Effect of UV radiation on the structure of graphene oxide in water and its impact on cytotoxicity and As(III) adsorption

• Published in: Chemosphere (Oxford) Vol. 249; p. 126160
• Main Authors: Gallegos-Pérez, Waldo Roberto, Reynosa-Martínez, Ana Cecilia, Soto-Ortiz, Claudia, Angélica Álvarez-Lemus, Mayra, Barroso-Flores, Joaquín, García Montalvo, Verónica, López-Honorato, Eddie
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2020
• Subjects: Adsorption; Arsenic - chemistry; Arsenic - toxicity; Arsenic adsorption; Cytotoxicity; Graphene oxide; Graphite - chemistry; Models, Chemical; Oxides - chemistry; Physical Phenomena; Reduction; Ultraviolet radiation; Ultraviolet Rays; Water; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity; Water Purification; Arsenic adsorption; Cytotoxicity; Ultraviolet radiation; Reduction; Graphene oxide
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126160

Graphene oxide (GO) is widely used in different applications, however once released into the environment it can change its structure and affect the transport of important contaminants such as arsenic. In this work we show that UV radiation, even in the range of 28-74 μW/cm2 of irradiance up to 120 h of exposure, can induce important changes in the structure of graphene oxide, by eliminating -OH and CO functional groups. This reduction affected the stability of graphene oxide in water by decreasing its zeta potential from -41 to -37 mV at pH=7 with the increase of the exposure time. Our results showed that after 24 and 120 h of UV exposure, As(III) adsorption capacity decreased from 5 mg/g to 4.7 and 3.8 mg/g, respectively, suggesting a lower capacity to transport contaminants with time. Computer modelling showed that even a degraded GO structure can have an interaction energy of 223.84 kJ/mol with H3AsO3. Furthermore, we observed that the cytotoxicity of graphene oxide changed after being irradiated at 74 μW/cm2 for 120 h, showing 20% more cell viability compared to as-produced GO. Our results stress the importance of considering the microstructural and compositional changes that GO undergoes even under low irradiance and short periods, when studying its fate and behavior in the environment and possible applications in water treatment.
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•Low ultraviolet irradiance induced important structural changes in graphene oxide.•Exposure time was the most important on graphene oxide reduction by UV light.•UV irradiance reduced 24% As(III) adsorption capacity of graphene oxide.•Graphene oxide cytotoxicity can change with UV irradiance and time.