Evaluation of SDS-coated iron nanostructure on the gene expression of bio surfactant-producing genes by Pseudomonas aeruginosa.

Bio surfactants are natural surfactants that induce emulsification, displacement, increased solubility, and mobility of hydrophobic organic compounds. In this study, the gene expression of biosurfactant production genes by Pseudomonas aeruginosa in the presence of sodium dodecyl sulfate coated iron nanostructure (Fe/SDS) were evaluated. Emulsification Index and Surface Tension reduction test to check stability and emulsification the rhamnolipid were done. Purification was evaluated using thin layer chromatography (TLC) and expression of rhlA, mvfR, lasR, rhlR genes was determined using q-PCR technique. Binding of nanoparticles to bio surfactants was confirmed by TEM. The best emulsification index, was by the sample that exposed to 1 mg/L Fe/SDS nanoparticles for 2 days. Rhamnolipid produced in the presence of nanoparticles had an acceptable ability to reduce surface tension. The Rf (retention factor) value obtained was 0.63 by chromatography. q-PCR results showed that the expression of rhlA, mvfR, lasR, rhlR genes was significantly increased in Fe/SDS treated cells, which indicates the significant positive effect (P < 0.05) of nanoparticles on biosurfactant production of treated cells. While, SDS and Fe alone were not affected significantly (P > 0.05) on the expression of these genes. Our findings indicated the importance of nanoparticles in increasing the expression of genes involved in the bio surfactant production pathway of Pseudomonas aeruginosa.

Simultaneous extraction and fractionation of petroleum biomarkers from tar balls and crude oils using a two-step sequential supercritical fluid extraction.

In this study a novel sustainable method based on supercritical fluid extraction (SFE) method was developed for simultaneous extraction and fractionation of petroleum biomarkers. We herein proposed a two-step supercritical fluid extraction method for crude oil and tar ball to separate the petroleum biomarkers into aliphatic and aromatic fractions. In the first step, pure scCO2 was used, while scCO2 modified was used as a solvent in the subsequent step. CO2 SFE can serve as an environmental-friendly alternative to common column chromatography method for petroleum biomarker or compositional analysis by GC-MS. The extraction process was shown to be selective, according to the polarity of the solvent, providing fractionation of aliphatic and aromatic hydrocarbons. Yet the total extraction procedure in SFE was significantly faster than column chromatography methods (~80 min vs. 8 h). We will discuss the implications of this SFE method as a novel sustainable alternative to the existing extraction techniques.

Facile Synthesis of Mixed Metal-Organic Frameworks: Electrode Materials for Supercapacitors with Excellent Areal Capacitance and Operational Stability.

Electrode materials with high surface area, tailored pore size, and efficient capability for ion insertion and enhanced transport of electrons and ions are needed for advanced supercapacitors. In the present study, a mixed metal-organic framework (MOF) (cobalt- and manganese-based MOF) was synthesized through a simple one-pot solvothermal method and employed as the electrode material for the supercapacitor. Notably, a Co-Mn MOF electrode displayed a large surface area and excellent cycling stability (over 95% capacitance retention after 1500 cycles). Also, superior pseudocapacitive behavior was observed for the Co-Mn MOF electrode in the KOH electrolyte with an exceptional areal capacitance of 1.318 F cm-2. Moreover, an asymmetric supercapacitor was assembled using Co-Mn MOF and activated carbon electrode as positive and negative electrodes, respectively. The fabricated supercapacitor showed a specific capacitance of 106.7 F g-1 at a scan rate of 10 mV s-1 and delivered a maximum energy density of 30 W h kg-1 at 2285.7 W kg-1. Our studies suggest the Co-Mn MOF as promising electrode materials for supercapacitor applications.