Comparison of the effects of three drying methods on lignin properties.

In the last few years, a serious effort has been initiated to develop standard methods for lignin characterization at the national and international levels. Thus, several Canadian and ISO standards were recently developed. The current results were generated in an effort to assist the ISO/TC6 Committee come up with a reliable standard method for the measurement of the dry solids content of lignins. In particular, this work investigated the drying of lignin using three different drying methods: conduction oven drying (105 °C), vacuum oven drying at (60 °C), and freeze drying. Ten different lignins were used in this study including wet and air-dried softwood and hardwood kraft lignins in the acid and base forms from the industrial LignoForce™ process and hydrolysis lignin from the TMP-Bio™ process. The results showed that 7 h, 48 h and 24 h were sufficient to reach a constant solids content in the case of all lignins when oven drying, vacuum oven drying under negative pressure (150 mbar), and freeze drying (25 mT) were used, respectively. Kraft lignins in the base form showed higher sensitivity to degradation compared to lignins in the acid form. The total hydroxyl group content of air-dried and wet hardwood lignins in the base form decreased by more than 50 % after vacuum oven-drying for 71.5 h or oven-drying for 16 h compared to freeze-drying for 68 h. The decrease in the total hydroxyl groups was more pronounced (70 %) when the wet softwood lignin in the base form was dried in the oven compared to freeze drying for 68 h.

New approach to recycle and valorize the first filtrate of the LignoForce system™: Lignin extraction and its use in rigid lignin-based polyurethane foams.

In this work, we report on the fractionation, recovery and characterization of softwood kraft lignin from the first filtrate of the LignoForce™ process. It is estimated that the lignin content in this stream could be >20-30 % of the lignin present initially in the black liquor. The use of a membrane filtration system was experimentally validated as an effective method for fractionating the first filtrate. Two membranes with different nominal molecular weight cut-offs (4000 and 250 Da) were tested. Higher lignin retention and recovery was obtained using the 250-Da membrane. This lignin (lignin_250) was found also to have a lower molecular weight and a tighter molecular weight distribution compared to the lignin obtained using the 4000-Da membrane (lignin_4000). The lignin_250 was characterized for it's hydroxyl group content and used to produce polyurethane (PU) foams. Up to 30 wt% petroleum-based polyol replacement by lignin_250, the resulting lignin-based PU (LBPU) foams presented the same thermal conductivity as the control (0.0303 W/m.K (control) vs 0.029 W/m.K (30 wt%)), as well as comparable mechanical (max stress: 145.8 kPa (control) vs 222.7 KPa (30 wt%), modulus 64.3 kPa (control) vs 75.1 (30 wt%)) and morphological properties to the petroleum polyol-based PU foams.

Ultrasound-Assisted Extraction of Isoquercetin from Ephedra alata (Decne): Optimization Using Response Surface Methodology and In Vitro Bioactivities.

Isoquercetin (ISQ) is reported to be a powerful antioxidant with extremely high bioavailability and structural stability compared to aglycone quercetin. Despite this, it is not well studied due to the limited methods for its extraction. With the growing interest in the research and analysis of ISQ-rich herbs, there is a need to optimize an efficient and rapid method for their extraction. In the present study, the ultrasound-assisted extraction of ISQ from Ephedra alata Decne was optimized by a response surface methodology (RSM) using high-performance liquid chromatography as a separation method. The best possible ranges for extraction time (10-30 min), temperature (50-70 °C), ultrasonic power (60-90 W), solvent-to-solid ratio (50-70 mL/g), and ethanol concentration (50-70%) were determined using a single factor analysis. Subsequently, an optimization of the extraction conditions was performed with RSM using the Box-Behnken design. An ultrasonication time of 10 min, a temperature of 60 °C, a power of 75 W, a solvent-to-solid ratio of 60 mL/g, and an ethanol concentration of 70% were determined to be the optimal conditions for the highest recovery of isoquercetin (1033.96 ± 3.28 µg/g). Furthermore, E. alata powder morphology (using a scanning electron microscope), antioxidant activities, and the inhibition potential of key enzymes involved in skin aging (elastase and collagenase), hyperpigmentation (tyrosinase), diabetes (α-amylase), inflammation (hyaluronidase), and neurodegenerative disorders (cholinesterase) were determined and compared with those using the Soxhlet method. This study established a highly efficient method for ISQ extraction and suggested several potential applications of ISQ in the pharmaceutical and cosmetics industries.