Exploiting Deep Eutectic Solvents and Ionic Liquids for the Valorization of Chestnut Shell Waste

Abstract

The full utilization of agricultural waste and its recycle into a new chain of value are of primary importance for the development of a sustainable and profitable agricultural industry. Chestnut shell waste (CSW) is an interesting case of study, whose valorization has been though partially investigated to date. This work aims at exploring the complete utilization of CSW, in terms of obtaining both value-added compounds and enriched cellulose and lignin fractions. The results were obtained via the unreported combined use of two classes of nonconventional organic solvents, namely natural deep eutectic solvents and bio-based ionic liquids (bio-ILs). At first, combinations of choline chloride (ChCl)-based DESs with an acid, a polyol, or a sugar as hydrogen bond donors were employed for the extraction of polyphenols from the CSW. The best performing system was found to be ChCl:oxalic acid dihydrate (ChCl:Oax2H 2 O). The extraction efficiencies of the DESs tested correlate well with the measured Kamlet−Taft α parameters. After polyphenol removal, the residual solid material was treated with a bio-IL [cholinium glycinate (ChGly)] for further separation of lignin and cellulose. The products obtained by the fractionation process were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis, which confirmed the separation of the residue into a lignin-rich material and a cellulose-rich material. The results obtained were further corroborated by a three parallel reaction model combined with the distributed activation energy model, which allowed for predicting the composition of the pristine CSW and of the ChCl:Oax2H 2 Otreated CSW as well as the two fractions obtained after ChGly treatment. The recyclability of the best performing DES and the recovery of the bio-IL have also been proven, which make the whole process viable and amenable for large-scale applications.

Combining acid-based deep eutectic solvents and microwave irradiation for improved chestnut shell waste valorization

“…The polyphenols extracted from CSW were analyzed using a HPLC-DAD system using a method previously reported. 36 Briefly, an HPLC gradient pump (LC 20, Shimadzu) was coupled with a vacuum membrane degasser and a UV diode array detector. The separations of polyphenols were carried out using a reversed-phase HPLC column C18 Shimadzu (150 mm × 46 mm, 4.5 µm).…”

“…Indeed, DESs have been used during the last years for the valorization of different lignocellulosic and food waste biomasses, among which is CSW. [35][36][37][38][39][40][41][42][43][44] DESs are composed of a hydrogen bond acceptor (HBA), often quaternary ammonium salts, and a hydrogen bond donor (HBD), such as carboxylic acids, polyols, amides and carbohydrates. The mixture of the HBA and the HBD at a specific molar ratio causes the decrement of the freezing temperature at the eutectic point below that expected for an ideal behavior.…”

Fruit Wastes as a Valuable Source of Value-Added Compounds: A Collaborative Perspective

“…Corn husk and grape stalk [118], pomegranate peel, marc of strawberry-tree fruit [119], chestnut shell [120], banana [121], and orange peel [122] are sources of cellulose. Being a natural, biodegradable, and versatile polymer, cellulose can be used for a variety of several food and nonfood applications as in textile, paper, wood, pharmaceutical, and industrial chemistry.…”

Lignin Extraction from Waste Pine Sawdust Using a Biomass Derived Binary Solvent System

“…Recent studies demonstrate the suitability of eutectic solvents and ionic liquids for biomass fractionation [20][21][22][23][24]. These systems are reasonably easy to prepare in a pure state, do not require the presence of any solvent and produce no waste.…”