Modification of PES ultrafiltration membranes for removal of caffeine

This study describes the removal of caffeine by means of low-pressure filtration with thin-film composite (TFC)/thin-film nanocomposite (TFN) membranes prepared through the interfacial polymerization process. This type of membrane contains a thick dense polyethersulfone (PES) layer and a thin-film polyamide layer. The composite/nanocomposite membranes were prepared by a reaction between the aqueous solution of meta-phenylenediamine and a hexane solution of trimesoyl chloride on the surface of the PES support. TFC/TFN membranes were also modified with single-walled carbon nanotubes (SWCNTs) functionalized with carboxyl groups in the support and thin film layer. TFN/TFC membranes are mainly used for high-pressure techniques such as reverse osmosis or nano-filtration processes, but it has been found that they may be also applied in low-pressure filtration. The conducted research showed that fabricated TFN membranes had properties coherently linking with nanofiltration. This means that we achieved the similar retention performance with lower costs. The presence of the nanocomposite material greatly improved retention with the preservation of high flux during filtration. It was also found that the addition of SWCNTs changed the porosity and water contact angle of the membrane.