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As a renewable and sustainable resource, lignocellulosic biomass serves as a crucial raw material for the production of biofuels, biochemicals, and various value-added products. This paper aims to develop and optimize a mild alkaline treatment of sawdust assisted by ultrasound, along with enzymatic hydrolysis of the pretreated material. The alkaline sonochemical pretreatment emerged as the optimal approach to enhance the susceptibility of cellulose to subsequent enzymatic hydrolysis to improve the yield of reducing sugars. A comparative study was performed using various ultrasonic applicators (horn and bath) and conventional assisted alkaline pretreatment. The ultrasonic-assisted pretreatment revealed a higher delignification of 68% (horn) and 57% (bath) compared with conventional pretreatment. Processes were optimized using a statistical analysis based on a 23 factorial design. The ratios between sawdust and alkaline solution (RSL = 0.5–1.5 g/100 mL), US amplitude (A = 20–60%), and working temperature (t = 30–50 °C) were selected as process factors. The optimal operating conditions to maximize the reducing sugar yield (138.15 mg GE/gsubstrate) were found as follows: a solid/liquid ratio of RSL,opt = 1.25 g/100 mL, US amplitude of Aopt = 60%, and pretreatment temperature of topt = 50 °C. The overall outcomes clearly confirmed the intensification of delignification by ultrasound-assisted alkaline pretreatment. [ABSTRACT FROM AUTHOR]

In this paper, the essential oil (EO) extraction from thyme by the consecutive use of ultrasound and microwave treatments is presented. The aim of this study was to apply an ultrasound pre-treatment of thyme leaves to enhance the thymol content and the extraction yield of the EO obtained by microwave-assisted hydro-distillation (MWHD). Compared with conventional hydro-distillation (CHD), the consecutive use of ultrasound pre-treatment and microwave extraction resulted in a 72% lower extraction time. When the ultrasound pre-treatment (using the ultrasonic processor with an amplitude of 70%) was applied, the EO content was 23% higher compared to the extraction without pre-treatment (2.67 ± 0.06 g EO/100 g DM for the MWHD with ultrasound pre-treatment compared with 2.18 ± 0.07 g EO/100 g DM for the MWHD without pre-treatment). The EO samples were analyzed by GC/MS. The results showed that the major component, thymol, varied from 43.54% (by CHD) to 65.94% (by the consecutive use of ultrasound and microwave treatments). [ABSTRACT FROM AUTHOR]

The oil extraction from a spherical particle in an adequate solvent is analyzed by a dynamic model. The oil extraction occurs by moving the unsolubilized solid/solute-free phase interface toward the center of the particle. We assume that the transport of solute molecules has three resistances: (1) the resistance due to oil core dissolving; (2) the resistance due to the solute-free portion of the particle; (3) the resistance due to a surface layer near solid-liquid interface. Generally, the equation governing the dynamic behavior of oil extraction is numerically solved. However, sometimes analytical expressions for the time dynamics of the size of the unsolubilized oil portion can be obtained in some special cases. The present analysis on oil process extraction takes into account the effect of variable bulk solute concentration and of seed internal characteristics such as particle porosity, particle tortuosity and core oil dissolving kinetics. Result consists in a general mathematical model whose particularization is given for the case of Camelina seeds oil extraction. For Camelina seeds the oil hexane extraction has been characterized by particularization of the general modified shrinking core model. It has obtained that the particle dimensionless porosity is set to 0.08, while the constant of kinetic process from the shrinking core surface is strongly dependent on core position and on the temperature after relation kd = kd0(t)(rc/R)n with n = 4 and kd0(t) in the range 4.3-8.3 10-8 m/s. [ABSTRACT FROM AUTHOR]