不同稀土离子对海藻酸钠凝胶特性的影响

本文主要研究了四种稀土离子Y3+、Ce3+、La3+、Er3+对海藻酸钠凝胶特性的影响，通过研究海藻酸钠-稀土凝胶的机械性质、平衡含水量、离子交换率及凝胶机理。结果发现:La3+、Y3+、Er3+、Ce3+可以与M/G≈1的海藻酸钠形成不可逆凝胶，其凝胶强度在32~41 N之间，杨氏模量在14~20 N之间，弹性在55%~59%之间，平衡含水量均大于93%，四种凝胶的强度为Ce3+>Er3+>Y3+>La3+，弹性为Ce3+1时，大小依次为Er3+>Ce3+>Y3+>La3+；当M/G=0.99≈1、M/G=0.19<1时，大小依次为Ce3+>Er3+>Y3+>La3+，其中Ce3+、Y3+、La3+对海藻酸钠中的G片段有一定的偏好性，Er3+对M片段有一定的偏好性。本文研究为海藻酸钠的精深加工利用与稀土元素的新功能性材料的开发奠定理论基础。

Effects of Different Rare Earth Ions on the Gel Properties of Sodium Alginate

In this paper, the gel properties of sodium alginate with Y3+, Ce3+, La3+ and Er3+ were studied. By studying the mechanical properties, equilibrium water content, ion exchange rate and gel mechanism of seaweed rare earth gel, it was found that: The coordination form of rare earth ions and carboxyl group in sodium alginate was pseudo-bridged monodentate coordination and bridge coordination. At the same time, the special three-dimensional network structure of the rare earth gel was formed through the planar and non-planar geometry formed by intramolecular and intermolecular chelation, and the gel strength of the gel formed by La3+, Y3 +, Er3+, Ce3+ and sodium alginate M/G≈1 was between 32 and 41 N, the Young’s modulus was between 14 and 20 N, the elasticity was between 55% and 59%, the equilibrium water content was greater than 93%, the strength of the four gel was Ce3+> Er3+> Y3+> La3+, the elasticity was Ce3+1, the affinity of seaweed rare earth gel was in this order: Er3+>Ce3+>Y3+>La3+. When M/G=0.99≈1 and M/G=0.19<1, the affinity of seaweed rare earth gel was in this order: Ce3+> Er3+> Y3+> La3+. Among them, Ce3+, Y3+ and La3+ had a certain preference for G fragment of sodium alginate, and Er3+ had a certain preference for M fragment. This study would lay a theoretical foundation for the intensive processing and utilization of sodium alginate and the development of new functional materials of rare earth elements.