Metal Oxide Nanomaterials for the Photodegradation of Phenol

The decomposition of phenol by four metal oxide nanomaterials was investigated by adsorption and photocatalytic degradation. The results from adsorption experiments were fit to a Langmuir model. The theoretical monolayer adsorption capacities for nano-TiO2, -Al2O3, -ZnO, and -CuO were approximately 14.35, 14.28, 13.72, and 5.29mg/g, respectively. Nano-TiO2 and -CuO had the largest Langmuir model coefficients: both were 0.0324L/mg. The adsorption capacity of phenol was higher in basic conditions than in acidic solution. Photodegradation was characterized by pseudo-first-order models. The total removal rates for nano-TiO2, -Al2O3, -ZnO, and -CuO after 3 hours of irradiation were 89.0%, 70.8%, 57.3%, and 61.6%, respectively. The differences between phenol and total organic carbon concentrations for nano-TiO2, -Al2O3, -ZnO, and -CuO were 42.92%, 20.11%, 8.29%, and 16.78%, respectively. Nano-TiO2 provided the maximum capacity for photodegradation and produced the most intermediates. The majority of the phenol was degraded to resorcinol and hydroquinone as intermediates to acetic acid.