Photo-degradation dynamics of five neonicotinoids: Bamboo vinegar as a synergistic agent for improved functional duration

Abstract

The effects of photo-degradation on the utilization of pesticides in agricultural production has been investigated. Various influencing factors were compared, with results showing that the initial pesticide concentration, light source, water quality and pH possessed different effects on neonicotinoids photo-degradation. The initial concentration and pH were found to be most critical effects. The photo-degradation rate decreased by a factor of 2–4 when the initial concentration increased from 5 mg L-1 to 20 mg L-1, particularly for acetamiprid and imidacloprid. The photo-degradation pathways and products of the five neonicotinoids were also investigated, with similar pathways found for each pesticide, except for acetamiprid. Degradation pathways mainly involved photo-oxidation processes, with products identified using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) found to be consistent with literature reported results. Bamboo vinegar exerted a photo-quenching effect on the neonicotinoids, with an improved efficiency at higher vinegar concentrations. The photo-quenching rates of thiamethoxam and dinotefuran were 381.58% and 310.62%, respectively, when a 30-fold dilution of vinegar was employed. The photo-degradation products in bamboo vinegar were identical to those observed in methanol, with acetic acid being the main factor influencing the observed quenching effects.

Degradation of Sulfoxaflor in Water and Soil: Kinetics, Degradation Pathways, Transformation Product Identification, and Toxicity

“…The possible reason is that the trifluoromethyl group on the pyridine ring of sulfoxaflor, the nitrile group on the side chain, and double bonds on the S atom are strong electron-withdrawing groups, and the positively charged S atom is vulnerable to attack by hydroxyl groups under alkaline conditions . Compared with that in the pH values of 7 buffer solution, the degradation rate of sulfoxaflor in ultrapure water was faster, which was consistent with the photolysis results of diclofenac, imidacloprid, and acetamiprid. , …”

“…22 Compared with that in the pH values of 7 buffer solution, the degradation rate of sulfoxaflor in ultrapure water was faster, which was consistent with the photolysis results of diclofenac, imidacloprid, and acetamiprid. 23,24 3.2.3. Soil Degradation Test.…”

Neonicotinoid contamination in tropical estuarine waters of Indonesia

“…The use of high amounts of neonicotinoids by farmers could result in more neonicotinoids being leached into water bodies, which could cause a lower photo-degradation and biodegradation rates of these neonicotinoids in water, further resulting in neonicotinoids remaining in the sampling sites. A lower photo-degradation may occur because of increased photon absorption competition among neonicotinoid molecules in water and lead to less light energy absorbed per unit molecule ( Liang et al., 2019 ), while higher initial concentrations may result in toxic effects on the microbial cells and disrupt the enzymatic degradation process of the pollutants by degrading microbes ( Phugare et al., 2013 ).…”

Insights into the Toxicity and Degradation Mechanisms of Imidacloprid Via Physicochemical and Microbial Approaches

“…Bamboo vinegar can be used as an imidacloprid synergistic agent in agricultural production activities, mainly leading to a light quenching effect. The photodegradation rate decreases with an increase in the concentration of the vinegar under irradiation of a high-pressure mercury lamp [83]. In recent years, heterogeneous photocatalysis has emerged as a completely green environmental application technique.…”