Synergistic Interaction Between Cationic Novel Gemini Surfactant and Non-ionic Conventional Surfactants in Aqueous Medium

The interaction between novel gemini surfactant (alkane-α, ω-bis(dimethyl hexadecyl ammonium bromide) (G6)) and two different non-ionic surfactants (Triton X-114 (TX-114), Tween 20 (T-20)) has been investigated in the current study at temperature 298.15 K. The critical micelle concentration (cmc) values of mixed systems were computed by the conductometric titration in the aqueous medium. The results have been examined by utilizing numerous theoretical models (Clint, Rubingh, Motomura, Maeda, and Lange models). The experimentally determined cmc were lower than corresponding ideal values (cmc*) and decreased with the mixtures' stoichiometric mole fraction (α1) of G6. This shows non-ideal behavior between two employed components. The interaction parameter at mixed micelle (β) has been analyzed by using regular solution approximation. The attractive interaction or synergistic behavior in both mixed systems is confirmed by the negative values of β. The various energetics parameters were also evaluated and discussed.

Рotentiometric and conductometric determination of amine and acid numbers of reaction mixture from fatty acid amidation

The possibility of simultaneous potentiometric and conductometric titration is considered for determination of the acid (A.N.) and amine (AM.N.) numbers of the amidation reaction mixture for technical fatty acids (F.A.) by diethylenetriamine (DETA). Interpretation of titration curves was performed on the basis of model mixtures for DETA and F.A. industrial sample. The obtained results indicate the possibility of determining A.N. and AM.N. values by sequential titration of one sample for industrial organic products and amidation reaction mixtures.

Green Chemistry: A Simple Manual Apparatus for Potentiometric and Conductometric Micro-Titration of Small Samples for the Educational Laboratory

A simple manual micro-titration method is proposed for the potentiometric and conductometric titration of 200 to 800 µL of liquid samples. The sample to be titrated is dispensed into the titration chamber; the bottom section of a plastic test tube that is glued to the center of a small stirring magnet. After inserting the sensing probe and the tip of the titrant delivery tip into the titration chamber, the chamber-stirring magnet assembly is spun at low speed using a conventional magnetic stirrer. Titrant is delivered (with 0.2 µL resolution) from the submerged tip of a 100-µL capacity micro-pipette by rotating the plunger with the locking ring unlocked. The apparatus has been used for potentiometric titration and conductometric titration of acids and bases usually encountered in educational laboratories. Compared with macro-scale titrations, the obtained accuracy was between +2.2% and -3.9% relative error and the precision ranged between 1.6% and 2.9% relative standard deviation. The proposed procedure cuts the reagent consumption to 1% or less compared with conventional macro-scale titrations.

Evaluation of Keratin/Bacterial Cellulose Based Scaffolds as Potential Burned Wound Dressing

The study presents the preparation and characterization of new scaffolds based on bacterial cellulose and keratin hydrogel which were seeded with adipose stem cells. The bacterial cellulose was obtained by developing an Acetobacter xylinum culture and was visualized using SEM (scanning electron microscopy) and elementally determined through EDAX (dispersive X-ray analysis) tests. Keratin species (β–keratose and γ-keratose) was extracted by hydrolytic degradation from non-dyed human hair. SEM, EDAX and conductometric titration tests were performed for physical–chemical and morphological evaluation. Cytocompatibility tests performed in vitro confirmed the material non-toxic effect on cells. The scaffolds, with and without stem cells, were grafted on the burned wounds on the rabbit’s dorsal region and the grafts were monitored for 21 days after the application on the wounds. The clinical monitoring of the grafts and the histopathological examination demonstrated the regenerative potential of the bacterial cellulose–keratin scaffolds, under the test conditions.

EFFECT OF DEGREE OF SULFONATION IN NANOCELLULOSE/CHITOSAN COMPOSITE ON ADSORPTION OF CATIONIC DYE AS OPIOID SIMULANT

In this study, the effect of nanocellulose sulfonate group content on adsorption of an opioid simulant was tested. The opioid simulant used was Victoria blue R, an amine dye. Nanocellulose filters were fabricated by crosslinking cellulose nanocrystals (CNCs) with chitosan to improve the mechanical stability of freeze-dried CNCs. Thermogravimetric analysis confirmed the filter’s thermal stability and operating temperatures. Conductometric titration, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques were used to characterize the degree of nanocellulose functionalization. Lastly, the adsorption performance of the sulfonated nanocellulose filter was tested and fitted to kinetic models and adsorption isotherms. The adsorption of the dye by the sulfonated nanocellulose followed pseudo-second order kinetics and the Langmuir isotherm. The maximum adsorption of Victoria blue R dye by sulfonated nanocellulose (68.56 mg/g) is significantly higher than those of other adsorbents, like activated carbon (0.59-2.97 mg/g) and magnetic microparticles (40.98 mg/g). Thus, sulfonated cellulose nanocrystals are a promising material for the sequestration of opioids from water.

Development of a spectrophotometric method for determination of ions Cu (II) C N- (2-hydroxybenzoyl) -N '- (p-tosil)hydrazine in ammonia media

A spectrophotometric method for the determination of Cu (II) ions with N- (2-hydroxybenzoyl) -N '- (p-tosyl) hydrazine (GBSH) in ammonia media has been developed. The optimal conditions for the formation of a complex compound are found: the wavelength of maximum light absorption; pH complexation; optimal time for color development; the amount of photometric reagent. Under optimal conditions of complexation of GBSG with Cu (Ⅱ) ions (λ = 401 nm, pH = 9.2, τ = 30 minutes, VGBSG = 3.75 ml), a calibration graph is constructed. The Bouguer-Lambert-Beer law is fulfilled in the range from 0.13 to 1.59 mg Cu (II) / 25 ml. The true molar light absorption coefficient of the complex compound of HBSG with Cu (Ⅱ) ions in the ammonia medium was 1480. The molar ratios in the solution of the complex compound were determined by the methods of saturation, shift of equilibria and conductometric titration - [Cu (Ⅱ)]: [HBSG] = 1: 1. According to Babko's method, the conditional constant of stability of the GBSG complex with Cu (Ⅱ) ions was calculated and it was 4.4 × 1010. The reproducibility and relative error of the developed photometric technique were determined by the method of mathematical statistics.

Determination of alkylbenzolsulphonic acid in aqueous solutions

The possibility of determining the anionic surfactant alkylbenzenesulfonic acid by various methods: potentiometric and conductometric titration with sodium hydroxide, conductometric titration with cationic surfactants (tetrabutylammonium bromide, cetyltrimethylammonium bromide) and spectrophotometry in the UV region, was considered. The acid-base titration method allows to determine the alkylbenzenesulfonic acid concentration in pure aqeous solutions. The content of anionic surfactant in the presence of nitric acid can be determined by conductometric titration with cetyltrimethylammonium bromide. The optimal conditions for alkylbenzenesulfonic acid spectrophotometric determination (light absorption maxima, linearity range of the calibration graph, molar absorption coefficient) have been established.