α-pinene from simulating waste gas was degraded by vacuum ultraviolet in a spiral photo-reactor at various process parameters

media and active radicals

and the effects of them on the removal efficiency were studied systematically.The results showed that the efficiency gradually decreased with increasing flow rate and inlet concentration

and was of the maximum value 39.003 mg·m-3·s-1 at 15 s of residence time.It was also found that the removal efficiency followed first order kinetics at low concentration whose rate constant was affected more by the reaction medium and reached the maximum 0.0520 s-1 at air with 35%—45% relative humidity

and second order kinetics at high concentration.In the system of photo-degradation there existed two kinds of strong oxidizer

hydroxyl radical and ozone

that were detected indirectly or directly.Although hydroxyl radicals reacted with α-pinene first

ozone played significant role for the removal of α-pinene.The photo-degradation products were mainly low weight molecule organic aldehydes

ketones and acids

which were of better water-solubility.