Abstract
BACKGROUND: Surface modification by doping with metal ions and organic polymers has been proven to be an efficient route to improve the photocatalytic activity of TiO~2~. Pesticide photocatalysis has been conducted with fine TiO~2~ particles suspended in an aqueous phase.
RESULTS: It has been found that the Ag dopant accelerates TiO~2~ anatase to rutile transformation. At relatively low Ag concentrations (2β6%), anatase grain sizes decreased and specific surface areas of the TiO~2~ powders increased. The presence of Ag in crystalline TiO~2~ was found to increase the photocatalytic activity of TiO~2~ in the photocatalytic degradation of acetamiprid at 25 Β°C.
CONCLUSION: All photocatalytic degradations of acetamiprid followed pseudoβfirstβorder degradation kinetics (C~t~ = C~0~e^βkt^) and parameters like the concentration of doped Ag appeared to play an important role affecting the reaction rate. The photocatalytic degradation velocity constant (k) was found to increase quickly with the Ag content, increasing from n = 0.02 to 0.06, and decreased slowly from n = 0.08 to 0.12. The halfβlives of degradation (t~1/2~) were 18.8, 11.3, 16.2, 10.0, 6.9, 8.4 and 14.7 min at n = 0, 0.02, 0.04, 0.06, 0.08 and 0.12, respectively. The optimal mole percentage of Ag in TiO~2~ should be between 4% and 8%. Copyright Β© 2008 Society of Chemical Industry