Hesperidin and rutin are two sought-after natural flavonoids, traditionally extracted from abundant natural citrus fruits and tea leaves using large amounts of ethanol or methanol solvents. Recent trends in extractions have focused on minimizing the use of solvents and creating simpler cost-effective processes. This study aims to apply the concept of chemical valorization in the context of a circular economy, by using agro-industrial waste and biobased alternatives to traditional solvents, which are of environmental concern. We use minimum amounts of solvent/sample (5 mL/0.25 or 0.5 g) to extract hesperidin and rutin in a single-stage solid–liquid extraction. Thirty individual solvents and HSPiP were applied to find the best solvents/blends for extraction. The type of solvent, sample preparation, maceration time, and extraction temperature were studied. Results showed that the biobased solvent Cyrene is very effective when mildly heated to 65 °C (up to 91%) or mixed with water. Adding water to Cyrene forms its geminal diol hydrate, this enhances the solubility and extraction of hesperidin and rutin up to ten times than those of the original pure ketone form. Quantitative sustainability metrics from the CHEM21 Toolkit demonstrated that our extraction methodology is environmentally friendly and offers future potential of isolation of other flavonoids.
One of the keys to achieving the United Nation’s Sustainable Development Goals (SDGs) in education is to introduce novel pedagogical strategies into university curricula in order to promote an enhanced acute sense of sustainability in future professionals, teachers, and decision-makers. This paper aims at analyzing the effectiveness of including green and sustainable chemistry on the basis of a systems thinking framework to introduce a glocal (global scale, local impact) hot-type topic in an experimental chemistry course for first-year undergraduate Chemical Engineering students from a public Brazilian university located in São Paulo state, Brazil. The enormous amount of waste generated locally by the citrus processing industry was used as a case study for a guided-inquiry laboratory experiment that addressed concepts found in interfaces with other systems, such as biorefineries, biocircular economies, and green technologies and professional education programs. On the basis of student feedback, the alternative procedure proved to be technically and pedagogically effective, showing that problem-based glocal issues can be useful tools for developing sustainability-minded future professionals. Additionally, a set of green and sustainable chemistry education (GSCE) principles composing a new metric called the Green and Sustainable Chemistry Education Compass Rose was proposed that could help educators develop and assess novel experiments to modernize and introduce the scientific concepts and tools needed to face the world’s greatest challenges.
Increasing demands to obtain chemicals via greener and more sustainable materials and processes introduces concepts that should be considered and applied from lab to larger scales. Obtaining bioactive chemicals from agro-industrial non-food biomass waste can combine benign techniques and bio-circular economy to reach this goal. After extraction, evaluating profitability and environmental impacts to decide whether separation – and to what extent – is necessary or not is indispensable. This could be integrated into an approach known as sufficiency, as an important criterion for sustainability. From this perspective, Brazil’s annual generation of 8 million tons of orange waste is relevant, since citrus waste has large amounts of high-value compounds, such as pectin, d-limonene and flavonoids. This case study aimed at developing and comparing green and sustainable analytical methods to obtain flavonoids from orange peel. Homogenizer, ultrasound and microwave-assisted extractions were employed using chemometric tools, considering time, sample/solvent ratio, temperature and ethanol concentration as variables to obtain extracts containing hesperidin, naringenin, hesperetin and nobiletin. The bioactive flavonoids were determined by high-performance liquid chromatography (HPLC-UV). Microwave extraction was the most efficient method for obtaining the majority of flavonoids studied, six times more for hesperidin. Moreover, orange waste from different farming models showed diverse chemical profiles showing the importance of this alternative in natural product resources.
Brazilian biodiversity and favourable environmental conditions open up possibilities not yet explored, showing potential to shift the country’s monochromatic economy into an emancipated, diversified and sustainable economic environment. This can be made possible through the integral use of its resources, exploring every functional fraction to create novel solutions to modern problems. Biorefineries present an interesting strategy to fully use the potential of agricultural feedstocks and together with green separation methods can contribute to the generation of sustainable processes and products. Passion Fruit (Passiflora edulis Sims f. flavicarpa Deg species) is produced on a large scale in Brazil and in other tropical countries, and its processing plants generate tons of residues that basically consist of peel, seeds and bagasse, which account for around 75% of its mass. These fractions of P. edulis can contain significant amounts of flavonoids, secondary metabolites that are the main compounds responsible for the fruit’s bioactivity (antioxidant, anti-inflammatory, pesticide and biocide, in general). Therefore, this work aims to develop, apply and compare the best conditions for the extraction of isoorientin, orientin and isovitexin from passion fruit applying solid–liquid methodologies, followed by analyte quantification using UHPLC-PDA. Homogenizer-assisted (HAE), ultrasound-assisted (UAE) and microwave-assisted (MAE) extraction techniques were used, as well as a full factorial design to reach optimal parameters concerning the extraction yield and energy and solvent efficiencies. According to the results, the procedure based on HAE presented the best conditions for the extraction of selected flavonoids (1.07, 0.90 and 0.33 mg g−1 of isoorientin, orientin and isovitexin, respectively) and was considered the best method according to the green and sustainable described factors.
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