Biomimetic way to improve liquid membranes. Facilitated transport with a mobile carrier and mediator

Abstract

One of the major obstacles to the practical application of liquid membranes, separating two aqueous solutions, is their limited lifetime, which is determined at least in part by leaching of not very hydrophobic carrier from the membrane. If the carrier is too hydrophobic, the transport rate is low due to the phase separation of the carrier and hydrophilic species, which have to be transferred. It is suggested to use the more complex system for facilitated transport, which has the extremely hydrophobic carrier and at least one mildly hydrophilic mediator (interface catalyst). In the case of transmembrane electron transfer, this system is similar to the chain of electron transport in biomembranes. Theoretical steady state description of the process with one mediator and one carrier is given. The model assumes the simultaneous and parallel diffusion and reactions both in aqueous solutions and liquid membrane. It is demonstrated that small concentrations of effective mediator can dramatically change the kinetics of transmembrane processes.