The effects and mechanism of using ultrasonic dishwasher to remove five pesticides from rape and grape

In this study, the ultrasonic dishwasher was used to remove five pesticides known to be frequently used on rape and grape. As compared with normal water washing, washing with the ultrasonic dishwasher was demonstrated to be more effective for pesticides removal, achieving removal rates between 14.7% and 59.8% on rape, and between 72.1% and 100% on grape. However, there were significant differences in order of the removal rate of five pesticides on rape and grape. From the adsorption experiments and analysis via Freundlich equation, the adsorption index (n, 0.551-1.056 on rape and 0.362-1.478 on grape) and adsorption coefficient (K_F, 10^-2.47-10^-1.65 and 10^-3.64-10^-1.56 (mg·dm^-2)/(mg·L^-1)^-n on rape and grape) were obtained. Taken together with the observation of the matrix surface by scanning electron microscopy and the evaluation of the physicochemical properties of pesticides, the different pesticides removal may be related to surface structure of the matrix.