Functional stability of novel homogeneous and heterogeneous cation exchange membranes for abiotic and microbial electrochemical technologies

Abstract

Two novel cation exchange membranes (CEM) denoted as PSEBS SU and CF22R14 were examined for two electrochemical applications, and compared to a commercial membrane (Fumasep FKE). Application in microbial electrolysis cells (MEC) and abiotic electrochemical cells (EC) were selected as low and high current density systems (∼1 A m−2 and 50 A m−2, respectively). Hydration number (λ), ion exchange capacity (IEC) and ionic conductivity (σ), as well as changes in these parameters during 10 days of operation were studied. λ was stable after MEC operation, however EC mode caused remarkable changes and a decrease of λ (by −8.2 ± 0.3, −13.8 ± 0.8 and −39.3 ± 8.8% for FKE, PSEBS SU and CF22R14, respectively). The decrease of IEC was significant for each membrane regardless of the operation mode. However, only MEC operation led to reversible functionality losses, whereas EC mode caused permanent decrease of IEC (87.9 ± 2.8, 85.3 ± 3.8 and 46.6 ± 4.4% re-activation efficiency for FKE, PSEBS SU and CF22R14, respectively). The EC operation resulted in more severe loss of σ for each CEM, among which PSEBS SU showed the best re-activation efficiency (74.9 ± 8.1%). In general, the membrane properties were much more impaired during EC operation due to higher current densities.