The cleaning of machinery, petroleum storage tanks and equipment leads to the accumulation of petroleum products in the environment. The removal of grease adhered to motors is a specific challenge. Cleaning processes require direct application of surfactants or solvents, which most often generate further environmental problems due to the accumulation of these toxic substances. The majority of available surfactants are synthesized from petroleum derivatives. However, environmental laws have motivated the development of natural surfactants as an alternative to existing products. Biosurfactants can be obtained from microorganisms and plants. Biodegradable detergents can also be obtained through chemical synthesis. This review presents different alternatives for obtaining biodetergents as well as their industrial applications for the removal of heavy oils and the reduction of cleaning and labor costs in industries.

The present study aimed to produce a biosurfactant from Candida yeast cultivated in a low-cost medium made of sugar-cane molasses (5%), frying oil waste (5%), and corn steep liquor (5%). Initially, the production at the flask-scale was investigated and then scaled up in bioreactors to 1.2, 3.0, and 50 L to simulate a real production scale. The products obtained an excellent reduction in surface tensions from 70 to 29 mN·m⁻¹ in the flask-scale, comparable to 33 mN·m⁻¹ in the 1.2-L reactor, to 31 mN·m⁻¹ in the 3-L reactor, and to 30 mN·m⁻¹ in the 50-L reactor. Regarding the yield, it was observed that the isolation by liquid-to-liquid extraction aided biosurfactant production up to 221.9 g·L⁻¹ with a critical micellar concentration of 0.5%. The isolated biosurfactant did not exhibit an inhibitory effect on the germination of vegetable seeds and presented no significant acute toxicity in assays with Artemia salina and Allium cepa. Among the different formulations of mayonnaise-like sauces, the most stable formula was observed with the addition of the biosurfactant at a concentration of 0.5% and the greatest results were associated with the guar and carboxymethyl cellulose gums. Thus, the biosurfactant from C. bombicola represents a promising alternative as a food additive in emulsions.

Contamination by oil and its derivatives causes serious damage to the environment, motivating the development of innovative technologies for the removal of these contaminants, such as the use of biosurfactants. In the present study, the biosurfactant from Candida tropicalis UCP0996 produced in the low cost-medium formulated with molasses, residual frying oil, and corn steep liquor, was characterized and its toxicity, formulation, and application in removal and biodegradation of oil were investigated. The surface tension of the medium was reduced to 30.4 mN/m, yielding 4.11 g/L of isolated biosurfactant after 120 h. Tests under extreme environmental conditions indicated the stability of the biosurfactant. Chemical characterization by thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (¹H NMR), and gas chromatography and mass spectroscopy (CG-MS) revealed the glycolipidic nature of the biosurfactant. The isolated biosurfactant showed no toxicity against the microcrustacean Artemia salina, while the properties of the formulated biosurfactant remained stable during 120 days of storage. The biosurfactant removed 66.18% of motor oil adsorbed in marine stones and dispersed 70.95% of oil in seawater. The biosurfactant was also able to increase by 70% the degradation of motor oil by seawater indigenous microorganisms, showing great potential to be applied as a commercial additive in the bioremediation of oil spills.

Silver nanoparticles have great potential in a wide range of applications. Therefore, the purpose of this work was to synthesize, in a simple and green way, via the Tollens method, silver nanoparticles (AgNPs), using as a stabilizer the biosurfactant produced by Bacillus cereus UCP 1615 cultivated in a low-cost medium, with waste frying oil as a substrate. The obtained nanoparticles were identified and morphologically characterized using ultraviolet/visible (UV/vis) spectroscopy, scanning electron microscopy (SEM), and zeta potential. The maximum UV/vis absorption was observed at 400 nm for newly formed silver nanoparticles, while, for silver nanoparticles stored for 120 days, the peak was observed at 430 nm. SEM micrographs confirmed the formation of nanoparticles, with predominantly spherical structures. The average size of the formed nanoparticles was estimated to be 20 nm. The presence of the biosurfactant promoted stability, as a zeta potential of −23.4 mV was observed. The antimicrobial potential of AgNPs was evaluated at different concentrations against three pathogenic fungi (Aspergillus niger, Penicillium fellutanum, and Cladosporium cladosporioides). No less than 100% and 85% inhibitions of P. fellutanum and A. niger growth were observed, respectively, at the AgNP concentration of 16.50 µg/mL in potato dextrose agar medium. These results suggest the potential use of the biosurfactant as a stabilizer for silver nanoparticles and its application as an antimicrobial agent.

Biosurfactants are amphipathic molecules with considerable potential for application in different industries due to their biochemical characteristics, low toxicity as well as greater biodegradability and stability compared to chemical surfactants when submitted to adverse environmental conditions. The aim of the present study was to investigate the production of a biosurfactant by Candida lipolytica UCP 0988 grown in a medium containing 4.0% molasses, 2.5% used soybean frying oil, and 2.5% corn steep liquor for 144 h at 200 rpm. The biosurfactant was characterized; its stability and toxicity were investigated, and the compound was applied in oil removal tests. In the C. lipolytica growth and biosurfactant production studies, the surface tension of the medium was reduced from 72 mN/m to 25 mN/m, the critical micellar concentration (CMC) was 0.5 g/L (w/v), and the yield was 12 g/L. Tests under extreme conditions of temperature, pH, and NaCl indicated the stability of the biosurfactant. Fourier-transform infrared and nuclear magnetic resonance spectroscopy of the chemical structure of the purified biosurfactant suggested that the biosurfactant is a glycolipid. The anionic biosurfactant exhibited no toxicity to the microcrustacean Artemia salina or vegetable seeds (Brassica oleracea). Dispersion tests in seawater demonstrated 100% efficiency of the biomolecule against motor oil. The biosurfactant was efficient at removing oil from sand in static and kinetic tests at concentrations of ½ CMC (0.25 g/L), CMC (0.5 g/L), and 2 × CMC (1.0 g/L), with removal rates of 70 to 96%, whereas the synthetic surfactants tested removed only 10 to 18% of the oil. Based on the findings, the biosurfactant analyzed has considerable potential for the remediation of contaminated coastal and marine environments due to oil spills.

With the increased demand for sustainable, hypoallergenic products, plant surfactants are a promising, eco-friendly option for cleaning products due to their low toxicity or even the absence of toxicity. In the present study, surfactant-rich extracts from Chenopodium quinoa, Glycine max, and Malpighia emarginata were assessed for their stability, antioxidant capacity, toxic potential, and cleaning potential in shampoo formulations. The surfactants in the extracts were isolated and characterized by NMR, UV-Vis, and FTIR spectroscopy. The results demonstrated that the extracts remained stable within the temperature and pH ranges tested. The antioxidant properties were also determined. In the analysis of irritation potential, G. max and C. quinoa exhibited low toxicity and no toxicity, respectively. The cleaning potential analysis confirmed that the extracts could be used as primary surfactants. Seven shampoo formulations were developed, which showed potential to reduce surface tension to the range of 27.1–31.7 mN/m and interfacial tension to the range of 5.4–7.3 mN/m. The wettability, percentage of solids, density, pH, and dirt dispersion of the formulas were within standard ranges, and the sebum removal capacity of the seven formulations was similar to or even better than that of a commercial shampoo.