Preparation and characterization of alginate–carrageenan hydrogel films crosslinked using a water-soluble carbodiimide (WSC)

The preparation of alginate–carrageenan (AL–CG) blend films by the film immersion method was optimized for blend polymer ratio, water sorption capability, and the pH, non-solvent (ethanol) content, and crosslinking agent concentration of the crosslinking medium. The aim of this work was to produce a hydrophilic film with the potential for use as a coating for hydrophobic membranes of the types used in membrane distillation and osmotic distillation for protection against wet-out by surface-active agents such as oils, fats and detergents. Films were characterized using swelling measurements, scanning electron microscopy (SEM), differential scanning calorimetry, X-ray diffraction, Fourier Transform infrared (FT-IR) spectroscopy and durability towards water. Optimum conditions were achieved with a carrageenan concentration of 20 wt.% in the blend film and a crosslinking medium that contained 60 vol.% ethanol and 120 mM WSC at pH 4.