Chlorothalonil In Water Research Articles

Feasibility of Using Terahertz Toroidal Metasurface Sensor for Detection and Quantification of Chlorothalonil in Water

Feasibility of Using Terahertz Toroidal Metasurface Sensor for Detection and Quantification of Chlorothalonil in Water

Flavonoid-sensitized photolysis of chlorothalonil in water.

Chlorothalonil is a conventional chloroaromatic fungicide and is toxic to many aquatic species. This study was designed to investigate the effects of six flavonoids on the photolysis of chlorothalonil under sunlight and artificial light. Flavonoids sensitized the photolysis of chlorothalonil under sunlight and artificial light by 6.7-18.3 and 2.4-7.5 times, respectively, in comparison with a flavonoid-free control. Photosensitization effect of each of the six flavonoids was greater under sunlight irradiation than under high-pressure mercury lamp irradiation. Cyanidin showed greater photosensitization effects than luteolin, galangin, quercetin, morin and kaempferol. Chlorothalonil underwent photo-reductive dechlorination and no hydrolysis product was formed in the presence of flavonoids. Hydroxyl and hydrogen radicals were detected in the absence and presence of cyanidin, respectively, under light irradiation. The photosensitization effect of flavonoids on chlorothalonil photolysis is apparently related to flavonoid structure and might be due to their hydrogen donation capacity. These results highlight benefit of using flavonoids to manage aquatic pollution and reduce aquatic toxicity, and have great relevance in predicting the degradation kinetics and biological impacts of chlorothalonil in surface water. © 2020 Society of Chemical Industry.

Detection of pesticide in water using two-dimensional fluorescence correlation spectroscopy and N-way partial least squares.

To determine the concentration of carbaryl and chlorothalonil in water, the potential of two-dimensional (2D) fluorescence correlation spectra with N-way partial least squares (N-PLS) was investigated. A total of 40 mixture solutions of carbaryl and chlorothalonil were prepared and 27 of them were used to form a calibration set. The excitation-emission matrix (EEM) fluorescence spectra of all samples were measured. Under the excitation perturbation, 2D fluorescence correlation spectra of all samples were calculated and formed a 2D correlation spectral matrix. And N-PLS models for determination of carbaryl and chlorothalonil in water were built based on 2D correlation fluorescence spectral matrix and traditional EEM spectral matrix, respectively. Finally, the performances of N-PLS models using both methods were compared. For chlorothalonil, the root mean square error of calibration (RMSEC) were 3.43×10-6gL-1 and 5.08×10-6gL-1, the root mean square errors of prediction (RMSEP) were 5.86×10-6gL-1 and 8.99×10-6gL-1 for 2D correlation spectra and EEM spectra, respectively. For carbaryl, the RMSEC were 5.24×10-7gL-1 and 6.18×10-7, the RMSEP were 9.20×10-7gL-1 and 9.63×10-7gL-1 for 2D correlation spectra and EEM spectra, respectively. From the results of this study, it may conclude that 2D fluorescence correlation spectra is superior over the traditional EEM fluorescence spectra in terms of predictability and can be used as an alternative method for detection of organic pollutants in environment.

Procyanidolic oligomers enhance photodegradation of chlorothalonil in water via reductive dechlorination

Chlorothalonil is an important broad-spectrum fungicide with an annual application rate of above ten thousands of tons of its active ingredient on agricultural crops world-wide. The effect of procyanidolic oligomers on photo degradation of chlorothalonil was investigated under sunlight and artificial lights. Procyanidolic oligomers enhanced photodegradation of chlorothalonil in paddy, reservoir, pond and distilled waters for 1.8, 4.6, 2.7 and 22.8 fold, respectively, relative to the procyanidolic oligomers free control. The mechanism was evidenced as a radical reduction reaction by electron paramagnetic resonance spectroscopy. Upon exposure to high-pressure mercury light, chlorothalonil produced 2,4,5-trichloro-1,3-dicyanobenzene, 2,5-dichloro-1,3-dicyanobenzene and 5-chloro-1,3-dicyanobenzene that were isolated, identified and characterized. Chlorothalonil underwent primarily step-wide photo reductive dechlorination in the presence of procyanidolic oligomers, which avoided the production of the highly toxic 4-hydroxy chlorothalonil. Procyanidolic oligomers possessed strong reductive property to photo reductive dechlorination. The results contributed to understanding of chlorothalonil phototransformation and high potential of using natural product procyanidolic oligomers as an additive to minimize aquatic toxicity and pollution of chlorothalonil.

Catalytic degradation of chlorothalonil in water using bimetallic iron-based systems

Modified zero valent iron (MZVI) was used to study the transformation of a chlorothalonil (CLT) solution and the variation of the observed degradation rate of the reduction reactions. This was carried out when transition metals e.g. Pd, Cu and Co plated on the surface of micrometric iron particles (<150 μm) were used as reducing catalytic agents for pesticide removal. Reactions were undertaken under both oxic and anoxic conditions in the presence and the absence of a phosphate buffer solution (PBS). Results of batch studies in nitrogen sparged solutions revealed that incomplete slow dechlorination merely occurred with zero valent iron (ZVI), however, complete rapid dechlorination reactions took place with MZVI especially Fe/Pd. Dechlorination was depicted by studying UV absorbance and MS spectra of CLT and all corresponding by-products. Typical blue shifts (Δ λ = 4–6 nm/chlorine atom) were observed at the same time as chlorine cluster isotopes disappeared. After the plating process, metal loading was controlled by analyzing the remaining metal in the solution by atomic absorption spectroscopy. Experiments showed that CLT degradation mechanism is faster in nitrogen sparged solutions in the absence of PBS. Time needed for complete removal of 2.08 ± 0.19 μM CLT solution was about 2 h when experiments were conducted with ZVI ( t 1/2 = 15.0 min) and about 10 min when the reaction was carried out under the same conditions with Fe/Pd 1% ( t 1/2 = 1.0 min). Degradation rates for all bimetallic systems were determined showing that Pd is the more exciting catalytic transition metal followed by Cu and Co. Furthermore, MZVI method showed obvious advantage to traditional CLT treatment methods.

Photodegradation and stability of chlorothalonil in water studied by solid-phase disk extraction, followed by gas chromatographic techniques.

Photodegradation of chlorothalonil was studied in deionized and ground water with sunlight and Suntest apparatus, with and without FeCl3/H2O2 and TiO2/H2O2. After irradiation of the water samples spiked at 28-100 micrograms/l of chlorothalonil, the water solutions were preconcentrated using solid-phase disk extraction with C18 and analyzed by gas chromatography-electron capture and gas chromatography-mass spectrometric detection. The degradation products identified by GC-MS were: trichloro-1,3-dicyanobenzene, dichloro-1,3-dicyanobenzene and chloro-1,3-dicyanobenzene. The degradation kinetics followed a first order reaction and the R.S.D. of rate constants, for n = 3, varied from 2 to 14%. Halflives varied between 0.7 and 101 h. The stability of chlorothalonil on C18 Empore disks was also investigated at 20 degrees C, 4 degrees C and -20 degrees C for periods of up to 3 months. Chlorothalonil was not degraded on C18 Empore disks.

Abiotic Degradation of Halobenzonitriles: Investigation of the Photolysis in Solution

This paper presents first experiments of laboratory investigations of the photodegradation by direct photolysis (λ>290 nm) of cholorotahlonil, dichlobenil, chloroxynil, bromoxynil, and ioxynil in aqueous, pH-buffered, and organic solutions and the calculation of the quantum yields. The photolysis of chlorothalonil in water is low, with a corresponding low quantum yield (Φ=0.0001). Dichlobenil is photostable under the laboratory conditions used. The photoreactivity of bromoxynil and ioxynil was found to be comparable in aqueous solutions and about three times lower with respect to chloroxynil. The quantum yields obtained in water of chloroxynil, bromoxynil, and ioxynil are Φ=0.0060, 0.0093, and 0.0024, respectively. Half-lives of the pesticides in the environment with respect to direct irradiation are estimated using UV spectra and quantum yields as input variables obtained in the laboratory.

Determination of chlorothalonil in water and agricultural products by a magnetic particle-based enzyme immunoassay

A competitive enzyme immunoassay for the quantitation of chlorothalonil in water and agricultural products was developed. This immunoassay utililizes amine-terminated superparamagnetic particles as the solid phase to covalently attach polyclonal rabbit anti-chlorothalonil antisera. Specificity studies indicate that the antibody can distinguish chlorothalonil from its major metabolites and structurally similar pesticides. The immunoassay has a detection limit of 0.07 parts per billion (ppb, ng/mL) in water. The assay compares favorably with GC measurements when water samples are analyzed (r = 0.984). Studies indicate that the assay can potentially be used to analyze agricultural products after homogenization with acetone (detection limit of 20 ppb for celery) or to analyze dislodgable residues after a methanol surface wash (detection limit of 5 ppb for snow pea pods).