Gelatin/alginate composite nanofiber membranes for effective and even adsorption of cationic dyes

Nanofiber membranes from natural alginate are ideal adsorption materials for removing cationic dyes in solution, yet the regulations to their adsorption and desorption properties are of great challenges. In this research, gelatin/calcium alginate (GA) composite nanofiber membranes were successfully prepared via electrospinning to resolve these issues. The structural changes of composite membranes induced by the gelatin addition were confirmed by SEM, FT-IR and BET analysis. The enhanced mechanical strength of GA membranes disclosed the strong interactions between gelatin and alginate chains. Taking methylene blue (MB) as the model cationic dye, it was found the resultant composites could slow down the adsorption rate and obviously improve the adsorption evenness without apparent influences on its adsorption capacity. Moreover, the gelatin modification would generate better reusability for the composite membranes during a serial of adsorption and desorption cycles for strong electrostatic repulsions induced by protonated amino groups in gelatin chains. This effective composite strategy would pave the way for the development of natural alginate to the next generation high-performance adsorbent for cationic dyes.