Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/75719
Title: Valorization of cellulosic food waste into levulinic acid catalyzed by heterogeneous Bronsted acids : temperature and solvent effects
Authors: Chen, SS 
Yu, IKM 
Tsang, DCW 
Yip, ACK
Khan, E
Wang, L 
Ok, YS
Poon, CS 
Keywords: Biomass valorization
Food waste
Levulinic acid
Hydroxymethylfurfural
Bronsted acid
Solid catalyst
Issue Date: 2017
Publisher: Elsevier
Source: Chemical engineering journal, 2017, v. 327, p. 328-335 How to cite?
Journal: Chemical engineering journal 
Abstract: This study presents the catalytic valorization of vegetable waste into levulinic acid (LA) over a solid Bronsted acid, Amberlyst 36, in aqueous solution with/without polar aprotic solvent (dimethyl sulfoxide, DMSO). With the aid of microwave heating, the cellulosic structure in the vegetable started hydrolysis at 120 degrees C. Increasing temperature to 135-150 degrees C accelerated the yield of LA to 13-17 C mol% in 5 min in aqueous solution due to the reduction of mass transfer limitations. At the same time, the generation of insoluble humins became more rapid and significant, leading to lesser amount of total soluble products. In comparison, in the DMSO-water mixture, the early-stage reaction produced up to 17 C mol% of hydroxymethylfurfural (HMF), which was gradually rehydrated to LA with increasing reaction time. This probably illustrated the effects of DMSO, i.e., increased accessibility of glucose to protons for rapid HMF formation and preferential solvation of HMF to dampen further rehydration. The maximum yield of soluble products in DMSO-water mixture at 120-150 degrees C was higher than that in aqueous solution, which was attributed to the enhanced dissolution of cellulose in DMSO as supported by the SEM images. The XRD patterns of the reacted solids demonstrated more intensive peaks at the early stage of the reaction followed by broadening peaks at the later stage, indicating the hydrolysis of amorphous cellulose and formation of insoluble solids on the surface. Therefore, water serves as a green solvent for LA production while DMSO-water mixture is needed for HMF production from vegetable waste.
URI: http://hdl.handle.net/10397/75719
ISSN: 1385-8947
EISSN: 1873-3212
DOI: 10.1016/j.cej.2017.06.108
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