ABSTRACT
Graphene is a carbon allotrope and possesses numerous unique properties which make it an attractive material in many areas. In this work, graphene oxide (GO) was added to polyethersulfone (PES) mixed matrix membranes (MMMs) to improve the performance of hemodialysis membranes. GO was synthesized from tartaric acid by pyrolysis with various temperatures of the pyrolysis and the membrane was fabricated by a casting solution method followed by its characterization. The MMMs showed better mechanical properties than pristine PES with a tensile stress and tensile strain value of 5.55 MPa and 0.039 m, respectively. The hydrophilicity of the membranes which is in agreement with contact angle values showed that GO addition increased the hydrophilicity of the MMMs. Hence, the solute flux and clearance of creatinine gave values of 2.94 L m-2 h-1 and 78.3%, respectively. Cross sectional images and the surface morphology were also recorded using scanning electron microscopy (SEM). The resulting data proved that the modified MMMs can be a potential material for hemodialysis.
ABSTRACT
AIMS: To examine the reliability of membrane cultures as a model solid-state fermentation (SSF) system. METHODS AND RESULTS: In overcultures of Aspergillus oryzae on sterilized wheat flour discs overlaid with a polycarbonate membrane, we demonstrated that the presence of membrane filters reduced the maximum respiration rate (up to 50%), and biomass and alpha-amylase production. We also show that the advantage of membrane cultures, i.e. total recovery of biomass, is not very evident for the system used, while the changes in metabolism and kinetics are serious drawbacks. CONCLUSIONS: The use of membrane cultures is artificial and without substantial benefits and therefore has to be carefully considered. SIGNIFICANCE AND IMPACT OF THE STUDY: In future studies on kinetics and stoichiometry of SSF, one should not completely rely on experiments using membrane cultures as a model SSF system.