Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy) Nanoparticles

Cohen, Juan D.; Sierra-Gallego, G.; Tobón, Jorge Iván

doi:10.3390/coatings5030465

Cited by 24 publications

(18 citation statements)

References 18 publications

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“…TiO 2 is shown as three crystalline structures: rutile, anatase, and brookite, being the first two forms as the most suitable for photocatalysis [23]. The photooxidation of organic matter has been evaluated in different construction materials such as bricks [24], stone [18,25], and mortars based in different binders [19,26,27]. Most of the research focused on self-cleaning has been made using the TiO 2 product as a coating [21,26].…”

Section: Introductionmentioning

confidence: 99%

Aesthetic Effects on Granite of Adding Nanoparticle TiO2 to Si-Based Consolidants (Ethyl Silicate or Nano-Sized Silica)

2020

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Considering that consolidant products are commonly used in the cultural heritage field and the titanium oxide nanoparticles (TiO 2 ) have been used to develop photocatalyst films to induce self-cleaning property, the scientific research on consolidants doped with TiO 2 is justified. However, the addition of TiO 2 can affect to the physical properties of the cultural heritage object, questioning the adequacy of the procedure. In this paper, we evaluated the influence of nanoparticle TiO 2 addition to two different commercial consolidant products (ethyl silicate or nano-sized silica) on the appearance and the color of a granite and the penetration through its fissure system. The stone was previously subjected to high temperature simulating the effect of a fire and the subsequent tap water jet to cool down. Therefore, different concentrations of nanocrystalline TiO 2 (0.5, 1, and 3 wt %) were considered. The different compositions were also studied considering the compactness, the extent and the thickness of the superficial xerogel coating, and as well the penetration of the consolidant.The minimal TiO 2 concentration tested (0.5 wt %) implied a low-medium risk of incompatibility as an intervention in cultural heritage field, because its low-medium potential as inducer of visible color changes of the granite surface. Regardless of the TiO 2 content, the nano-sized silica induced surface xerogel coatings more compact and continue than those formed in the ethyl silicate coated surfaces. Higher penetration rates were identified in the granite treated with nano-sized silica colloidal solution, while ethyl silicate was only found in the first few µm. It was found that penetration could depend on the application procedure, the solvent of the consolidant and the silica particle size. The TiO 2 addition reduced the penetration of the nano-sized silica consolidant.

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Section: Introductionmentioning

confidence: 99%

Aesthetic Effects on Granite of Adding Nanoparticle TiO2 to Si-Based Consolidants (Ethyl Silicate or Nano-Sized Silica)

2020

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“…It should be noted that sunlight shows 60% of visible photons in comparison with a mere 4.5% of UV photons. So far, just very few works have been devoted to the study of these doped photocatalysts when incorporated into cementitious matrices [10].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytically active coatings for cement and air lime mortars: Enhancement of the activity by incorporation of superplasticizers

Perez-Nicolas

Plank

Ruiz-Izuriaga

et al. 2018

Construction and Building Materials

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Coatings made with water dispersions of different nano-particles of photocatalytic additives (titania and titania doped with iron and vanadium) were prepared with diverse superplasticizers, SPs, to optimize the atmospheric NO removal efficiency when applied onto cement-and air-lime mortars. The use of different polycarboxylate-based superplasticizers (52IPEG, 23APEG and 45PC6) prevented nano-particles from agglomeration. The steric hindrance, provided by a large density and length of side chains, was ascertained as the most effective repulsion mechanism and 52IPEG was the most efficient SP. In PC-and air-lime mortars, the coatings with polycarboxylatebased SPs improved the NO removal rates as compared with the SP-free coating: an average increase of NO degradation by 15% under UV and by 76% under solar light was found. This finding was related to the drop in the agglomeration of the photocatalysts, with more exposed active sites and a decrease of the electron-hole recombination rates. Capillary water absorption and water vapour permeability values showed that the coatings did not alter the performance of the mortars. SEM examination showed that the use of SPs enhanced the distribution of the photocatalysts yielding thinner coating layers and boosting the percolation of the active material within the mortars. Accelerated weathering showed a moderate reduction of NO removal efficiency. Coating with 52IPEG was the most efficient in preserving the activity. Measurements of Ti content showed a low washout of the TiO 2 nano-particles, supporting the long-run activity of these coatings.

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“…In the low concentration region illustrated in Figure 6 (0.1-1.0 g/L of TiO 2 ) the direct linear dependence of the removal percentage with the photocatalyst concentration is observed. On the other hand it was found that for relatively high concentrations (2.0-2.5 g/L of TiO 2 ) this behavior continues; Whereas for the highest concentration, which corresponds to 3.0 g/L of TiO 2 , the removal percentage shows a tendency to decrease due to an excessive opacity of the solution which prevents titanium dioxide from the innermost part of the reactor being illuminated by directly affecting the reaction rate when the photocatalyst is in suspension Of shielding) 19 . Figure 7 shows the decrease in Cr (VI) concentration for different initial concentrations.…”

Section: Effects Of Tio 2 Dosage (Cr +6 )mentioning

confidence: 99%

Cr+6 and Zn+2 Removal for Heterogeneous Photocatalysis with TiO2 in Synthetic Wastewater

2018

IJCTR

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Water sources pollution caused by the presence of metals, it`s actually one of the environmental major concerns. In the present study, the hexavalent Chromium (Cr +6) and divalent Zinc (Zn +2) removal efficiency was evaluated using heterogeneous photocatalysis with titanium dioxide (Degussa P25) in a batch reactor. Both metal presents have harmful effects on public health and environment. The photocatalytic reduction process from Cr +6 to Cr +3 and Zn +2 to Zn 0 in aqueous solutions with hexavalent Chromium or divalent Zinc initial concentrations of 5, 15 and 25 mg/L. It was performed in a batch reactor with a stipulated reaction volume of 250 mL, for the purpose it was provided a wooden box, which have a 20 W ultraviolet light lamp, installed in the chamber superior part. The tests were performed with pH initial conditions (2, 6 and 10 pH units) and photocatalyst doses (2.0, 2.5 y 3.0 g/L de TiO 2), from a multifactorial experimental design of three factor and three levels. From the obtained results it is noticed that the heterogeneous photocatalysis is an excellent instrument for the removal Cr +6 in aqueous solutions, when their concentrations are relatively low, because for the initial concentration of 5 mg/L from Cr +6 is possible its total removal. Furthermore, it was found that this technology is less effective for Cr +6 removal in high concentrations (15, 25 ppm), because this one presents slow reaction kinetics, which were studied in this investigation. For other hand, it was found that this technology is not effective for Zn +2 , because only 3% of removal was achieved.

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Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy) Nanoparticles

Cited by 24 publications

References 18 publications

Aesthetic Effects on Granite of Adding Nanoparticle TiO2 to Si-Based Consolidants (Ethyl Silicate or Nano-Sized Silica)

Aesthetic Effects on Granite of Adding Nanoparticle TiO2 to Si-Based Consolidants (Ethyl Silicate or Nano-Sized Silica)

Photocatalytically active coatings for cement and air lime mortars: Enhancement of the activity by incorporation of superplasticizers

Cr+6 and Zn+2 Removal for Heterogeneous Photocatalysis with TiO2 in Synthetic Wastewater

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