Ozone Treatment for Pesticide-Contaminated Water
摘要
Brazil is one of the largest consumers of pesticides worldwide. Using these chemical compounds in agriculture leads to serious environmental issues, such as contamination of surface and underground waters that supplies drinking water. This study aims to evaluate the degradation of seven types of pesticides: atrazine (atz), chlorpyrifos (cps), malathion (mlt), trifluralin (tfl), lambda-cyhalothrin (lcl), chlorothalonil (ctl), and trifloxystrobin (tft) mixed in water at a concentration of 1.0 ng mL−1. The methodology was based on a chemical oxidation system with the application of ozone at a concentration of 2.0 g h−1, with reaction times (RT) of 5—150 min. After the treatment with ozone, the samples went through solid phase extraction (SPE) with detection and quantification by gas chromatography coupled to triple quadrupole mass spectrometry (GC–MS/MS) and subsequent acute toxicity assay with Artemias Salinas (brine shrimp), to check whether the samples presented toxicity even after ozonation. As a result, detection limits were observed between 0.011 and 0.164 ng mL−1 and quantification limits between 0.050 and 0.498 ng mL−1, for the method of pesticides analyzing in water. Degradation by ozonation reached 100% for the pesticide’s atrazine, chlorpyrifos, malathion, trifluralin and lambda-cyhalothrin in up to 20 min of reaction, being considered “non-toxic” for the target species of this study. Trifloxystrobin reached 100% degradation in 120 min of reaction and chlorothalonil had a maximum percentage of degradation of 84%, for the RT of 150 min. The toxicity test for trifloxystrobin and chlorothalonil found the samples to be “toxic” to Artemias salinas.
Graphical Abstract