The aquatic macrophytes Salvinia sp. and Pistia stratiotes have a natural capacity to adsorb various elements, including heavy metals. This capacity was enhanced with a chemical treatment using NaOH alkaline solution for Salvinia sp. and a mixture of both Salvinia sp. and Pistia stratiotes at a proportion of 1:1, whose respective biosorbents were called SSOH and MBOH. Adsorption tests were done in a ternary system containing the metals copper, lead and manganese; the parameters considered were: starting concentration, kinetics, pH and temperature. The adsorption isotherms for SSOH had a maximum adsorptive capacity of 50.20, 53.85 and 14.68 mg g⁻¹ for Cu, Pb and Mn, respectively; for MBOH, maximum values were 44.62, 35.17 and 15.74 mg g⁻¹ for Cu, Pb and Mn, respectively. The metals displayed different behaviors with pH variation. The results also showed an adsorption preference of Cu > Pb > Mn for SSOH. Desorption and readsorption studies were also carried out, showing 100% desorption and increased adsorption capacity in readsorption tests. Surface area and porosity analysis with the Brunauer–Emmett–Teller (BET) method indicate that after chemical modification, MBOH and SSOH biomasses had their surface increased in comparison to SS, with values of 165.5657 (MBOH), 157.4392 (SSOH) and 78.9432 m² g⁻¹ (SS).

Bioremediation using microorganisms offers a sustainable approach to addressing hydrocarbon contamination. This study explores biosurfactant production by Yarrowia lipolytica IMUFRJ 50682 during crude oil and asphaltene-free fraction biodegradation in corn steep liquor (CSL)-based media. By evaluating CSL concentrations (5–30 g/L) and combinations with glucose, molasses, and crude oil, this study demonstrates that CSL is an effective nutrient source for supporting microbial growth and biosurfactant production. The highest emulsification index (EI = 73.3%) was achieved with 20 g/L of CSL after 48 h, while media containing mixed carbon sources (glucose and crude oil) enhanced metabolic efficiency, yielding a maximum cell growth of 8 g/L after 150 h. Despite inhibiting cell growth, the asphaltene-free fraction promoted biosurfactant activity, with the EI reaching 35.8% after 264 h. The results emphasize the importance of pH control, with the optimal emulsification being observed at pH ~6. This work highlights the potential of CSL as a cost-effective and sustainable additive, advancing applications in bioremediation and biosurfactant production and contributing to the development of environmentally compatible hydrocarbon degradation strategies.

This study used two biosorbents obtained from the aquatic plants Salvinia sp. and Pistia stratiotes to establish a sustainable and alternative treatment for industrial wastewater and other water bodies that contain Pb(II). The biosorbent named Salvinia with NaOH (SOH) was obtained from Salvinia sp., and Salvinia and Pistia mixture with NaOH (SPOH) was obtained from a mixture of the two plants in a 1:1 ratio. The biosorbents were characterised by zeta potential, infrared (IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy and Boehm titration. The results of Boehm titration and IR analysis indicated the presence of basic functional groups, whereas those of SEM analysis indicated that the biosorbents have a structure conducive to adsorption. Batch adsorption experiments were performed to observe the effects of pH, contact time, initial lead concentration and temperature on the metal removal process. The results revealed that the biosorbents efficiently removed Pb(II) from aqueous solutions, with a maximum observed adsorption capacity (saturation limits, q_max) of 202 mgg⁻¹ and 210.1 mgg⁻¹ for SPOH and SOH, respectively. The Freundlich, Langmuir and Dubinin–Radushkevich models were applied to the data; these biosorbents studies did not satisfactorily adjust to either of the models, but the information obtained helped us understand the adsorption mechanism.

The use of enzymes to hydrolyze the plant cell matrix is a method known for extracting bioactive substances. The current work used this strategy to produce a rose petal extract rich in anthocyanins that is stable in the presence of marine polysaccharides and has a high antioxidant activity. The process evaluation was carried out sequentially, initially comparing water, ethanol, and their mixtures to anthocyanins extracted in the presence or absence of enzymes. Then, a multi-objective desirability function optimized experimental conditions such as solvent and enzyme concentrations. This study is the first report describing the use of a statistical tool, the central composite rotatable design (CCRD), to optimize anthocyanin extraction from rose petals. This method obtained a maximum extraction of 9.99 mg/g of phenols. The stability of the rose petal extract when using marine polysaccharides retained 60% of the anthocyanins over 28 days without deterioration when protected from sunlight but was practically degraded upon exposure to sunlight. The rose petal extract demonstrated a very high antioxidant capacity of 3.19 μg/mL, close to the literature data for citrus compounds, known to be high in antioxidant compounds for cosmetic food purposes.