Fractionation of Raw and Parboiled Rice Husks with Deep Eutectic Solvents and Characterization of the Extracted Lignins towards a Circular Economy Perspective
Chiara Allegretti,
Emanuela Bellinetto,
Paola D’Arrigo,
Monica Ferro,
Gianmarco Griffini,
Letizia Anna Maria Rossato,
Eleonora Ruffini,
Luca Schiavi,
Stefano Serra,
Alberto Strini,
Stefano Turri
Affiliations
Chiara Allegretti
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Emanuela Bellinetto
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Paola D’Arrigo
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Monica Ferro
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Gianmarco Griffini
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Letizia Anna Maria Rossato
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Eleonora Ruffini
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
Luca Schiavi
Istituto per le Tecnologie della Costruzione, Consiglio Nazionale delle Ricerche (ITC-CNR), Via Lombardia 49, 20098 San Giuliano Milanese, Italy
Stefano Serra
Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”, Consiglio Nazionale delle Ricerche (SCITEC-CNR), Via Luigi Mancinelli 7, 20131 Milano, Italy
Alberto Strini
Istituto per le Tecnologie della Costruzione, Consiglio Nazionale delle Ricerche (ITC-CNR), Via Lombardia 49, 20098 San Giuliano Milanese, Italy
Stefano Turri
Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza L. da Vinci 32, 20133 Milano, Italy
In the present work, rice husks (RHs), which, worldwide, represent one of the most abundant agricultural wastes in terms of their quantity, have been treated and fractionated in order to allow for their complete valorization. RHs coming from the raw and parboiled rice production have been submitted at first to a hydrothermal pretreatment followed by a deep eutectic solvent fractionation, allowing for the separation of the different components by means of an environmentally friendly process. The lignins obtained from raw and parboiled RHs have been thoroughly characterized and showed similar physico-chemical characteristics, indicating that the parboiling process does not introduce obvious lignin alterations. In addition, a preliminary evaluation of the potentiality of such lignin fractions as precursors of cement water reducers has provided encouraging results. A fermentation-based optional preprocess has also been investigated. However, both raw and parboiled RHs demonstrated a poor performance as a microbiological growth substrate, even in submerged fermentation using cellulose-degrading fungi. The described methodology appears to be a promising strategy for the valorization of these important waste biomasses coming from the rice industry towards a circular economy perspective.
