions of TiO₂ particles in aqueous solution was investigated. The addition of an ionic surfactant, sodium lauryl sulfate, which can be absorbed strongly at the TiO₂/aqueous interface, increases the stability of the TiO₂ dispersion effectively by increasing the absolute value of the ζ potential of the TiO₂ particles. The adsorption of the nonionic surfactant, Triton X‐100, on the surface of TiO₂ particles is less than that of the ionic surfactant. Fourier transform IR spectroscopy was used to measure the content of MAA composite particles. Dynamic light scattering characterized the composite particle size and size distribution. The field‐emission scanning electron microscopy results for the composite particles showed a regular spherical shape, and no bare TiO₂ was detected on the entire surface of the samples. The composite particles that were produced showed good spectral reflectance compared to bare TiO₂. Thermogravimetric analysis results indicated the encapsulated TiO₂ and estimated density of composite particles. There was up to 78.9% encapsulated TiO₂ and the density ranged from 1.76 to 1.94 g/cm³. The estimated density of the composite particles is suitable at 1.73 g/cm³, which is due to density matching with the suspending fluid. The sedimentation experiment indicates that reducing the density mismatch between the composite particles and suspending fluid may enhance the stability. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 72–79, 2005     

Photoactive behavior of polyacrylonitrile fibers based on silver and zirconium co‐doped titania nanocomposites: Synthesis,characterization, and comparative study of solid‐phase photocatalytic self‐cleaning

Silver and zirconium co‐doped and mono‐doped titania nanocomposites were synthesized and deposited onto polyacrylonitrile fibers via sol–gel dip‐coating method. The resulted coated‐fibers were characterized by X‐ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, thermogravimetric analysis, and BET surface area measurement. Photocatalytic activity of the TiO₂‐coated and TiO₂‐doped coated fibers were determined by photomineralization of methylene blue and Eosin Y under UV–vis light. The progress of photodegradation of dyes was monitored by diffuse reflectance spectroscopy. The XRD results of samples indicate that the TiO₂, Ag‐TiO₂, Zr‐TiO₂, and Ag‐Zr‐TiO₂ consist of anatase phase. All samples demonstrated photo‐assisted self‐cleaning properties when exposed to UV–vis irradiation. Evaluated by decomposing dyes, photocatalytic activity of Ag–Zr co‐doped TiO₂ coated fiber was obviously higher than that of pure TiO₂ and mono‐doped TiO₂. Our results showed that the synergistic action between the silver and zirconium species in the Ag‐Zr TiO₂ nanocomposite is due to both the structural and electronic properties of the photoactive anatase phase. These results clearly indicate that modification of semiconductor photocatalyst by co‐doping process is an effective method for increasing the photocatalytic activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Experimental analysis and optimization of the synthesizing property of nitrogen‐modified TiO2 visible‐light photocatalysts

BACKGROUND: The aim of this study was to investigate improvement of the photocatalytic activity of visible‐light driven nitrogen‐modified TiO₂ (N‐TiO₂) powder toward methyl blue (MB) and direct blue‐86 (DB‐86) dyes. The Taguchi method with an L₉ orthogonal array was applied to plan the synthesis parameters, i.e. nitrogen sources, nitrogen source concentrations, stirring time and calcined temperatures. 95% confirmation experiments were undertaken to verify the effectiveness of the Taguchi method. RESULTS: All N‐TiO₂ photocatalysts were shifted toward the visible light region with the optical band gap (Eg). Nitrogen source concentrations were significant parameters for the photocatalytic decolorization rate constants (k values). In comparison with pure TiO₂, the photodecolorization behavior of N‐TiO₂ toward DB‐86 was superior with a reaction rate constant of 1.68 × 10^?3 min^?1, and a 4 h photodecolorization efficiency of 34%. CONCLUSION: The Taguchi method was reported to alter the surface properties of commercial Degussa P25 TiO₂, which could then be used as a visible‐light driven photocatalyst. The visible‐light‐driven photocatalyst was investigated to determine material characteristics. Greater photodecolorization of MB and DB‐86 dye pollutants using optimally‐prepared N‐TiO₂ under visible light irradiation was successfully obtained. Copyright © 2011 Society of Chemical Industry