Ultrasound-assisted extraction of oil from hempseed (Cannabis sativa L.): Part 2

BACKGROUND

Oilseed-matrix consolidation is a crucial factor when talking about oil expression because, as the cake consolidates, the coefficient of permeability inevitably decreases. Thus, any treatment that extensively ruptures cell walls reduces rigidity and hardness of the oilseed press-cake, while improving the oil expression. Such process intensification was investigated in the present study through the introduction of the ultrasound (US) technology. Screw pressing of Cannabis sativa L. seeds was operated using a pilot scale equipment set at three different pressures (low, medium and high) to understand the correlation with the ultrasound effectiveness. Samples of non-exhausted press-cakes were tested for objective instrumental indices of compressibility and oil expression yields prior and after the US treatment.

RESULTS

US led to a drag resistance reduction within press-cakes, improving oil flowability through a decrease in the material cohesiveness and adhesiveness. Consistently, sonication favoured oil extraction yields and oil antioxidant capacities, which increased with respect to the untreated samples, respectively equal to +19.2% and + 29.4% for the press-cake screwed at low pressure, to +21.8% and + 49.3% at medium pressure, and to +15.4% and + 0.5% at high pressure. Overall, US highest effectiveness was accounted for samples screwed at medium pressure.

CONCLUSION

Press-cake compressibility can be well described by macroscopic texture parameters; indeed, their decrease is linked to higher oil expression efficiencies. Sonication can help boosting oil extraction yields reducing drag resistance within the mechanical screwing equipment. These outcomes offer good potentials for US application in the hempseed technology and, more extensively, in the oil seed industry. © 2022 Society of Chemical Industry.

Impacts of Modified Graphite Oxide on Crystallization, Thermal and Mechanical Properties of Polybutylene Terephthalate

In this study, the surface modification on graphene oxide (GO) was performed using octadecylamine (ODA). Furthermore, polybutylene terephthalate/GO (PBT/GO) composites were prepared to elucidate the role of GO surface modification on the mechanical performance, thermal stability and crystallization behavior. Results of Fourier transform infrared spectra (FT-IR), Raman spectrum, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) revealed that ODA was successfully grafted on GO. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), tensile test, Izod impact strength test and TGA were carried out on the PBT/GO composites. Results indicated that the addition of raw GO can enhance the crystallization temperature and degree of crystallinity and can slightly improve the thermal stability and tensile strength of the composites. However, the impact strength and elongation at break were seriously decreased owing to the poor compatibility between the GO and PBT matrix. Once the modified GO was added, the crystallization temperature and degree of crystallinity were greatly increased. The tensile strength increased greatly while the elongation at break and Izod impact strength were efficiently maintained; these were evidently higher than those of PBT/raw GO. Moreover, thermal stability was greatly enhanced. SEM (scanning electron microscope) observation results on the impact-fractured surface clearly confirmed the improved compatibility between the modified GO and PBT matrix. A related mechanism had been discussed.