Silica nanoparticle-doped polyurethane membranes for reverse osmosis applications

Nanofiltration Composite Membranes Based on KIT-6 and Functionalized KIT-6 Nanoparticles in a Polymeric Matrix with Enhanced Performances

The nanofiltration composite membranes were obtained by incorporation of KIT-6 ordered mesoporous silica, before and after its functionalization with amine groups, into polyphenylene-ether-ether-sulfone (PPEES) matrix. The incorporation of silica nanoparticles into PPEES polymer matrix was evidenced by FTIR and UV–VIS spectroscopy. SEM images of the membranes cross-section and their surface topology, evidenced by AFM, showed a low effect of KIT-6 silica nanoparticles loading and functionalization. The performances of the obtained membranes were appraised in permeation of Chaenomeles japonica fruit extracts and the selective separation of phenolic acids and flavonoids. The obtained results proved that the PPEES with functionalized KIT-6 nanofiltration membrane, we have prepared, is suitable for the polyphenolic compound’s concentration from the natural extracts.

Sodium alginate blended membrane with polyurethane: Desalination performance and antimicrobial activity evaluation

A series of polymeric membranes were synthesized by blending polyurethane with sodium alginate (0.2, 0.4, 0.6, 0.8 and 1.0%). The structural, morphological and thermal properties of the membranes were examined by FTIR, SEM, AFM and TGA, respectively. Performance evaluation (salt rejection and flux) was assessed through reverse osmosis technique (RO). The FTIR spectra of membranes confirmed extensive hydrogen bonding (3350 cm^-1). The SEM and AFM analyses supported a progressively rising surface roughness of blended membranes. The hydrophilicity, crosslinking density and thermal stability of the membranes were improved with an increase in alginate content. The capability of salt (NaCl and MgCl₂) rejection was improved with alginate up to 0.8%. In addition, the rejection of divalent ions was better than monovalent ions (94 ± 0.96% for NaCl and 98 ± 0.98% for MgCl₂). The blended membranes ascertained an effective chlorine resistivity. The antibacterial activity was also promising, which enhanced with the alginate content in the membrane. The sodium alginate blended membrane with polyurethane proved to be an efficient approach to develop the blended membranes with tunable properties for water desalination.