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The review discusses the development of a quantum chemical approach for calculating the thermodynamic clusterization parameters of surfactants at the air/water interface. It characterizes the intermolecular interactions that govern the process of surfactant association. Of particular interest are the dispersion interactions CH···HC between the hydrophobic chains of surfactants, as well as their accurate description within the exploited scheme and semiempirical methods. The scheme is based on calculating the thermodynamic parameters of formation for a certain number of surfactant monomers and small clusters with different chain lengths using the supermolecule approximation. Furthermore, it enables the construction of an additive scheme with assessed values of the increments of CH···HC interactions and interactions between the hydrophilic parts. This scheme provides equations for thermodynamic clusterization parameters per one surfactant molecule of infinite 2D films. The number of parameters adequately assessed within this approach is described in the previous review in Colloid Polym. Sci., 2015, 293, 3065–3089: the threshold chain length of spontaneous clusterization, the “temperature effect” of clusterization, and the assessment of the molecular tilt angle of the surfactant with respect to the interface. In this context, our aim is to describe additional parameters and experimental phenomena. These include the dependence of the area per surfactant molecule in a 2D monolayer at the LE-LC phase transition on temperature and chain length, the correlation of the surfactant clusterization threshold with the solubility threshold, and with the donor-acceptor properties of the substituents included in the hydrophilic part. We also explore surfactant binary mixtures, surfactant – alkane mixtures, and the role of amphiphiles in the formation of alkane adsorption layers. Additionally, we investigate the shifting of the acid or base value (pK_a, pK_b) of surfactants with chain elongation during monolayer formation, as well as the dendricity of surfactant domains with an increase in temperature or shortening of chain length.

Rapid, inexpensive, and low-power/solar light-driven photocatalytic degradation of organic pollutants to deal with annually produced trillion tons of synthetic dye wastewater to prevent water scarcity issues, ecotoxicological risks, and human health has always been challenging. To overcome this limitation, the present study synthesized earth-abundant, inexpensive copper oxide nanosheets using a simple single-step hydrothermal route. The structural, physicochemical, and functional properties of the nanosheets have been characterized using several characterization techniques. The photocatalytic activity was studied for two commonly industrially used organic dyes, Methylene Blue (MB) and Rhodamine B (RhB). The importance of this work is the usage of a cheap commercially available Phillips UV light (11 W) as well as direct sunlight. With several optimized conditions, almost complete degradation of both dyes was achieved within 35 minutes under low-power UV light and within 70 minutes by the direct illumination of natural sunlight. The enhanced photocatalytic performance can be correlated to the synergetic effect of a higher charge transfer mechanism, good catalytic ‘active surface area’ availability (13.2 m²/g), and several optimized parameters that affect the reaction efficacy. Additionally, five repeated uses of nanosheets without sacrificing performance confirmed their stability and sustainability as a promising candidate for large-scale industrial textile wastewater remedies.

There are two commonly used drilling fluids, namely water-based muds (WBMs) and oil-based muds (OBMs); however, the latter type is more desirable for drilling unconventional oilfield reserves. To account for the potential encounter of hydrogen sulfide (H₂S) while drilling, the utilized OBMs should contain scavenger(s) with an effective H₂S mitigation capability in order to in-situ capture this very lethal and corrosive gas. To the best of our knowledge, studies on incorporating H₂S scavengers in OBMs and their testing are still greatly lacking in open literature. Thus, this study contributes into the filling of this gap by preparing a mineral oil-based drilling mud (MOBM) containing potassium permanganate as a promising, widely available, safe, and cheap H₂S scavenger. The MOBM also comprised other ingredients including rhamnolipid biosurfactant as an emulsifier and octadecanethiol-modified (i.e., hydrophobized) zinc nanoparticles (serving as weighting agent). These materials have not been widely utilized so far in open literature for the preparation of MOBM. The results obtained from this study demonstrated that this mud could fully scavenge H₂S for up to 22.7 h (i.e., breakthrough time), and it took about 63 h for the MOBM to become fully saturated with H₂S. The scavenged amounts of H₂S at these times reached 324.4 and 485.8 g/barrel MOBM, respectively. The formulated MOBM also displayed an appropriate non-Newtonian shear thinning behavior, where the apparent viscosity dropped sharply from about 1.96 to 0.71 Pa.s upon increasing the shear rate to from 1 to 10 s⁻¹, followed by a gradual decrease down to 0.31 Pa.s at a shear rate of 1000 s⁻¹. Additionally, the formulated mud is able to dissipate a significant amount of thermal energy as inferred from its estimated high activation energy of 34.93 kJ/mol, suggesting a good thermal stability of the MOBM. The present study reveals the possibility of formulating mineral OBMs with effective H₂S for safely drilling sour oil and gas reservoirs.

Evaporation can drive initially homogeneous multiphase liquid systems out of equilibrium to induce liquid-liquid phase separation (LLPS). Here, we demonstrate evaporative LLPS in microfluidic-generated emulsion microdroplets of polymer mixtures. The evaporation produces distinct polymer phases within the microdroplets. Phase separation occurs even with polymer combinations that do not form distinct phases in sessile droplet evaporation. We attribute this aspect to evaporation-driven solutal Marangoni flows and the interface capture accumulating the nuclei at the apex where the evaporation rate is the maximum. A fast coalescence and growth of the accumulated polymer nuclei occurs inside the droplets, unlike the capillary-flow-induced spread-out of the nuclei along the contact line in sessile drops. Our method of evaporation of the droplet cluster may facilitate studying LLPS in volume-limited environments and have implications for understanding LLPS in biological systems.

In the current research, acyclovir-loaded microbeads were formulated via ionotropic gelation using sodium alginate-gellan gum and sodium alginate-xanthan gum. In the preparation of these acyclovir-loaded microbeads, aluminium chloride and barium chloride were used as cross-linking agents. All these ionotropically-gelled acyclovir-loaded alginate-gellan gum microbeads and alginate-xanthan gum microbeads exhibited good percent yields (85.07 ± 1.58 to 92.17 ± 3.02%) and drug entrapment efficiencies (74.09 ± 1.38 to 95.16 ± 3.37%). Acyclovir-loaded alginate-gellan gum microbeads exhibited comparatively smaller average particle sizes (0.54 ± 0.02 to 0.71 ± 0.03 mm) than those of acyclovir-loaded alginate-xanthan gum microbeads (0.60 ± 0.02 to 0.82 ± 0.04 mm). Acyclovir-loaded alginate-xanthan gum microbeads exhibited comparatively higher swelling than that of acyclovir-loaded alginate-gellan gum microbeads. A sustained pattern of acyclovir release over 240 min was noticed by these microbeads. Surface morphology analysis of the best microbeads formulation (on the basis of sustained acyclovir release data) was done by scanning electron microscopy (SEM). These kinds of ionotropically-gelled alginate-based microbeads might be advantageous to facilitate enhanced patient compliances with minimal dosing frequency and enhanced oral bioavailability.

Tocopherols are fat soluble substances with antioxidant properties. The α-Tocopherol (T) is the major form of Tocopherols and can decrease the risk of cancer. F127-based and Lignin-based oil-in-water microemulsions seem to increase the bioavailability of T and cause better release of this therapeutic agent. Thus, T-loaded microemulsions were designed by means of density functional theory (DFT) and semi-empirical methods. Atoms in molecules (AIM), natural bond orbital (NBO) analyses, localized molecular orbital energy decomposition analysis (LMO-EDA), and density of states plots were employed to explore the effective factors on the strength of the interactions between surfactants and T. Results indicate that F127-T complexes are more stable than Lignin-T ones. Furthermore, the stable release of T in microemulsions is due to the electrostatic interactions between surfactants and T. Formation of hydrogen bond (HB) interactions between surfactants and T stabilizes the microemulsion system. These interplays are suggested to take part in the better function of T in microemulsions compared to free T. The semi-empirical study reveals that the heats of formation (ΔH_f values) of the F127-T complexes are less negative than those for the Lignin-T ones.

A new mathematical solution to the non-linear Poisson-Boltzmann differential equation for solid-liquid dispersions in presence of different dissymmetrical electrolytes was given. The analytical expressions of the surface and charge density of solid particles were given. The variations of electrostatic potential ψ (x) and charge density σ (x) of dispersed particles against the distance x were obtained. For colloidal particles in presence of E(m-n) electrolytes with $m\ne n$ with $m\ge 3,n\ge 3$ and for E(2–3) and E(3-2) electrolytes, the mean electrostatic potential as a function of the distance was numerically integrated by Mathematica program version 13.

The experimental study of silica suspensions in presence with the following electrolytes $NaCl$, ${Na}_2{SO}_4$, $Ca{Cl}_2$, ${Na}_3{PO}_4$, $Al{Cl}_3$, ${Al}_2{\left({SO}_4\right)}_3$, ${Ca}_3{\left({PO}_4\right)}_2$, ${Na}_4{P_{2}O}_7$ and ${Na}_5{P_{3}O}_{10}$ led to confirm the theoretical predictions obtained from the analytical solution of Poisson-Boltzmann equation. The results obtained allowed to determine the surface potential as a function of pH of the suspension and the electrostatic potential versus the distance x. The variations of the dissociation coefficient of silica surfaces were determined. An important effect of the anion and cation valences of the dissymmetrical electrolytes on the surface charge density and potential was highlighted.

The spread of bacterial infections aggravated by the development of microbial resistance to antibiotics requires the creation of protective antibacterial materials. Nanomaterials with biocides can provide antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria. In this work, we synthesized nanocomposites with silver nanoparticles and different polyoxometalates of Keggin-structure (phosphomolybdic, phosphotungstic, and tungstosilicic acids) on eco-friendly nanoclay called halloysite. We found that the nanocomposite containing silver nanoparticles and phosphomolybdic acid deposited on the halloysite possesses the best antibacterial performance of all the obtained composites, having a minimal inhibitory concentration of 0.5 g/L against S. aureus, 0.25 g/L against P. aeruginosa and A. baumannii. This composite reduces the viability of formed biofilms at a concentration of 2.5 g/L.