Synthesis, structure and performance of calcium silicate ion exchangers from recycled container glass
Qui Li 2
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School of Science, University of Greenwich, UK
School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK.
Nichola J. Coleman   

University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
Publication date: 2014-01-01
Physicochem. Probl. Miner. Process. 2014;50(1):5–16
Numerous technical, economic and societal factors limit the recycling of waste soda-lime-silica glass back into the primary production process and accordingly alternative applications for this material are sought. This study demonstrates that waste soda-lime-silica container glass is a suitable feedstock material for the production of tobermorite, a calcium silicate cation exchanger. Tobermorites were synthesised at 100°C from stoichiometric mixtures of container glass and lime under alkaline hydrothermal conditions. Increasing concentrations of sodium hydroxide (between 1.0 M and 4.0 M) in the reaction mixture promoted the formation and crystallisation of tobermorite, and also resulted in greater fragmentation of the silicate chains along the b-axis direction. The maximum removal capacities of these tobermorite specimens for Cd2+ (441 mg g-1) and Zn2+ (122 mg g-1) compared well with those of other waste-derived sorbents. Superior Cd2+- and Zn2+-uptake capacities and kinetics were observed for the least crystalline tobermorite specimen, indicating that stacking defects facilitate the transport and exchange of cations within the lattice.