Alkali activation-induced cold consolidation of waste glass: Application in organic-free direct ink writing of photocatalytic dye destructors

Additive manufacturing, with its ability to assemble a variety of materials in complex and customized architectures, is developing rapidly. The integration of technologies and materials into a sustainable production, however, is still challenging. The present investigation offers new functional glass-based products, from nearly room temperature processing, based on direct ink writing (DIW) of pastes from ‘light’ alkali activation (2.5 M NaOH) of pharmaceutical glass waste, added with 20 wt% of TiO2 nanoparticles. The inks were refined by the inclusion of porous glass microspheres (PGMs, 20–30 wt%), previously fabricated from fiber glass waste. Printed scaffolds, stabilized by simple drying (i.e. ‘unfired’), were successfully applied in the photodegradation of methylene blue. The degradation efficiency reached 100% within 75 min, and the 3D-printed composites could be easily separated from the solution for subsequent reuse. The degradation efficiency declined only by 7.5%, after 5 cycles.