Graphene Oxide/Titanium Dioxide Membranes

Student thesis: Master Thesis and HD Thesis

  • Thomas Reinhald Jensen
  • Morten Lykke Krogh Pedersen
4. term, Chemical Engineering, Master (Master Programme)
During recent years, graphene has been studied intensively because of its
unique characteristics, making it usable for a variety of applications. In order to produce graphene, it is rst necessary to oxidize graphite to graphene
oxide and then reduce it to graphene. Tests have shown that graphene oxide
could possibly be used as a membrane material for water treatment, as its
oxygen-rich functional groups provide high hydrophilicity, while the graphene
structure ensures excellent selectivity. A major limitation in membrane ltration is the fouling phenomena, which is why TiO2 could be of interest in
membrane usage. TiO2 is used to clean surfaces via its photocatalytic properties.
The purpose of this project was therefore to investigate graphene oxide as
a membrane material and incorporate TiO2. Dierent graphene oxide syntheses were tested and dierent GO/TiO2 ratios were also tested. The thermal treatment process for reducing graphene oxide was also tested in order
to nd optimal reduction time and temperature for stable membranes. The
thermal reduction was evaluated using X-ray diraction (XRD), dierential
scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier
transform infrared spectroscopy (FT-IR). The surface characteristics were examined before and after UV-C irradiation, in order to see if the TiO2 provided
signicant changes. Surface characteristics were analyzed using drop shape
analysis (DSA), zeta potential measurements and FT-IR. The vapor permeance of the membranes produced was tested with water, ethanol and hexane.
Scanning electron microscopy (SEM) was also done in order to see any potential membrane damage as a result of UV-C irradiation. The membrane surface
characteristics and permeance were compared to that of two commercial membranes; Alfa Laval NF99HF and NFT50.
By comparing the dierent syntheses via XRD and FT-IR, it was concluded
that the Tour's method was best suited for further experiments. From the reduction experiments done, it was found that reduction at 140◦C for one hour
produced the most stable and hydrophilic membranes. The optimal GO/TiO2
ratio was found to be in the range of 15:1 - 30:1. The TiO2 added to the
graphene oxide membranes was found to signicantly enhance hydrophilicity
and anti-fouling properties, caused by the formation of hydroxyl groups at the
surface. SEM tests were inconclusive as to whether the membrane is damaged by the photocatalytic activity of TiO2. The water vapor permeance was
found to be close to unimpeded and at least 55% higher than the commercial
membranes tested
Publication date9 Jun 2016
Number of pages138
ID: 235031528