This may be important in the context of anionic complexes extraction from water because the positive potential on the interface attracts anionic complexes to the interface, thereby increases/increasing their concentration at the interface and facilities transfer of them to the IL phase via an ion exchange mechanism.
Is it "increases" or "increasing" after "thereby"? The sentence may seem too long, however, I don't know how to shorten it. Moreover, I am not sure about "transfers of them". Could it be "their transfer" or just "transfer"?