Colloids and Interfaces

Wettability determination is of crucial importance for multiphase flow in porous media. Currently available methods are either applied to simplified geometries (sessile drop) or are time-consuming (Amott, USBM) and cost-intensive (micro-CT scanning). The purpose of this study is to systematically test the streaming potential method as a fast, cheap, and in situ applicable method for surface probing and determination of the wetting state of soda lime glass beads through zeta potential. Different wetting states are achieved by means of silanization and are characterized by an average contact angle. Comparison of contact angles measured by sessile drop on plate geometries and contact angles derived from bead pack micro-CT images confirmed that the treatment is transferable to the bead packs. The correlation between the zeta potential of the single bead size packing with a single wetting state and the contact angle is non-unique over the entire range of tested treatment volume ratios. The contact angle plateaus at higher degrees of silanization, while the zeta potential values still change. Before the plateau, a correlation between contact angle and zeta potential is present. Zeta potential measurements on the mixtures of the same-sized beads with two different wetting states confirm the existing theory that the apparent zeta potential is a surface area-weighted average of constituents. For a mixture where the zeta potential is size dependent, a new correlation for a dual bead system was derived. The non-unique correlation between zeta potential and contact angle, combined with a bead size-dependent zeta potential, will limit the use of zeta potential for contact angle derivation for the system of soda lime glass beads with various silanization coatings used here. Monitoring relative changes of wetting conditions might still be possible.

In this preliminary study, chitosan-based molecularly imprinted polymers crosslinked with glutaraldehyde were synthesized and evaluated for the selective removal of m-cresol, a volatile phenol associated with the sensory defect known as smoke taint in wine. Three formulations of chitosan-based molecularly imprinted polymers (MIP-Gs) were synthesized using glutaraldehyde as a crosslinker and m-cresol as a template. Non-imprinted polymers (NIP-Gs) served as controls. The polymers were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, which confirmed successful crosslinking and structural differences between MIPs and NIPs. Adsorption performance was evaluated using solid-phase extraction cartridges packed with the synthesized polymers, employing a Cabernet Sauvignon wine. The MIPs exhibited higher adsorption efficiency and selectivity toward m-cresol compared to NIPs, achieving removal rates of 15% to 40%, depending on polymer formulation and analyte concentration. Molecular dynamics simulations were used to investigate polymer–analyte interactions at the molecular level, providing mechanistic insight into the preferential binding of m-cresol within the imprinted cavities. Physicochemical analyses of red wine showed that m-cresol removal occurred with minimal impact on key phenolic parameters, supporting the functional selectivity of MIPs. These results demonstrate that chitosan-based MIPs constitute a promising class of materials for selective adsorption applications in complex liquid systems.

Herein, a cobalt–molybdenum bimetallic oxide precursor was synthesized via a hydrothermal route, followed by a phosphidation strategy in a tube furnace to produce a CoMoP cocatalyst. Subsequently, a CoMoP/BiVO₄ composite photoanode was successfully constructed by loading the CoMoP cocatalyst onto the surface of an electrodeposited BiVO₄ film using a drop-casting method. A suite of analytical tools such as TEM, XRD, and XPS was utilized to comprehensively examine the material morphology and crystalline features, verifying that CoMoP was effectively anchored on the BiVO₄ surface with intimate interfacial contact. Photoelectrochemical (PEC) performance testing indicated that the composite photoanode achieved optimal performance with a 200 µL loading of the CoMoP dispersion (2 mg/mL). Under front-side illumination, the photocurrent density of the CoMoP/BiVO₄ composite photoelectrode reached a photocurrent density of 2.8 mA/cm² at 1.23 V (vs. RHE), which is approximately 3.1 times higher than that of unmodified BiVO₄ (0.9 mA/cm²). Under back-side illumination, the composite photoanode generated 3.5 mA/cm², representing a 2.3-fold improvement over the 1.5 mA/cm² recorded for bare BiVO₄. The bandgap energy of BiVO₄ was determined to be approximately 2.44 eV based on UV–vis absorption spectra and the corresponding Tauc plot. Owing to its metallic nature, CoMoP exhibits strong broadband absorption in the visible-light region and does not display an intrinsic semiconductor bandgap behavior. Combined with photoluminescence (PL) spectroscopy and PEC results, it was demonstrated that the CoMoP loading effectively promoted interfacial charge separation and transport while accelerating water oxidation kinetics. These results demonstrate that the CoMoP/BiVO₄ system serves as an advanced semiconductor material with excellent performance for photoelectrocatalytic water splitting.