| In recent years,superhydrophobic surfaces play important roles in environmental protection,energy,green industry,and many other important fields,attracting great interest from researchers.Brass is one of the most widely used alloys in industry,with excellent electrical conductivity,thermal conductivity,and diamagnetic properties.In this paper,different methods are used to hydrophobically modify brass substrates,and the following two aspects of research are carried out around these hydrophobic brass materials:(1)Brass wires with different surface wettability were used for in-tube solidphase microextraction to explore the effect of hydrophobic/hydrophilic interactions on the enrichment mechanism of model analytes;(2)Two controllable water infiltration methods are demonstrated.One was performed via rough brass mesh membranes modified by three pH-responsive molecules;the other was to construct Janus membranes(JM)with hierarchical micro/nanostructures and pH-responsive properties.In previous studies on solid-phase microextraction,the mechanism of strong enrichment and high selectivity was usually explained by the synergistic effect of multiple actions.To explore the main interactions between coating materials and model analytes during extraction,brass wires with different surface wettability were prepared for in-tube solid-phase microextraction.Here,a series of brass wires were soaked in an acidic ferric chloride solution and sonicated,and the surface wettability of the pristine brass wires changed from hydrophobic to hydrophilic due to the formation of micro/nano-scale hierarchical structures.After modification with n-octadecanethiol(ODT)and 2-naphthalenethiol(NT),respectively,both brass wires exhibited superhydrophobicity.To construct an in-tube solid-phase microextraction-high performance liquid chromatography(HPLC)online system,the extraction tube was connected to the HPLC instead of the loop.Four types of brass wires,original hydrophobic brass wire,chemically etched hydrophilic brass wire and two superhydrophobic brass wires,were used for the extraction of six estrogens.The extraction and elution conditions were investigated,and the extraction efficiency of the NT-modified superhydrophobic brass wire was the highest under the optimal conditions,and the enrichment factor was in the range of 36-350.Furthermore,the superhydrophobic NT brass wire exhibited higher extraction efficiency than the ODT brass wire with the same superhydrophobicity.This indicates that the higher extraction efficiency mainly depends on the interaction between the naphthalene ring-containing adsorbent and the benzene ring-containing target compound.Based on the preparation of superhydrophobic brass wire using 2-naphthalene thiophenol(NT),through a simple chemical corrosion method and surface modification,two formulations were obtained to prepare pH-responsive intelligent brass meshes,which can be used for continuous separation of acid-alkali waste water.Type Ⅰ smart brass meshes were modified by 3-mercaptobenzoic acid and NT,and type Ⅱ intelligent brass meshes were modified by 11-mercaptoundecanoic acid and NT.The three pHresponsive molecules were self-assembled on the etched brass meshes,and the pHresponsive self-assembled monolayer was formed by chemical adsorption onto the etched brass meshes,thereby different surface wetting characteristics were generated according to the pH value,and realizes the on-off control of water penetrating intelligently.In addition,the pH-responsive smart JMs obtained by integrating smart brass mesh and hydrophobic nickel foam by pressure method on the basis of the abovementioned type Ⅰ and Ⅱ pH-responsive smart brass mesh membranes exhibit liquid unidirectional transport performance and pH-responsive liquid transport properties.Here,the two sides of the JM are modified separately and then tightly combined by pressure,which avoids the solvent permeating the entire membrane when the same membrane is modified on one side.The resulting smart JMs have been applied in scenarios such as smart switches in air-water systems and liquid-liquid systems,providing another strategy for exploring novel applications of JMs for advanced separations. |
