Visible light induced photoacid generation within plasticized PVC membranes for copper (II) ion extraction

We present here an approach for light induced generation of lipophilic cation-exchangers in plasticized PVC membranes. Using camphorquinone as photosensitizer, a lipophilic cationic photoacid generator can produce protons under visible light illumination and endow the polymeric membrane with ion-exchanging property. After light illumination, the membrane containing a Cu²⁺ ionophore, is able to extract Cu²⁺ ions from the contacting aqueous solution. The acid generation upon light irradiation is relatively fast (ca. 100 s). The Cu²⁺ extraction process was imaged with fluorescence microscopy using Calcein, a fluorescence indicator whose fluorescence is quenched by Cu²⁺. Such a technique may form a new platform for light triggered ion concentration perturbation.