Engineering Photocatalytic Cements: Understanding TiO₂ Surface Chemistry to Control and Modulate Photocatalytic Performances

Abstract

The present work addresses the aggregation/dispersion properties of two commercial titanias for application as photocatalysts in concrete technology. A microsized m‐TiO2 (average particle size 153.7 ± 48.1 nm) and a nanosized n‐TiO2 (average particle size 18.4 ± 5.0 nm) have been tested in different ionic media (Na+, K+, Ca2+, Cl−, SO42−, synthetic cement pore solution) at different pHs and in real cement paste specimens. Results highlighted that ion–ion correlations play a fundamental role in TiO2 particles aggregation in the cement environment. A particle aggregation model derived from TiO2 surface chemistry is proposed here and used to justify such aggregation phenomena in real cement paste. Scanning electron microscopy–energy‐dispersive X‐ray spectroscopic investigations on hardened cement specimens completely confirmed the qualitative model based on titania surface chemistry. Experimental results also show how size and nature of TiO2 aggregates dramatically influence the overall photocatalytic activity of cementitious materials containing TiO2.

Design and performance study of hybrid photocatalytic reactor-PVDF/MWCNT nanocomposite membrane system for treatment of petroleum refinery wastewater

“…Moreover, oxidation of CNTs by acid mixture, photooxidation wet chemical methods, gas phase treatment, or oxygen plasma can improve CNT stability when they are dispersed in many polar solvents such as ethanol, methanol, isopropanol, and water [30]. Base on the previous study, acid mixture purification of MWCNTs showed a negative charge property [31], which makes TiO 2 rejection easier due to negative charge property of TiO 2 [32].…”

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

“…16,32 The decrease was mostly attributed to reduced specific surface area and mass diffusion in large aggregates. However, the two-phase variation of the UV irradiation induced TiO 2 aggregates does not correlate with the change of specific surface area.…”

Photocatalytic degradation of paraquat herbicide in the presence TiO 2 nanostructure thin films under visible and sun light irradiation using continuous flow photoreactor

“…The significance of each mechanism depends on the pH. The presumed reason is so as to TiO 2 particle surfaces can adsorb water molecules and forming fresh hydroxyl groups (TiOH) (Folli et al, 2010). This clarification is in agreement with FT-IR results.…”