Porous Glass Beads with a Core-Shell Structure: Preparation and Applications

A simple and environment friendly method, subcritical water treatment, was proposed to prepare porous glass beads with a core-shell structure from ordinary soda-lime glass beads in one step. In this method, reactive subcritical water rather than any other chemical additive was utilized to selectively corrode the glass and mainly leach the alkali ions from the glass. The core-shell structure has been characterized by SEM observation. The treated alkali-lime-silicate glass beads have mesopores narrowly distributed around 4nm, and a layer of uniform nanoflake on the surface. The shell structure can be easily tailored by changing the treatment temperature and water flow rate. A possible mechanism of corrosion-ion immigrating-recondensation pattern was hypothesized to explain the formation of the core-shell porous structure. The product has high adsorption capacity and fast mass transfer properties due to their structure, and can serve as inorganic adsorbent. Accordingly, its applications in fast separation of protein mixture as well as ion-exchange of heavy metal ions were studied.

Key words: Porous glass, Core-shell structure, Subcritical water treatment, Fast separation