School of Materials Science and Engineering, Fuzhou University, Fuzhou, 350108, Fujian, China.
Fujian Key Laboratory of Green Extraction and High-Value Utilization of Energy Metals, Fuzhou University, Fuzhou, 350108, Fujian, China.
Environ Sci Pollut Res Int. 2023 Apr;30(16):47025-47037. doi: 10.1007/s11356-023-25676-4. Epub 2023 Feb 3.
Adding organics in the process of geopolymer synthesis can combine the functional groups of organics with the three-dimensional structure of geopolymer, thus changing the properties of geopolymer such as compressive strength, flexural strength, and acid resistance. In this work, excellent mechanical properties and acid resistance of metakaolin-blast furnance slag (Mk-BFS)-based geopolymer were synthesized by the incorporation of chitosan. The formation of sodium-alumino-silicate-hydrate (N-A-S-H) gel and calium-alumino-silicate-hydrate (C-A-S-H) gel in geopolymerization were characterized by Si nuclear magnetic resonance (NMR). At 5% of chitosan, the compressive strength of Mk-BFS-based geopolymer could reach to 33.7 MPa. The results could be ascribed to that chitosan reacts with geopolymer to generate new C-O-Si structure meanwhile adhesion produced by the combination of positively charged cations and negatively charged ions makes the structure of geopolymer denser. After 7 days of sulfuric acid immersion, the reduction of compressive strength is less than 3 MPa, demonstrating its great acid resistance. The acid resistance of Mk-BFS-based geopolymer could attribute to that the free amino groups in chitosan preferentially react with acid solution and weakened the erosion of sulfuric acid. This study optimizes the compressive strength and acid resistance of geopolymer by adding appropriate amount of chitosan.
在地质聚合物合成过程中添加有机物可以将有机物的官能团与地质聚合物的三维结构结合起来，从而改变地质聚合物的性能，如抗压强度、弯曲强度和耐酸性。在这项工作中，通过加入壳聚糖，合成了具有优异机械性能和耐酸性的偏高岭土-高炉矿渣（Mk-BFS）基地质聚合物。通过 Si 核磁共振（NMR）对地质聚合反应中形成的硅酸钠-水合物（N-A-S-H）凝胶和钙铝硅酸盐水合物（C-A-S-H）凝胶进行了表征。壳聚糖含量为 5%时，Mk-BFS 基地质聚合物的抗压强度可达 33.7 MPa。这可归因于壳聚糖与地质聚合物反应生成新的 C-O-Si 结构，同时正电荷阳离子和负电荷离子的结合产生的粘附作用使地质聚合物的结构更加致密。在硫酸浸泡 7 天后，抗压强度的降低小于 3 MPa，表现出良好的耐酸性。Mk-BFS 基地质聚合物的耐酸性可归因于壳聚糖中的游离氨基基团优先与酸溶液反应，从而减弱了硫酸的侵蚀。本研究通过添加适量的壳聚糖优化了地质聚合物的抗压强度和耐酸性。
