sodium dodecylsulfate
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2021 ◽  
Vol 26 (3(79)) ◽  
pp. 77-85
Author(s):  
O. M. Guzenko ◽  
O. M. Zhukovetska ◽  
D. M. Mukienko ◽  
V. V. Shopovalenko ◽  
A. N. Chebotarev ◽  
...  

In the current paper, adsorbent based on silica gel L 40/100 modified with cetylpyridinium bromide was obtained. The presence of cetylpyridinium cations on the silica gel surface was confirmed by the diffuse reflectance infrared fourier transform spectroscopy method. The sorption conditions of erythrosine from dilute aqueous solutions with the proposed sorbent were studied and optimized. It is shown that the use of modified silica gel allows efficient (>95%) extraction of erythrosine from aqueous solutions. Under optimal sorption conditions (pH 7, sorbent dosage 0.1 g and sorption time is 15 min), the sorption capacity of modified erythrosine sorbents was determined. It is shown that, with increasing temperature, a change in the isotherm type from the H‑type to the L‑type is observed. This change can be explained by the aggregation of erythrosin in solution, which is a competitive sorption process. It was shown that adsorption isotherms were well described by the Langmuir equation. Thermodynamic studies have made it possible to establish the spontaneous sorption. The desorption of erythrosine from the surface of silica gel modified with cetylpyridinium bromide was studied. It is shown that when using solutions of sulfuric acid, sodium hydroxide and distilled water, desorption does not occur. It was shown that the most effective eluent is solution of sodium dodecylsulfate in alkaline medium, and desorption of erythrosine occurs due to the destruction of ion pairs of dye anions with cetylpyridinium cations fixed on the surface. The data obtained can then be used to develop a test system for determination of erythrosine via corresponding colorimetric scales or for quantitative solid phase extraction and adsorption-spectroscopic quantification of erythrosine in some real samples.


2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Jana Marešová ◽  
Miroslav Horník ◽  
Martin Pipíska ◽  
Jozef Augustín

Surfactants are frequently used as adjuvants for improving the efficiency of foliar applied fertilizers, pesticides and other biologically active substances. In our paper we used detached leaves of ivy (Hedera helix L.) for the study of the influence of anionic surfactants sodium dodecylsulfate (SDS) and sodium dicyclohexyl sulfosuccinate (DCSS) on zinc and strontium uptake by leaf surface and transport by radiotracer technique with 65ZnCl2 and 85SrCl2. Accumulated amounts of Zn2+ and Sr2+ ions by the surface of detached intact ivy leaves were 5.0 and 1.1 μg/g, respectively. Ivy leaves pretreated for 24 h in 1 mM SDS or DCSS solutions accumulated approx. twice more Zn and five time more Sr than non treated leaves. Pretreatment with surfactants increased mobility of zinc and strontium in leaf tissues. Separate experiments showed that both SDS and DCSS were sorbed onto the leaf tissue reaching equilibrium within several hours of immersing leaf blades to surfactant solutions. The process can be described in terms of partition equilibria P = [C]leaf/[C]solution with log P = 1.396 within surfactant concentration studied Co ≤ 100 μmol/L. The mechanism of action of surfactants on metal ion uptake is discussed.


2021 ◽  
pp. 14-16
Author(s):  
Tojum Gongo

Introduction: myopia is the most common eye disease in the world in with substantial social, educational and economic impact. Some studies have shown changes in aqueous humour proteins in myopic patients. To estimate total Aim: protein concentration, types of proteins in aqueous humour and the correlation with myopic patients. This is a Material and Methods: Prospective study conducted on 36 eyes of 36 patients attending Department of Ophthalmology, TRIHMS, Naharlagun, who were undergoing cataract operation. Group A served as a control group with 22 eyes of non myopic patients. Group B consisted of 14 eyes of 14 myopic patients having axial length more than 26mm.Aqueous humour collected from both the groups during cataract surgery was sent for Sodium dodecylsulfate polyacrylamide gel electrophoresis ( SDS-PAGE). Signicant diffe Result: rence in relative bands width (%) in the gel patterns in myopic and non myopic patient was seen.Myopic patients had higher magnitude of protein expressions /bands in molecular weights being 55kDa (Transthyretin), 69kDa ( Albumin) and 110kDa ( Vitamin-D binding protein) than non-myopic patients. In non myopic patients ,70-90 kDa (Heat shock Protein) were very highly expressed than myopic patients. Aqueous humour proteins were Conclusions: estimated to be different between myopic and non myopic patients signicantly. These proteins can be candidates for broadening of our existing knowledge of the pathophysiological characteristics of myopia. They may help in early diagnosis and monitoring of the myopic patients can be done. They may also help in deeper understanding of mechanism which cause axial elongation in myopia.


Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2800
Author(s):  
Christopher Hill ◽  
Wasiu Abdullahi ◽  
Robert Dalgliesh ◽  
Martin Crossman ◽  
Peter Charles Griffiths

Oppositely charged polymer–surfactant complexes are frequently explored as a function of phase space defined by the charge ratio Z, (where Z = [+polymer]/[−surfactant]), commonly accessed through the surfactant concentration. Tuning the phase behaviour and related properties of these complexes is an important tool for optimising commercial formulations; hence, understanding the relationship between Z and bulk properties is pertinent. Here, within a homologous series of cationic hydroxyethyl cellulose (cat-HEC) polymers with minor perturbations in the degree of side chain charge modification, phase space is instead explored through [+polymer] at fixed Cpolymer. The nanostructures were characterised by small-angle neutron scattering (SANS) in D2O solutions and in combination with the oppositely charged surfactant sodium dodecylsulfate (h- or d-SDS). Scattering consistent with thin rods with an average radius of ∼7.7 Å and length of ∼85 Å was observed for all cat-HEC polymers and no significant interactions were shown between the neutral HEC polymer and SDS (CSDS < CMC). For the charge-modified polymers, interactions with SDS were evident and the radius of the formed complexes grew up to ∼15 Å with increasing Z. This study demonstrates a novel approach in which the Z phase space of oppositely charged polymer–surfactant complexes can be controlled at fixed concentrations.


Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 687
Author(s):  
Lawrence W. Honaker ◽  
Anjali Sharma ◽  
Andy Schanen ◽  
Jan P. F. Lagerwall

Liquid crystal (LC) phases typically show anisotropic alignment-dependent properties, such as viscosity and dielectric permittivity, so it stands to reason that LCs also have anisotropic interfacial tensions. Measuring the interfacial tension γ of an LC with conventional methods, such as pendant drops, can be challenging, however, especially when we need to know γ for different LC aligning conditions, as is the case when we seek Δγ, the interfacial tension anisotropy. Here, we present measurements of Δγ of the common synthetic nematic LC compound 5CB against water using a microfluidic droplet aspiration technique. To ensure tangential and normal alignment, respectively, we add poly(vinyl alcohol) (PVA) and sodium dodecylsulfate (SDS), respectively, as a stabilizer and measure γ for different concentrations of stabilizer. By fitting the Szyszkowski equation to the data, we can extrapolate to zero-stabilizer concentration, obtaining the γ of 5CB to pure water for each alignment. For normal alignment, we find γ⊥=31.9±0.8 mN·m−1, on the order of 1 mN·m−1 greater than γ||=30.8±5 mN·m−1 for tangential alignment. This resonates with the empirical knowledge that 5CB aligns tangentially to an interface with pure water. The main uncertainty arises from the use of polymeric PVA as tangential-promoting stabilizer. Future improvements in accuracy may be expected if PVA can be replaced by a low molar mass stabilizer that ensures tangential alignment.


Author(s):  
I M Tucker ◽  
A Burley ◽  
R E Petkova ◽  
S L Hosking ◽  
J R P Webster ◽  
...  

Author(s):  
Anastasia S. Polyakova ◽  
Nataliya M. Murashova

The article is concerned with study of diameters of reverse microemulsion droplets depending on the water content in sodium bis-(2-ethylhexyl)phosphate – decane – water and sodium dodecylsulfate – butanol-1 – decane – water systems. Hydrodinamic diameters of microemulsion droplets were determined by the method of dynamic light scattering. It increases from 5.9 to 9.7 nm with an increase in the molar ratio of water and sodium bis-(2-ethylhexyl)phosphate from 5.0 to 20.0 in the sodium bis-(2-ethylhexyl)phosphate – decane – water microemulsion. Diameter of microemulsion droplets in the sodium dodecylsulfate – butanol-1 – decane – water system increases from 2.4 to 8.6 nm with an increase in the molar ratio of water and dodecylsulfate from 7.5 to 30.0. It was shown that the dependence of the diameter (d) on the water content (W) is linear. The applicability of the experimental data on the area per surfactant molecule at the "water-oil" interface and literature data on the values of molar volumes of microemulsion components to calculate the diameter of microemulsion droplets was analyzed. It was shown that the equation of the form d = kW + b is suitable for describing the dependence of the diameter of microemulsion droplets on the water content in the sodium dodecyl sulfate-butanol – 1-decane-water system. Parameters k and b of this equation are calculated using the value of the area per surfactant molecule at the "water-oil" interface, which can be obtained from experimental data on interfacial tension. Values of the diameter of microemulsion droplets calculated using the proposed equation differ by no more than 1 nm from the values obtained by dynamic light scattering. Values of the droplet diameter of microemulsion in the DEHPA – decane – water system calculated using this equation are underestimated by 1.0-2.5 nm relative to the experimental values, while the slope of the lines obtained from the experimental data and during the calculation is almost the same.


Author(s):  
Silvia M. Calderón ◽  
Nønne L. Prisle

AbstractSurfactants exist in atmospheric aerosols mixed with inorganic salts and can significantly influence the formation of cloud droplets due to bulk–surface partitioning and surface tension depression. To model these processes, we need continuous parametrizations of the concentration dependent properties of aqueous surfactant–salt solutions for the full composition range from pure water to pure surfactant or salt. We have developed density functions based on the pseudo-separation method and Young’s mixing rule for apparent partial molal volumes for solutions that mimic atmospheric droplets of marine environments. The developed framework requires only model parameters from binary water–salt and water–surfactant systems and includes the effect of salinity on micellization with composition-dependent functions for the critical micelle concentration (CMC). We evaluate different models and data available in the literature to find the most suitable representations of the apparent partial molal volume of sodium chloride (NaCl) in aqueous solutions and the CMC of selected atmospheric and model surfactants in pure water and aqueous NaCl solutions. We compare model results to experimental density data, available in the literature and obtained from additional measurements, for aqueous solutions containing one of the ionic surfactants sodium octanoate, sodium decanoate, sodium dodecanoate or sodium dodecylsulfate mixed with NaCl in different relative ratios. Our model follows the experimental trends of increasing densities with increasing surfactant concentrations or increasing surfactant–salt mixing ratios both, below and above the CMC, capturing the effect of the inorganic salt on the surfactant micellization.


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