The present study examined the effects of anatase nanometer TiO2 on photochemical degradation of chlorothalonil in aqueous solution and on the plant surface. Results showed that nanometer TiO2 exhibited a strong photosensitizing effect on the degradation of chlorothalonil both in aqueous solution and on the surface of green pepper. The photosensitization rate was the highest in the sunlight compared to illumination under high-pressure mercury and UV lamps. Use of distinct hydroxyl radical scavengers indicated that nanometer TiO2 acted by producing hydroxyl radicals with strong oxidizing capacity. Notably, nanometer TiO2 facilitated complete photodegradation of chlorothalonil with no detectable accumulation of the intermediate chlorothalonil-4-hydroxy. Nanometer TiO2 was also active on the surface of green pepper under natural sunlight both inside and outside of plastic greenhouse. These results together suggest that nanometer TiO2 can be used as a photosensitizer to accelerate degradation of the pesticides under greenhouse conditions.

Chlorothalonil is a widely used fungicide on pepper and other vegetables in China. The present study was aimed to evaluate effects of three different surfactants, sodium dodecyl sulfonate (SDS), Span-20, and cetyltrimethylammonium bromide (CTAB), on the photolysis of chlorothalonil on peppers under irradiation of either high-pressure mercury lamp (HPML) or sunlight inside and outside greenhouse. Results showed that both SDS and Span-20 at a low concentration exhibited a photosensitization effect on the photolysis of chlorothalonil under HPML. Such effect gradually decreased with increasing concentrations of either surfactant prior to photoquenching effects observed. In contrast, CTAB showed a photoquenching effect on chlorothalonil photolysis, which was gradually enhanced with an increasing CTAB concentration. SDS, Span-20, and CTAB had consistent effects on the photolysis of chlorothalonil under sunlight as those observed under HPML irradiation. The use of appropriate surfactants as pesticide additives at optimal concentrations could decrease the residue of pesticide in agricultural food and improve food safety.

In order to obtain much better control effect, position control system uses position-speed dual closed loop structure in the testing system of hard air refuel tanker drag system. According to the characteristics of nonlinear system, PID controller and fuzzy controller were taken as the outer loop controllers. The simulation results show that the fuzzy control system is superior to PID control. By comparing response curves with different load, it is easy to see that fuzzy control can be more effective than PID control in restraining overshoot and improving the dynamic performance.