Development of ultrathin durable membrane for efficient oil and water separation
Researchers led by Professor MATSUYAMA Hideto and Professor YOSHIOKA Tomohisa at Kobe University's Research Center for Membrane and Film Technology have succeeded in developing an ultrathin membrane with a fouling-resistant silica surface treatment for high performance separation of oil from water.
Furthermore, this membrane was shown to be versatile; it was able to separate water from a wide variety of different oily substances.
These results were published online in the Journal of Materials Chemistry A on October 3 2019.
The development of technology to separate oil from water is crucial for dealing with oil spills and water pollution generated by various industries. By 2025, it is predicted that two thirds of the world's population won't have sufficient access to clean water. Therefore the development of technologies to filter oily emulsions and thus increase the amount of available clean water is gaining increasing attention.
Compared with traditional purification methods including centrifugation and chemical coagulation, membrane separation has been proposed as a low cost, energy efficient alternative. Although this technology has been greatly developed, most membranes suffer from fouling issues whereby droplets of oil get irreversibly absorbed onto the surface. This leads to membrane pore blocking, subsequently reducing its lifespan and efficiency.
One method of mitigating the fouling issues is to add surface treatments to the membrane. However, many experiments with this method have encountered problems such as changes in the original surface structure and the deterioration of the treated surface layer by strong acid, alkaline and salt solutions. These issues limit the practical applications of such membranes in the harsh conditions during wastewater treatment.
In this study, researchers succeeded in developing a membrane consisting of a porous polyketone (PK) support with a 10 nano-meter thick silica layer applied on the top surface. This silica layer was formed onto the PK fibrils using electrostatic attraction- the negatively charged silica was attracted to the positively charged PK.
The PK membrane has a high water permeance due to its large pores and high porosity. The silicification process- the addition of silica on the PK fibrils- provides a strong oil-repellant coating to protect the surface modified membrane from fouling issues.
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