Essential oils have important commercial applications as preservatives and flavours, and more recently as natural antimicrobial agents. These applications require a suitable formulation constituted by biodegradable compounds that protect the essential oil from degradation and evaporation at the same time that allows for a sustained release. Microcapsules of biopolymers loaded with essential oils meet these requirements. Such microcapsules can be prepared with different processes such as spray-drying, freeze-drying and coacervation, and supercritical fluids are an advantageous medium for this purpose. Some supercritical fluid-based precipitation processes have already been applied to produce these microcapsules. Amongst them, the results obtained with Particles from Gas Saturated Solutions (PGSS), PGSS-drying and Concentrated Powder Form (CPF) processes are particularly promising. Recent developments in the preparation of formulations with supercritical fluids include the preparation of liposomes and micelles, which can be suitable carriers for essential oils.

The encapsulation of antioxidants with biocompatible polymers is essential for their protection against degradation factors like light and oxygen, and facilitates its solubility in the target medium. This work presents the co-precipitation of an ethanolic extract of rosemary leaves by supercritical antisolvent (SAS) process in poloxamers in order to improve the aqueous solubility of the extract. In a first step, the precipitation of antioxidants by SAS was studied in the range of temperatures from 25 to 50°C and pressures from 8 to 12 MPa. Total content of polyphenols was quantified according to the Folin-Cicalteu method. Also HPLC analyses were performed to verify the presence of some of the major rosemary antioxidants, carnosic and rosmarinic acid. The dissolution rate of rosemary polyphenols from particles was measured in isotonic phosphate buffer solution (pH = 6.8). The encapsulation of the extract was successfully achieved with a yield up to 100%. The total polyphenolic content was dissolved from the encapsulated product, in the aqueous medium, after one hour, whereas only 15% of the antioxidants of the pure precipitate were dissolved after 8 hours.

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The use of renewable energy (RE) to transform carbon dioxide into commodities (i.e., CO2 valorization) will pave the way towards a more sustainable economy in the coming years. But how can we efficiently use this energy (mostly available as electricity or solar light) to drive the necessary (catalytic) transformations? This paper presents a review of the technological advances in the transformation of carbon dioxide by means of RE. The socioeconomic implications and chemical basis of the transformation of carbon dioxide with RE are discussed. Then a general view of the use of RE to activate the (catalytic) transformations of carbon dioxide with microwaves, plasmas, and light is presented. The fundamental phenomena involved are introduced from a catalytic and reaction device perspective to present the advantages of this energy form as well as the inherent limitations of the present state‐of‐the‐art. It is shown that efficient use of RE requires the redesign of current catalytic concepts. In this context, a new kind of reaction system, an energy‐harvesting device, is proposed as a new conceptual approach for this endeavor. Finally, the challenges that lie ahead for the efficient and economical use of RE for carbon dioxide conversion are exposed.

This article seeks to be a handy document for the academy and the industry to get quickly up to speed on the current status and prospects of biomass pretreatment for biorefineries. It is divided into two biomass sources: vegetal and animal. Vegetal biomass is the material produced by plants on land or in water (algae), consuming sunlight, CO2, water, and soil nutrients. This includes residues or main products from, for example, intensive grass crops, forestry, and industrial and agricultural activities. Animal biomass is the residual biomass generated from the production of food from animals (e.g., manure and whey). This review does not mean to include every technology in the area, but it does evaluate physical pretreatments, microwave-assisted extraction, and water treatments for vegetal biomass. A general review is given for animal biomass based in physical, chemical, and biological pretreatments.