Oxidative Degradation and Detoxification of Chlorpyrifos by Ultrasonic and Ozone Treatments

Abstract

Chlorpyrifos is an organophosphate pesticide, widely used on fruit and vegetable crops. Here, we report on the oxidative degradation of standard chlorpyrifos by individual and combined effects of ultrasonic irradiation (US) and ozone (O 3 ). A standard chlorpyrifos solution (1 mg L -1 ) was treated with 1 MHz US, O 3 and its combination (US/O 3 ) for 0, 10, 20, 30, 40, 50 and 60 min. Reduction of residual chlorpyrifos was determined by gas chromatography with flame photometric detection (GC-FPD) while ion chromatography (IC) was used to determine the concentration of anions as major degradation products. US/O 3 combined treatment had a synergistic effect in reducing chlorpyrifos concentrations, with the highest rate of degradation occurring within the first 10 min. Moreover, chloride, nitrate and sulphate anion concentrations obtained from chlorpyrifos treated with US/O 3 combination, were significantly higher, compared to those treated with ultrasonic irradiation or ozone alone. A sharp decrease in pH from 7.46 to 4.49 was also observed for the combined treatment. The degradation pathway of chlopyrifos, after treatment, was confirmed by gas chromatography mass spectrometry (GC-MS). All treatments resulted in similar main fragment ions at m/z 351, 314, 286, 258, 197 and 97. The lethal concentration (LC 50 ), over a series (0-100) mg L -1 of standard chlorpyrifos solutions, was estimated and compared to the treated chlorpyrifos. All the treatments directly detoxified chlorpyrifos with LC 50 values against brine shrimps (Artemia salina L.) of 10.21, 103.54 and 234.09 mg L -1 for US, O 3 and US/O 3 treated chlorpyrifos solutions, respectively. The brine shrimp test showed highest toxicity in standard chlorpyrifos with an LC 50 value of 7.22 mg L -1 .

Chlorpyrifos: pollution and remediation

“…Oxidative degradation of standard chlorpyrifos by individual and combined effects of ultrasonic irradiation and ozone showed that US/O 3 combined treatment had a synergistic effect that significantly lowered the toxicity of chlorpyrifos with increased production of chloride, nitrate, and sulfate. However, decrease in pH (from 7.46 to 4.49) observed during the degradation process points towards the release of HCl which is unacceptable (Pengphol et al 2012).…”

Effect of aqueous ozone treatment on the reduction of chlorpyrifos and physicochemical and microbial qualities of cucumber (Cucumis sativusL.): Process modeling and optimization

“…At present, pesticide application in vegetables has become increasingly frequent to control plant pests and thus reduce productivity losses (Oerke & Dehne, 2004;Ooraikul et al, 2011;Panuwet et al, 2012). One of the most popular groups of pesticides used in agricultural fields is organophosphates, and among all the organophosphates, chlorpyrifos stands out as the most popular due to its high efficiency and reasonable price (Harnpicharnchai et al, 2013;Ooraikul et al, 2011;Pengphol et al, 2012). Nonetheless, organophosphates possess a high level of toxicity and result in the persistence of hazardous residues harmful to individuals, leading to health problems like impaired neuromuscular transmission and respiratory and cardiac issues (Chowdhury et al, 2012;Duangchinda et al, 2014;Ooraikul et al, 2011).…”