Fabrication and Use of Alginate-Based Cryogel Delivery Beads Loaded with Urea and Phosphates as Potential Carriers for Bioremediation

Alginate-based cryogel beads loaded with urea and phosphates were fabricated by the microinjecting and cryo-cross-linking method and coated with ethyl cellulose films, and their properties were investigated. The cryogel beads had narrow diameter distributions and fracture-like supermacropores with the width of 1 to 3 μm and length up to more than 30 μm. Their porosities were from 74.9% to 92.2%, and the diameters were influenced by the microtube diameter, the injection flow velocity, and the freezing temperature. The cryogel beads had higher loading capacities of 13.4 mg phosphates and 33.2 mg urea/g wet bead, and the release rate of phosphates was much lower than that of urea. The beads with coating-films with the thickness of 3 to 8 μm had a lower release rate for phosphates than those without films. The inherent characteristic of alginate beads to be fully biodegradable makes them an interesting candidate for the bioremediation of coastal sediments.