Surface tension of multicomponent organic mixtures: Measurement and correlation

Dong

et al. 2023

Preprint

The present work designs a series of cycloalkyl ester oils and reports a comparative study on their physicochemical and tribological properties, biological toxicity and degradability. From the perspective of molecular structure, the factors affecting their physicochemical, tribological properties, biological toxicity and degradability were discussed, including steric hindrance, group polarity and so on. The results demonstrated that cycloalkyl ester oils had better thermal stability and viscidity-temperature capability than the reference oils. Additionally, their friction reducing and anti-wear performance was superior to the reference samples. Unexpectedly, the cycloalkyl ester oils were found to have higher toxicity to the experimental plants (wheat and pak choi) due to the introducing of the cycloalkyl group, which enhanced the lipophilicity of the corresponding oils and then strengthen the damaging of the oils to plant cell. Some of the cycloalkyl ester oils, on the other hand, were proved to be more biodegradable than the reference samples. On the whole, developing green lubricants by replacing aromatic rings is not entirely successful. Lubricants' biodegradability can be improved with this replacement, but their ecotoxicity cannot be reduced. Anyway, the present work provides a specific benchmark for the subsequent development of environmentally friendly, high-performance synthetic ester lubricants.

Section: Adsorption Propertymentioning

confidence: 99%

WITHDRAWN: Is Replacement of Aromatic Compounds with Alkyl Ones Really the Effective Way toward Developing Greener Lubricants?

Dong

et al. 2023

Preprint

“…Surface tension (top) and interfacial thickness (bottom) for the pure substances toluene (black), CO 2 (blue), and N 2 (light blue). Crosses are experimental data from the literature: toluene, ,− CO 2 , − and N 2 . − Solid lines are the results from DGT (this work). Open symbols a...…”

Section: Resultsmentioning

confidence: 99%

Vapor–Liquid Interfacial Properties of the Systems (Toluene + CO₂) and (Toluene + N₂): Experiments, Molecular Simulation, and Density Gradient Theory

Stephan,

Fleckenstein,

Hasse

2023

J. Chem. Eng. Data

Vapor−liquid interfacial properties of the binary systems (toluene + CO 2 ) and (toluene + N 2 ), as well as for the three pure components toluene, CO 2 , and N 2 , were studied using experimental and theoretical methods. Data on the surface tension and the relative adsorption were obtained from pendant drop experiments as well as from molecular dynamics (MD) simulations and density gradient theory (DGT) + perturbed-chain polar statistical associating fluid theory (PCP-SAFT). The experiments were carried out at temperatures between 303.15 and 373.15 K and pressures up to 5.7 MPa. MD and DGT calculations were carried out at 283.15, 303.15, 323.15, and 343.15 K in the entire composition range. MD and DGT were also used for studying the enrichment of the low-boiling component and the thickness of the interface. Furthermore, the vapor−liquid equilibrium (VLE) bulk phase properties were computed by MD and PCP-SAFT and compared to experimental data from the literature. The data from the different methods were found to be in good agreement throughout. The comparison of the results for the two studied mixtures provides insights into the link between phase behavior, interfacial properties, and molecular interactions.

“…Posteriormente se centrifugó a 5000 r/min durante 15 min (centrífuga Eppendorf 5804, Alemania) y se separó el sobrenadante. Se realizaron diluciones seriadas del cultivo libre de células, se midió la tensión superficial de cada dilución por el método del anillo de Du Noüy (tensiómetro Kruss K100, Alemania) (Vakili-Nezhaad et al 2019) y se calculó la dilución mínima del tensioactivo a partir de la cual se forman micelas en una disolución e manera espontánea (dilución micelar crítica, CMD). Además, se determinó la concentración de ramnosa por el método espectrofotométrico de Chandrasekaran y Bemiller (1980) empleando una solución de ramnosa como patrón (espectrofotómetro UV-visible, Genesys 10S).…”

Section: Producción Del Crudo De Ramnolípidosunclassified

Aplicación de ramnolípidos de Pseudomonas sp. Y3-B1A en la biodegradación de hidrocarburos a diferentes escalas

Martín

León²,

Rodríguez³

et al. 2022

RICA

La acumulación en suelos de petróleo crudo y sus derivados es un problema ambiental grave. La biorremediación es una tecnología de saneamiento de ecosistemas contaminados ampliamente estudiada y aplicada, cuya eficiencia puede estar limitada por la baja solubilidad y toxicidad de los contaminantes. El empleo de biotensioactivos favorece la solubilización de moléculas hidrofóbicas e incrementa la biodisponibilidad. En este trabajo se evaluó la influencia de la bioestimulación con ramnolípidos de Pseudomonas sp. Y3-B1A en la degradación de hidrocarburos a diferentes escalas, determinando a su vez la toxicidad de estas moléculas. En el laboratorio se evaluó la degradación en medio líquido suplementado con crudo e incubado por 28 días. El empleo de ramnolípidos incrementó en 61.7 % el porcentaje de degradación de hidrocarburos totales del petróleo (HTP) con relación al tratamiento sin aditivos. En los microcosmos y parcelas de suelo, se calculó la degradación de HTP, grasas y aceites (GA), compuestos saturados, aromáticos, resinas y asfaltenos a los 30 días. Además, se determinaron las concentraciones de nitrógeno y fósforo, así como el crecimiento microbiano. En los microcosmos la aplicación de ramnolípidos incrementó en más del 40 % la degradación de HTP, compuestos saturados y aromáticos. En las parcelas el incremento de la degradación de HTP y compuestos aromáticos fue de 33 a 34 %, mientras que la de GA alcanzó 86.5 %. La aplicación de ramnolípidos incrementa la biodegradación de hidrocarburos sin provocar efectos tóxicos en el ecosistema.