Evaluation of mechanical-green solvent pretreatment of oil palm wastes for reducing sugars production in North-Colombia

The aim of this work was to define optimum conditions to perform the mechanical and chemical pretreatment of empty fruit bunches (EFBs) and kernel shell (KS). Mechanical pretreatment was based on particle size reduction to 0.5, 1, and 2 mm. For chemical pretreatment, a solution of urea (2, 4, and 6 %w/v) was added to the residues under stirring for 18 h and 80 °C. Then, samples were hydrolyzed with sulfuric acid and the resulting reducing sugars were quantified using the 3,5- dinitrosalicyclic acid method. In addition, Van Soest and FTIR analyzes were performed to characterize the biomass suggesting acceptable cellulose contents (EFBs: 36.47%; KS: 20.06 %) and high lignin values (EFBs: 31.27%; KS: 66.49%). Results showed that the highest amount of TRS for EFBs was 105.3 g/L with urea concentration of 4% w/v and a particle size of 0.5 mm. For the KS, the highest amount of TRS was 98.62 g/L using a urea concentration of 6% w/v and a particle size of 0.5 mm. According to these results, it was concluded that pretreatments of oil palm biomass significantly enhance the performance of lignocellulosic material conversion into reducing sugars. Effect of particle size on TRS yield for empty fruit bunch. [Display omitted] •Particle size and acid solution concentration influence the TRS production from agroindustrial residues.•The particle size of 0.5 mm for empty fruit bunches and kernel shells showed the highest TRS yields.•The urea concentration of 4 and 6 % w/v reported the highest TRS yields for both palm oil residues.•The use of green solvents such as urea allowed to produce sugars from palm oil wastes in a more sustainable route.