Development of superhydrophobic and superoleophilic CNT and BNNT coated copper meshes for oil/water separation.

In this research, chemical vapor deposition (CVD) method was used to synthesize boron nitride nanotube (BNNT) powder. This method involves heating multi-walled carbon nanotube (MWCNT) and boric acid in the presence of ammonia gas up to 1000 °C. Then MWCNT and synthetic BNNT were coated on the copper mesh via dip-coating method separately to prepare nano-structured membranes for efficient oil/water separation. Various analyzes were performed to identify the synthetic BNNT properties (X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and prepared coated membranes (FESEM, atomic force microscopy (AFM), water contact angle (WCA), oil contact angle (OCA) and oil/water separation process). Water and oil contact angle analyzes showed the super-oleophilic properties of both membranes with the underwater OCA of about 128°. For the separation process, a dead-end filtration setup was used, and free oil water mixture and o/w emulsion were prepared. So, in the separation process water was retained and decalin passed through both prepared membranes. The flux of CNT coated membrane was about 458 L m2 h-1, while this amount was 1834 L m2 h-1 for BNNT coated membrane and 99% separation efficiency was achieved by both of them. This four-fold increase in flux is due to the fact that the inner diameter of boron nitride nanotubes synthesized is four times larger than the inner diameter of MWCNT.

Robust and stable superhydrophilic MIL-101 (Cr)-coated copper mesh for highly efficient oil/water emulsion separation.

In this study, dip coating method was investigated to prepare superhydrophilic MIL-101 (Cr)-coated copper mesh for highly efficient oil/water emulsion separation. To increase the surface area of synthesized MIL-101 (Cr), a purification procedure was developed to remove unreacted H2BDC crystals present in the channel of the initial MIL-101 (Cr) sample synthesized. After that, a dispersing solution of MIL-101 (Cr) was needed to coat on the copper mesh. Thermoplastic polyurethane (TPU) was used as a binder in this procedure. The prepared membranes of M1 (once coated mesh) to M6 (six times coated mesh) were performed to separate oil/water emulsion effectively. Contact angle tests showed the superhydrophilic/underwater superoleophobic wettability behavior of MIL-101 (Cr)-coated copper meshes. The wetting mechanism of the prepared membranes is mostly relevant to the surface functional groups of purified MIL-101 (Cr). Also, the roughness of the nanostructured coated membranes was improved because of the uniform coating of MIL-101 (Cr) which is integrated into hydrophilic TPU. Oil/water separation results showed that M2 (twice coated mesh) showed the maximum amount of water flux (83076 L m-2 h-1) in oil/water separation and M3 (three times coated mesh) had the best performance of oil/water emulsion with 99.99% separation efficiency.

Pervaporative removal of acrylonitrile from aqueous streams through polydimethylsiloxane membrane.

This study describes the successful separation of acrylonitrile (ACN) from dilute aqueous streams using pervaporation process. The influences of ACN feed concentration, permeate pressure, operating temperature, feed flow rate and membrane thickness on the membrane separation performance were investigated. The results showed that with an increase in ACN concentration in the feed solution, the permeation flux of ACN increased while the enrichment factor decreased. It was also indicated that increasing the permeate pressure reduced the driving force for mass transfer and consequently the permeation flux dropped while the enrichment factor enhanced. Polydimethylsiloxane membranes used in this study showed very good properties in the separation process, leading to enrichment factors in the range of 70-140. Furthermore, the activation energy for pervaporation of both ACN and water calculated from Arrhenius plot indicated that the permeation of water through the membrane was more temperature dependant than ACN.