Chlorpyrifos degradation via photoreactive TiO2 nanoparticles: Assessing the impact of a multi-component degradation scenario

Abstract

High concentrations of pesticides enter surface waters following agricultural application, raising environmental and human health concerns. The use of photoreactive nanoparticles has shown promise for contaminant degradation and surface water remediation. However, it remains uncertain how the complexity of natural waters will impact the photodegradation process. Here, we investigate the photoreactivity of titanium dioxide nanoparticles, the capability to degrade the pesticide chlorpyrifos, and the effect of and impact on bacteria during the photodegradation process. Loss of chlorpyrifos in solution resulted solely from photocatalytic oxidation, with 80% degradation observed after 24 h in our reactor, either in the presence or absence of bacteria. Degradation of chlorpyrifos to chlorpyrifos oxon and 3,5,6-trichloro-2-pyridinol was observed via LC/MS-MS and effectively modeled for the given reactor conditions. Bacterial inactivation occurred over 60 min and was not impacted by the presence of chlorpyrifos. The relative affinity of bacteria and chlorpyrifos for the nanoparticle surface decreased the amount of Reactive Oxygen Species (ROS) detected in the bulk by up to 94%, suggesting that ROS measurements in simplified systems may overestimate the reactivity of photoreactive nanoparticles in complex environments.

Residue Content of Organophosphorus Pesticides and their Toxic Metabolites in Greenhouse-Grown Tomatoes during Pre-Harvest Interval and Post-Harvest Processing: A Kinetic Study

“…It was observed that the concentration of chlorpyrifos oxon was higher than the MRLs established by the European Union and the national standards. In two previously conducted studies, the formation of chlorpyrifos oxon was detected and increased toxicity after photodegradation and ultrasonic irradiation; nonetheless, the oxidation of diazinon was not the predominant reaction (25,26).…”

Reduction of Pesticide Toxicity Under Field‐Relevant Conditions? The Interaction of Titanium Dioxide Nanoparticles, Ultraviolet, and Natural Organic Matter

“…The 96‐h EC50s of dimethoate that indicate higher toxicity at test series PEST + nTiO 2 than at test series PEST despite more efficient degradation (Table 4) could, in addition, be induced by the formation of metabolites that are more toxic than the parent substance (Evgenidou et al 2006; Farner Budarz et al 2017). It was shown that during photocatalytic degradation with nTiO 2 , dimethoate is degraded into 9 by‐products (Evgenidou et al 2006), whereas the major by‐product, omethoate (Van Scoy et al 2016), is 90‐fold more toxic than the mother compound (Pesticide Properties Database; Lewis et al 2016).…”

Viscose-derived activated carbons fibers as highly efficient adsorbents for dimethoate removal from water

“…Different methods have been reported for OPs remediation, such as bioremediation (Chishti et al, 2013;Ishag et al, 2016), photodegradation (Chen et al, 2007;Farner Budarz et al, 2019;Samy et al, 2020), membrane filtration (Ahmad et al, 2008) and adsorption techniques (Jacob et al, 2020;Lazarević-Pašti et al, 2016;Liu et al, 2018;Momić et al, 2016). Among the mentioned methods, adsorption has been considered one of the most suitable techniques for OP removal from an aqueous medium due to its simplicity, cost effectiveness, environment friendliness, and the possibility of scaling up the process (Liu et al, 2018).…”