Improving bioethanol production from olive pruning biomass by deacetylation step prior acid hydrolysis and fermentation processes

In order to produce bioethanol from olive tree pruning biomass, deacetylation was performed employing sodium hydroxide. Optimal conditions were determined using experimental design techniques. The highest acetic acid removal (3.8 g/dm(3)), obtained by response surface methodology, was at optimum pretreatment conditions of temperature 60 degrees C, 0.8% NaOH and residence time 60 min. After oxalic acid hydrolysis of pretreated biomass, the hydrolysates were directly used for ethanol production without further detoxification process. Ethanol yields ranged from 0.19 to 0.45 g/g, reaching the maximum yield value when pretreatment was carried out at 130 degrees C with 100 mM oxalic acid, involving a combined severity factor (CSF) of 1.05. The highest ethanol concentration obtained from pretreated biomass was 6.2 g/dm(3) at 150 degrees C, using 75 mM of oxalic acid (CSF = 1.53). (C) 2016 Elsevier Ltd. All rights reserved.