Effect of 2D Alpha-Zirconium Phosphate Nanosheets in Interfacial Tension Reduction and Wettability Alteration: Implications for Enhanced Oil Recovery

Summary α-Zirconium phosphate (α-ZrP) nanocrystals were synthesized by refluxing method and subsequently exfoliated into extremely thin 2D nanosheets by tetrabutylammonium hydroxide (TBAOH) solution. Dynamic light scattering, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the size distribution and morphology of α-ZrP nanosheets. Interfacial tension (IFT) and contact angle measurement were conducted by different concentrations of α-ZrP nanosheets solutions. The results displayed that the wettability of porous media surface was altered from oleophilic to hydrophilic and the IFT decreased with the increasing of α-ZrP nanosheets concentrations. A new method was proposed to calculate the Hamaker constant for 2D α-ZrP nanosheets. The calculated results displayed that α-ZrP nanosheets were not easy to agglomerate under experimental environment and when the interaction energy barrier increased, the transport amount of α-ZrP nanosheets also increased. Coreflooding tests were also performed with various concentrations and the oil recovery efficiency increased from 33.59 to 51.26% when α-ZrP nanosheets concentrations increased from 50 to 1,000 ppm.

The Determination of Metronidazole and Chlorhexidine Gluconate in Metronidazole and Chlorhexidine Lotion by HPLC

Objective “To establish an HPLC method for the determination of metronidazole and chlorhexidine gluconate in metronidazole and chlorhexidine lotion. Method Using Agilent Eclipse-XDB-C18 chromatographic column, with 0.05 mol·L-1 potassium dihydrogen phosphate solution 1000 ml plus 13.2 ml 10% tetrabutylammonium hydroxide aqueous solution (pH adjusted to 3.5 by phosphoric acid)-acetonitrile (77:23) as Mobile phase, detection wavelength 230 nm. Results The two components could be separated well. The linear ranges of metronidazole and chlorhexidine acetate were 36.33~59.04 μg·ml-1 (r = 0.9994) and 35.45~220.11 μg·ml-1 (r = 1).); The average recoveries were 100.6% and 100.5 %, and the RSD were 0.42% and 0.58%. Conclusion: The method is simple and specific, and the result is more accurate and reliable. Which is suitable for simultaneous determination of two components in compound preparations.