Synthesis, characterization and adsorption properties of alginate porous beads

Original calcium alginate beads with porous structure and high adsorption surface are proposed. The beads were synthesized using sodium alginate in the presence of sodium dodecyl sulfate as foaming agent, NaCl as porogen agent and CaCl2 as cross-linker. They were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and Brunauer-Emmett-Teller method. The adsorption capacity of beads was tested with methylene blue (MB). The data show that the adsorption efficiency increases with the amount of beads, decreases with pollutant concentration, and is maximal at pH = 9. The adsorption is fast in the first 3 hours, and slows down thereafter. The kinetic results show that the adsorption of MB on alginate porous beads obeys the Langmuir model. A scheme of MB adsorption taking into account the ionic interactions with calcium alginate beads has been proposed.