The Chubut River estuary as a source of microplastics and other anthropogenic particles into the Southwestern Atlantic Ocean.

This is the first report of anthropogenic particles (APs), including microplastics and synthetic, semi-synthetic and anthropogenically-altered natural fibers, in water and sediment of the Chubut River estuary. This river is the main source of freshwater in Chubut Province (Patagonia, Argentina), where wastes and pollutants are poured and finally end in the Atlantic Ocean. The average concentration in surface and bottom water samples was 5.5 items/L, while in sediment was 175.4 items/kg dw. Raman's analysis identified particles dominated by polyethylene terephthalate (PET) (35.5 %), dye signature only (18.5) and anthropogenic cellulose (10 %). Fibers were the prevalent shape (83 %), and the chemical identification evidenced a textile origin. The highest APs concentration was found in sediments from the site with the finest grain size and the greatest amount of organic matter. Present results will provide a baseline for future studies and raise public and governmental awareness.

Optimizing graphene production in ultrasonic devices.

In this work, we investigate the efficiency of graphene production from graphite by ultrasonic-induced exfoliation under different operational conditions. An ultrasonic bath and an ultrasonic horn tip were used, to show how the graphene production efficiency depends on the acoustic intensity and cavitation mechanism using graphite crystal with different initial sizes and characteristic lengths. Operational variables such as geometry, location and type of vessel containing the liquid phase, were also explored. All of them have effect on the cavitation process and directly influence the amount of graphene obtained. Remarkably, we found that the initial size of the graphite crystals has a marked impact in exfoliation process. Based on the above arguments we propose a combined protocol with a specific sequence to maximize the amount of graphene obtained.