Microplastics remediation in aqueous systems: Strategies and technologies

Ecosafety Screening of Photo-Fenton Process for the Degradation of Microplastics in Water

“…Advanced oxidation processes (AOPs) including Fenton reaction, ozonation or electrochemical treatment are applied in the degradation of organic waste in water (Nakata and Fujishima, 2012) and recently have been extended to microplastic remediation (Hu et al, 2021). In principle, the combination of photocatalysis (Tofa et al, 2019a,b;Uheida et al, 2021) and Fenton processes (Hamd and Dutta, 2020) could lead to a faster photogenerated electron production, and the rapidly transferred electrons to iron reduce its state from Fe 3+ to Fe 2+ leading to the charge separation and resultant Fenton processes.…”

“…Therefore, in this work, the degradation of microplastics was performed using heterogeneous photo-Fenton reaction utilizing solid catalyst consisting of zero valent iron oxide (Fe 0 ) nanoparticles as a source of iron ions (Fe 2+ ) and zinc oxide nanorods coated with tin chloride (ZnO/SnO x ) to generate electrons as a result of visible light absorption in order to facilitate the recycling of Fe 2+ and promotion of the Fenton cycle (Fe 3+ + e − → Fe 2+ ) in the presence of hydrogen peroxide (H 2 O 2 ) and the oxidation reactions. According to our knowledge, the published literature work focused mainly on presenting data about technologies adopted for microplastics photocatalytic degradation (Tofa et al, 2019a,b;Ariza-Tarazona et al, 2020;Llorente-Garcia et al, 2020;Nabi et al, 2020;Hu et al, 2021), so far no studies to assess the toxicity of the degradation byproducts have been conducted, which is highly recommended as it represents a knowledge gap for microplastics degradation studies, as reported in the review recently published by Du et al, 2021. In this work we have extended the photocatalytic reactions that are suitable for the degradation of microplastics, by introducing the Fenton reactions through smart design of the catalysts. Since iron nanoparticles are present in the reactor, and as hydrogen peroxide was used for the Fenton reaction, necessity for toxicity determination was essential to reduce any potential risks to human or aquatic environments.…”

Photocatalytic Conversion of Plastic Waste: From Photodegradation to Photosynthesis

“…[97][98][99] Figure 4 shows the typical assembly process of a photocatalyst/plastics composite film and its degradation mechanism. [100] First, the plastics are dissolved in organic solvents such as tetrahydrofuran, cyclohexane, or toluene. Then, the photocatalysts are added into solvent with vigorous stirring and heating.…”

Microplastics in ecosystems: their implications and mitigation pathways

“…Various methods, such as advanced oxidation processes, 31,217–219 photocatalysis, 220 microwave 221 and bioremediation 222–226 have been employed to degrade/eliminate microplastics (MPs) from soil and water (Fig. 6).…”

“…MPs in terrestrial and aquatic ecosystems and food systems have been extensively studied; 17,26–29 however, there are no studies that compiled the information on plastics/MPs/NPs in terrestrial ecosystems and food systems highlighting either recent technological advances or environmental, economic, and societal issues of plastic pollution, especially MPs from biodegradable plastics. Several reviews have been conducted on plastic/MP/NP pollution in aquatic ecosystems, 28–33 terrestrial ecosystems 34–36 and food systems, 37 where the authors have discussed either physiochemical properties, behavior, toxicity or remediation of MPs/NPs. This study compiles information on plastic pollution in terrestrial and aquatic ecosystems, and food systems and discusses some recent initiatives to combat the evolving problems associated with plastic pollution, especially MPs in the atmosphere, water, soil, and food chains from both conventional and biodegradable plastics, and their implications in ecosystems.…”