Effects of sulfide reduction on adsorption affinities of colloidal graphene oxide nanoparticles for phenanthrene and 1-naphthol

Environmental transformation of natural and engineered carbon nanoparticles and implications for the fate of organic contaminants

“…These observations indicate that the pCNPs discussed above may be more prone to transformation than eCNPs as they generally contain Environmental Science: Nano Critical review smaller aromatic sheets, as well as more structural irregularities and mineral phases. 28,50 Chemical transformation of pCNPs can be influenced by environmental factors such as light, 15,16,51 or the presence of oxidants (e.g., O 2 ), 15 reductants (e.g., Fe 2+ and S 2− ), 6,[52][53][54] and natural organic matter (NOM). 55,56 The factors driving chemical transformation differ markedly between (i) soot, which is mainly transported via the atmosphere and more susceptible to photochemical reactions involving reactive oxygen species (ROS), and (ii) other pCNPs, which are mainly transported by surface runoff and subsurface infiltration, where redox reactions with O 2 or S 2− are likely to be more important.…”

“…For example, GO can be transformed in aquatic environments because of its abundant surface O-functional groups, while Fe 2+ and S 2− can reduce GO thereby increasing its hydrophobicity. 6,52,54 However, Wang et al 53 found that GO reduction by Fe 2+ resulted in a reduced content of alkoxy and hydroxy groups and an increased content of carboxy groups because of the hydrolysis reaction of acid anhydrides on GO. Chemical reduction can therefore also result in the formation of polar surface groups and the effect of redox reactions needs to be evaluated on a case-by-case basis.…”

“…The reduction of oxidized surfaces during CNP transformation in natural environments can increase the electron density on CNP surfaces, which can in turn enhance the π-π interactions between CNPs and organic contaminants. 6,124,125 In addition, Wang et al 6 found that reductions by sulfide can open the epoxy rings on GO surface to form hydroxyl and carbonyl groups. Because these two functional groups have the ability to form hydrogen bonds, the reduction could increase the sorption of a polar contaminant (1-naphthol).…”

“…The accumulation of organic contaminants onto CNPs may significantly alter the effects of the CNPs (e.g., their toxicity), as well as the transport, reactivity, and bioavailability of environmental contaminants. [4][5][6]…”

Dehydrochlorination of adsorbed 1,1,2,2-tetrachloroethane on graphene oxide-based materials’ surface: Comparison with dissolved form in aqueous environment

“…Due to their remarkable electronic, mechanical, and chemical properties, GO-based materials have wide applications and may act as catalysts [1][2], adsorbents [3], transistors [4], sensors [5][6], supercapacitors [7]. Large-scale production and use have inevitably released these nanomaterials into the environment, increasing the potential for interaction with other environmental contaminants and then changing the environmental fates of these contaminants [8][9][10][11]. Many researchers have reported that GO-based materials can affect the transformation of organic contaminants in environment and even have potential to facilitate the degradation of some organic contaminants [1,[12][13][14][15].…”