Determination of surface free energy components of organic liquids by the thin layer wicking method

Using the layer wicking method (TLW method) the electron-donor interactions of surface free energy of the organic liquids: benzene (C6H6), toluene C6H5CH3), and tetrahydrofuran ((CH2)4O) was determined. For this purpose the penetration rate measurements of these liquids in the porous layers of silica gel and alumina were performed. The obtained values of the electron-donor parameter of surface free energy of the studied organic liquids were compared with the literature data obtained by the direct measurement of the interface tensions of water/organic liquids

Surface Activity of Natural Surfactants Extracted from Sapindus mukorossi and Sapindus trifoliatus Soapnuts

Surfactants derived from renewable sources such as plants are an ecological alternative to synthetic surfactants. Aqueous solutions of natural surfactants extracted from soapnuts obtained from two plants, Sapindus mukorossi and Sapindus trifoliatus, were studied. Their properties in terms of surface tension reduction and wettability were examinated. The natural surfactants show the ability to reduce the surface tension and increase the wettability of the hydrophobic polytetrafluoroethylene surface. These nuts can be used repeatedly for washing also in hard water. Crude extracts from Sp. trifoliatus exhibit better surface properties than those from Sp. mukorossi. This makes these soapnuts a good potential source of biosurfactants for household use

Spectroscopic studies of dual fluorescence in 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole : effect of molecular aggregation in a micellar system

The article presents the results of spectroscopic studies focused on a selected compound from the 1,3,4-thiadiazole group—2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thia-diazole (FABT)—in a micellar system formed by Triton X-100, a non-ionic detergent. Fluorescence measurements revealed the phenomenon of dual fluorescence whose emergence is related to the particular molecular organisation of the compound, which depends both on the concentration of the detergent and, most of all, the concentration of the compound itself. Dual fluorescence of FABT in a micellar system was observed for the compound dissolved in a methanol aqueous system, i.e., an environment wherein the dual fluorescence of the compound had never been reported before. Based on the interpretation of UV-Vis electronic absorption, resonance light scattering (RLS), emission and excitation fluorescence spectra, as well as measurements of dynamic light scattering (DLS) and Principal Component Analysis (PCA), we were able to relate the occurrence of this effect to the process of molecular aggregation taking place between FABT molecules in the micellar system in question. Results of fluorescence spectra measurements and time-correlated single photon counting (TCSPC) indicate that dual fluorescence occurs at detergent concentrations necessary to form micellar systems, which in turn facilitate the process of aggregation of FABT molecules. The correlation between the observed fluorescence effects and the previous measurements performed for analogues from this group suggests the possibility of charge transfer (CT) within the range of detergent concentrations wherein the aforementioned fluorescence effects are observed. It ought to be emphasised that this type of fluorescence effects are relatively easy to induce, which predisposes this groups of fluorophores as ideal fluorescence probes in the context of biological samples

Microwave assistant synthesis of calcium phosphate minerals using hen’s eggshells as a calcium source

In this study raw hen’s eggshells were used as a calcium source for calcium phosphate mineral synthesis. The materials composed of brushite and different amounts of HA (hydroxyapatite) and β-TCP (β-tricalcium phosphate) with the needle-like, sheet-like and hexagonal structures were synthesized in the presence of the microwave. It was found that the time of microwave action, temperature and initial pH are parameters affecting the morphology and composition of the obtained materials, i.e. the increasing duration of MW exposure increases the amount of HA increases, whereas the temperature increase causes an increase in the contents of brushite and β-TCP. The lowering of initial pH leads to an increase in the brushite content

Synthesis of hydroxyapatite derived from agricultural waste and its applications as an adsorbent for heavy metal removal from wastewater

 The presence of heavy metals in aquatic systems can be harmful to living species. Heavy metals are not biodegradable, and their tendency to accumulate in living organisms often causes different, undesirable consequences. Therefore, removing these impurities from wastewater has become one of the key issue related to environmental protection [Babel and Kurniawan 2004].There are many methods developed to remove heavy metals from wastewater and adsorption is one of the most popular one. Despite of the diversity of these technologies there is still a need to develop methods that do not require a large financial input [Hegazi 2013, Renu et al. 2017].The most important features that determine materials used as adsorbent is their low cost, biocompatibility and environmental friendly nature and hydroxyapatite presents all of them. Moreover, hydroxyapatite particles are characterized by high specific surface area and simple method of synthesis. It is also reported that it can be obtained from agricultural waste based on calcium like eggshells [Akram et al. 2014].The aim of this paper is to show and compare different methods of hydroxyapatite synthesis using eggshells as a source of calcium and it sorption capacity due to different metal cations from aqueous solution

Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water

Using neodymium ring magnets (0.5⁻0.65 T), the experiments on the magnetic field (MF) effects on water evaporation rate and surface tension were performed at room temperature (22⁻24 °C). In accordance with the literature data, the enhanced evaporation rates were observed in the experiments conducted in a period of several days or weeks. However, the evaporated amounts of water (up to 440 mg over 150 min) in particular experiments differed. The evaporated amounts depended partially on which pole of the ring magnet was directed up. The relatively strong MF (0.65 T) caused a slight decrease in surface tension (−2.11 mN/m) which lasted longer than 60 min and the memory effect vanished slowly. The surface tension data reduced by the MF action are reported in the literature, although contrary results can be also found. The observed effects can be explained based on literature data of molecular simulations and the suggestion that MF affects the hydrogen bonds of intra- and inter-clusters of water molecules, possibly even causing breakage some of them. The Lorentz force influence is also considered. These mechanisms are discussed in the paper