A novel supramolecular solvent (SUPRAS) based on hexafluoroisopropanol (HFIP)/Brij-35 was proposed for liquid-phase microextraction (LPME) of parabens in water samples, pharmaceuticals and personal care products. Brij-35 is a cost-effective and non-toxic non-ionic surfactant, but it has a high cloud point (>100 °C). HFIP, with the features of strong hydrogen-bond donor, high density and powerful hydrophobicity, was used as the cloud point-reducing agent and self-assembling and density-regulating solvent of Brij-35. Upon adding HFIP into the Brij-35 aqueous solution, the cloud point of Brij-35 was decreased to below room temperature, and the SUPRAS was formed in the bottom over a wide range of HFIP and Brij-35 concentrations at room temperature. The SUPRAS was composed of Brij-35, HFIP and water, having a density larger than water, and it showed a large spherical structure of positive micellar aggregates (2–8 μm). The HFIP/ Brij-35 SUPRAS-based LPME procedure was non-thermodependent and could be performed at room temperature with centrifugation using normal centrifuge tubes, being very simple. In the extraction of six parabens, the HFIP/ Brij-35 SUPRAS-based LPME method showed short extraction time (3.3 min), low solvent consumption (0.3 mL), and large enrichment factor (26–193). The method of HFIP/ Brij-35 SUPRAS-based LPME with HPLC-DAD gave good linearity for the quantification of parabens with correlation coefficients larger than 0.9990. The limits of detection based on a signal-to-noise ratio of 3 were from 0.042 to 0.167 μg L −1 . The recoveries for the spiked real samples were in the range of 90.2–112.4% with relative standard deviation less than 8.9%. Except for tap water, one or several paraben (s) were detected in all the other real samples.
TiO 2 with different morphology as supports can lead to different surface properties and catalytic activities of catalysts. Herein, we reported a novel facile evaporation-induced assisted hydrothermal approach to synthesize three-dimensional hierarchical structure TiO 2 assembled from needle flakes by using Brij-35 as the morphology-directing agent. The morphology of the prepared TiO 2 from flower-like (TiO 2 -FT), sea urchin-like (TiO 2 -SUT), to ball-like (TiO 2 -BT), as well as the size of needle flakes, were controlled by adjusting the amount of Brij-35. These TiO 2 supported palladium catalysts were facilely prepared using a green bio-reductive method with Catalpa Fruit extract as reducing agent, where they showed remarkable catalytic activity in selective hydrogenation of 4-nitrophenol by sodium borohydride. Especially, 1 wt%Pd/TiO 2 -SUT with sea urchin-like exhibited higher reaction rate constant (1.44 min −1 ) than 1 wt%Pd/TiO 2 -FT (1.08 min −1 ) and 1 wt%Pd/TiO 2 -BT (0.72 min −1 ). Furthermore, XRD, N 2 adsorption–desorption, SEM, TEM, CO-FTIR, XPS and CO chemisorption measurements were performed to study the effects of different surface morphologies on the surface properties of catalysts. It reveals that the high catalytic performance of 1 wt%Pd/TiO 2 -SUT can be attributed to its specific hierarchical structure and much higher surface area, improving the uniform dispersion of Pd nanoparticles on the support to expose extra active surface Pd atoms (Pd 0 species) over 1 wt%Pd/TiO 2 -SUT.
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