The Raman detection of trace substances in complex oil is still a great challenge at present because of the strong disturbance of background activity and the suppression of intensity in spectra caused by complicated components. In this work, a simple and robust approach based on microdroplet liquid–liquid extraction for the real-time Raman spectroscopy monitoring of trace substances in complex oil is reported. Based on unbalanced chemical potentials between water and oil on a microfluidic chip, a target trace molecule is extracted from complex mineral oil to a water microdroplet. Benefiting from the real-time fluorescence intensities of fluorescein in a water microdroplet, the extraction performance is investigated and optimized. The optimal water microdroplet is implemented for the Raman detection of furfural in a complex mineral oil, a typical trace performance marker in electric power equipment, and this exhibits excellent sensitivity with a limit of detection (LOD) of 26 ppb. Compared to traditional detection technology for trace substances in complex oil (high performance liquid chromatography, HPLC), this method greatly simplified the process of measurement, reduced the volume of sample required, had a fast measurement time, and exhibited the prospect of real-time monitoring applications with high sensitivity, which not only promotes the development of oil quality but also enlarges existing knowledge related to using Raman spectroscopy in chem−/bio-sensing.
Despite advances in membrane technology, the separation of complex oily wastewater using membrane filtration remains a daunting challenge for the industry. Recent approaches including membrane modification with two-dimensional (2D) nanosheets, showed susceptibility to swelling, fouling, and instability during operation. As a game-changer approach, a polyacrylonitrile (PAN) UF membrane modified with 3D nanostructured composite of MXene and O-MWCNT was introduced for the first time to treat complex oily wastewater. The composite membrane showed high separation performance of soluble dye-oil-water emulsion while maintaining high water permeability. Moreover, during the operational period, the composite membrane exhibits excellent antifouling and anti-swelling properties due to the synergetic effects conferred by the 3D nanostructures. Furthermore, the composite membrane possesses remarkable chemical stability evidenced by its high corrosion resistance when exposed to a strong acid (3 M HCl) and oxidant (NaOCl) solution for a long-time period. Overall, the operational stability was maintained in terms of flux and high rejection of oil and dye over a 45 h long-term operation. Consequently, this work provides an innovative, stable, and highly facile process for fabricating scalable UF composite membrane for the treatment of complex oily wastewater in a harsh chemical environment.
危险品化学品经营许可证（带存储）