Nano Focus: Detoxifying the oceans by using reused polystyrene
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Nano Focus Detoxifying the oceans by using reused polystyrene
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esearchers have found a way to remove toxic chemicals from the sea using polystyrene (PS)—which is an abundant, undesirable waste product in the environment, arising from packaging, cutlery, and other disposable objects that are used on a daily basis. This
attributed to the inter-molecular interactions (isotropic repulsion and anisotropic attraction) among the individual protein molecules, which can be altered by nucleation initiators of different compositions and concentrations. The pathways revealed in this study do not involve a metastable dense liquid intermediate state as reported in previous studies, and thus deviates from the current understanding of protein nucleation. Yuki Kimura of Hokkaido University, Japan, says, “Their achievements not only present a deeper understanding of nucleation of a protein material, but also open up opportunities for controlling polymorphs. I believe we have advanced into a new stage of the nucleation study
[since this work is published].” Kimura was not involved in this study. “In a nutshell, our results are advancing the fundamental understanding of nucleation and polymorph selection. These insights are not only relevant for macromolecules but can also be translated to other crystal-forming substances including pharmaceutical compounds,” the authors say. “Now we are very interested to apply the same workflow to other protein molecules, because we are convinced, considering the complex nature of macromolecules, that many more unexpected findings will pop up along the (nucleation path) way.” The research team is also searching for alternative strategies to control polymorph selection. Tianyu Liu
leads to many problems, and recycling of PS is still limited. A collaborative effort between researchers in Brazil and the UK has now found a valuable application for this waste polystyrene— to degrade toxic and carcinogenic dyes such as Rhodamine B (RhB) through photocatalysis. This work was reported in a recent issue of ACS Applied Materials & Interfaces (doi:10.1021/ acsami.7b19834).
Nanofoams of PS and tin oxide (SnO2) were developed through a thermally induced phase-separation process combined with lyophilization, where the solvent is frozen and converted into vapor without going through the liquid phase. The concentration of PS in solution affects the strength of the resulting nanofoam. A 1% PS concentration in a cyclohexane solvent did not result in a stable nanofoam. Therefore, 2.5% and 5% solutions were employed to generate the stable nanofoams that are essential for the photocatalytic activity required to break down the dyes. This fabrication method has previously only been demonstrated to form oxide-based nanofoams. “Our article describes the fabrication and applications of new and exciting second-generation systems, which are now functional nanocomposite (polymer and oxide) foams,” says Rodrigo J. de Oliveira from Universidade Estadual da Paraíba, who is a lead researcher of the study. X-ray diffraction res
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