Conventional manufacturing techniques face the challenge of creating conformable porous structures with complex shapes for real-world applications. Additive manufacturing, with its ability to assemble various materials in complex and customized architectures, is developing rapidly. As materials development advances, the integration of additive manufacturing and porous structures offers unprecedented new opportunities for the conception, design, and fabrication of multiscale porous networks. The present investigation provides a novel strategy based on the direct ink writing (DIW) of pastes (solid loading of 65 wt.%) from ‘light’ alkali activated (2.5 M NaOH) pharmaceutical glass waste, including also TiO2 nanoparticles (20 wt. %). The effect of incorporating porous glass microspheres (PGMs) into the pastes is studied regarding the ink formulation and the mechanical stability of the printed composites after drying and solidifying at ambient temperature. DIW-fabricated glass composites are applied to the photodegradation of methylene blue (as a reference dye) and possess the advantages of easy separation and operation of the solution. The degradation efficiency of methylene blue reached 100 % in 75 min by using printed scaffolds. The result has been compared to other photocatalytic materials reported recently.

Acknowledgments
This work is a part of the dissemination activities of project “FunGlass” (Centre for Functional and Surface Functionalized Glass). This project has received funding from the European Union´s Horizon 2020 research and innovation program under grant agreement no. 739566. The authors also gratefully acknowledge the financial support from the Slovak Grant Agency of the Ministry of Education, Science, Research and Sport, VEGA No 1/0456/20.