Gelatin is a derivative of collagen that exhibits gel formation ability via physical crosslinking in water. Gelatin molecules aggregate and undergo a conformational change from a random coil to a triple helix during the gelation process. Concurrently, intermolecular hydrogen bonds form between carboxylic acid, hydroxyl and amino groups in polymer chains [41]. Gelatin-based hydrogels have also been used as biomaterial adsorbents for remediation of heavy metals and dye contamination [42]. Efforts have been made to construct high stability hydrogels by blending alginate with gelatin [43,44]. Because of the good compatibility of alginate and gelatin, a cross-linked double network will consequently be formed by electrostatic interaction and hydrogen bonding through carboxylic sites and amino groups.