TiO2-photocatalytic transformation of Cr(VI) in the presence of EDTA: Comparison of different commercial photocatalysts and studies by Time Resolved Microwave Conductivity

Photocatalytic reduction of Cr(VI) over titania suspensions

“…>250 m 2 g −1 compared to 80-100 m 2 g −1 and 50 m 2 g −1 for PC-100 and P25, respectively) that seems to facilitate the adsorption of Cr(VI) on its surface. In a recent work [35], the photocatalytic activity for the reduction of Cr(VI) in the presence of EDTA was positively correlated to the surface area of several commercial titania samples, postulating that the effects of competitive adsorption of Cr(VI) and organics are more pronounced at catalysts with lower surface areas [22]. Comparing Millenium PC-100 and TiO 2 P-25, the latter appears to be slightly more effective than the former although its surface area is somewhat lower; it can be postulated that the photocatalytic properties associated with the unique crystal form of P-25 are capable of promoting reduction rates.…”

Acid-treated g-C3N4 with improved photocatalytic performance in the reduction of aqueous Cr(VI) under visible-light

“…Hence, it is obliged to develop effective, economical and environmental-friendly methods of treating Cr(VI)-containing wastewaters. Photocatalytic reduction has now been considered as a promising method of treating Cr(VI)-containing wastewaters [7][8][9][10][11][12][13][14], due to its distinguished characteristics such as (i) low cost, (ii) good ability to use ''free'', infinite, clean and safe solar energy, (iii) no use and no release of other undesirable chemicals, e.g., less solid wastes (iv) reusability, and (v) the reduced product, Cr(III) is much less toxic than Cr(VI) and can be easily precipitated in aqueous solution (K > sp (Cr(OH) 3 ) = 6.3 Â 10 À31 ) and treated as a solid waste. However, by now, the lack of efficient, stable, nontoxic and inexpensive visible-lightactive photocatalysts hinders the practical application of photocatalysis technology in treating large-scale Cr(VI)-containing wastewaters.…”

Photocatalytic Nanoparticulate ZrxTi1‐xO2 Coatings with Controlled Homogeneity of Elemental Composition

“…A deeper inspection of the charge carrier kinetics in semiconducting materials can be performed via Time‐Resolved Microwave Conductivity (TRMC) measurements after pulsed UV−A laser irradiation, which reflect depletion of light‐induced charges, conduction band (CB) electrons and valence band (VB) holes. The analysis of experimental data in this method is generally performed in the log‐log frame, which provides a better visibility to different stages of the relaxation process . In particular, on a short ps‐ns time‐scale, the TRMC decay is due to the electron‐hole plasma recombination, while at late sub‐μs and μs time scales the decay is due to a reverse transfer of charges from low‐mobility regions back to high mobility regions of the material .…”