Photoinduced Glycerol Oxidation over Plasmonic Au and AuM (M = Pt, Pd and Bi) Nanoparticle-Decorated TiO2 Photocatalysts

In this study, sol-immobilization was used to prepare gold nanoparticle (Au NP)-decorated titanium dioxide (TiO2) photocatalysts at different Au weight % (wt. %) loading (Aux/TiO2, where x is the Au wt. %) and Au–M NP-decorated TiO2 photocatalysts (Au3M3/TiO2), where M is bismuth (Bi), platinum (Pt) or palladium (Pd) at 3 wt. %. The Aux/TiO2 photocatalysts exhibited a stronger visible light absorption than the parent TiO2 due to the localized surface plasmon resonance effect. Increasing the Au content from 1 wt. % to 7 wt. % led to increased visible light absorption due to the increasing presence of defective structures that were capable of enhancing the photocatalytic activity of the as-prepared catalyst. The addition of Pt and Pd coupled with the Au3/TiO2 to form Au3M3/TiO2 improved the photocatalytic activity of the Au3/TiO2 photocatalyst by maximizing their light-absorption property. The Au3/TiO2, Au3Pt3/TiO2 and Au3Pd3/TiO2 photocatalysts promoted the formation of glyceraldehyde from glycerol as the principle product, while Au3Bi3/TiO2 facilitated glycolaldehyde formation as the major product. Among all the prepared photocatalysts, Au3Pd3/TiO2 exhibited the highest photocatalytic activity with a 98.75% glycerol conversion at 24 h of reaction time

Optimal Hydrogen Production Coupled with Pollutant Removal from Biodiesel Wastewater Using a Thermally Treated TiO2 Photocatalyst (P25): Influence of the Operating Conditions

This work aimed to produce hydrogen (H2) simultaneously with pollutant removal from biodiesel wastewater by photocatalytic oxidation using a thermally-treated commercial titanium dioxide (TiO2) photocatalyst at room temperature (~30 °C) and ambient pressure. The effects of the operating conditions, including the catalyst loading level (1–6 g/L), UV light intensity (3.52–6.64 mW/cm2), initial pH of the wastewater (2.3–8.0) and reaction time (1–4 h), on the quantity of H2 production together with the reduction in the chemical oxygen demand (COD), biological oxygen demand (BOD) and oil and grease levels were explored. It was found that all the investigated parameters affected the level of H2 production and pollutant removal. The optimum operating condition for simultaneous H2 production and pollutant removal was found at an initial wastewater pH of 6.0, a catalyst dosage of 4.0 g/L, a UV light intensity of 4.79 mW/cm2 and a reaction time of 2 h. These conditions led to the production of 228 μmol H2 with a light conversion efficiency of 6.78% and reduced the COD, BOD and oil and grease levels by 13.2%, 89.6% and 67.7%, respectively. The rate of pollutant removal followed a pseudo-first order chemical reaction with a rate constant of 0.008, 0.085 and 0.044 min−1 for the COD, BOD and oil and grease removal, respectively