Biodegradation and proton exchange using natural rubber in microbial fuel cells

One of the constraints holding back microbial fuel cell (MFC) progress is the cost of reactor components. Utilising waste materials could make the technology more desirable opening up the potential for novel niche applications. A costly but vital constituent of the MFC is the IEM (ion exchange membrane), a material prone to failure over time. The current study investigated the use of natural rubber as an alternative to IEM in MFCs. Initially, the material proved impermeable to protons, but gradually a working voltage was generated that improved with time. After 6 months the latex MFC outperformed anion exchange membrane (AEM) but was inferior both in terms of power (109%) and current (16%) to cation exchange membrane (CEM). After 11 months, latex outperformed both commercially available IEMs where power (12%) and current (54%) were higher than CEM. A combination of continuous latex MFC improvement with CEM decline, possibly due to biofouling, was responsible for this superiority. SEM images revealed pores in the used latex suggesting that biodegradation was enabling proton exchange. The research demonstrates for the first time that the biodegradation of a ubiquitous waste material operating as IEM can benefit MFC performance while also improving the reactors lifetime compared to commercially available membranes.