Evidence for covalently bonded chlorine–fullerene formed by ozonation and chlorination at room temperature

• Published in: Environmental chemistry letters Vol. 11; no. 3; pp. 309 - 313
• Main Authors: Alpatova, Alla L, Baumann, Melissa J, Davies, Simon H, Masten, Susan J
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-09-2013; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: absorption; Absorption spectroscopy; Aggregates; Ambient temperature; Analytical Chemistry; Aqueous chemistry; byproducts; carbon; Chlorination; Chlorine; Disinfection; Drinking water; Earth and Environmental Science; Ecotoxicology; energy; Environment; Environmental Chemistry; fullerene; Fullerenes; Geochemistry; Nanomaterials; Nanotechnology; Original Paper; Ozonation; ozone; Physicochemical properties; Pollution; scanning electron microscopy; Toxicity; transmission electron microscopy; Water conveyance; Water supply; Water treatment; X-ray photoelectron spectroscopy; Fullerene; Ozonation; Disinfection by-products; Chlorination
• ISSN: 1610-3653; 1610-3661
• DOI: 10.1007/s10311-013-0422-6

This article reports for the first time that fullerene (nC₆₀) can form chlorinated disinfection by-products in aqueous systems at ambient temperature. The ability of nC₆₀ to form colloidal suspensions in aqueous media increases the chance that these particles will migrate in the environment and then in drinking water supply systems. Since nC₆₀ is not completely removed by conventional water treatment, any residual nC₆₀ is likely to be oxidized during disinfection process. While the ozonation of nC₆₀ has been studied, little is known about the reaction between nC₆₀ and chlorine. To address this issue, we subjected aqueous nC₆₀ suspensions to chlorination and sequential ozonation/chlorination at ozone dosages of 4.5, 10, 15 and 24 mg O₃/mg nC₆₀. The morphology and physicochemical properties of oxidized nC₆₀ aggregates were evaluated by scanning electron microscopy, transmission electron microscopy, UV–visible absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). We found that while the particles in the as-prepared nC₆₀ were predominantly spheres, the ozonation of nC₆₀ resulted in the formation of irregularly shaped aggregates. The concentration of atomic carbon found by XPS in the nC₆₀ samples decreased from 92 % for the as-prepared nC₆₀ to 50 % for the aggregates ozonated at 24 mg O₃/mg nC₆₀ and then chlorinated at 68 mg Cl₂/L and allowed to react for 100 min. The presence of Cl atoms covalently bonded to C atoms was confirmed by XPS peaks corresponding to a binding energy (E b) of 200.1–202.4 eV. This demonstrates the need to better assess and monitor the formation of potentially toxic chlorinated disinfection by-products from carbon nanomaterials during water treatment.