Photochemical Transformation and Photoinduced Toxicity Reduction of Silver Nanoparticles in the Presence of Perfluorocarboxylic Acids under UV Irradiation

Abstract

The impact of perfluorocarboxylic acids (PFCAs) with carbon chain length C2 to C8 on the dissolution, aggregation, reactive oxygen species (ROS) generation, and toxicity of citrate-coated AgNPs was investigated under UV irradiation. The presence of PFCAs decreased dissolution, aggregation, ROS generation, and toxicity of AgNPs because the negatively charged PFCAs sorbed on AgNP surface enhanced their stability. Both dissolution and aggregation rate of AgNPs decreased with chain length of PFCAs under UV irradiation, primarily because PFCAs with longer chain length sorbed on AgNP surface could form thicker coatings. The dissolution of AgNPs followed pseudo-first-order kinetics, and the rate constant decreased from 0.58 h(-1) with C2 to 0.30 h(-1) with C8. The hydrodynamic diameters of AgNPs linearly increased under UV irradiation with aggregation rates ranged from 72.1 to 143.5 nm/h. O2(•-) generation was observed in AgNP suspension with quantum yield of 0.12%, but was completely suppressed by PFCAs because they inhibited the interaction between photoelectrons and O2. A linear correlation was established between dissolved Ag(+) and bacterial survival rates of AgNPs with and without PFCAs under UV irradiation. This study highlights the necessity of considering coexisting organic contaminants when investigating the environmental behaviors of AgNPs.

Impact of light and Suwanee River Fulvic Acid on O2 and H2O2 Mediated Oxidation of Silver Nanoparticles in Simulated Natural Waters

“…It is also reported that the physicochemical properties of AgNPs are influenced by light since AgNPs are photo sensitive. − Earlier studies suggested that fragmentation of AgNPs occurs via photoejection of electrons, which accelerates the release of ionic silver. , Furthermore, organic coatings (such as citrate) on the surface of AgNPs may oxidize on irradiation with resultant formation of electrons which may reduce any silver ions present to form Ag(0) which would then be expected to coalesce to form new AgNPs. Alternatively, these electrons may be stored by AgNPs thereby enhancing the reactivity of AgNPs. , …”

Simulation and comparative study on the oxidation kinetics of atrazine by UV/H2O2, UV/HSO5− and Luo1, Ma2, Jiang3 et al. 2015Water Research3251290View full textAdd to dashboardCite

“…Because many micro-pollutants are very reactive with HO and/or SO À 4 , these processes have been widely used to oxidize organic pollutants, such as ATZ (Li et al, 2014;He et al, 2013;Liu et al, 2013). For instance, Khan et al (2013) studied ATZ degradation by UV/H 2 O 2 /Fe 2þ , UV=S 2 O 2À 8 =Fe 2þ , and UV=HSO À 5 =Fe 2þ .…”

Silver nanoparticles in aquatic environments: Physiochemical behavior and antimicrobial mechanisms

“…For instance, the cell 757 damage caused by nanosilver to several organisms, such as E. coli, C. elegans, Raphidocelis 758 subcapitata, Chydorus sphaericus, Danio rerio, and Daphnia magna, could be alleviated by fulvic acids (FA), HA, and/or dissolved organic matter (DOM) because these organic substances can inhibit silver ion release (Cupi et al 2015, Seitz et al 2015, Yang et al 2014b. In addition, one study showed that under UV irradiation, perfluorocarboxylic acids (PFCAs) could significantly decrease nanosilver dissolution rate (as well as its aggregation and ROS generation) and hence reduce its toxicity to E. coli (Li et al 2014). Similarly, alginate could even mute the toxicity of nanosilver towards N. europaea by binding to (or covering) the nanosilver surface and blocking its dissolution (Ostermeyer et al 2013).…”