Chromatographic Analysis Unit, Soil Science Department, College of Food & Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia.
Department of Chemistry, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh 11564, Saudi Arabia.
Molecules. 2022 Jan 19;27(3):634. doi: 10.3390/molecules27030634.
Organic pesticides are major sources of soil pollution in agricultural lands. Most of these pesticides are persistent and tend to bio accumulate in humans upon consumption of contaminated plants. In this study, we investigate different natural soil samples that were collected from agricultural lands. The samples revealed the presence of 18 pesticides that belong to four different groups including organochlorines (OCP), organophosphorus (OPP), carbamates (Carb), and pyrethroids (Pyrth). The photocatalytic degradation of the five most abundant pesticides was studied in the presence and absence of 1% TiO or ZnO photocatalysts under UV irradiation at a wavelength of 306 nm. The five abundant pesticides were Atrazine (OCP), Chlorpyrifos methyl (OPP), Dimethoate (OPP), Heptachlor (OCP), and Methomyl (Carb). The results showed that photolysis of all pesticides was complete under UV radiation for irradiation times between 64-100 h. However, both photocatalysts enhanced photocatalytic degradation of the pesticides in comparison with photolysis. The pesticides were photocatalytically degraded completely within 20-24 h of irradiation. The TiO photocatalyst showed higher activity compared to ZnO. The organochlorine heptachlor, which is very toxic and persistent, was completely degraded within 30 h using TiO photocatalyst for the first time in soil. The mechanism of photocatalytic degradation of the pesticides was explained and the effects of different factors on the degradation process in the soil were discussed.
有机农药是农业用地土壤污染的主要来源。这些农药大多数具有持久性，并且在人类食用受污染的植物后，往往会在体内生物累积。在本研究中，我们研究了从农业用地采集的不同天然土壤样本。这些样本揭示了存在 18 种属于四类农药的农药，包括有机氯（OCP）、有机磷（OPP）、氨基甲酸酯（Carb）和拟除虫菊酯（Pyrth）。在 306nm 波长的紫外线照射下，研究了在存在和不存在 1%TiO 或 ZnO 光催化剂的情况下，五种最丰富的农药的光催化降解情况。这五种丰富的农药分别是莠去津（OCP）、毒死蜱甲基（OPP）、乐果（OPP）、七氯（OCP）和灭多威（Carb）。结果表明，在紫外线辐射下，所有农药在 64-100 小时的辐照时间内完全光解。然而，与光解相比，两种光催化剂都增强了农药的光催化降解。在 20-24 小时的辐照时间内，农药完全光催化降解。与 ZnO 相比，TiO 光催化剂表现出更高的活性。非常有毒且持久的有机氯七氯在 TiO 光催化剂的作用下，在 30 小时内首次完全降解，这是在土壤中首次实现的。解释了农药光催化降解的机理，并讨论了不同因素对降解过程的影响。
