Jennifer Wu, our Honours student, has just had her first paper accepted in Soft Matter. This is the same work for which she recently won a poster prize at an engineering showcase/outreach event at Adelaide Uni.
The paper focuses on the study of bubble collisions on hydrophobic surfaces, in this case graphite, and the effect of molecularly thin layers of polymer on the attachment of bubbles and the dewetting (water displacement) at the interface. Dewetting (and wetting) of solid interfaces is an important aspect of a number of industrial processes, including coatings and mineral flotation. It is the latter of these two processes that was the motivation for this work.
Depending on the mineral processing goal, graphite/graphitic material either needs to be recovered or rejected in flotation. When pure graphite is the target valuable material (which can then be further processed to make graphene), one needs to understand the factors that would prevent recovery, such as the presence of biopolymers or surfactants.
Conversely, sometimes minerals of little value are coated with carbon material, which results in collection of unwanted waste. In this situation, it is important to discourage recovery of graphite-like material, which can be achieved with biopolymers. It was for this reason that carboxymethylcellulose was studied for its interaction with graphite, the subsequent effect on bubble attachment onto graphite, and flotation of graphite particles.
Jennifer’s work, although using an applied system, was quite fundamental in nature. Jennifer was able to correlate coverage of the polymer (determined using the atomic force microscope) with an enhanced effect on graphite recovery, and on the slowing down of the dewetting process. In addition, she was able to make connections between the polymer layer characteristics and the molecular motion of water at the interface during the dewetting process. This level of fundamental understanding is required if advances are to be made in developing polymers to influence flotation outcomes.