Catalytic activity of commercial of TiO2 powders for the abatement of the bacteria (E. coli) under solar simulated light: Influence of the isoelectric point

Gumy, D.; Morais, C.R.S.; Bowen, Paul; Pulgarín, C.; Giraldo, Sonia A.; Hajdu, R.; Kiwi, J.

doi:10.1016/j.apcatb.2005.09.013

Cited by 207 publications

(119 citation statements)

References 27 publications

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“…The starting TiO 2 suspension had an IEP of pH 7.00, in agreement with previously reported value for P25 TiO 2 . 22 This IEP is much higher than the native pH of the suspension (pH 5.40), indicating that the nanoparticle surface is positively charged, and the suspension is relatively stable due to electrostatic repulsion. Interestingly, the IEP gradually shifted to lower values with prolonged UV irradiation.…”

Section: ■ Introductionmentioning

confidence: 92%

UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity

Sun

Guo

Zhang

et al. 2014

Environ. Sci. Technol.

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Transformation of nanomaterials in aqueous environment has significant impact on their behavior in engineered application and natural system. In this paper, UV irradiation induced transformation of TiO 2 nanoparticles in aqueous solutions was demonstrated, and its effect on the aggregation and photocatalytic reactivity of TiO 2 was investigated. UV irradiation of a TiO 2 nanoparticle suspension accelerated nanoparticle aggregation that was dependent on the irradiation duration. The aggregation rate increased from <0.001 nm/s before irradiation to 0.027 nm/s after 50 h irradiation, resulting in aggregates with a hydrodynamic diameter of 623 nm. The isoelectric point of the suspension was lowered from 7.0 to 6.4 after irradiation, indicating less positive charges on the surface. ATR-FTIR spectra displayed successive growth of surface hydroxyl groups with UV irradiation which might be responsible for the change of surface charge and aggregation rate. UV irradiation also changed the photocatalytic degradation rate of Rhodamine B by TiO 2 , which initially increased with irradiation time, then decreased. Based on the photoluminescence decay and photocurrent collection data, the change was attributed to the variation in interparticle charge transfer kinetics. These results highlight the importance of light irradiation on the transformation and reactivity of TiO 2 nanomaterials. ■ INTRODUCTIONSemiconductor nanomaterials have attracted intensive interest due to their ability to drive photochemical reactions under solar light irradiation. 1−4 In particular, TiO 2 nanoparticles are widely used in photocatalytic devices to achieve environmental remediation and water splitting because of their low-cost, low toxicity and robust performance. 5,6 Modeling studies predicted the annual production of nano-TiO 2 would exceed 2.5 million tons by 2025. 7 With the high reactivity and the rising demand of nano-TiO 2 , it is essential to elucidate both their stability in the practical devices during the life cycle of these products and their transformation process after discharge into the natural environment.Typical transformation processes of nanomaterials include aggregation, dissolution, redox reaction, photochemical reaction, and biocatalyzed degradation. 8−10 A nanomaterial may participate in one or more processes, depending not only on its inherent properties but also on the surrounding environmental factors. Indeed, once introduced to the practical applications, nano-TiO 2 encounters the environmental factors (e.g., natural organic matter, ionic species and sunlight) and then nano-TiO 2 will inevitably undergo physical and chemical transformations due to their high surface reactivity and large specific surface area. These transformation pathways will in turn govern their photoreactivity and environmental fate. Because of its high chemical stability, studies on the nano-TiO 2 behavior are mainly related to aggregation process. 11−13 Typically, The hydroxyl groups covered on nano-TiO 2 surface would interact with differe...

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Section: ■ Introductionmentioning

confidence: 92%

UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity

Sun

Guo

Zhang

et al. 2014

Environ. Sci. Technol.

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“…7(b) means that the present Gly-modified titania nanoparticles could be used for attack against bacteria within enclosed space under soft blue illumination. By referring the literature, [35][36][37][38][39][40] these results suggest that the .N-doping has created intermediate energy levels in the band gap, which allow the production of some type of oxidizing species. Because of the relatively low energy of these wave lengths, species such as oxygen singlet O 2 1 are expected rather than the hydroxyl radical, *OH.…”

Section: B Photocatalytic Activitymentioning

confidence: 99%

Modification of titania nanoparticles for photocatalytic antibacterial activity via a colloidal route with glycine and subsequent annealing

et al. 2012

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Changes in the colloid-chemical and photocatalytic properties of titania nanoparticles by attrition milling in the presence of glycine (Gly) and subsequent heat treatment were examined. By milling at 1500 rpm for 6 h, the average particle size was decreased from 123 to 85 nm, with simultaneous decrease in the specific surface area from 35.1 to 23.5 m 2 /g. Interfacial reactions between titania and Gly were confirmed by Fourier transform infrared spectroscopy, from the blue shift of the COO À related vibrational bands by 25 cm À1, relative to the same band from the pristine Gly. The bimodal N1s x-ray photoelectron spectroscopy peak similar to that from the reported titania-amino acid complex is another indication of the complex formation with the participation of nitrogen. When the dispersion was dried and calcined at 500°C in air, the powder exhibited pale yellow color. Diffuse reflectance spectroscopy showed significant visible light absorption, suggesting nitrogen incorporation into titania. The fired product showed high photocatalytic antibacterial activity by irradiation of blue light centered at around 440 nm, using Escherichia coli as a specimen of bacterial species. Thus, the present Gly-modified titania nanoparticles could be used for eliminating indoor bacteria under soft blue illumination. The series of interfacial chemical processes involved are also discussed.

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“…The mechanism of E. coli disinfection by TiO 2 photocatalysis has been documented recently in aqueous solution [20,21] and at the solid-air interface [22,23]. Bacterial inactivation on TiO 2 films sputtered on polyester (PES) [24,25] and on polyethylene (PE) [26] presented fast bacterial inactivation kinetics in over many cycles under light irradiation.…”

Section: Introductionmentioning

confidence: 99%

Supported TiO2 films deposited at different energies: Implications of the surface compactness on the catalytic kinetics.

Rtimi

Giannakis

Bensimon

et al. 2016

Applied Catalysis B: Environmental

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a b s t r a c tInsight is provided in this study for the effect of the TiO 2 film densification/compactness on polyethylene (PE-TiO 2 ) by sputtering TiO 2 at two very different energy levels. Uniform, adhesive low energy films were prepared by direct current magnetron sputtering (DCMS) and compared with films sputtered at high energy levels by high power impulse magnetron sputtering (HIPIMS). Nano-particulate TiO 2 films sputtered by HPIMS presented sizes of ∼10.2 nm compared to films sputtered by DCMS with TiO 2 sizes of ∼16.5 nm as determined by X-ray diffraction (XRD). The E. coli inactivation kinetics was three times faster for the samples sputtered by HIPIMS compared to their DCMS counterparts. This is an unexpected finding since the DCMS presenting larger TiO 2 sized nanoparticles released a higher amount of Ti-ions compared to the HIPIMS samples as monitored by inductively coupled plasma mass-spectrometry (ICP-MS). The Ti-ions released do not seem to react through an oligodynamic effect but diffuse through the less compact TiO 2 sputtered by DCMS. The faster bacterial inactivation kinetics observed by the HIPIMS sputtered samples can be understood in terms of the complete of Ti 4+ /Ti 3+ redox conversion during bacterial inactivation detected by X-ray photo-electron spectroscopy (XPS) compared to the smaller Ti 4+ /Ti 3+ effect observed in the DCMS-samples. A higher optical density was detected for the HIPIMS sputtered samples by diffuse reflectance spectroscopy (DRS). Evidence is presented for the shift in surface potential and local pH during bacterial inactivation under aerobic and anaerobic conditions. A reaction mechanism is suggested based on the findings described in this study. The sputtered films present the potential to hinder biofilm formation on flexible thin polymers/textiles widely used in hospitals and health facilities.

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Catalytic activity of commercial of TiO2 powders for the abatement of the bacteria (E. coli) under solar simulated light: Influence of the isoelectric point

Cited by 207 publications

References 27 publications

UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity

UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity

Modification of titania nanoparticles for photocatalytic antibacterial activity via a colloidal route with glycine and subsequent annealing

Supported TiO2 films deposited at different energies: Implications of the surface compactness on the catalytic kinetics.

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Catalytic activity of commercial of TiO2 powders for the abatement of the bacteria (E. coli) under solar simulated light: Influence of the isoelectric point

Cited by 207 publications

References 27 publications

UV Irradiation Induced Transformation of TiO2 Nanoparticles in Water: Aggregation and Photoreactivity

UV Irradiation Induced Transformation of TiO2 Nanoparticles in Water: Aggregation and Photoreactivity

Modification of titania nanoparticles for photocatalytic antibacterial activity via a colloidal route with glycine and subsequent annealing

Supported TiO2 films deposited at different energies: Implications of the surface compactness on the catalytic kinetics.

Contact Info

Product

Resources

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UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity

UV Irradiation Induced Transformation of TiO₂ Nanoparticles in Water: Aggregation and Photoreactivity