Sustainable Chemistry

20 pages, 921 KiB

Open AccessArticle

Teaching the Nature of Science Through Biodiesel Synthesis from Waste Cooking Oil: A Literature Review with Experimental Insights

by Juan Peña-Martínez, Jessica Beltrán-Martínez, Ana Cano-Ortiz and Noelia Rosales-Conrado

Sustain. Chem. 2025, 6(2), 15; https://doi.org/10.3390/suschem6020015 - 19 May 2025

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Abstract

This work reviews the use of biodiesel synthesis experiments in science education, emphasising their potential for explicit nature of science (NOS) teaching. Through a literature review and experimental insights, it highlights how transesterification of waste cooking oil (WCO) with a basic catalyst can serve as an educational tool. While biodiesel reaction conditions are well-documented, this study presents them in a pedagogical context. Simple viscosity and density measurements illustrate empirical analysis, while a design of experiments (DoE) approach using a Hadamard matrix introduces systematic optimisation and scientific reasoning. By integrating biodiesel synthesis with explicit NOS instruction, this work provides educators with a framework to foster critical thinking and a deeper understanding of scientific inquiry. Additionally, this approach aligns with green chemistry principles and resource efficiency, reinforcing the broader relevance of sustainable chemistry. Full article

(This article belongs to the Collection New and Unconventional Strategies in Sustainable Chemistry Education at All Levels)

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14 pages, 1519 KiB

Open AccessArticle

Antiviral Activity of Rambutan Peel Polyphenols Obtained Using Green Extraction Technology and Solvents

by Christian Hernández-Hernández, Luis E. Estrada-Gil, Sonia A. Lozano-Sepúlveda, Ana M. Rivas-Estilla, Mayela Govea-Salas, Jesús Morlett-Chávez, Cristóbal N. Aguilar and Juan A. Ascacio-Valdés

Sustain. Chem. 2025, 6(2), 14; https://doi.org/10.3390/suschem6020014 - 29 Apr 2025

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Abstract

Rambutan peel is a great source of bioactive compounds, the same that, over the years, has been extracted using conventional technologies which have been proven to be harmful to the environment and potentially toxic to human beings. This study aimed to extract the same compounds using a hybridization of ultrasound/microwave extraction. The results were promising, as a total of 378.48 ± 9.19 mg/g of polyphenols were recovered from this procedure, and the most important molecules (geraniin, corilagin, and ellagic acid) were identified, giving this much more relevance. Furthermore, treatment with rambutan peel extract recovered with green technologies significantly reduced cell viability in HCV-infected liver cells. Notably, higher concentrations (4000 and 5000 ppm) led to more pronounced cell death in huh7 cells. The treatment also led to a significant reduction in viral protein and RNA expression in HCV-infected cells. These findings suggest that rambutan peel extract obtained from the combination of ultrasound and microwave extraction, particularly the ellagitannins present, have potential antiviral properties. Further research is needed to explore its mechanism of action and its potential as a therapeutic agent for Hepatitis C. Full article

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36 pages, 971 KiB

Open AccessReview

Physical Pretreatments of Lignocellulosic Biomass for Fermentable Sugar Production

by Damázio Borba Sant’Ana Júnior, Maikon Kelbert, Pedro Henrique Hermes de Araújo and Cristiano José de Andrade

Sustain. Chem. 2025, 6(2), 13; https://doi.org/10.3390/suschem6020013 - 14 Apr 2025

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Abstract

Physical pretreatments play a crucial role in reducing the recalcitrance of lignocellulosic biomass, facilitating its conversion into fermentable sugars for bioenergy and chemical applications. This study critically reviews physical pretreatment approaches, including mechanical comminution, irradiation (ultrasound, microwave, gamma rays, and electron beam), extrusion, and pulsed electric field. The discussion covers the mechanisms of action, operational parameters, energy efficiency, scalability challenges, and associated costs. Methods such as ultrasound and microwave induce structural changes that enhance enzymatic accessibility, while extrusion combines thermal and mechanical forces to optimize hydrolysis. Mechanical comminution is most effective during short periods and when combined with other techniques to overcome limitations such as high energy consumption. Innovative approaches, such as pulsed electric fields, show significant potential but face challenges in large-scale implementation. This study provides technical and strategic insights into developing more effective physical pretreatments aligned with economic feasibility and industrial sustainability. Full article

(This article belongs to the Special Issue Innovations in Energy Engineering and Cleaner Production: A Sustainable Chemistry Perspective)

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16 pages, 1536 KiB

Open AccessArticle

Assessment of Co-Pyrolysis of Polypropylene with Triacylglycerol-Based Waste Biomass to Obtain Sustainable Hydrocarbons

by Isaac de Carvalho Guimarães, Mirele Santana de Sá, Tarcísio Martins and Alberto Wisniewski, Jr.

Sustain. Chem. 2025, 6(2), 12; https://doi.org/10.3390/suschem6020012 - 8 Apr 2025

Viewed by 771

Abstract

Sustainable hydrocarbons are one of the main methods of decreasing the use of fossil fuels and derivatives, contributing to the mitigation of environmental impacts and greenhouse gas emissions. Circular economic concepts focus on reusing waste by converting it into new products, which are then input again into industrial production lines, thus decreasing the necessity of fossils. Polypropylene-based plastic waste can be depolymerized into smaller chemical chains, producing a liquid phase rich in hydrocarbons. In the same way, triacylglycerol-based waste biomasses can also be converted into renewable hydrocarbons. Our research studied the co-processing of polypropylene (PP) and cottonseed oil dreg (BASOs) waste from the biodiesel industry using a micropyrolysis system at 550 °C, previously validated to predict the scale-up of the process. PP showed the production of alkanes and alkenes, while BASOs also produced carboxylic acids in addition to the PP products. The main impacts were observed in the conversion yields, reaching the highest values of pyrolytic liquid (64%), gas (14%), and solid product (13%) compared to the co-processing mixture of BASO:PP (1:2). Also, in this mixture, the production of carboxylic acids decreased to the lowest value (~10%), improving the conversion to sustainable hydrocarbons. Full article

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13 pages, 1477 KiB

Open AccessArticle

Cultivation of Chlorella sp. in a Closed System Using Mining Wastewater and Simulated Flue Gas: Biomass Production and CO₂ Fixation Potential

by Thiago J. T. Cruz, Guilherme Q. Calixto, Fabiana R. de A. Câmara, Dárlio I. A. Teixeira, Renata M. Braga and Sibele B. C. Pergher

Sustain. Chem. 2025, 6(2), 11; https://doi.org/10.3390/suschem6020011 - 31 Mar 2025

Viewed by 395

Abstract

Chlorella sp. was cultivated in a closed system using PET bottles (5 L) and with the continuous injection of air and commercial gas (98% CO₂) and in simulated conditions (15% CO₂, 73% N₂, and 12% O₂). The culture medium was prepared using well water and mining wastewater, the cultivation period occurred in a 10-day cycle, and the cell growth curves were evaluated through cell counting using a Neubauer chamber. The cultivation was carried out under the following conditions: temperature at 22 °C to 25 °C; aeration rate with commercial and simulated CO₂ gas at 0.01 vvm; and synthetic air containing 0.042% CO₂. The dry biomass productivity was 0.81 g·L⁻¹·day⁻¹ and the maximum CO₂ fixation rate was 0.90 g·L⁻¹·day⁻¹ when the microalgae were cultivated with a continuous flow of simulated waste gas and a culture medium composed of wastewater. The percentages of macromolecules obtained in the biomass cultivated in wastewater reached 20.95%, 26.48%, and 9.3% for lipids, proteins, and carbohydrates, respectively. Full article

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Sustain. Chem., Volume 6, Issue 2 (June 2025) – 5 articles

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