Efficient photodecomposition of herbicide imazapyr over mesoporous GaO-TiO nanocomposites.

The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous GaO-TiO nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous GaO-TiO nanocomposites with varied GaO contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO phase at low GaO content which gradually reduced with the increase of GaO content. TEM images display uniform TiO particles (10±2nm) with mesoporous structure. The mesoporous TiO exhibits large surface areas of 167mg, diminished to 108mg upon 5% GaO incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized GaO-TiO nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous GaO under UV illumination. 0.1% GaO-TiO nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% GaO-TiO nanocomposite is nearly 10 and 3-fold higher than that of mesoporous GaO and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous GaO-TiO nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO, GaO or commercial UV-100.