Коллоидный журнал

The sorption of thiocyanate ions under various conditions on a Cr-polymer composite and, for comparison, on a strongly basic anion exchanger Purolite A-400(Cl) was studied. Temperature has a significant effect on sorption on the composite and a minor effect on Purolite A-40(Cl). The sorption of thiocyanate ions on both sorbents practically does not depend on the pH of the solution in the range 2-12. The rate of thiocyanate ion sorption is limited by mixed intra-particle and boundary layer diffusion. The sorption isotherms obtained at 18 and 60 ^oC on Purolite A-400 are well described by the Langmuir sorption model, and on the Cr-polymer composite – by the Freundlich model. The difference in the magnitude of sorption on these composites is explained by the fact that on Purolite A-400(Cl) the retention of thiocyanate ions occurs as a result of ion exchange, while on the Cr-polymer composite it occurs as a result of ion exchange and complex formation. The Cr-polymer composite loaded with thiocyanate ions becomes a sorbent with selective sorption properties in relation to heavy metal cations, which is confirmed by the retention of Hg²⁺ ions from solution.

Amorphous titanium dioxide (TiO₂) nanoparticles were synthesized via a sol–gel reaction using titanium tetrachloride (TiCl₄) as the precursor. Acrylic acid (AA) was introduced to modify the particle surface, preventing aggregation and enabling functionalization. Fourier transform infrared analysis revealed that a reaction time of 48 hours was necessary to complete the surface modification through chelation and condensation. To optimize processing conditions, reactions were performed at 25 °C and 50 °C with varied TiO₂: AA molar ratios. Results showed that at 50 °C, excessive AA (1:14) led to over-polymerization, while insufficient AA (1:6) failed to stabilize the particles. In contrast, the intermediate concentration (1:10) produced well-dispersed spherical nanoparticles (10-15 nm), as confirmed by dynamic light scattering (DLS) and transmission electron microscope (TEM). This study demonstrates that tuning AA concentration and reaction temperature enables kinetic control over surface modification, effectively stabilizing amorphous TiO₂ in aqueous media. It offers a simple and scalable approach for preparing size-controlled, surface-functionalized amorphous TiO₂ nanoparticles with potential optical and functional applications.

Modernization raised many concerns for environment, growing industrialization created major issues for fresh water bodies. In this study, magnetite nanoparticle modified Pennisetum glaucum was employed for the adsorptive removal of Crystal violet (CV), Safranine O (SO), and Mmethylene blue (MB) dye in single, binary and ternary system. The optimization of adsorption parameters was evaluated with the help of Response Surface Methodology (RSM). Adsorption kinetics, isotherm, and thermodynamics study were employed to study the effect of time, concentration, and temperature respectively. Pseudo second order model was the best fitted kinetic model and Freundlich isotherm model was the best suited Isotherm model for all the three dyes. The q_max value (Maximum adsorption capacity) obtained from Langmuir model were 158.22 mg/g (SO), 217.39 mg/g (CV), and 122.10 mg/g (MB). The modified Langmuir isotherm model was explored to study the adsorption interaction mechanism in binary and ternary system. The competitive interactions between the co-existing dyes in the binary and ternary system resulted into the decreased maximum adsorption capacity. The adsorption mechanism was concluded as a result of electrostatic interactions, H-bonding, and pi-pi stacking. Overall, magnetite nanoparticle modified Pennisetum glaucum biosorbent can be helpful for reducing water pollution associated with dye pollutants.

Ultra-high molecular weight polyethylene (UHMWPE) has become the preferred material for joint liners due to its excellent wear resistance and chemical stability. This study provides a basic investigation into how water absorption influences the tribological behavior and mechanical characteristics of UHMWPE. The surface plastic deformation layer formed during UHMWPE wear was found to exhibit significant changes after water absorption. Experimental results demonstrate that water absorption not only reduces the friction coefficient of the material by 7.79%, but also exacerbates plastic deformation, resulting in an increase of wear up to 4-fold compared to the control group. Raman spectroscopy analysis further confirmed a notable rise in surface crystallinity after water absorption. Indentation tests show water absorption decreases indentation depth. Molecular simulation results suggest that water absorption in UHMWPE chains tends to reduce the inter-molecular interactions and thereby facilitates the formation of ordered arrangements of surface polyethylene, leading to an anisotropic distribution, i.e., ordered alignment in parallel to the frictional direction, and anisotropic mechanical properties. The anisotropic distribution of surface polymer chains during friction, which was also strengthened after water absorption, in turn increases the resistance to indention. The investigation results of the tribological properties and mechanical characteristics of water-absorbed UHMWPE may provide useful insights for the evaluation and performance of artificial joints.

Silver nanoparticles (AgNPs-E) biosynthesized at room and boiling T, stabilized by blackberry plant extracts (E) obtained by maceration at room T and reflux extraction at boiling T, are presented in this work. The obtained AgNPs-E were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and zeta potential measurement. XRD analysis confirmed that the 2θ peak at 38.2°, corresponding to the (111) plane, was the most intense, with the average crystallite size in the range of 18.0±3 − 21.1±2 nm. SEM spectroscopy showed that spherical shapes of nanoparticles dominate in the reaction mixture. EDX spectroscopy showed the presence of elemental silver in the formed AgNPs-E, along with the presence of C and Mg, which probably originate from the biomolecules of the extracts. DLS provides the size distribution with the average particle size in the range of 50.93±0.83 − 74.48±1.84 nm, with negative zeta potential ranged from -25.87±1.63 mV to -0.3027±0.36 mV indicating the AgNPs stability. The antimicrobial activity of AgNPs-E was tested by microdilution method confirming that both nanoparticles and extracts show the ability to inhibit all the bacteria and a fungus tested. The presented results suggest further investigations of synthesized AgNPs-E for application in topical cosmetic preparations.