Fabrication and Characterization of Nanofibers Membranes using Electrospinning Technology for Oil Removal

Oily wastewater is one of the most challenging streams to deal with especially if the oil exists in emulsified form. In this study, electrospinning method was used to prepare nanofiberous polyvinylidene fluoride (PVDF) membranes and study their performance in oil removal. Graphene particles were embedded in the electrospun PVDF membrane to enhance the efficiency of the membranes. The prepared membranes were characterized using a scanning electron microscopy (SEM) to verify the graphene stabilization on the surface of the membrane homogeneously; while FTIR was used to detect the functional groups on the membrane surface. The membrane wettability was assessed by measuring the contact angle. The PVDF and PVDF / Graphene membranes efficiency was tested in separation of emulsified oil from aqueous solutions. The results showed that PVDF-Graphene nanofiber membrane exhibited better performance than the plain PVDF nanofiber membrane with average water flux of 210 and 180 L.m-2.h-1, respectively. Both membranes showed high oil rejection with more than 98%.

Preparation and Evaluation of the Polyethylene Film Deposited With a Multilayer Graphene Membrane for Tensile Properties

This study aims to improve the tensile properties of the polyethylene film deposited with a multilayer graphene membrane, in order to establish the understanding of the influence of the methane to hydrogen ratio on the tensile properties of the multilayer graphene membrane. Multilayer graphene membranes were prepared using the chemical vapor deposition method. Four types of multilayer graphene membranes were prepared with different ratios of methane to hydrogen before depositing a membrane on the polyethylene film. Experiments showed that the tensile strength of the polyethylene films with multilayer graphene deposition increased 7 times and the Young’s modulus 5 times more than that of pure polyethylene films, when the ratio of methane to hydrogen was set to 35/100 sccm. A compromise between hydrogen and methane mixture is required to achieve uniform growth of graphene. Insufficient hydrogen cannot activate the surface bound carbon that is necessary for continuous growth. Continuous and well-defined multilayer graphene was synthesized when the ratio of methane to hydrogen reached up a proper value.

Graphene Membranes: From Reverse Osmosis to Gas Separation

Graphene membrane is a promising technology to help both carbon dioxide separation from flue gas and water desalination. This work reported the importance of membrane separation processes, the evolution of polymeric membranes before the discovery of graphene and how this material fits into this scenario. In addition, reverse osmosis and gas separations have been discussed as promising methods to reduce the occurrence of freshwater scarcity events and slow global warming. For all these separation techniques, the current state of graphene membranes technology and what advances might be brought by such one atom thick skin layer were presented, as well as the results of theoretical and experimental research. Finally, the challenges that still need to be overcome by this innovative technology as well as the perspectives were shown.

From a gas thermometer to a terahertz matrix (a review)

The history of the invention and development of the gas thermometer and the ap-pearance of optical-acoustic receivers (OAP) based on it, starting from the first works of Bell, Hayes, Golay, and up to the present time, are considered. The ad-vantages of the OAP, consisting in a constant and high sensitivity in a wide range of the spectrum and the highest detection ability among thermal receivers, are not-ed. The main characteristics of membranes – the main elements of OAP-are con-sidered, and the physical properties of graphene, as the most preferred material for membranes, are analyzed. Estimates have been made showing that the use of SLG graphene membranes makes it possible to create IR and THZ radiation re-ceivers with cells of the order of tens of microns with extremely high sensitivity. A new design scheme is proposed for uncooled matrix helium-graphene optical-acoustic receivers with theoretically extreme sensitivity and speed and an operating range extended to helium temperatures.