Department of Materials and Ceramic Engineering, CICECO- Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Department of Materials and Ceramic Engineering, CICECO- Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
J Hazard Mater. 2018 Sep 15;358:69-81. doi: 10.1016/j.jhazmat.2018.06.047. Epub 2018 Jun 22.
In this study, and for the first time, red mud (RM)-based geopolymer spheres were synthesised, with varying porosity and RM content, and then their use as pH regulators was evaluated. The aluminosilicate sources of these inorganic polymers were 100% waste-based, consisting of a mixture of RM and fly ash wastes. Geopolymer spheres containing up to 60 wt.% RM were successfully produced, while higher RM contents distorted the specimens' spherical shape. Results showed that alkalis leaching from the spheres over time can be controlled by their porosity, while the RM content induces only minor changes to leaching. The RM-based spheres leached up to 0.0237 mol/dmg of OH ions from their structure, this being among the highest values ever reported for geopolymers. This allowed a continuous and prolonged pH buffer capacity with narrow pH decay over the 28 days (2.4 pH units), suggesting the use of the RM-based spheres as pH buffering materials in wastewater treatment and anaerobic digestion systems.
在这项研究中，首次合成了基于赤泥（RM）的具有不同孔隙率和 RM 含量的地质聚合物球体，并评估了它们作为 pH 调节剂的用途。这些无机聚合物的铝硅酸盐来源完全基于废物，由 RM 和粉煤灰废物的混合物组成。成功制备了 RM 含量高达 60wt.%的地质聚合物球体，而更高的 RM 含量会使试件的球形变形。结果表明，随着时间的推移，球体中碱的浸出可以通过其孔隙率来控制，而 RM 含量仅对浸出产生微小影响。RM 基球体从其结构中浸出了高达 0.0237mol/dmg 的 OH 离子，这是地质聚合物中报道的最高值之一。这允许在 28 天（2.4pH 单位）内持续且长时间的 pH 缓冲能力，窄的 pH 衰减，表明 RM 基球体可用作废水处理和厌氧消化系统中的 pH 缓冲材料。
