Abstract text (incl. figure legends and references)

Due to its critical role in batteries, lithium has recently become a rather important element. Moreover, many efforts are being made to mine primary lithium sources, while lithium recycling and recovery are almost lacking. In addition to batteries, glasses and glass ceramics are an important and as yet unexploited source of lithium. Recently, we published an article on a novel mechanochemical recycling approach using end-of-life glass-ceramics from spend cooktops as feedstock for lithium extraction and simultaneous zeolite synthesis [1]. The experimental results indicate an effective particle size reduction and amorphization of the crystal structure of the high quartz lattice by intensive milling during the alkaline leaching process as the main driving forces for the reaction, significantly accelerating lithium extraction in parallel to zeolite synthesis.

The aim of this study is to investigate the physiochemical changes and amorphization of glass-ceramic material during ball milling without any chemical side reaction (mechanical activation).

In order to study the amorphization process, the glass-ceramic powder was mechanically activated in a planetary ball mill at 600 rpm in deionized water. After different times of 30, 60 and 120 min of ball milling, samples were taken and characterized by powder X-ray diffraction (PXRD), N2 adsorption/desorption analysis and transmission microscopy (TEM) including selected area electron diffraction (SAED).

Analysis of N2 adsorption/desorption by the Brunauer-Emmet-Teller (BET) method showed an increase in surface area with time, which can be attributed to a significant reduction in particle size due to intensive ball milling. With increasing time of mechanical activation, the PXRD measurements showed a decrease and broadening of the diffraction peaks. Moreover, the calculation on the crystallite size using Scherrer"s equation resulted in a clear trend to smaller crystallites with an increase of mechanical activation. Finally, TEM studies reveal the microstructural features of the samples, while the SAED patterns confirm the PXRD measurements and show the transformation of a well-ordered material into a (nano)crystalline or partially amorphous material.

The analytical results of BET, XRD and TEM/SAED measurements confirm a stepwise amorphization of the high-quartz structure and the transformation of a well-ordered source material into a (nano)polcrystalline material. Therefore, amorphization can be rationalized as the driving force for the mechanochemical reaction during lithium extraction and zeolite synthesis.

[1] Necke, T.; Wolf, D.M.; Bachmann, A.L.; Berberich, K.; Kleebe, H.-J.; Weidenkaff, A. Mechano­chemical Lithium Extraction and Zeolite Synthesis from End-of-Life Glass−Ceramics, ACS Sustainable Chemistry & Engineering (advance online publication) 2022. https://pubs.acs.org/doi/10.1021/acssuschemeng.2c02342