Photo-Catalytic Remediation of Pesticides in Wastewater Using UV/TiO2

Modhi O. Alotaibi,Murefah Al-Anazy,Mohamed H. EL-Saeid,Mashael Alshabanat,Khadiga Alharbi,Abeer S. Altowyan

doi:10.3390/w13213080

Modhi O. Alotaibi, Murefah Al-Anazy + Show 4 more

Open Access

https://doi.org/10.3390/w13213080

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Abstract

One of the most serious environmental concerns worldwide is the consequences of industrial wastes and agricultural usage leading to pesticide residues in water. At present, a wide range of pesticides are used directly to control pests and diseases. However, environmental damage is expected even at their low concentration because they are sustained a long time in nature, which has a negative impact on human health. In this study, photolysis and photocatalysis of the pesticides dieldrin and deltamethrin were tested at two UV wavelengths (254 and 306 nm) and in different test media (distilled water, wastewater, and agricultural wastewater) to examine their ability to eliminate pesticides. TiO2 (0.001 g/10 mL) was used as a catalyst for each treatment. The purpose was to determine the influence of UV wavelength, exposure time, and catalyst addition on the pesticide decomposition processes in different water types. Water was loaded with the tested pesticides (2000 µg) for 12 h under UV irradiation, and the pesticide concentrations were measured at 2 h intervals after UV irradiation. The results showed a clear effect of UV light on the pesticides photodegradations that was both a wavelength- and time-dependent effect. Photolysis was more effective at λ = 306 nm than at λ = 254 nm. Furthermore, TiO2 addition (0.001 g/10 mL) increased the degradation at both tested wavelengths and hence could be considered a potential catalyst for both pesticide degradations. Deltamethrin was more sensitive to UV light than dieldrin under all conditions.

Highlights

Agrochemicals are substances that are commonly used in agriculture to protect crops and ensure their productivity [1]
The photolysis process of dieldrin and deltamethrin was examined in the current study for three different types of water: distilled water (DW), wastewater (WW). and agricultural wastewater (Ag.WW) using UV radiation at varied wavelengths with and without a catalytic agent (TiO2 )
The results indicated that the amount of both dieldrin and deltamethrin decreased gradually with increasing time after photolysis

Summary

Introduction

Agrochemicals are substances that are commonly used in agriculture to protect crops and ensure their productivity [1]. Such chemicals are commonly applied to eliminate pests (such as rodents), and include pesticides—namely, insecticides, fungicides, and herbicides—and un-wanted plants [2]. Agrochemicals are used to combat human disease vectors such as mosquitoes; they are used against crop-damaging epidemics in the agricultural sector [3,4] that offer producers an efficient means to manage crop pests that decrease yield and threaten food security [5]. Crop-based agrochemicals such as pesticides are dissolved in water, and the crop are sprayed in the fields. Commercial pesticide formulations often include additional compounds (such as solvents and surfactants) to increase their activity; solvents and other co-formulants often increase the environmental impact of the formulation as well

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