Effective Elimination and Biodegradation of Polycyclic Aromatic Hydrocarbons from Seawater through the Formation of Magnetic Microfibres.

Supramolecular aggregates formed between polycyclic aromatic hydrocarbons and either naphthalene or perylene-derived diimides have been anchored in magnetite magnetic nanoparticles. The high affinity and stability of these aggregates allow them to capture and confine these extremely carcinogenic contaminants in a reduced space. In some cases, the high cohesion of these aggregates leads to the formation of magnetic microfibres of several microns in length, which can be isolated from the solution by the direct action of a magnet. Here we show a practical application of bioremediation aimed at the environmental decontamination of naphthalene, a very profuse contaminant, based on the uptake, sequestration, and acceleration of the biodegradation of the formed supramolecular aggregate, by the direct action of a bacterium of the lineage Roseobacter (biocompatible with nanostructured receptors and very widespread in marine environments) without providing more toxicity to the environment.

Introducing Selectivity on Carbonaceous Material: Removing Noble Salts, Au3+, and Ag+ from Aqueous Media by Nanodiamonds Functionalized with Squaramides.

Nanodiamonds coated with dopamine-squaramide compounds have been prepared by a calcination/esterification synthetic process, which improves the efficiency of this carbonaceous material with respect to non-functionalized nanodiamonds. The modified nanodiamonds show excellent selective coordination of Ag+ and Au3+ cations in a Cd2+, Co2+, Cr3+, Cu2+, Pb2+, and Zn2+ mixture in water. The coordination capacity of the carbonyl squaramide groups with the silver and gold cation is based on purely electrostatic cation-dipole interactions. Overall, it is demonstrated that the conjunction between the nanodiamonds and the organic receptor improves the selectivity of the material toward noble cations.

A Very Highly Efficient Magnetic Nanomaterial for the Removal of PAHs from Aqueous Media.

Two new hybrid magnetic recyclable nanomaterials are developed. These new materials are based on bisimide perylene dopamine or bisimide perylene 3-aminopropyltriethoxysilane and iron oxide nanoparticles. One of them, the bisimide perylene dopamine, has proven to be very efficient in the removal, by magneto filtration, of 15 carcinogenic polycyclic aromatic compounds (PAHs), especially naphthalene, acenaphthene, anthracene, phenanthrene, and fluorene. These compounds are known to be common contaminants of drinking and underground water. This nanomaterial presents a high dispersivity and stability in an aqueous media, and it is capable of forming supramolecular fluorescent magnetic nanofibers with benzo-alpha-pyrene or benzo[k]fluoranthene, BKF. This strong association is due to hydrophobic forces and the π-π interaction, between the bisimide perylene motif and the polycyclic aromatic compounds. The resilience of this material is tested in different media. No good results are obtained in ethanol, acetone, or acetonitrile, but an 85% recovery is achieved using toluene or hexane. Once washed, nanoparticles are shown to retain their ability to continue capturing PAHs.

Removal of Au3+ and Ag+ from aqueous media with magnetic nanoparticles functionalized with squaramide derivatives.

New magnetic hybrid nanoparticles of Fe3O4 coated with organosulfur-squaramide compounds are prepared. The modified-nanoparticles show a good coordination for Ag+ and Hg2+ cations in water, and present a high affinity for Au3+ ions. The behaviour of the squaramide-coated nanoparticles differs significantly from that previously reported for nanoparticles used as Au3+ scavengers. In the presence of organosulfur-squaramide, the Au3+ salt is reduced to gold nanoparticles that are deposited upon Fe3O4 nanoparticles. For the first time, the coordination capacity of the carbonyl squaramide groups with the gold cation, based on purely electrostatic cation-dipole interactions, is proved.