Significant influences of TiO_(2)crystal structures on NO_(2)and HONO emissions from the nitrates photolysis

The emissions of NO_(2)and HONO from the KNO_(3)photolysis in the presence of TiO_(2)were measured using a round-shape reactor coupled to a NO_(x)analyzer.TiO_(2)played important roles in the emission flux density of NO_(2)(R_(NO_(2)))and HONO(R HONO),depending on crystal structures and mass ratios of TiO_(2).R NO_(2)and R HONO significantly decreased with increasing the rutile and anatase mass ratios from 0 to 8 and 0.5 wt.%,respectively.Nevertheless,with further increasing the anatase mass ratio to 8 wt.%,there was an increase in R_(NO_(2))and R HONO.R NO_(2)on KNO_(3)/TiO_(2)/SiO_(2)had positive correlation with the KNO_(3)mass(1–20 wt.%),irradiation intensity(80–400 W/m^(2))and temperature(278–308 K),while it had the maximum value at the relative humidity(RH)of 55%.R HONO on KNO_(3)/TiO_(2)/SiO_(2)slightly varied with the KNO_(3)mass and temperature,whereas it increased with the irradiation intensity and RH.In addition,the mechanism for NO_(2)and HONO emissions from the nitrates photolysis and atmospheric implications were discussed.