Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, 34132, South Korea.
Division of Materials Science, Korea Basic Science Institute, Daejeon, South Korea.
J Environ Manage. 2018 Jan 1;205:192-200. doi: 10.1016/j.jenvman.2017.09.072. Epub 2017 Oct 3.
Alginate bead is a promising strontium (Sr) adsorbent in seawater, but highly concentrated Na ions caused over-swelling and damaged the hydrogel bead. To improve the mechanical stability of alginate bead, flexible foam-type zeolite-alginate composite was synthesized and Sr adsorption performance was evaluated in seawater; 1-10% zeolite immobilized alginate foams were prepared by freeze-dry technique. Immobilization of zeolite into alginate foam converted macro-pores to meso-pores which lead to more compact structure. It resulted in less swollen composite in seawater medium and exhibited highly improved mechanical stability compared with alginate bead. Besides, Sr adsorption efficiency and selectivity were enhanced by immobilization of zeolite in alginate foam due to the increase of Sr binding sites (zeolite). In particular, Sr selectivity against Na was highly improved. The 10% zeolite-alginate foam exhibited a higher log K of 3.3, while the pure alginate foam exhibited 2.7 in the presence of 0.1 M Na. Finally, in the real seawater, the 10% zeolite-alginate foam exhibited 1.5 times higher Sr adsorption efficiency than the pure alginate foam. This result reveals that zeolite-alginate foam composite is appropriate material for Sr removal in seawater due to its swelling resistance as well as improved Sr adsorption performance in complex media.
海藻酸钠珠是一种很有前途的海水中锶（Sr）吸附剂，但高浓度的 Na 离子会导致过度溶胀并破坏水凝胶珠。为了提高海藻酸钠珠的机械稳定性，合成了柔性泡沫型沸石-海藻酸钠复合材料，并在海水中评估了 Sr 吸附性能；通过冷冻干燥技术制备了 1-10%沸石固定化海藻酸钠泡沫。沸石固定在海藻酸钠泡沫中会将大孔转化为中孔，从而形成更紧密的结构。这导致在海水介质中复合珠的溶胀程度更小，与海藻酸钠珠相比，机械稳定性得到了极大的提高。此外，由于 Sr 结合位点（沸石）的增加，沸石固定在海藻酸钠泡沫中提高了 Sr 的吸附效率和选择性。特别是，Sr 对 Na 的选择性得到了极大的提高。在存在 0.1 M Na 的情况下，10%沸石-海藻酸钠泡沫的 log K 值为 3.3，而纯海藻酸钠泡沫的 log K 值为 2.7。最后，在实际海水中，10%沸石-海藻酸钠泡沫的 Sr 吸附效率比纯海藻酸钠泡沫高 1.5 倍。结果表明，由于沸石-海藻酸钠泡沫复合材料具有抗溶胀性以及在复杂介质中提高 Sr 吸附性能，因此是一种适用于海水除 Sr 的材料。
