Reclined trend of alkyl chain of sodium dodecylbenzenesulfonate molecules induced by friction

Surfactants tend to adsorb on the surface/interface mostly in a directional manner. The alkyl chain orientation and conformation order for molecular monolayers of sodium dodecylbenzenesulfonate (SDBS) at low concentrations are studied by using the sum frequency generation vibrational spectroscopy (SFG-VS). The molecular arrangement of the surfactants adsorbed at the solid/liquid interface is further investigated. It is found that the arrangement of the SDBS at the interface becomes relatively ordered with increasing bulk concentration. Meanwhile, the orientation angle reduces gradually, and the molecules tend to be upright state. In addition, the effect of friction on the conformation order and orientation angle are also analyzed. The intensity of the SDBS vibrational contraction peak becomes lower after friction, which indicates that the anion has a reorientation process at the interface. The arrangement of molecules becomes more disordered due to friction. The orientation angle increases slightly, which indicates the monolayer has an inclined trend relative to the lateral direction on the interface. A modified adsorption model considering friction effect is proposed. This work may provide a reference for the further study of adsorption mechanism and application of surfactants.

Confined Pulsed Diffuse Layer Charging for Nanoscale Electrodeposition with a Scanning Tunnelling Microscope

Regulating the state of the solid-liquid interface by means of electric fields is a powerful tool to control electrochemistry. In scanning probe systems, this can be confined closely to a...

Contact Electrification through Interfacial Charge Transfer: A Mechanistic Viewpoint on Solid-liquid interface

Contact Electrification (Triboelectrification) has been a long-standing phenomenon for 2600 years. The scientific understanding of contact electrification (triboelectrification) remains un-unified as the term itself implies complex phenomena involving mechanical contact/sliding...

The relationship between solid-liquid interface interaction and gelling capacity of h-BN 2D material: a rheological study

Diurea modified h-BN nanosheet is a novel kind of 2D gelator that could gel the lubricating oils under the stimulus of ultrasound. Morphological analyzations in previous study confirmed that the ultrasound induced layer-by-layer (LBL) structure of BN gelator is critical for the gelation. However, the elastic response in LBL structure, which is crucial for the formation of a stable gel system, has not been explicitly illustrated yet. The challenge is that the LBL gelator structure is based on 2D material and thus lacks vertical linkage between gelator layers, which is significantly different from the traditional gel systems that generally possess highly crosslinked gelator network. In this work, by investigating the viscoelastic behavior of the BN-based gel via rheometer, it is found the solid-liquid interface interaction, which is regulated by the diurea molecular structure in the BN gelator, is the key factor for triggering the stable elastic response in the LBL structure, and the elasticity mainly originates from the interface interaction induced bending deformation of h-BN 2D material. The findings further elucidate the gelling mechanism of BN gelators and enlighten the structure design of ultrasound-responsive gelator based on 2D materials.

Application of Surfactant Modified Natural Zeolites for the Removal of Salicylic Acid—A Contaminant of Emerging Concern

This work aimed to test composites (surfactant modified zeolites prepared by treatment of natural zeolites—clinoptilolite (IZ CLI) and/or phillipsite (PHIL75)-rich tuffs with two different amounts of cationic surfactants: cetylpyridinium chloride (CPyCl) and Arquad® 2HT-75 (ARQ)) for the adsorption of salicylic acid (SA)—a common contaminant of emerging concern. Adsorption of SA was studied at different initial drug concentrations (in the range of 2–100 mg/L) in water solution. The Langmuir isotherm model showed the highest adsorption was achieved by bilayer composite of IZ CLI and CPyCl—around 11 mg/g. Kinetic runs were performed by using the initial drug concentration of 20 mg/L in the time interval from 0 to 75 min and pseudo-second order had good correlation with experimental data. The influence of the four different temperatures on the SA adsorption was also investigated and thermodynamic parameters suggested that the adsorption drug onto composites is an exothermic and nonspontaneous process, followed by the decrease of randomness at the solid/liquid interface during the adsorption. Zeta potential and Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) had been performed for the characterization of composites after adsorption of SA confirming the presence of the drug at composite surfaces.