Addition Of Cationic Surfactant Research Articles

Photometrische Untersuchungen zum Übergang der Dianionen in Trianionen von o,ó-Dihydroxyazofarbstoffen und zur Assoziatbildung mit kationaktiven Tensiden in diesem pH-Bereich

Photometric Investigations in Transition of the Dianions in the Trianions of o,o-Dihydroxyazodyes and to the Forming of Associates with Cationic Surfactants in this pH-range. In transition of the dianions in the trianions of the investigated dyes take place preferred the deprotonation of the tautomeric form A12− by forming of the equilibrium H ⇄ A3−. The addition of cationic surfactants to the dye solution caused the increase of the pKa3-values of the dyes. That proved among other things the formation of associates is dye and cationic surfactants determined composition.

Determination of zinc in aluminum metal and alloys using a sensitized murexide reaction

AbstractThe spectrophotometric properties of zinc complexes with murexide in the absence and presence of cationic, anionic and nonionic surfactants were studied. The addition of cationic surfactants stabilized the complex and hence improved the intensity of the absorption band (sensitized the reaction). A method for the determination of >0.01% zinc in aluminum metal and some aluminum base alloys was developed. The method was based on measuring the absorbance of the formed complex with murexide and cetylpyridinium bromide at pH 8. The apparent molar absorptivity was 4.7 ± 0.01 × 104 litre mol−1 cm−1 at 470 nm. A linear calibration curve was obtained for up to 1.44 ppm of zinc. In the presence of sodium fluoride and thiourea masking solutions, common ions in aluminum metal and alloys did not interfere.

Graphite Fluoride-Nickel Plating and a Property of the Codeposit

(CF)n-Ni plating is expected to have an excellent physical property as for the water repellency, due to the extremely low surface energy of (CF)n such as 6 ± 3 ergs. cm-2.(CF) n was dispersed with the addition of cationic surfactant to Watt bath.(CF)n was codeposited with nickel on platinum or stainless steel electrochemically from this bath. The state and chemical stability of (CF) n in the nickel matrix was examined by the methods of surface analysis such as EPMA, SEM, X-ray diffraction. The wettability of (CF)n-Ni composite material was estimated from the measurement of the contact angle of water on it.

Surfactant‐induced fluorescence changes in fluorescein dye

Synopsis Addition of non-ionic surfactants revealed changes in the visible absorbance and fluorescence characteristics of fluorescein dyes. Non-ionic surfactants induced a shift in Delta(max), towards shorter wavelengths along with a decrease in absorbance of the dye. On the other hand, addition of anionic surfactants induced a shift of Delta(max), towards longer wavelengths along with enhancement in absorbance and fluorescence. The absorbance value decreased initially, but increased on further addition of cationic surfactant, whereas fluorescence increased initially but decreased on further addition of cationic surfactant. These changes are attributed to the interaction of surfactant micelle with dye molecules, resulting in change of the coloured quinoid form to the colourless lactone form and vice versa.

Biological membrane modeling with a liquid/liquid interface. Probing mobility and environment with total internal reflection excited fluorescence

Total internal reflection of exciting light, in combination with fluorescence intensity and polarization measurements, was used to selectively study fluorescent compounds adsorbed to the interface region between two immiscible liquids. A fluorometer was constructed which provided excitation at variable angles of incidence and allowed sensitive detection of polarized fluorescence emitted from the interface. The compound 4,4'-bis-1-phenylamino-8-naphthalenesulfonate (bis-ANS) was examined at a decalin/water interface and was found to possess remarkable affinity for the interface region with the bulk of the adsorbed molecule residing in the decalin phase. The adsorbed fluorophore displayed an apparent hindered rotation in the plane of the interface with a rotational diffusion coefficient 3- to 12-fold lower than that expected for bis-ANS in solution. While other dyes examined were not found to be significantly surface active, the addition of cationic surfactant sufficed to induce adsorption of the anionic fluorophore 1-aminonaphthalene-3,6,8-trisulfonic acid. This fluoropore was found to reside in an aqueous environment when bound to the interface, and it also exhibited hindered rotation in the plane of the interface. As the concentrations of the dyes were increased, both adsorbed dyes exhibited polarization reductions consistent with excitation energy transfer. Adsorption of bis-ANS was reversed by addition of bovine serum albumin. The membrane protein cytochrome b5 was found not to bind at the decalin/water interface, indicating that interaction with lipid is required for its adherence to biological membranes.

Effect of cationic surfactant on the formation of ferron complexes

In the spectrophotometric determination of aluminium and iron with ferron (7-iodo-8-quinolinol-5-sulphonic acid, H 2L), the addition of cationic surfactants greatly improves the linearity of the calibration curve and widens the useful pH range. The effect of cetyltrimethylammonium chloride (CTMAC) on the stepwise stability constants ( K 1, K 2 and K 3) of the ferron complexes of aluminium and iron (ML +, ML − 2 and ML 3− 3) and on the acid-dissociation constants ( K a1 and K a2) of ferron has been studied in connection with the role of the surfactant. CTMAC greatly increases the value of K 3 while exerting little effect on K 1 and K 2, thus rendering ML 3− 3 the predominant species even at very low concentration of free L 2−. It also has some effect on the acid-dissociation constants of ferron, but sometimes it acts to decrease the free L 2− concentration. At is therefore concluded that the improvements due to addition of surfactant should be attributed to the increased K 3 value. The presence of surfactant micelles is not essential, because the surfactant has a favourable effect when present at well below its critical micelle concentration, and because the continuous variations plots show a peak at a point corresponding to the composition M: L: Q (Q = cationic surfactant) = 1:3:3.

Determination of niobium with p-arsonophenylazochromotropic acid and cetylpyridinium bromide

Color stabilization and modification of the visible spectrum of the p-arsonophenylazochromotropic acid (L) and Nb(V) binary complex by the addition of surfactants has been studied in the course of a search for improved spectrophotometric methods for niobium. Addition of cationic surfactants resulted in an effective means of color stabilization and brought about a drastic improvement in the intensity of the absorption band maximum (sensitized reactions). The surfactant which gave the most intense absorption band maximum was cetylpyridinium bromide (CPAB). Spectrophotometric measurements indicate the formation of two Nb-L-CPAB ion-association ternary complexes: a complex with the stoichiometry 1:2:4 was formed in approximately 1 M HCl. The other complex had the stoichiometry 1:1:2 and formed in 2 to 4 M HCl mediums. Both ternary complexes mentioned can be applied to the spectrophotometric determination of niobium and two different analytical methods have been established: the complex formed in a 1.0 M HCl medium provides a method less selective than the complex formed in 2 to 4 M HCl. The method provided by the former complex is sensitive (epsilon = 1.87 x 10/sup 4/ L mol/sup -1/ cm/sup -1/), has a working range of 0.5 to 5 ppm Nb, and has a relative standard deviationmore » of 0.5%. The complex formed in the higher acidity range provides a less sensitive method. The working range is 1 to 9 ppm and epsilon = 7.40 x 10/sup 3/ L mol/sup -1/ cm/sup -1/. This latter method is most adequate for a selective spectrophotometric determination of niobium (relative standard deviation being 0.5%). 5 figures, 2 tables.« less

Reduction of Methylene Blue with l-Ascorbic Acid or l-Cysteine in Micellar Systems

Abstract The reduction of Methylene Blue (MB) with l-ascorbic acid to the corresponding leuco compound has been studied in aqueous surfactant solutions. The reduction was accelerated in the presence of cationic surfactant hexadecyltrimethylammonium bromide, but tetrabutylammonium bromide, which has no ability of micelle formation, does not show any effects on the reaction rate. The micellar effects are largely affected by pH of the medium, and the rate enhancing effects of the micelles are retarded by KCl. These results could be interpreted by the change in dissociation state of the substrate on the micelle surface and by the binding of the reaction product, leuco MB, to the micelles. The binding site of leuco MB was found to be outer core of the HTAB micelle by NMR. Similar results were obtained in the reduction of MB with l-cysteine, although the reduction did not proceed without the addition of cationic surfactant. The interaction between dissolved oxygen and the substrate in HTAB micellar solutions was also investigated.