Fragmentation of polymer nanocomposites: modulation by dry and wet weathering, fractionation, and nanomaterial filler.

In recent years, an increasing number of polymeric composites incorporating engineered nanomaterials (ENMs) have reached the market. Such nano-enabled products (NEPs) present enhanced performance through improved mechanical, thermal, UV protection, electrical, and gas barrier properties. However, little is known about how environmental weathering impacts ENM release, especially for high-tonnage NEPs like kaolin products, which have not been extensively examined by the scientific community.

Modification of pyrogenic carbons for phosphate sorption through binding of a cationic polymer.

This study reports on the development of modified pyrogenic carbonaceous materials (PCMs) for recovering orthophosphate (PO-P). The PCMs include softwood and hardwood biochars and a commercial granular activated carbon (GAC) that were modified by irreversible adsorption of the quaternary ammonium polymer, poly(diallyldimethylammonium) chloride (pDADMAC), which reverses electrokinetic charge and increases PO-P sorption. MgO-doped biochars were prepared by a literature method for comparison.

Reactivity of graphene oxide with reactive oxygen species (hydroxyl radical, singlet oxygen, and superoxide anion).

Increases in the production and applications of graphene oxide (GO), coupled with reports of its toxic effects, are raising concerns about its health and ecological risks. To better understand GO's fate and transport in aquatic environments, we investigated its reactivity with three major reactive oxygen species (ROS): HO˙, O, and O˙. Second-order degradation rate constants were calculated on the loss of dissolved organic carbon (DOC) and steady-state concentration of individual ROS species.

Environmental fate of multiwalled carbon nanotubes and graphene oxide across different aquatic ecosystems.

The industrial use and widespread application of carbon-based nanomaterials have caused a rapid increase in their production over the last decades. However, toxicity of these materials is not fully known and is still being investigated for potential human and ecological health risks. Detecting carbon-based nanomaterials in the environment using current analytical methods is problematic, making environmental fate and transport modeling a practical way to estimate environmental concentrations and assess potential ecological risks.

Simulating graphene oxide nanomaterial phototransformation and transport in surface water.

The production of graphene-family nanomaterials (GFNs) has increased appreciably in recent years. Graphene oxide (GO) has been found to be the most toxic nanomaterial among GFNs and, to our knowledge, no studies have been conducted to model its fate and transport in the environment. Lab studies show that GO undergoes phototransformation in surface waters under sunlight radiation resulting in formation of photoreduced GO (rGO).

Light-independent reactive oxygen species (ROS) formation through electron transfer from carboxylated single-walled carbon nanotubes in water.

Promising developments in application of carbon nanotubes (CNTs) have raised concern regarding potential biological and environmental effects upon their inevitable release to the environment. Although some CNTs have been reported to generate reactive oxygen species (ROS) under light, limited information exists on ROS generation by these materials in the dark. In this study, generation of ROS was examined, initiated by electron transfer from biological electron donors through carboxylated single-walled carbon nanotubes (C-SWCNT) to molecular oxygen in water in the dark.