Fabrication of Sodium Alginate Porous Scaffolds for Heavy Metal Ion Removal from Aqueous Solution

The adsorption method is recognized as an effective technology for dealing with water pollution caused by heavy metal ions. For a highly efficient, eco-friendly and low-cost adsorption process, the adsorbent is the deciding factor. In this study a porous sodium alginate scaffold was prepared by the method of freeze-drying as a heavy metal ion adsorbent. The parameters affecting the morphology and adsorption characteristics of the scaffolds were investigated. The results showed that sodium alginate porous scaffolds could be prepared under the concentration in the range of 1–5%. After calcium ion pre-crosslinking, the sodium alginate scaffold was used to adsorb the heavy metal ions of Cd2+, Pb2+, and Cu2+ from aqueous solution and the maximum adsorption efficiency under optimized adsorption conditions were 99.43%, 73.67%, and 59.25%, respectively. At the same time, the scaffold could be used for desorption and recycling. After five cycles, the removal percentages of Pb2+, Cd2+, and Cu2+ by the sodium alginate scaffold decreased by 25%, 25%, and 16%, respectively.