2026-04-18T21:38:08Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/64412022-12-02T01:05:47Zcom_10259_4244com_10259_5086com_10259_2604col_10259_4245

00925njm 22002777a 4500 dc Benito Román, Oscar author Alonso Riaño, Patricia author Díaz de Cerio Alonso de Mezquía, Elixabet author Sanz Díez, Mª Teresa author Beltrán Calvo, Sagrario author 2022-06 The semi-continuous hydrolysis of onion skin wastes (OSW) using subcritical water (SubW; working conditions: 105-180 ºC; 5 MPa; 2.5 mL/min) has been studied in this work. Liquids after hydrolysis showed a sharp increase in total organic carbon (>30 mg/g OSW) at temperatures above 145 ºC, when SubW began to promote the partial hydrolysis of the structural components of OSW. Among them, pectin was one of main components recovered (extraction yield up to 9% at 145 ºC), whereas cellulose was barely hydrolyzed in the range of temperatures studied. The composition of pectin demonstrated that SubW promoted the recovery of the valuable RG-I (21.1±1.1 mol %) regions compared to acid water extraction processes (10.8±0.9 mol %). The control of the hydrolysis conditions was found to be critical, since high temperatures and long hydrolysis times led to the formation of organic acids (acetic, formic and levulinic) and degradation products such as furfural (up to 0.8 mg/g OSW) from the C5 sugars. Finally, the High Heating Value (HHV) calculated for the solid residue obtained at 180 ºC (16.4±0.2 MJ/kg) indicated the potential use of this residue as a fuel, once the valuable compounds (phenolics and pectins) have been recovered. 2213-3437 http://hdl.handle.net/10259/6441 10.1016/j.jece.2022.107439 Onion Subcritical water Pectin Hydrolysis Biomass RG-I Semi-continuous hydrolysis of onion skin wastes with subcritical water: pectin recovery and oligomers identification