Synergistic sono-adsorption and adsorption-enhanced sonochemical degradation of dyes in water by additive manufactured PVDF-based materials

Franziska Bößl; Stefano Brandani; Valentin C Menzel; Matilda Rhodes; Mayra S Tovar-Oliva; Caroline Kirk; Ignacio Tudela

doi:10.1016/j.ultsonch.2023.106602

Synergistic sono-adsorption and adsorption-enhanced sonochemical degradation of dyes in water by additive manufactured PVDF-based materials

Ultrason Sonochem. 2023 Nov:100:106602. doi: 10.1016/j.ultsonch.2023.106602. Epub 2023 Sep 19.

Authors

Franziska Bößl¹, Stefano Brandani², Valentin C Menzel³, Matilda Rhodes⁴, Mayra S Tovar-Oliva³, Caroline Kirk⁴, Ignacio Tudela⁵

Affiliations

¹ School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK; Edinburgh Electrochemical Engineering Group (e3 Group), The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK. Electronic address: f.boessl@ed.ac.uk.
² School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK.
³ School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK; Edinburgh Electrochemical Engineering Group (e3 Group), The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK.
⁴ School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, UK.
⁵ School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK; Edinburgh Electrochemical Engineering Group (e3 Group), The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK. Electronic address: ignacio.tudela@ed.ac.uk.

Abstract

The present study proposes the first mechanistic model accounting for the most meaningful physico-chemical phenomena taking place in liquid phase adsorption processes under ultrasound. Initially, this study was aimed at developing an easy-to-make and easy-to-recover piezocatalyst for the degradation of RhB in water by combining the high piezocatalytical performance of BaTiO₃ with a compatible piezoelectric support such as PVDF, manufactured by a customised additive manufacturing - direct ink writing system with in-situ poling. However, initial results showed that the resulting PVDF-BaTiO₃ composite slabs performed worse than BaTiO₃ piezocatalysts on their own, and that poling did not have any effect on their performance (82% RhB removal after 2 h when using either poled or unpoled PVDF-BaTiO₃ composite slabs compared to 92% RhB removal after 2 h in presence of BaTiO₃ piezocatalysts). Further investigation with pure PVDF materials demonstrated that, instead of piezocatalysis, synergistic ultrasound-assisted adsorption and sonochemical degradation were taking place, enabling the removal of >95% of the dye within 40 min of ultrasound treatment in the presence of 4 g L^-1 of additive manufactured PVDF slabs. The results of this study and their evaluation with the mechanistic model proposed for liquid phase adsorption under ultrasound suggest that the adsorption of RhB on additive manufactured PVDF slabs was enhanced by the structure, higher specific surface ratio and higher volume of mesopores achieved through the 3D-printing process, as well as the minimisation of film resistance to mass transport due to ultrasound. Moreover, adsorption on additive manufactured PVDF enhanced the sonochemical degradation of the dye due to its high concentration in the adsorbed phase. This study demonstrates that adsorption processes, especially in the presence of PVDF materials, may be significantly more important in piezocatalysis than what has been reported to date, to the point that the synergistic combination of sono-adsorption and sonochemical degradation in presence of additive-manufactured PVDF slabs may be enough to achieve high removal rates of dyes in water.

Keywords: Additive manufacturing; Composite materials; Piezocatalysis; Sono-adsorption; Sonochemistry.