Two aspects of interfacial phenomena were discussed in the manuscript. The first one concerns the adsorptive removal of two azo dyes such as C.I. Acid Yellow 219 (AY219) and C.I. Direct Yellow 142 (DY142) as well as the phtalocyanine C.I. Reactive Blue 21 (RB21) on the alumina-silicatitania oxide (4% wt. Al2O3-8% wt. SiO2-88% wt. TiO2; AST88) in the ionic surfactants presence. The second one deals with the determination of interaction mechanism in the dyes-AST88, dyes-surfactant-AST88 systems using the data obtained from the surface charge density and zeta potential studies. The sodium dodecyl sulphate (SDS) with anionic character and hexadecyltrimethylammonium bromide (CTAB) with cationic ones were used. The adsorption capacities of 205.2 mg/g for AY219, 36.5 mg/g for RB21 and 18 mg/g for DY142. The potentiometric titration and Doppler laser electrophoresis methods enable determination of sign and magnitude of charge located in both the surface and the slipping plane layers around the solid particles. The structure of electrical double layer was determined in the AST88 systems without as well as with dyes and with mixed dye + surfactant adsorbates.
In this work, a new material for in vitro plant rooting based on highly dispersed polyacrylamide hydrogel (PAAG) enriched with amber powder was synthesized and investigated. PAAG was synthesized by homophase radical polymerization with ground amber addition. Fourier transform infrared spectroscopy (FTIR) and rheological studies were used to characterize the materials. They showed that the synthesized hydrogels have physicochemical and rheological parameters similar to those of the standard agar media. The acute toxicity of PAAG-amber was estimated based on the influence of washing water on the viability of plant seeds (pea and chickpea) and Daphnia magna. It proved its biosafety after four washes. The impact on plant rooting was studied using the propagation of Cannabis sativa on synthesized PAAG-amber and compared with agar. The developed substrate stimulated the rooting of the plants to more than 98% in comparison to standard agar medium (95%). Additionally, the use of PAAG-amber hydrogel markedly enhanced metric indicators of seedlings: root length increased by 28%, stem length—by 26.7%, root weight—by 167%, stem weight—by 67%, root and stem length—by 27%, root and stem weight—by 50%. This means that the developed hydrogel significantly accelerates reproduction and allows obtaining a larger amount of plant material within a shorter period of time than the standard agar substrate.
ABSTRACT:Composites based on fumed silica with surface hydrophobic groups were synthesized by chemical substitution of silanol groups' proton for trimethylsilyl (TMS) groups, adsorption of poly(dimethylsiloxane) (PDMS) and combined chemical-adsorption methods. Microcalorimetry measurements and values of the wetting contact angle with water (Θ) were obtained to investigate the hydrophobic properties of prepared materials. The hydrophilicity indexes (K h ) were determined from the relationship of heat of immersion in water Q w to non-polar decane Q d . The Θ and Q w demonstrated changes with increase of modification degree (d m ) for composites containing a monolayer of PDMS. All samples with excess of PDMS had high Θ (>110°) and relatively low Q w and K h .Composites modified with TMS groups demonstrated hydrophobic properties in accordance with K h at d m 0.7, whereas Θ > 90° is observed only for those samples with d m = 1.0. The different methods of synthesis may be applied based on the morphological characteristics and hydrophobicity of the samples.
Introduction. The actual scientific task is to establish the regularities of the structure formation of marmalade on agar polysaccharides and pectins with low sugar content (saccharose, glucose, fructose). Materials and methods. Rheological characteristics were studied by rotational viscometry. Structural and mechanical characteristics were investigated by penetration method. Marmalade with a low content of saccharose, glucose, fructose with the correction of the content of sugars by the addition of polydextrose and the introduction of natural flavoring additives in the form of fruit and berry puree were used in the research. Results and discussion. It has been established that the sweet taste of marmalade with the use of any formulation is ensured by the dosage of saccharose and glucose at 35 g / 100 g of product, and fructose-by 25 g/100 g. However, the decrease in the amount of sugars in the system is reflected in the increased index of total deformation and proves that structural and mechanical properties essentially depend on their content. The rheological studies of each marmalade mass have identified a range of values of the gradient of displacement, which recommended its transportation in the technological process. So, for marmalade mass on agar with glucose and saccharose γ = 10-20 sec-1 (t = 55±3 °C), with fructose-γ = 5.4-10 sec-1 , or it is possible to use lower temperatures (t = 50±3 °С); for k-carrageenan-for all types of sugars γ = 5.4-10 sec-1 (t = 77±3 °C), for the masses with fructose and saccharose, lower temperatures are allowed (t = 72±3 °C); on H-pectin-γ = 5.4-8 sec-1 (t = 85±3°C), for mass with glucose and with fructose (t = 88±3 °C); on l-pectin-with glucose γ = 2-8 sec-1 (t = 80±3 °С), for masses with saccharose and with fructose γ = 5-10 sec-1 (t = 85±3 °C). Time of structuring of marmalade, which is lengthened in comparison with traditional products has been established, on agar from 60 minutes to 120 minutes, on k-carrageenan from 15 minutes to 60 minutes, on Н-pectin from 12 minutes to 20 minutes. To a greater extent, such changes are related to the introduction of a significant amount of polydextrose for replacing sugar, which has a higher hydration ability. The most springy properties has marmalades on agar and k-carrageenan, and on pectins, they are characterized by greater plasticity. Conclusions. The following parameters are set and recommended: maximum speed of the rotary movement during pumping; temperature of transportation and tempering of masses; the duration of cooling and withstanding on the finished marmalade.
The mixed SiO2-TiO2 oxide obtained by the pyrogenic method with the silica:titanium percentage ratio equal to 20:80 (ST80) was used in the experiments. The influence of azo dye C.I. Direct Yellow 142 (DY) adsorption at the mixed oxide-solution interface on the electrokinetic properties of solid particles was studied. To determine solid surface charge density and zeta potential of examined suspensions the potentiometric titration and Doppler laser electrophoresis techniques were applied. The changes in structure of electrical double layer formed on the mixed oxide surface in the dye presence were specified as a function of DY concentration, inorganic salt addition and surfactant introduction. The effects of surfactant type and its concentration were determined. Three surfactants of different ionic character (anionic SDS, cationic CTAB and nonionic Triton X-100) were used in measurements. The obtained electrokinetic characteristics of ST80 mixed oxide dispersed in aqueous solutions with various adsorbate compositions is essential for such suspensions stability.
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