Fabrication and characterization of affordable hydrophobic ceramic hollow fibre membrane for contacting processes

Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique,followed by a grafting with fluoroalkylsilane(FAS).The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes(gas permeation,mechanical strength,pore size,porosity,tortuosity,morphology,and contact angle)by the addition of alumina(Al2O3)to the pure kaolin with mono or multiparticle sizes.By varying the overall loading and particle size of alumina addition,different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange.The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140°after grafting.Kaolin-alumina-4,one of the hollow fibres fabricated in this work,achieved a mean pore size of 0.25μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10^(-5) mol·m^(-2)·Pa^(-1)·s^(-1),which makes the hollow fibre most suitable for the membrane contactor application.

Eco-friendly method for synthesis of zeolitic imidazolate framework 8 decorated graphene oxide for antibacterial activity enhancement

We report a rapid method for synthesis of zeolitic imidazolate framework 8(ZIF-8)-decorated graphene oxide(GO)composites(ZGO)with good antibacterial properties.The ZGO composites were synthesized at room temperature with low GO to metal salt ratios.The samples were characterized by X-ray diffraction,transmission electron microscopy,Fourier transform infrared spectroscopy,thermal gravimetric analysis,and surface area analysis.The characterization results show that ZIF-8 with a size of approximately 120 nm is successfully decorated on the surface of GO sheets with the host ZIF-8 framework maintained in the synthesized composite,but there is a significant reduction in the Brunauer-Emmett-Teller surface area.The antibacterial activities of the samples against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538 as model strains of gram-negative and-positive bacteria,respectively,were determined by disc diffusion and minimum inhibitory concentration(MIC)tests.ZGO-1.0(1 wt%of ratio of GO to metal salt)shows the highest antibacterial activity with MIC values required to inhibit bacterial growth of E.coli and S.aureus of 5 times lower than those of pristine ZIF-8.Different antibacterial mechanisms are proposed based on field-emission scanning electron microscope images of the two bacteria after contact with the synthesized composite.Overall,owing to the simple synthesis,good stability,low chemical usage,and excellent antibacterial activity of the ZGO composites,they show great potential for application in the field of microbial contamination control.