Current approaches to dewatering aviation fuel such as kerosene are adsorption by activated charcoal, gravity separation, etc. The objective of this work is to develop and demonstrate the filtration and dewatering of kerosene using a carbon nanotube immobilised membrane (CNIM). Highly hydrophobic membranes were prepared by immobilising carbon nanotube (CNTs) over polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF) microfiltration membrane for the dewatering of ppm level water from kerosene. The effects of different CNT concentrations on membrane morphology, hydrophobicity, porosity, and permeability were characterised. After immobilising CNT into membranes, the contact angle increased by 9%, 16%, and 43% compared to unmodified 0.1 μm PTFE, 0.22 μm PTFE and 0.22 μm PVDF membranes, respectively. The CNIM showed remarkable separation efficiency for the fuel-water system. The micro/nano water droplets coalesced on the CNT surface to form larger diameters of water droplets detached from the membrane surface, leading to enhanced water rejection. In general, the water rejection increased with the amount of CNT immobilised while the effective surface porosity over pore length and flux decreased. PTFE base membrane showed better performance compared to the PVDF substrate. The CNIMs were fabricated with 0.1 and 0.22 μm PTFE at an optimised CNT loading of 3 and 6 wt.%, and the water rejection was 99.97% and 97.27%, respectively, while the kerosene fluxes were 43.22 kg/m2·h and 55.44 kg/m2·h respectively.
Superhydrophobic surfaces, as indicated in the name, are highly hydrophobic and readily repel water. With contact angles greater than 150° and sliding angles less than 10°, water droplets flow easily and hardly wet these surfaces. Superhydrophobic materials and coatings have been drawing increasing attention in medical fields, especially on account of their promising applications in blood-contacting devices. Superhydrophobicity controls the interactions of cells with the surfaces and facilitates the flowing of blood or plasma without damaging blood cells. The antibiofouling effect of superhydrophobic surfaces resists adhesion of organic substances, including blood components and microorganisms. These attributes are critical to medical applications such as filter membranes, prosthetic heart valves, extracorporeal circuit tubing, and indwelling catheters. Researchers have developed various methods to fabricate blood-compatible or biocompatible superhydrophobic surfaces using different materials. In addition to being hydrophobic, these surfaces can also be antihemolytic, antithrombotic, antibacterial, and antibiofouling, making them ideal for clinical applications. In this review, the authors summarize recent developments of blood-compatible superhydrophobic surfaces, with a focus on methods and materials. The expectation of this review is that it will support the biomedical research field by providing current trends as well as future directions.
Ethyl acetate (EA) is an extensively used industrial
solvent, and
typically, aqueous mixtures containing EA are discarded as hazardous
waste. The recovery of EA from wastewater streams would have significant
environmental benefits and be a circular economy approach to solvent
recycling. However, with a relatively high water solubility (8.3%
w/v at room temperature), it remains a challenge. In this paper, we
report the recovery of EA from water using air-sparged sweep gas membrane
distillation (AS-SGMD) with carbon nanotube-immobilized membranes.
A central composite rotatable design was used to study the effect
of process parameters on flux and selectivity via conventional SGMD
and AS-SGMD. The experiments were run at different operating conditions
of temperature, concentration, and flow rate. The flux reached as
high as 1.41 kg/m2 h–1, and selectivity
as high as 10.8 was obtained. The introduction of air sparging improved
the flux by as much as 12% and the selectivity by 17%. The response
surfaces of flux and selectivity as a function of operating variables
were studied, and regression models were developed. For both regular
SGMD and AS-SGMD, the selectivity of EA recovery followed a quadratic
model, while the flux showed a linear response. The predicted and
experimental responses were in agreement with a R
2 value of 0.94. The optimization efforts showed that
relatively low temperatures, higher concentrations, and high flow
rates favored higher selectivity.
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