• Energy Research

The feasibility of in situextraction and transesterification of spent coffee ground oil into fatty acid methyl esters with supercritical methanol has been investigated in the temperature range 473–603 K, and in the pressure range 10.0–30.0 MPa. At 30.0 MPa and 603 K, a fatty acid methyl esters (FAME) yield of 84.9% was obtained. Carbon dioxide was added to methanol with the aim of reducing the operating temperature and pressure. It was demonstrated that at a reaction temperature of 573 K, pressure of 10.0 MPa and a CO2/MeOH molar ratio of 0.11, a FAME yield of 93.4% was obtained.

COVID-19, caused by a member of the coronavirus family of viruses, has spread to most countries around the world since it was first recorded in humans in China in late 2019. Closing universities and cancelling all face-to-face activities have become a COVID-19 inevitable reality in many parts of the world. Its impact on university programs, particularly to maintain academic standards and quality assurance procedures, has become significantly more challenging and complex. New ways of working digitally, to minimize disruption to daily operations, have also led to enormous anxiety and uncertainty within the student population, and meeting students’ expectations has also become significantly more difficult. This paper reviews actions taken by universities to safeguard high academic standards and quality assurance procedures during this time and appraise the challenges and impacts on students’ academic performance.

To fulfill the conditions required for a nuclear renewable energy concept, one has to explore a combination of processes going from the front end of the nuclear fuel cycle to the fuel production and the energy conversion using specific fluid fuels and reactors.

Spent coffee grounds (SCGs) have a potential to be used as a feedstock for higher value-added products, such as biodiesel. However, the environmental implications of the valorisation of SCGs are largely unknown. This study evaluates the life cycle environmental impacts of utilising SCGs for biodiesel production in comparison with the widely used disposal of SCGs as a waste stream: incineration, landfilling, anaerobic digestion, composting and direct application to land. The scope is from cradle to grave and the functional unit is defined as ‘treatment of 1 tonne of SCGs’. The results show that the most environmentally sustainable option is incineration of SCGs, with net-negative impacts (savings) in 14 out of 16 categories, followed by direct application of SCGs to land with 11 net-negative impacts. Biodiesel production is the least sustainable option with the highest impacts in 11 categories, followed by composting. The paper also demonstrates that following various waste hierarchy and resource valorisation guidelines instead of a life cycle approach could lead to a choice of environmentally inferior SCG utilisation options. Therefore, these guidelines should be revised to ensure that they are consistent and underpinned by life cycle thinking, thus aiding sustainable resource management in a circular economy context.

Despite offering low-carbon and reliable energy, the utilization of nuclear energy is declining globally due to high upfront capital costs and longer returns on investments. Nuclear cogeneration of valuable chemicals from waste biomass-derived feedstocks could have beneficial impacts while harnessing the underutilized resource of ionizing energy. Here, we demonstrate selective methanol or acetaldehyde production from ethylene glycol, a feedstock derived from glycerol, a byproduct of biodiesel, using irradiations from a nuclear fission reactor. The influence of radiation quality, dose rate, and the absorbed dose of irradiations on radiochemical yields (G-value) has been studied. Under low-dose-rate, γ-only radiolysis during reactor shutdown rate (<0.018 kGy min-1), acetaldehyde is produced at a maximum G-value of 8.28 ± 1.05 μmol J-1 and a mass productivity of 0.73 ± 0.06% from the 20 kGy irradiation of neat ethylene glycol. When exposed to a high-dose-rate (6.5 kGy min-1), 100 kGy mixed-field of neutron + γ-ray radiations, the radiolytic selectivity is adjusted from acetaldehyde to generate methanol at a G-value of 2.91 ± 0.78 μmol J-1 and a mass productivity of 0.93 ± 0.23%. Notably, utilizing 422 theoretical systems could contribute to 4.96% of worldwide acetaldehyde production using a spent fuel pool γ-ray scheme. This research reports G-values and production capacities for acetaldehyde for high-dose scenarios and shows the potential selectivity of a nuclear cogeneration process to synthesize chemicals based on their irradiation conditions from the same reagent.

L'industrie de l'huile d'olive génère d'énormes quantités de noyaux d'olive chaque année, qui ont le potentiel d'être utilisés comme biocarburant mais ont une teneur élevée en huile, ce qui a un impact négatif sur le processus de combustion. En outre, les noyaux d'olive contiennent des antioxydants de grande valeur, et leur exploitation peut fournir des revenus supplémentaires pour l'industrie des biocarburants. Dans ce travail, nous rapportons l'effet de différents solvants d'extraction sur l'extraction des antioxydants et leur activité. De plus, la digestion gastro-intestinale in vitro a été utilisée pour évaluer la teneur et l'activité antioxydante des extraits de noyaux d'olives après digestion gastro-intestinale. Les extraits obtenus par solvant éthanolique aqueux (50% vol) présentaient l'activité antioxydante la plus élevée avec l'IC50 DPPH de 1,27 mg mL−1 et le pouvoir antioxydant réducteur ferrique (FRAP) de 6,33 mg AAE g−1. Après une digestion in vitro composée de processus gastriques et intestinaux, l'activité antioxydante des noyaux d'olives a diminué : la valeur de l'IC50 DPPH a été multipliée par trois (une valeur plus élevée de l'IC50 indique une activité antioxydante plus faible) et le FRAP a diminué de près de cinq fois par rapport aux valeurs obtenues pour les extraits originaux. De plus, des modèles de noyau phénoménologiques et de rétrécissement ont été utilisés pour adapter les données de cinétique d'extraction d'huile expérimentale et ont montré un bon accord. L'analyse thermodynamique a montré que le processus d'extraction est endothermique et irréversible tout en étant spontané et thermodynamiquement favorable pour toutes les conditions à l'exception de l'extraction d'huile à partir de noyaux d'olive de 3,10 mm de taille de particule à 20 °C. La valeur calculée pour le coefficient de température est en bon accord avec les valeurs précédemment rapportées pour l'extraction d'huile à partir d'une biomasse similaire. La industria del aceite de oliva genera enormes cantidades de huesos de aceituna cada año, que tienen el potencial de ser utilizados como biocombustible pero tienen un alto contenido de aceite, lo que afecta negativamente al proceso de combustión. Además, los huesos de aceituna contienen antioxidantes de alto valor, y su explotación puede proporcionar ingresos adicionales para la industria de los biocombustibles. En este trabajo, informamos el efecto de diferentes disolventes de extracción sobre la extracción de antioxidantes y su actividad. Además, se utilizó la digestión gastrointestinal in vitro para evaluar el contenido y la actividad antioxidante de los extractos de hueso de oliva después de la digestión gastrointestinal. Los extractos obtenidos por solvente de etanol acuoso (50% vol) exhibieron la mayor actividad antioxidante con la IC50 de DPPH de 1.27 mg mL−1 y el poder antioxidante reductor férrico (FRAP) de 6.33 mg de AAE g−1. Después de una digestión in vitro compuesta por procesos gástricos e intestinales, la actividad antioxidante de los huesos de aceituna disminuyó: el valor de IC50 de DPPH aumentó tres veces (un valor más alto de IC50 indica una menor actividad antioxidante) y el FRAP disminuyó casi cinco veces con respecto a los valores obtenidos para los extractos originales. Además, se utilizaron modelos de núcleo tanto fenomenológicos como de contracción para ajustar los datos experimentales de cinética de extracción de aceite y mostraron un buen acuerdo. El análisis termodinámico mostró que el proceso de extracción es endotérmico e irreversible, mientras que espontáneo y termodinámicamente favorable para todas las condiciones, excepto para la extracción de aceite de huesos de aceituna de 3.10 mm de tamaño de partícula a 20 ° C. El valor calculado para el coeficiente de temperatura está en buena concordancia con los valores previamente informados para la extracción de aceite de biomasa similar. The olive oil industry generates enormous amounts of olive stones each year, which have the potential to be used as a biofuel but have high oil content, which negatively impacts the combustion process. In addition, olive stones contain high-value antioxidants, and their exploitation can provide additional revenues for the biofuel industry. In this work, we report the effect of different extraction solvents on the extraction of antioxidants and their activity. In addition, in vitro gastrointestinal digestion was used to evaluate the content and antioxidant activity of the olive stone extracts after gastrointestinal digestion. The extracts obtained by aqueous ethanol solvent (50% vol) exhibited the highest antioxidant activity with the DPPH IC50 of 1.27 mg mL−1 and ferric reducing antioxidant power (FRAP) of 6.33 mg AAE g−1. After in vitro digestion composed of gastric and intestinal processes, the antioxidant activity of olive stones decreased: DPPH IC50 value increased three times (a higher value of IC50 indicates lower antioxidant activity) and FRAP decreased almost five times with respect to the values obtained for original extracts. Furthermore, both phenomenological and shrinking core models were used to fit experimental oil extraction kinetics data and showed good agreement. Thermodynamic analysis showed that the extraction process is endothermic and irreversible while spontaneous and thermodynamically favourable for all conditions except for oil extraction from olive stones of 3.10 mm particle size at 20 °C. The calculated value for temperature coefficient is in good agreement with the previously reported values for the oil extraction from similar biomass. تولد صناعة زيت الزيتون كميات هائلة من أحجار الزيتون كل عام، والتي يمكن استخدامها كوقود حيوي ولكنها تحتوي على نسبة عالية من الزيت، مما يؤثر سلبًا على عملية الاحتراق. بالإضافة إلى ذلك، تحتوي أحجار الزيتون على مضادات الأكسدة عالية القيمة، ويمكن أن يوفر استغلالها إيرادات إضافية لصناعة الوقود الحيوي. في هذا العمل، نبلغ عن تأثير مذيبات الاستخلاص المختلفة على استخراج مضادات الأكسدة ونشاطها. بالإضافة إلى ذلك، تم استخدام الهضم المعدي المعوي في المختبر لتقييم المحتوى والنشاط المضاد للأكسدة لمستخلصات حجر الزيتون بعد الهضم المعدي المعوي. أظهرت المستخلصات التي تم الحصول عليها بواسطة مذيب الإيثانول المائي (حجم 50 ٪) أعلى نشاط مضاد للأكسدة مع DPPH IC50 من 1.27 mg mL−1 وقوة مضادات الأكسدة المخفضة للحديد (FRAP) من 6.33 mg AAE g−1. بعد الهضم في المختبر الذي يتكون من عمليات المعدة والأمعاء، انخفض النشاط المضاد للأكسدة لحصى الزيتون: زادت قيمة DPPH IC50 ثلاث مرات (تشير القيمة الأعلى لـ IC50 إلى انخفاض النشاط المضاد للأكسدة) وانخفض FRAP خمس مرات تقريبًا فيما يتعلق بالقيم التي تم الحصول عليها للمستخلصات الأصلية. علاوة على ذلك، تم استخدام كل من النماذج الأساسية الظاهرية والمتقلصة لتناسب بيانات حركية استخراج النفط التجريبية وأظهرت توافقًا جيدًا. أظهر التحليل الديناميكي الحراري أن عملية الاستخراج ماصة للحرارة ولا رجعة فيها بينما تكون عفوية وملائمة من الناحية الديناميكية الحرارية لجميع الظروف باستثناء استخراج الزيت من أحجار الزيتون بحجم جسيم 3.10 مم عند 20 درجة مئوية. تتوافق القيمة المحسوبة لمعامل درجة الحرارة بشكل جيد مع القيم المبلغ عنها سابقًا لاستخراج النفط من الكتلة الحيوية المماثلة.