Synthetic dyes are persistent organic environmental pollutants that can cause extensive damage to living beings and to the ecosystem as a whole. Cost-effective, sustainable, and efficient strategies to deal with this type of pollution are necessary as it commonly resists conventional water treatment methods. Silver nanoparticles (AgNPs) synthesized using the aqueous extract from the leaves, stem, and fruits of Leucaena leucocephala (Leucena) were produced and characterized through UV–vis, TEM, EDS, SDL, XPS, XRD, and zeta potential, and they proved to be able to promote adsorption to remediate methylene blue and tartrazine pollution in water. The nanoremediation was performed and did not require direct exposure to sunlight or any special lamp or a specific reduction agent. The AgNPs produced using the extract from the leaves exhibited the best performance in nanoremediation and also presented antioxidant activity that surpassed the one from butylated hydroxytoluene (BHT). Consequently, it is an interesting nanotool to use in dye nanoremediation and/or as an antioxidant nanostructure.

Background: Biosurfactants are natural bioactive compounds produced from fungi, bacteria and plants. These molecules have several properties that enable them to be involved in various industrial applications. The surface-active properties of biosurfactants allow their use in various sectors, such as agriculture, health, cosmetics, bioremediation/ petroleum, mining, and bioprocess. Objective: The objective of this study was to analyze the patents deposited in intellectual property databases for applications of biosurfactants in the areas of agriculture, health, cosmetics, bioremediation/petroleum, mining, and bioprocesses, with the research period consisting of the last six years. Methods: This study targeted the use of biosurfactants in various industrial sectors. The patent search was carried out using the Google Patents platform, a platform that is commonly used for this purpose and freely accessible. Results: During the search for patents related to applications of biosurfactants in industry filed in the last 6 years, results were found to be distributed in the following areas: agriculture (70), cosmetics (2311), bioremediation/petroleum (179), health (1794), mining (5), and bioprocess (133). Six patents were selected from each area, except for health and mining, for which the search resulted in only 5 and 4 patents, respectively, to be discussed and provide information on the biotechnological applications of biosurfactants in the industry. Conclusion: The present study showed a wide area of application of biosurfactants in industry. The interest in the inclusion of biosurfactants in the industry is directly related to the need for more sustainable solutions to solve real market problems. The cosmetics sector presented the most patents that employ the use of biosurfactants.

Currently, the whole world strives for a sustainable development to avoid the depletion of natural resources. Therefore, the search for new biotechnological products such as biosurfactants has generated interest due to its low toxicity, biodegradability and ecological acceptability. Furthermore, biosurfactants have several applications such as emulsification, wettability, foaming, cleaning, and reduction of crude oil viscosity. The objective of this work was to identify the bacteria collected in Antarctica and evaluate their capacity to produce biosurfactants. In this study, bacteria collected in diesel contaminated soil around the Comandante Ferraz Antarctic Station were identified (Rhodococcus erythropolis, Rhizobium radiobacter, Microbacterium liquefacien, Pseudomonas libanensis and Pseudomonas veronii) and analyses were carried out to confirm whether these bacteria produce biosurfactants. Interestingly, the compounds isolated from the bacteria showed droplet propagation and reduced the surface tension of the water, which are properties of biosurfactants. Furthermore, these compounds showed carbohydrates in their molecular composition. Given these findings, these species have potential application in biotechnological areas, such as bioremediation of environments contaminated by diesel oil and in cosmetic and personal care as emulsifier. In addition, the use of diesel oil waste by bacteria as a carbon source becomes an attractive alternative because it reduces environmental contamination and has a low cost.

Synthetic dyes are commonly present in industrial wastewater and when discharged in water bodies without receiving a treatment capable of removing or destroying them, they turn into concerning water pollutants. These organic contaminants threaten living beings due to their toxicity, and some of them can even damage DNA. Consequently, in order to achieve sustainable development, it is necessary to develop eco-friendly tools that can efficiently manage this kind of pollution. In the present study the aqueous extract from the leaves of Leucaena leucocephala (an invasive plant species native to Mexico) was used to produce green nano zero-valent iron (nZVI). The nanomaterial was characterized (TEM, UV–vis, FTIR, SEM, EDS, XRD) and assayed regarding its antioxidant potential (DPPH test) and capacity to remediate the pollution caused by two dyes. It proved to be able to adsorb nigrosine (288.30 mg/g of nanomaterial) and tartrazine (342.50 mg/g of nanomaterial), and also displayed antioxidant activity (effective concentration to discolor 50% of the DPPH solution = 286.02 μg/mL). Therefore, the biogenic antioxidant nanoparticle proved also to be a possible nanotool to be applied to remediate water contamination caused by these synthetic dyes.