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1.
Viscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous
solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium
anthranilate, NaAn) and organic additives (1-hexanol, C6OH; n-hexylamine, C6NH2) at 30°C. On addition of C6OH or C6NH2, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This
is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts.
However, as the salt concentration was increased further, the effect of C6OH/C6NH2 addition was different with different salts: The viscosity first increased; then a decrease was observed with the former
while with C6NH2 a decrease followed by constancy appeared in plots of relative viscosities (η
r
) vs. organic additive concentrations. At further higher salt concentration, the magnitude of η
r
was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle
formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive
pseudophase). 相似文献
2.
Md. Sayem Alam Andleeb Z. Naqvi Kabir-ud-Din 《Journal of surfactants and detergents》2007,10(1):35-40
The effect of additives (surfactants and polymers) and pH on the clouding behavior of promethazine hydrochloride (PMT, a phenothiazine
drug) was investigated. Cloud point (CP) decreases with increase in pH due to deprotonation of drug molecules. The same trend
occurs in the presence of surfactants. However, at constant pH, and depending on their structure and nature, these additives
behave differently. Anionic surfactants show peaked behavior, whereas cationic (conventional as well as geminis) and non-ionic
surfactants increase the CP, although the mechanisms differ. Cationic surfactants hinder drug association (due to interaggregate
repulsion) resulting in an increase in CP, while non-ionic surfactants form mixed micelles with the drug, increasing micelle
hydration and CP. Polymers can cause both a decrease as well as an increase in CP, depending on their molecular weight. A
large CP increase (with the increase in surfactant concentration) for gemini surfactants suggests they are excellent candidates
for drug delivery.
相似文献
Kabir-ud-DinEmail: |
3.
Sanjeev Kumar Sara Liz David Kabir-ud-Din 《Journal of the American Oil Chemists' Society》1997,74(7):797-801
The effect of aliphatic and aromatic hydrocarbons on surfactant micellar growth has been investigated by viscosity measurements
at 40°C. Aqueous and aqueous KBr (0.1 M) solutions of 0.1 M cetylpyridinium bromide (CPB) showed that the viscosity behavior
changed substantially in the presence of KBr. This is attributed to favorable conditions produced by KBr that assist micellar
growth by addition of hydrocarbons. Reasons for the effectiveness of the solubilized hydrocarbons are suggested and supported
by theoretical arguments. The causes of viscosity decrease at higher aromatic hydrocarbon concentrations are also explained.
Micellar growth with soluble aromatic/aliphatic hydrocarbons could also be initiated if a moderate salt concentration is present
in CPB micellar solutions. The chainlength, solubilization site, and molar volume of the soluble hydrocarbons all affect the
bulk viscosity of the solution. Such surfactant and hydrocarbon combinations may find use in micellar-enhanced ultrafiltration
of benzene and its derivatives, but it should be kept in mind that micellar shape may change and be more curved at higher
benzene derivative concentrations. 相似文献
4.
Nazish Fatma Wajid Husain Ansari Manorama Panda Kabir-ud-Din 《Journal of surfactants and detergents》2013,16(4):609-620
A novel cationic biodegradable dimeric (gemini) surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16), containing an ester-linked spacer was synthesized. Its pure and mixed micellization properties with monomeric surfactants cetyl trimethyl ammonium chloride, cetyl pyridinium chloride, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, cetyl alcohol ethoxylate (20EO) and tert-octylphenol ethoxylate (9.5EO) were investigated by surface tension measurements at 30 °C. The critical micelle concentration (CMC) of 16-E2-16 is well below that of cetyl trimethyl ammonium chloride containing the same number of carbon atoms in the hydrophobic tail per polar head. At different mole fractions of the gemini surfactant, the CMCs of the gemini-conventional binary mixtures were determined and were found to be less than the ideal CMC values in all the cases indicating synergistic interactions. Aggregation number and Stern–Volmer constant, obtained by the fluorescence quenching technique, also support the synergistic behavior of the surfactant systems. 相似文献
5.
Kabir-ud-Din Mohammed D. A. Al-Ahmadi Andleeb Z. Naqvi Mohd. Akram 《Chemical Engineering Communications》2013,200(8):948-957
The work focuses on the clouding and dye solubilization phenomena in an amphiphilic drug, nortriptyline hydrochloride (NOT), which is a tricyclic antidepressant. A 30 mM drug solution prepared in 10 mM sodium phosphate buffer (pH: 7.07) showed CP at 45°C, which was found to decrease with the addition of long-chain alcohols and cyclohexanol but remained almost constant with short-chain alcohols. The behavior is explained on the basis of their nature: short-chain alcohols are water soluble and partition very little in micelles, whereas long-chain alcohols are hydrophobic and solubilize in drug aggregates. Diols decreased the CP. Addition of cationic surfactants increased the CP, whereas sugars caused a decrease. Dye solubilization results indicate micellar growth with fixed concentrations of surfactants. 相似文献
6.
Mohd Akram Hira Lal Mohammad Osama Farah Ansari Sana Anwar Kabir-ud-Din Ajaz Ahmad Samreen Naved Azum Hadi M. Marwani Abdullah M. Asiri 《Journal of surfactants and detergents》2021,24(1):35-49
In this study, we prepared a novel series of diester-functionalized cationic gemini surfactants (Cm-E2O2-Cm) containing ethylene oxide as a spacer with varying alkyl chain lengths and characterized by 1H NMR, FT-IR, elemental analysis, and ESI-MS. The physicochemical properties of the geminis were explored by tensiometry, fluorescence, dye solubilization, and Krafft point. These geminis acquire superior surface activity than the conventional surfactants. Fluorescence spectroscopy analysis affirmed that the micropolarity and aggregation number of micelles diminished with increase in the alkyl chain length. These geminis represent a new group of amphiphiles of considerably high biodegradability, better cleavability, and low toxicity as assessed by BOD test, FT-IR analysis, and HC50 analysis, respectively. They also showed significant level of antimicrobial activity toward some specified bacterial strains of Gram-positive and Gram-negative by using agar well diffusion method. Furthermore, the thermogravimetric analysis provided information regarding thermal stabilities of the newly synthesized gemini surfactants. 相似文献
7.
abstract This study deals with the enhanced solubilization of polycyclic aromatic hydrocarbons (PAHs) such as phenan-threne (PHE) and fluorene (FLR) in a pure cationic gemini (G6) and three conventiona... 相似文献
8.
The interactions of two gemini surfactants (16-s-16, s = 5, 6) and their conventional counterpart cetyltrimethylammonium bromide (CTAB) with polyvinylpyrrolidones (PVP K15 and PVP K90) were investigated using conductivity, steady-state fluorescence, and viscosity techniques. The results indicate that there is no PVP/CTAB complex formation if molecular weight of PVP < 15,000. Both PVP K15 and PVP K90 interact with gemini surfactants. The critical aggregation concentration (cac) and critical micelle concentration (cmc) increase with polymer concentration and do not depend on the polymer molecular weight. Fluorescence study shows that the addition of PVP results in a decrease of the aggregation number in all the systems investigated due to the adsorption of the PVP chain in the micelle palisade layer and the ensuing increase of micelle ionization. The viscosity results suggest that the interactions between the surfactants and the polymer affect both inter-polymer-polymer association and chain expansion. [Supplementary materials are available for this article. Go to the publisher's online edition of Chemical Engineering Communications for the following free supplemental resources: additional data tables and figures.] 相似文献
9.
Aqueous sodium dodecyl sulfate (SDS) solutions show clouding in the presence of tetra-n-butylammonium bromide (TBAB) and tetra-n-butylphosphonium bromide (TBPB). In this study, we report the effect of various volume percents of different polar nonaqueous
solvents (acetonitrile, AN; dimethylsulfoxide, DMSO; methyl ethylene glycol ether, MC; formamide, FA; ethylene glycol, EG)
on the clouding behavior of SDS + quaternary bromide (TBAB or TBPB) systems. The cloud point (CP) was found to decrease with
initial increase in the volume percent of the above solvents in mixtures (with water). After a minimum in CP vs. volume percent
plots, further increase in the volume percent caused an increase in the CP, followed by a near constant region. The data have
been discussed on the basis of the effect of the above solvents on the two types of water present in the system: hydrated
water and bulk water. As AN had shown a gradual decrease in the CP to a larger volume percent, it was chosen for detailed
studies. Compared to TBAB, TBPB has diminished the effect of AN on CP increase due to its bigger size. The limited CMC data
also run parallel to CP results.
相似文献
Kabir-ud-DinEmail: |
10.
Sanjeev Kumar Kirti Krishna Kumari Kabir-ud-Din 《Journal of the American Oil Chemists' Society》1995,72(7):817-821
We have measured the viscosity of solutions of 0.3 M sodium dodecyl sulfate (SDS) + 0.3 M NaBr +n-alkanols as a function of [alkanol] and temperature. When propanol was added, the viscosity of micellar solutions remained
almost constant and then decreased, whereas it continuously increased with hexanol. However, with butanol or pentanol, depending
upon the added concentration, increases followed by decreases in viscosity were observed. This behavior has been discussed
in light of solubility of alkanols in various soluble phases of the micellar system with a resultant change in the Mitchell-Ninham
parameter of the “effective surfactant” (i.e., SDS +n-alkanol). An increase in temperature caused a decrease in viscosity, which is related to micellar breakdown. Activation parameters
(ΔG* and ΔH*) were computed from the temperature dependence data. ΔH* Covered almost the total contribution to ΔG*. 相似文献