Hybrid response surface methodology-genetic algorithm optimization of ultrasound-assisted transesterification of waste oil catalysed by immobilized lipase on mesoporous silica/iron oxide magnetic core-shell nanoparticles

Experimental investigation on dispersing graphene-oxide in biodiesel/diesel/ higher alcohol blends on diesel engine using response surface methodology

Lower alcohols have long been the figureheads of diesel/biodiesel additives in characterizing renewable fuels. Next-generation alcohol like n-octanol occupied the reified position due to their better fuel properties. In this paper, combustion, performance and, emission of different graphene-oxide nanoparticles (nanoGO) added jatropha biodiesel, n-octanol and petrodiesel blends are investigated in a 4-stroke DI diesel engine. This article also aims to optimize the engine inputs accountable for better performance and emission characteristics of a diesel engine running with nanoGO dispersed biodiesel/diesel/higher alcohol blends. Full Factorial Design-based Response Surface Methodology (RSM) is utilized to model the experiments using Design-Expert software to optimize engine responses. Validation of the developed model is carried out using sophisticated error and performance metrics, namely, TheilU2, Kling-Gupta Efficiency (K-G Eff), and Nash-Sutcliffe coefficient of efficiency (N-S Eff) along with the conventional statistical database. The model optimized engine inputs of 3.898% n-Octanol, and 49.772 ppm nanoGO at 99.2% load with a desirability index of 0.997 as the optimum engine parameters. The experimental validation revealed that the model optimized blend at full load witnessed a reduction of 15.6% CO, 21.78% HC.u, and 3.26% NOx emission compared to petrodiesel. However, a slight increase in brake specific energy consumption (2.95%) is also recorded because of the lower heating value of the blend.

Transforming food waste: how immobilized enzymes can valorize waste streams into revenue streams

Food processing generates byproduct and waste streams rich in lipids, carbohydrates, and proteins, which contribute to its negative environmental impact. However, these compounds hold significant economic potential if transformed into revenue streams such as biofuels and ingredients. Indeed, the high protein, sugar, and fat content of many food waste streams makes them ideal feedstocks for enzymatic valorization. Compared to synthetic catalysts, enzymes have higher specificity, lower energy requirement, and improved environmental sustainability in performing chemical transformations, yet their poor stability and recovery limits their performance in their native state. This review article surveys the current state-of-the-art in enzyme stabilization & immobilization technologies, summarizes opportunities in enzyme-catalyzed valorization of waste streams with emphasis on streams rich in mono- and disaccharides, polysaccharides, lipids, and proteins, and highlights challenges and opportunities in designing commercially translatable immobilized enzyme systems towards the ultimate goals of sustainable food production and reduced food waste.

Green chromatography determination of fatty acid methyl esters in biodiesel

This work proposes a green, simple and rapid chromatographic methodology for separation and determination of a group of 13 fatty acids methyl esters (FAMEs) by using a capillary gas chromatography with a flame ionization detector. The method was successfully applied for the determination of FAMEs in biodiesel samples from commercial and waste cooking oils, synthesized by homogeneous catalysis. Detection and quantification limits were in the μg L(-1) level. Direct injection of sample solution was compared with solid-phase extraction and solid-phase microextraction procedures, giving similar results. The lower analysis time represent considerable improvement compared with other papers. The described methodology is especially suitable for process control applications. The samples analysed showed total contents of FAMEs higher than 96.5%, which verifies the European regulations.