Chemical Method for Recovery and Regeneration of Graphene Oxide.

Graphene oxide (GO) has been developed as a very effective medium for filtration and removal of microbial contaminants in fuel. GO is capable of filtering out microorganisms without needing micrometer and submicrometer pores for filtration. Our previous studies showed that microorganisms are attracted by GO and bind irreversibly to GO without promoting bacterial growth. Therefore, GO was tested as a filter medium to remove microorganisms in fuel. The characterization results showed that GO removed microbes in diesel fuel with >99% efficiency. However, the synthesis of GO using Hummers' method is labor intensive and a time-consuming. We present in this paper an economical, less labor intensive and a simple chemical approach to recover GO after it has been used as a filtration medium for the removal of microorganisms in fuels. In the GO recovery process, microbial and fuel contaminated GO is washed with hexane to remove any fuel from the GO sample. The hexane-washed GO is further washed with acetone and mixed with ethanol to kill and remove any microorganisms. After washing with ethanol, the GO sample is sonicated in water to remove impurities and re-establish the oxygen functionalities. The final recovered-GO (rec-GO) is obtained after removing water by rotary evaporation. The chemical characterization of rec-GO showed that rec-GO is similar in both chemical and physical properties compared to freshly synthesized-GO (as-syn-GO). Rec-GO was shown to perform similarly to as-syn-GO in filtration of biocontaminated fuel. We estimate that our rec-GO is at least 90% cheaper than high quality commercially available GO.

Selective hydrosilylation of alkynes and ketones: contrasting reactivity between cationic 3-iminophosphine palladium and nickel complexes.

The catalytic hydrosilylation of alkynes and ketones has been explored utilizing palladium- and nickel(allyl) complexes supported by 3-iminophosphine ligands. Palladium and nickel demonstrated distinctly different reactivity profiles, with palladium proving very effective for the hydrosilylation of electron-deficient alkynes, while nickel excelled with ketones and internal alkynes. Additionally, in many cases, regioselective hydrosilylation was observed.