Effect of Cross-Linking on the Structural, Thermal, and Photocatalytic Properties of Electrospun Chitosan-Based Membranes with TiO2 for the Heterogeneous Photocatalysis of Dyes

This study evaluated electrospun membranes based on chitosan (CTH)/polyethylene oxide (PEO) and polyvinyl alcohol (PVA)/CTH blends with titanium dioxide (TiO2), which were cross-linked for treatment with Reactive Red 195 dye. Characterization included SEM, FTIR, DSC, and TGA, while performance was assessed via photoelectrochemical degradation and electrocatalysis. Glutaraldehyde cross-linking was applied to CTH/PEO/TiO2, and citric acid with heat treatment to PVA/CTH/TiO2. SEM showed that CTH/PEO/TiO2 membranes had partial cross-linking and poor wet stability, whereas PVA/CTH/TiO2 exhibited satisfactory stability. FTIR confirmed structural changes in organic groups after cross-linking. DSC revealed reduced melting points for PEO and PVA, indicating cross-linking. TGA demonstrated improved thermal stability for both fiber types. In electrochemical tests, the cross-linked chitosan electrodes were non-conductive and unsuitable for photoelectrochemical degradation. The non-cross-linked electrode achieved 60% dye removal, but adsorption contributed significantly, so results could not be attributed solely to degradation. In photodegradation assays, crosslinked CTH/PEO/TiO2 membranes adsorbed 75% of the dye before light exposure and showed only 22% additional removal under irradiation. Non-crosslinked PVA/CTH/TiO2 membranes dissolved in the medium, making the tests invalid. Overall, cross-linking enhanced stability and adsorption but limited electrochemical applicability, highlighting the need to balance structural integrity and functional performance in membrane-based dye treatment systems.