Gas-Phase TiO2 Photosensitized Mineralization of Some VOCs: Mechanistic Suggestions through a Langmuir–Hinshelwood Kinetic Approach

A jointed experimental and theoretical investigation pointing out new insights about the microscopic mechanism of the volatile organic compounds (VOCs) photocatalytic elimination by TiO2 was done. Methane, hexane, isooctane, acetone and methanol were photomineralized in a batch reactor. Values of K (adsorption constant on TiO2) and k (mineralization rate constant) of the five VOCs (treating the kinetic data through a Langmuir–Hinshelwood approach) were determined. Recorded K (in the range of 0.74 × 10−2–1.11 × 10−2 ppm−1) and k (in the range of 1.9–9.9 ppm min−1) values and performed theoretical calculations allowed us to suggest the involvement of an electron transfer step between the VOC and the hole, TiO2(h+), as the rate-determining one.