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The recovery of valuable bioactive compounds from the main underutilised by-products of the food industry is one of the greatest challenges to be addressed in circular economy. Potato peels are the largest waste generated during potato processing. However, they could be a potential source of valuable bioactive compounds, such as polyphenols, that can be reused as natural antioxidants. Currently, environmentally benign enabling technologies and new types of non-toxic organic solvents for the extraction of bioactive compounds may dramatically improve the sustainability of these processes. This paper focuses on the potential inherent in the valorisation of violet potato peels (VPPs) by recovering antioxidants using natural deep eutectic solvents (NaDES) under ultrasound (US)- and microwave (MW)-assisted extraction. Both the enabling technologies provided performances that were superior to those of conventional extractions in terms of antioxidant activity determined by the DPPH· (2,2-diphenyl-1-picrylhydrazyl) assay. In particular, the most promising approach using NaDES is proven to be the acoustic cavitation with a Trolox eq. of 1874.0 mmolTE/gExtr (40 °C, 500 W, 30 min), vs. the 510.1 mmolTE/gExtr of hydroalcoholic extraction (80 °C, 4 h). The shelf-life of both hydroalcoholic and NaDES-VPPs extracts have been assessed over a period of 24 months, and found that NaDES granted a 5.6-fold shelf-life extension. Finally, the antiproliferative activity of both hydroalcoholic and NaDES-VPPs extracts was evaluated in vitro using the MTS assay on human tumour Caco-2 cells and normal human keratinocyte cells (HaCaT). In particular, NaDES-VPPs extracts exhibited a significantly more pronounced antiproliferative activity compared to the ethanolic extracts without a noteworthy difference between effects on the two cell lines.

In this paper, the dominance of the physical effects of ultrasound (US) pretreatment in improving the delignification of wheat straw at a 1:20 solid/liquid (biomass/water) ratio is reported showing low-frequency/high power (25 kHz, 2 or 3 kW) as preferred conditions. The sonochemical pretreatment with alkali was identified as an optimal method to make the cellulose more susceptible to further enzymatic hydrolysis, thereby increasing the yield of soluble sugars. Previous bench-scale studies have shown that US pretreatment has a positive effect on delignification, nevertheless this has not yet been demonstrated on a larger scale. The objective of this study was to demonstrate the effectiveness of US pretreatment for wheat straw delignification from lab to semi-industrial scale (40 kg biomass) in terms of sugar yield and energy efficiency. A 59.2% of lignin removal was recorded after the cavitational treatment of wheat straw with a subsequent 68 ± 5.7% yield in terms of enzymatic hydrolysis (52.6% glucose, 42.9% xylose and 4.5% arabinose). It was demonstrated that the positive effect of US alkali pretreatment of wheat straw on sugar yield was due to a combination of factors, including (i) an easier accessibility of the biomass carbohydrate network to enzymes due to the increased wheat straw porosity, (ii) the partial removal of lignin, which increases the relative proportion of carbohydrates in the treated biomass, and (iii) the disordering (amorphization) of the cellulose structure, which promotes carbohydrate hydrolysis as well as saponification of the acetyl groups in the hemicellulose. With respect to the Life Cycle Assessment (LCA) and the Cost Benefit Analysis the US pretreatment process herein reported was compared to an alternative Steam Explosion pretreatment. The results of the LCA analysis showed, that for all five environmental categories (energy consumption, global warming potential, water and fossil depletion, and the land occupation) the US pretreatment has advantages in comparison with the standard industrial Steam Explosion pretreatment.

Despite its severe toxicity and negative environmental impact, hexane remain the solvent of choice for the extraction of vegetable oils. This is in contrast with the constantly growing demand for sustainable and green extraction processes. In recent years a variety of alternatives to hexane have been reported, among them 2-methyloxolane (2-MeOx), which has emerged as a promising bio-based alternative. This study evaluates the possibility of replacing hexane, in the extraction of olive pomace (OP), with 2-MeOx, both dry and saturated with water (4.5%), the latter of which is called 2-MeOx 95.5%. The three solvents have been compared in terms of extraction yield and quality, as well as the lipid and polyphenol profiles of the extracts. The work concluded that both dry 2-MeOx and 2-MeOx 95.5% can replace hexane in OP extraction, resulting in higher yields and extracts richer in phenolic compounds. This study should open the road to further semi-industrial scale investigations toward more sustainable production processes.

This tutorial review focuses on the valorisation of biomass by sonochemical and mechanochemical activation. Although several of the examples reported herein rely on the use of model compounds rather than native feedstocks, the conversion of lignocellulosic fractions into valuable compounds is a great opportunity with which to more sustainably exploit natural resources, from environmental, economic and social points of view. The use of non-conventional technologies that generate high-energy microenvironments can improve biomass deconstruction and the accessibility of catalysts, granting higher conversion and selectivity. The critical parameters in sonochemical and mechanochemical conversions have been analysed together with the most common devices and reactors, and the potential of sonocatalysis and mechanocatalysis as emerging tools for both catalytic and biocatalytic biomass conversion will be discussed. A SWOT (strengths, weaknesses, opportunities and threats) analysis will provide an overview of the effective feasibility of these approaches in a biorefinery context. Although these technologies offer indisputable advantages (mild reaction conditions, enhanced reaction rates and mass transfer), their mechanisms and the systematic adjustment of parameters to give optimal outcomes still require further investigation, which will pave the way for reproducible and scalable experiments. Indeed, process scale-up can be accomplished both in batch and flow mode. However, results are not particularly predictable, despite the accurate control of instrumental variables, because of the variability found in biomass sources and the complexity inherent in structures.

Nowadays, the increasing concern about the declining fossil fuel reserves and the environmental impact derived from their use has put considerable interest in lignocellulose exploitation as a renewable source of biofuels and biomaterials, according to the biorefinery concept. Several processes and technologies have been extensively studied in order to optimize biomass treatments aiming to enhance the recovery of its main products: cellulose, hemicelluloses and lignin. Lignin is, in fact, considered a valid substitute to petroleum as a source of aromatics, thanks to its abundance in nature. However, its complex and highly resistant structure limits its further applications, therefore, lignin upgrading is considered extremely challenging: various processes have been developed in recent years, but their feasibility at industrial scale still represents a bottleneck. Recently, process intensification has gained considerable attention in the design of sustainable procedures for lignin valorization. In particular, non-conventional technologies such as Ball milling, Ultrasounds (US) and Microwaves (MW) have recently shown promising results in biomass exploitation, thanks to their ability in generating specific high-energy microenvironments which could enhance process efficiency: mechanochemical and US activation have been mostly applied to biomass pre-treatment, in order to separate its components and enhance lignin extraction yield, while MW have been exploited as a means for lignin depolymerization, achieving higher yields of aromatics in milder reaction conditions. However further efforts should be done to improve profitability through new processes, aiming to reduce the cost associated to bio-derived products. In the present review, recent approaches to lignin valorization are discussed, focusing on new alternative methodologies for process intensification, besides their challenges and feasibility at industrial scale.

Despite its severe toxicity and negative environmental impact, hexane remain the solvent of choice for the extraction of vegetable oils. This is in contrast with the constantly growing demand for sustainable and green extraction processes. In recent years a variety of alternatives to hexane have been reported, among them 2-methyloxolane (2-MeOx), which has emerged as a promising bio-based alternative. This study evaluates the possibility of replacing hexane, in the extraction of olive pomace (OP), with 2-MeOx, both dry and saturated with water (4.5%), the latter of which is called 2-MeOx 95.5%. The three solvents have been compared in terms of extraction yield and quality, as well as the lipid and polyphenol profiles of the extracts. The work concluded that both dry 2-MeOx and 2-MeOx 95.5% can replace hexane in OP extraction, resulting in higher yields and extracts richer in phenolic compounds. This study should open the road to further semi-industrial scale investigations toward more sustainable production processes.

Microwave (MW) -assisted levulinic acid (LA) hydrogenation has been performed over two gold catalysts (commercial 1 wt% Au/TiO2 by AUROlite™ and 2.5 wt% Au/ZrO2, prepared using deposition-precipitation). MW-assisted LA hydrogenation was carried out in water and in solvent-free conditions via (i) H-transfer and (ii) molecular H2. Au/TiO2 promoted complete LA conversion and the further reduction of the produced GVL to 1,4-pentanediol (1,4-PDO) in the presence of 50 bar H2 at 150 °C (4-hour reaction). Interestingly, selectivity to 1,4-PDO was complete at 200 °C. Extended characterisation highlighted the cooperative role played by the gold nanoparticles and the support, onto which activated hydrogen atoms spillover to react with LA. This results in the remarkable activity of Au/TiO2. Both catalysts showed structural and morphological stability under reaction conditions. It was possible to reactivate the Au/TiO2 catalyst by MW-assisted oxidation, paving the way for catalyst recycling directly inside the MW reactor.

Macroalgae are widespread on the coasts of all the globe and lead to a negative ecological impact, requiring expensive remediations. Therefore, the valorization of invasive seaweed as a renewable source of bioactive products could represent a valid solution. In this context, three algal biomasses, belonging to brown, green, and red families (Sargassum muticum, Ulva lactuca, Solieria filiformis), collected in the venetian Laguna, were investigated as a source of active compounds for the formulation of cosmeceutics. Microwave (MW) and ultrasound (US) were applied to enhance the algae extraction by means of a hydroalcoholic solution. According to total phenolic content (TPC) evaluation, MW demonstrated the best performing outcomes, resulting in 19.77, 22.02, and 16.94 mgGAE/gExtr (30 min at 90 °C) for brown, green, and red algae, respectively. Antioxidant activity was tested as well, showing comparable trends (49.19, 26.24, and 3.02 mmolTrolox eq./gExtr for brown, green, and red algae, respectively). Due to natural algae predisposition to absorb contaminants, the metal content analysis helped to screen the applicability of these extracts, identifying Ulva lactuca as the most suitable source of antioxidants for cosmetic formulations. This MW extract was then adopted to formulate two different preparations, namely a gel and an emulsion. Thermal and mechanical tests confirmed the stability of each formulation, together with neutral organoleptic characteristics. Finally, the actives release was investigated by means of a tape stripping essay, showing an efficient controlled release for gel formulation, even after 7 h of test. The produced cosmeceutics merged non-conventional extraction technologies with formulation expertise, offering a valuable alternative to solve the macroalgae disposal issue.

Residual biomass from agri-food production chain and forestry are available in huge amounts for further valorisation processes. Delignification is usually the crucial step in the production of biofuels by fermentation as well as in the conversion of cellulose into high added-value compounds. High-intensity ultrasound (US) and hydrodynamic cavitation (HC) have been widely exploited as effective pretreatment techniques for biomass conversion and in particular for cellulose recovery. Due to their peculiar mechanisms, cavitational treatments promote an effective lignocellulosic matrix dismantling with delignification at low temperature (35–50 °C). Cavitation also promotes cellulose decrystallization due to a partial depolymerization. The aim of this review is to highlight recent advances in US and HC-assisted delignification and further cellulose recovery and valorisation.

Lignocellulosic waste material serves as a considerable renewable feedstock that could be used to replace oil refineries with biorefineries. Indeed, all biomass components can be converted into platform chemicals, bioenergy and materials. However, thermochemical and conventional catalytic conversions suffer from a number of drawbacks. Enabling technologies, such as microwave (MW) technology, can reduce process times and energy consumption, leading to improvements in product quality and yields. The remarkable advantages of MW over conventional heating, which originate from its direct dielectric interaction with biomass, are documented in this comprehensive survey. Moreover, the use of alternative solvents that interact strongly with MW in biphasic systems can circumvent the need for additional upgradation and separation steps. Finally, this review discusses some of the challenges that MW irradiation faces, including the poor dielectric properties of some substrates and issues related to its large-scale application in pyrolysis, hydrothermal conversion and catalytic routes to biofuels, materials and platform chemicals. Waste biomass may well be the benchmark feedstock for the development of a circular bioeconomic approach.

Aiming to fulfil the sustainability criteria of future biorefineries, a novel biomass pretreatment combining natural deep eutectic solvents (NaDESs) and microwave (MW) technology was developed. Results showed that NaDESs have a high potential as green solvents for lignin fractionation/recovery and sugar release in the following enzymatic hydrolysis. A new class of lignin derived NaDESs (LigDESs) was also investigated, showing promising effects in wheat straw delignification. MW irradiation enabled a fast pretreatment under mild condition (120 °C, 30 min). To better understand the interaction of MW with these green solvents, the dielectric properties of NaDESs were investigated. Furthermore, a NaDES using the lignin recovered from biomass pretreatment as hydrogen bond donor was prepared, thus paving the way for a “closed-loop” biorefinery process.

In the search for a more sustainable future, the biorefinery approach can help by replacing fossil feedstocks with renewable sources. When biorefineries meet circular economy, the production of new platform chemicals from residual lignocellulosic biomasses becomes the joint goal. In this frame, the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) has gained increasing interest, with the aim of producing intermediates for the chemical industry. Enabling technologies, particularly microwaves, have proven to be an efficient tool for process intensification, as they can reduce the reaction time and the formation of byproducts. In this work, MW-assisted processes with heterogeneous Ru-based catalysts were exploited for the reduction of LA both with H2 and 2-PrOH as reductants. Different metal loadings and supports were considered, such as a commercial active carbon (Ru/AC) and titania (Ru/TiO2). Among the different hydrogen sources, molecular hydrogen led to milder reaction conditions, enabling the complete flash conversion of LA in only 2 min without any solvent. In terms of catalytic activity, AC showed slightly better performances as support. In addition, flow MW-assisted processes were tested using a multiphase reactor, reaching complete conversion in only 8 min in an open loop system for both the tested catalysts. Performance enhancement and material reuse support the suitability of flow approach, paving the way for a sustainable and scalable process.

A smart design of hierarchical SAPO-5 acid catalyst using biomass derived monosaccharides as sustainable and low-cost mesoporogens has been developed. The hierarchical SAPO-5 was characterized by several physico-chemical techniques to elucidate structure-properties relationships and was tested as a catalyst in the MW-assisted glucose transformation in 5-HMF using γ-valerolactone (GVL) as green solvent.

The burning of crop residues is still a common, but heavily polluting, means of overcoming the problem of agricultural waste disposal. The main environmental damage comes from changes in soil properties (physical, chemical and biological), greenhouse gas emissions and decreasing crop yields. The use of crop residue biomass to replace fossil fuels is a valid alternative as it also supports farmers for land release and protects the environment. Many developing countries produce large quantities of agro-waste including rice husks, palm kernel shells, coconut shells, bagasse, milling residue-sawdust and plant biomass, such as grass. Residual biomass is a negative-cost feedstock for the production of fuels and commodity chemicals but could be used on a much larger scale. The realization of these economic benefits could provide the motivation necessary to achieve this goal and increase worldwide interest in biomass conversion for energy, fuels and chemicals. This chapter will describe some alternative uses for agricultural waste in Sub-Saharan Africa from bioenergy production to biomass conversion and briquetting.

In Africa large areas of savannah, grass- and cropland are burned every year, mostly for agricultural management purposes. These fires influence nutrient cycling patterns and are still a controversial issue. Most importantly, biomass burning causes a loss in soil organic matter and nutrients by particulate dispersal or volatilization. In this chapter, the effects of fires on the physical, chemical and biological properties of the soil are evaluated. The question whether controlled biomass burning promotes or destroys biodiversity is also addressed. We show that in the long term, if not managed correctly, the environmental impact of crop residue burning will be detrimental, causing loss of nutrients, soil biota, total N and C in the topsoil layer and soil erosion. The sustainable utilization of residues should therefore be promoted by ensuring the correct management of low-intensity fires.

Microwaves (MW) are often the most efficient, in terms of heat exchange and conversion rate, of all the energy sources used to promote chemical reactions thanks to fast volumetric dielectric heating, and metal-catalysed synthetic reactions under heterogeneous conditions are an eloquent example. We herein report a MW-assisted green protocol for the C-H arylation of thiophenes with substituted aryl halides. This sustainable protocol is catalysed by Pd nanoparticles embedded in cross-linked β-cyclodextrin, and is carried out in γ-valerolactone (GVL). In view of the excellent results achieved with activated substrates, the one-pot synthesis of a 4(3H)-quinazolinone derivative has been accomplished. A pressure-resistant MW reactor, equipped with multiple gas inlets, was used for sequential (i) C-H arylation, (ii) reduction and (iii) carbonylation in the presence of the same catalyst, but under different gas atmospheres. The robust heterogeneous Pd catalyst showed limited metal leaching in GVL, making this an efficient MW-assisted process with high atom economy.

Solventless and solid-state reactions have become increasingly popular and appealing options in the field of green chemistry and process intensification as they can often minimise waste and energy costs. A variety of strategies and protocols (in particular ball milling, dielectric heating and reactive extrusion) have been developed and improved over the last two decades. Although this account cannot be comprehensive, it will, however, provide a glimpse of such methods, highlight the advantages and limitations of strategies and discuss some mechanistic considerations. A few examples for each case, often from our own laboratories, will be used to illustrate specific applications.

A smart design of hierarchical SAPO-5 acid catalyst using biomass derived monosaccharides as sustainable and low-cost mesoporogens has been developed. The hierarchical SAPO-5 was characterized by several physico-chemical techniques to elucidate structure–properties relationships and was tested as a catalyst in the MW-assisted glucose transformation in 5-HMF using γ-valerolactone (GVL) as green solvent.

In line with the Green Supply Chain Management, Sustainable Supply Chain Management and Natural-Resource-Based Views (NRBV), the present study is as further step of a long range research program initiated in 2004. The project aims to demonstrate municipal bio-waste (MBW) as feedstock to produce bio based chemicals alternative to fossil sourced products. Previous work demonstrated MBW as source of polymeric biosurfactants (BPS) with multiple properties for use in chemical and agriculture sectors. The present paper reports now a new BPS feature, i.e. that BPS are efficient active principles for soil remediation. The study involves three BPS obtained by alkaline hydrolysis from different streams of an MBW treatment plant: the anaerobic digestate of food kitchen waste (FORSUD), the compost (CV) of gardening residues and the compost (CVDF) of a mix of gardening residues, digestate and sewage sludge. The BPS have 5 to over 750 kg/mol molecular weight, characterized by the presence of aliphatic C chains substituted by aromatic moieties and several different acid and basic functional groups. They were used at 0.1–100 g L−1 in aqueous solution to wash soil sampled from an Italian metal polluted site. Collected data statistical analysis was carried out by ANOVA. The recovered washing solutions were analyzed for Cu, Cr, Ni, Zn, Pb. The 50–100 g/L CVDF BPS solutions exhibited 98-81% extraction efficiency, compared to 70-60% for CV and FORSUD. Compared to conventional commercial extractants, CVDF BPS extraction efficiency ranked as CVDF = diethylene triamine pentaacetic acid > ethylene diamine tetraacetic acid > sodium dodecyl sulphate. A new two steps process was studied: (1) use of BPS solution for washing the polluted soil; (2) treating the recovered solution by acidification and membrane filtration to separate a pollutant concentrate from water for further use. Results indicate membrane filtration more efficient and/or sustainable. They confirm BPS as value added products upgrading MBW from societal cost to source of benefits.

Two bio-based solvents, natural deep eutectic solvents (NaDESs) and γ-valerolactone (GVL), have been used under microwave (MW), and ultrasound (US) irradiation to design an efficient and sustainable process for wheat straw delignification and have been compared with the traditional alkali procedure. Best delignification (45%) was achieved with a three-component NaDES (lactic acid/glycerol/choline chloride) under MW irradiation (at 120 °C in 30 min), with solid/liquid ratio of 1:50. A GVL/water mixture (8:2) also gave an efficient delignification (27%) under US irradiation (40 kHz, 200 W) at 50 °C for 60 min. Analytical pyrolysis (Py) coupled with GC/MS/FID, provides valuable information on the extracts’ chemical profile. DPPH and Folin–Ciocalteu tests highlighted the efficiency of MW- and US-assisted extraction as well as the extracts quality. The highest antioxidant activity for the NaDES extracts was obtained under US irradiation.

Most of biorefinery technologies are focused on the utilization of plant polysaccharides into chemicals, whereas lignin, the second most abundant natural polymer, is commonly used as a resource to generate power. This is the first report on flavones-bound lignin obtained by wheat straw (WS) pretreatment under low-frequency ultrasound (US) and hydrodynamic cavitation (HC) in sugar production processing. US and HC procedures carried out in aqueous 0.2–0.4% NaOH solutions and various liquid/biomass ratios strongly decreased the lignin content in the solid fraction by 30–45% and 25%, respectively, compared to non-treated WS. Moreover, НС pretreatment increased (approximately tenfold) the portion of ordered cellulose in residual biomass that could hinder the further enzymatic hydrolysis of WS. By means of sequential HC and US pretreatment the ordered cellulose content in solid fraction significantly decreased, compared to the HC alone. Furthermore, it was demonstrated that, after US pretreatment, hemicelluloses and oligomeric fragments of lignin and ligno-carbohydrate complexes were transferred into the liquid phase. In particular, tricin derivatives were detected in liquid fractions with a concentration of 30–35% on o.v.d. ash free sample, and more than 50 compounds associated with low-molecular-weight lignin fragments. These compounds were tentatively identified using high-resolution mass spectrometry (HR-MS) based fragmentation (sequencing) and a self-made database, showing that 16 out of 50 identified compounds belonged to the fragments of model lignin structural units. Tricin and low molecular weight lignin derivatives may find applications as strong antioxidants (i.e. lipidic systems). These findings proved that waste lignin streams obtained after cavitational processes could be a source of value-added products from WS conversion.

The Pd-catalyzed C–H arylation of heterocycles with aryl halides is a straightforward and more environmentally-friendly route to the synthesis of well-defined, pi-conjugated polymers for challenging applications in electronic devices. Although this type of transformation is more atom efficient than cross-couplings, it still poses environmental issues in the form of reaction media and the use of phosphine ligands. A procedure for the C–H arylation of thiophenes, with a substantially improved environmental impact, and a promising application of this protocol to the synthesis of regioregular polythiophenes are reported in this work. γ-Valerolactone (GVL), a non-toxic biomass-derived solvent, has been used in this phosphine-free microwave-assisted process and replaces commonly used dipolar aprotic media. Activated aryl bromides gave arylthiophenes in good yields, while iodides were used and pivalic acid was added when electron-withdrawing groups were present. The reaction was also extended to C–H (hetero)arylation polycondensation and a high molecular weight poly(3-hexyl)thiophene was obtained, using low Pd loading, in high yields and good regioregularity in short reaction times. Computational studies have shed light on GVL's role as a ligand in the catalytic system.

Lignin is the second most abundant polymer in lignocellulosic biomass. A biorefinery approach to lignin valorisation, as an alternative to the use of heating, can produce bioaromatics, and this idea is attracting ever more interest. However, the isolation of lignin for further processing is really quite challenging, making the valorisation of native lignin (i.e., lignin in raw biomass) crucially important. An analysis of vanillin yields in relation to total reaction feedstock weight shows that the economic viability of the process depends on the valorisation of all biomass components. This paper reports a microwave-assisted, catalyst-free aerobic oxidation process for biomass. The protocol yields bioaromatics (mainly vanillin and syringaldehyde, with traces of p-hydroxybenzaldehyde and acetovanillone) and organic acids (38.4 wt % maximum total yield) in only 30 min. Vanillin is the most valuable of the aromatic compounds to be produced by lignin oxidation, accounting for 8.7 wt % of the initial lignin. Th...

International audience; SynopsisMicrowave-assisted reductive amination with aqueous ammonia: sustainable pathway using a recyclable magnetic nickel based nanocatalyst.AbstractThe development of sustainable protocols for the reductive amination is a highly desirable pursuit in the domain of green synthesis. Magnetic nanocatalysts have found a unique niche in chemical synthesis in recent years as the recovery of expensive and/or toxic catalysts after their use are some of the salient features of these greener processes. Herein, we report the application of a recyclable nickel silica eggshell iron-based magnetic nanoparticles (Fe3O4@SiO2-Ni) for the expeditious microwave-assisted reductive amination of aryl aldehydes and ketones in aqueous ammonia; several desired primary amines were produced in good-to-excellent conversions. Extensive characterization of both, fresh and recycled Fe3O4@SiO2-Ni catalysts, showed that the Ni nanoparticles are highly dispersed on the silica shell and that the metal active phase is highly stable as the core–shell morphology is maintained after reaction, indeed the catalyst is recyclable up to six runs without deactivating. A synergic effect between the Ni nanoparticles and the silica support has been hypothesized wherein the Fe3O4@SiO2-Ni system worked as a bifunctional catalyst; support facilitates the activation of the substrate, and the metal nanoparticles promote the subsequent imine hydrogenation.

New formulations based on red grape pomace polyphenols and deep eutectic solvents (DES) have been here evaluated as inhibitors of urease of agricultural interest (jack bean urease, JBU). DES based on choline chloride (CHO) and betaine (BET), combined with ethylene glycol (EG), citric acid (CA), and urea (U), were used both as extracting and carrying agents for polyphenols, becoming active components of the formulations here obtained. Among the various DES combinations, U- and CA-based ones gave the best polyphenol extraction performances, 1.2-1.4-times higher than those of the hydroalcoholic mixture. Among the various DES-polyphenols formulations, the one composed by CHO-EG showed the best antioxidant potential and urease inhibition: 60-90% inhibition of the total JBU activity was achieved with a CHO concentration of 5-20 mM. Good results were also achieved with the BET-EG polyphenol formulation, which was able to inhibit ca. 50% of urease activity at 20 mM concentration of BET. Low phytotoxicity of DES and their polyphenol formulations tested at a concentration of 34 mM of CHO or BET was here observed on cress seedlings and the early growth of oat, in particular, for EG-based DES. On the other hand, tests performed on earthworms showed that CHO-based DES could impair the reproduction, and U-based DES caused severe mortality.

Strict rules and environmental concerns make the production of clean fuels that display very low sulfur (S) content mandatory for the petroleum refining industry. In parallel, nitrogenated compounds present in feedstock are deleterious for the various processes in a refinery. Herein, diesel oil desulfurization and denitrification via adsorption or extraction have been investigated as sequential and complementary treatments to oxidative protocols. Diesel fuel (S = 231 ppm and N = 115 ppm) has been treated with a number of adsorbents (including commercial silica gel and Fuller’s Earth powder) at room temperature in fixed-bed cartridges. Comparisons with typical extraction procedures showed that processes with suitable adsorption agents were more efficient in terms of both residual S/N content and fuel mass balance. These simple adsorption methods can be applied to any refining process as pre- or post-treatment. The application of these methods in oxidative diesel desulfurization/denitrification has ...