Pham Anh Le-Tuan, Sedlak David L, Doyle Fiona M
Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, California 94720.
Appl Catal B. 2012 Sep 25;126:258-264. doi: 10.1016/j.apcatb.2012.07.018.
Under pH 7 - 10 conditions, the mesoporous silica supports proposed for use in water treatment are relatively unstable. In batch experiments conducted in pH 7 solutions, the commonly used support SBA-15 dissolved quickly, releasing approximately 30 mg/L of dissolved silica after 2 hours. In column experiments, more than 45% of an initial mass of 0.25 g SBA-15 dissolved within 2 days when a pH 8.5 solution flowed through the column. In a mixed iron oxide/SBA-15 system, the dissolution of SBA-15 changed the iron oxide reactivity toward H(2)O(2) decomposition, because dissolved silica deposited on iron oxide surface and changed its catalytic active sites. As with SBA-15, other mesoporous silica materials including HMS, MCM-41, four types of functionalized SBA-15, and two types of metal oxide-containing SBA-15 also dissolved under circumneutral pH solutions. The dissolution of mesoporous silica materials raises questions about their use under neutral and alkaline pH in aqueous solutions, because silica dissolution might compromise the behavior of the material.
在pH值为7 - 10的条件下，提议用于水处理的介孔二氧化硅载体相对不稳定。在pH值为7的溶液中进行的批量实验中，常用的载体SBA - 15迅速溶解，2小时后释放出约30 mg/L的溶解二氧化硅。在柱实验中，当pH值为8.5的溶液流经柱子时，初始质量为0.25 g的SBA - 15在2天内溶解了超过45%。在混合的氧化铁/SBA - 15体系中，SBA - 15的溶解改变了氧化铁对H₂O₂分解的反应活性，因为溶解的二氧化硅沉积在氧化铁表面并改变了其催化活性位点。与SBA - 15一样，其他介孔二氧化硅材料，包括HMS、MCM - 41、四种功能化的SBA - 15以及两种含金属氧化物的SBA - 15，在接近中性pH值的溶液中也会溶解。介孔二氧化硅材料的溶解引发了关于它们在中性和碱性pH值水溶液中使用的问题，因为二氧化硅的溶解可能会影响材料的性能。
