Facile photocatalytic immobilization strategy for P-25 TiO2 nanoparticles on low density polyethylene films and their UV-A photo-induced super hydrophilicity and photocatalytic activity

Abstract

Immobilization of TiO2-P-25 nanoparticles on low-density polyethylene films (LDPE) was successfully achieved through a simple and facile photocatalytic procedure leading to the polymer surface functionalization (generating -C = O species) by TiO2 photo-induced •OH radicals. A systematic study through a response surface methodology (RSM) of type central composite experimental design (DCC)-23 in 3 blocks to find optimal conditions of irradiation time, pH and P-25 amounts was performed. It was found that circumneutral pH (5.0), low amounts of P-25 nanoparticles (0.4 g L-1) and irradiation times of 5 h (LDPE-P25-5 films) may be the best immobilization conditions. This was confirmed by SEM-EDS micrographs and AFM images. LDPE-P25-5 films exhibited the best photocatalytic activity removing malachite green and it was also observed an interesting UV-A photo-induced super hydrophilicity since angle contact dropped from 118 to 4° after 60 min of UV-A irradiation. Furthermore, LDPE-P25-5 film kept its photoinduced self-cleaning properties after 4 reusing cycles (8 h of continuous UV-A + visible irradiation). These findings suggest that this simple and facile photocatalytic procedure may allow the preparation of TiO2-polymeric films with interesting properties to be applied as photoinduced self-cleaning surfaces.