Removal of ammonium from wastewater with geopolymer sorbents fabricated via additive manufacturing
Franchin, Giorgia; Pesonen, Janne; Luukkonen, Tero; Bai, Chengying; Scanferla, Paolo; Botti, Renata; Carturan, Sara; Innocentini, Murilo; Colombo, Paolo (2020-07-28)
Giorgia Franchin, Janne Pesonen, Tero Luukkonen, Chengying Bai, Paolo Scanferla, Renata Botti, Sara Carturan, Murilo Innocentini, Paolo Colombo, Removal of ammonium from wastewater with geopolymer sorbents fabricated via additive manufacturing, Materials & Design, Volume 195, 2020, 109006, ISSN 0264-1275, https://doi.org/10.1016/j.matdes.2020.109006
© 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2020081760698
Tiivistelmä
Abstract
Geopolymers have been recently explored as sorbents for wastewater treatment, thanks to their mechanical and chemical stability and to their low-energy manufacturing process. One specific application could be the removal of ammonium (NH₄+) through exchange with Na+ ions. Additive manufacturing (AM) represents an especially interesting option for fabrication, as it allows to tailor the size, distribution, shape, and interconnectivity of pores, and therefore the access to charge-bearing sites. The present study provides a proof of concept for NH₄+ removal from wastewater using porous geopolymer components fabricated via direct ink writing (DIW) AM approach. A metakaolin-based ink was employed for the fabrication of a log-pile structure with 45° rotation between layers, producing continuous yet tortuous macropores which are responsible for the high permeability of the sorbents. The ink consolidates in an amorphous, mesoporous network, with the mesopores acting as preferential sites for ion exchange. The printed sorbents were characterized for their physicochemical and mechanical properties and the NH₄+ removal capacity in continuous-flow column experiments by using a model effluent. The lattices present high permeability and high cation exchange capacity and maintained a high amount of active ions after four cycles, allowing to reuse them multiple times.
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