Evaluation of ozonation and ultrasound combination for the degradation of pesticide residues in guava: in vitro application

Pesticide residues in food pose significant health and environmental risks, necessitating effective decontamination strategies. Conventional removal methods, such as washing and peeling, are often insufficient for systemic pesticides that penetrate fruit tissues. This study evaluates the effectiveness of combining ultrasound-ozonation (US-OZ) treatment for degrading four pesticides—chlorpyrifos, imidacloprid, carbendazim, and malathion—in water and guava samples. Pesticide-spiked water and guava samples were treated using an ultrasonic bath sonicator (40 kHz, 25 °C) combined with ozone gas injection (30 g/h) at different exposure times (10, 20, 30, and 40 min). Pesticide degradation was quantified using gas chromatography–mass spectrometry (GC–MS), and the kinetics of degradation were analyzed using a pseudo-first-order model. The US-OZ treatment effectively degraded pesticides, with degradation efficiencies (DE%) after 40 min reaching 74.6% for imidacloprid, 70.3% for carbendazim, 69.2% for chlorpyrifos, and 65.7% for malathion in guava samples. The degradation followed pseudo-first-order kinetics, with carbendazim exhibiting the highest degradation rate constant (k1 = 0.0657 min−1, t1/2 = 10.55 min) and malathion the lowest (k1 = 0.0458 min−1, t1/2 = 15.13 min). Pesticide degradation was more efficient in water than in guava, likely due to matrix interactions, enzymatic activity, and pesticide adsorption within the fruit. The results indicate that combining ultrasound-ozonation significantly enhances pesticide degradation through oxidation and cavitation effects, improving pesticide removal efficiency compared to conventional methods. The findings highlight US-OZ as a promising non-thermal decontamination method for pesticide removal in food and water. Further optimization and toxicity assessments of degradation by-products are recommended to ensure food safety and environmental sustainability.