Abstract Metakaolin-based geopolymer spheres shaped by three different dripping techniques were investigated in terms of compressive strength and dye adsorption ability. Spheres were produced by injection and solidification in polyethylene glycol (PEG) or liquid nitrogen (ice-templating) and ionotropic gelation (alginate in calcium chloride). Mechanical tests by ISO 18591 evidenced that compressive strength was strictly linked to porosity and composition of the spheres, being 12.9 MPa with 29% of porosity for spheres produced in PEG, 2.1 MPa with a porosity of 64% for spheres shaped in liquid nitrogen and up to 19.6 MPa with a porosity of 59% for hybrid spheres with a skeleton of Ca-alginate. The influence of contact time and initial concentration on a cationic dye (methylene blue) adsorption was studied. Removal efficiency was related to morphology, porosity and specific surface area: after 24 h the percentage of adsorption was 94–98% for spheres shaped in liquid nitrogen while below 75% for hybrid spheres and spheres produced in PEG. By adding TiO2 P25 as photocatalytic phase to the hybrid spheres, an increase of removal efficiency of 33% was observed after 90 min under UV irradiation.

中文翻译：

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偏高岭土地质聚合物球体的机械强度和阳离子染料吸附能力

摘要 从抗压强度和染料吸附能力方面研究了通过三种不同滴涂技术成型的偏高岭土基地质聚合物球体。球体是通过在聚乙二醇 (PEG) 或液氮（冰模板）中注射和固化和离子型凝胶（氯化钙中的藻酸盐）产生的。ISO 18591 的机械测试证明，抗压强度与球体的孔隙率和成分密切相关，PEG 生产的球体为 12.9 MPa，孔隙率为 29%，液氮成型的球体为 2.1 MPa，孔隙率为 64% 及以上对于具有海藻酸钙骨架的混合球体，压力达到 19.6 MPa，孔隙率为 59%。研究了接触时间和初始浓度对阳离子染料（亚甲蓝）吸附的影响。去除效率与形态、孔隙率和比表面积有关：24 小时后，液氮中成形的球体的吸附百分比为 94-98%，而混合球体和 PEG 中产生的球体的吸附百分比低于 75%。通过将 TiO2 P25 作为光催化相添加到杂化球中，在紫外线照射下 90 分钟后观察到去除效率提高了 33%。