Mixed Micellization Behavior of<Emphasis Type="Italic"> m</Emphasis>-2-<Emphasis Type="Italic">m</Emphasis> Gemini Surfactants with Some Conventional Surfactants at Different Temperatures

Mixed micellization behavior of dimeric cationic surfactants ethanediyl-1,2-bis(dimethyl alkyl ammonium bromide) (m-2-m where m = 10, 12) with conventional single chain cationic surfactants like cetyltrimethyl ammonium bromide (CTAB), cetylpyridinium chloride (CPC), tetradecyl dimethyl benzyl ammonium chloride (C14BCl) and cetyl dimethyl benzyl ammonium chloride (C16BCl) were studied in aqueous and aqueous polyethylene glycol (PEG) solutions at 298.15, 308.15 and 318.15 K respectively using conductometric and viscometric methods. In aqueous solutions, all the combinations (except 12-2-12 + CTAB) were found to behave nonideally with mutual synergism which decreases with increase in temperature. Various thermodynamic parameters of micellization like \UpdeltaG_\textm^\texto {{\Updelta}}G_{\text{m}}^{\text{o}} , \UpdeltaH_\textm^\texto {{\Updelta}}H_{\text{m}}^{\text{o}} and \UpdeltaS_\textm^\texto {{\Updelta}}S_{\text{m}}^{\text{o}} were evaluated and discussed. Similarly in presence of PEG, the thermodynamic properties like \UpdeltaG_\textt^\texto {{\Updelta}}G_{\text{t}}^{\text{o}} , \UpdeltaH_\textt^\texto {{\Updelta}}H_{\text{t}}^{\text{o}} and \UpdeltaS_\textt^\texto {{\Updelta}}S_{\text{t}}^{\text{o}} associated with the transfer of surfactant monomers from the medium consisting of polymer-free mixed micelles to polymer-bound mixed micelles at various temperatures were also calculated. The negative values of \UpdeltaH_\textt^\texto {{\Updelta}}H_{\text{t}}^{\text{o}} show that aggregation process is more exothermic than micellization whereas the negative values of \UpdeltaS_\textt^\texto {{\Updelta}}S_{\text{t}}^{\text{o}} indicate that the presence of polymer bound mixed micelles decreases the degree of randomness of the system. Viscosity studies show that in aqueous solutions all the combinations of 10-2-10/12-2-12 display negative departure in the relative viscosity (η_r) from additivity rule which decreases with increase in temperature. Similarly in the presence of 5% PEG solutions the magnitude of the negative departure decreases for all the combinations and becomes positive in the case of C14BCl and CPC combinations with the studied gemini surfactants at higher temperatures.     

Synthesis and Some Properties of Fluorinated Cationic Surfactants

Three fluorinated cationic surfactants were prepared by condensing N-methyl diethanol amine pentafluoro benzoate with stoichiometric amounts of octyl, dodecyl or hexadecyl bromide. The surface properties and parameters were investigated to find the relationship between the structures of the hydrophobic portion of such compounds. The properties studied include surface tension, critical micelle concentration (CMC), effectiveness (Π_cmc), maximum surface excess (Γ_max) and minimum surface area (A_min) were investigated with respect to different concentrations at 25 °C. Standard free energies of micellization and adsorption of the prepared surfactants in the aqueous solution were studied. The values of Γ_max, standard free energies of micellization \Updelta \textG_\textmic^\texto \Updelta {\text{G}}_{\text{mic}}^{\text{o}} and adsorption \Updelta \textG_\textads^\texto \Updelta {\text{G}}_{\text{ads}}^{\text{o}} were found to increase with the chain length, while the cmc and minimum surface area occupied by one molecule A_min were found to decrease. The biocidal activity was determined through the inhibition zone diameter of prepared compounds which were measured against five strains of a representative group of microorganisms.     

Two New Organic–Inorganic Hybrids Based on [SiW12O40]4? Anion: Hydrothermal Syntheses, Crystal Structures, and Electrochemical Properties

Two new organic–inorganic hybrid compounds [\textCu^\textI ( \texten ) ₂ ( \textH ₂ \textO )] ₂ { ( \textSiW^\textVI _{1 1} \textW^\textV ₁\textO ₄₀ ) ₂ [ \textCu^\textII ( \texten ) ₂ ( \textH ₂ \textO )] ₂ [\textCu^\textII ( \texten ) ₂ ] ₂ }·6 \textH ₂ \textO [{\text{Cu}}^{\text{I}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)]_{ 2} \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1}{\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}{\cdot}6 {\text{H}}_{ 2} {\text{O}} (1) and (H₂ L)₂[SiW₁₂O₄₀]·H₂O (2) [en = ethylenediamine, L = 1,4-bis(3-pyridinecarboxamido)benzene], have been hydrothermally synthesized and characterized by IR, elemental analyses, TG analysis, and single-crystal X-ray diffraction. Structural analyses indicate that compound 1 exhibits an interesting three-dimensional(3D) cross-like supramolecular network through arrangement of a 1D organic–inorganic hybrid chain { ( \textSiW^\textVI _{1 1} \textW^\textV ₁ \textO ₄₀ ) ₂ [ \textCu^\textII ( \texten ) ₂ ( \textH ₂ \textO )] ₂ [\textCu^\textII ( \texten ) ₂ ] ₂ } ^2- . \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1} {\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}^{ 2- } . The compound 2 consists of protonated L ligand and [SiW₁₂O₄₀]⁴⁻ anion. The protonated L ligands have been extended into a 2D network via hydrogen-bonding interactions. The guest [SiW₁₂O₄₀]⁴⁻ clusters have been incorporated into the square voids of the 2D host network as templates. The electrochemical behavior and electrocatalysis of compound 2 bulk-modified carbon paste electrode (2-CPE) have been studied.     

Synthesis and Properties of Novel Alkyl Sulfonate Gemini Surfactants

A series of novel dialkyl disulfonate gemini surfactants (2C_n-SCT where n is the carbon number of the hydrophobic chain) were synthesized from cyanuric chloride, aliphatic amine and taurine. The chemical structures of the prepared compounds were confirmed by ¹H NMR, ¹³C NMR, IR spectra, and ESI–MS. Their critical micelle concentrations (CMC) in the aqueous solutions at 25 °C were determined by surface tension and electrical conductivity methods. With the increasing length of the carbon chain, the values of their CMC initially decreased, and then increased with an alkyl chain length of 14. The surface tension measurements of 2C_n-SCT (except for n = 14) determined that there is a low CMC, a great efficiency in lowering the surface tension, and a strong adsorption at the air–water interface. In addition, adsorption and micellization behavior of 2C_n-SCT were estimated from pC ₂₀, the minimum average area per surfactant molecule (A _min), and standard free energy micellization and adsorption ( \Updelta G_\textmic^°  \textand \Updelta G_\textads^° \Updelta G_{\text{mic}}^{^\circ } \,{\text{and}}\,\Updelta G_{\text{ads}}^{^\circ } ). These properties are significantly influenced by the chain length n, and the adsorption is promoted more than the micellization.     

Functionalization of cotton fabric orienting towards antibacterial activity

The primary objective of modifying cotton fabric was to impart bactericidal properties to attract various fields such as defence, space and textile industrial applications. Chemically initiated graft copolymerization of 4-vinyl pyridine (4-VP) and acrylonitrile (AN) onto cotton fabric was carried out using ceric ammonium nitrate as a redox initiator. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of concentration of initiator [CAN], concentration of nitric acid, monomer concentration, water, temperature and reaction time. Maximum grafting of 4-VP (51.63%) and AN (69.23%) was obtained respectively at optimum [ \textCAN ] = 2.738 ×10 ^{- 2} \left[ {\text{CAN}} \right] = 2.738 \times {10^{ - 2}} and 2.19 × 10⁻² moles/L, [ 4 - \textVP ] = 47.55 ×10 ^{- 22}\textmoles/\textL \left[ {4 - {\text{VP}}} \right] = 47.55 \times {10^{ - 22}}{\text{moles}}/{\text{L}} , [ \textAN ] = 18.85 ×10 ^{- 22}\textmoles/\textL \left[ {\text{AN}} \right] = 18.85 \times {10^{ - 22}}{\text{moles}}/{\text{L}} , [ \textHN\textO₃ ] = 11.9 ×10 ^{- 2} \left[ {{\text{HN}}{{\text{O}}_3}} \right] = 11.9 \times {10^{ - 2}} and 89.5 × 10⁻²² moles/L in 20 and 25 ml of water at an optimum temperature 70 °C and 60 °C with in 180 and 120 min. Antibacterial properties were induced into the modified cotton fabric by treating the grafted fabric with benzyl chloride. The grafted and quaternized copolymer were characterized by FTIR and Thermogravimetrical analysis. The bactericidal action of cotton fabric was tested by filtration test and it was observed that fabric grafted with 4-VP was more effective and efficient antibacterial as compared to AN grafted cotton sample.     

Structure and Spectral Characteristics of 3D-Supramolecular Coordination Polymers Based on Copper Cyanide and Dimethylquinoxaline

The reactions of K₃[Cu(CN)₄], R₃SnCl (R = Me or ph) and 2,3-dimethyl quinoxaline (dmqox) in H₂O/acetonitrile media at room temperature afford the 3D-supramolecular coordination polymers (SCP) ³_￥ [ \textCu ₂ ( \textCN ) ₂ \textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 2} {\text{dmqox}}} \right] , 1 and ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{dmqox}}} \right] , 2. The structure of the tin free 1 consists of parallel zigzag chains connected by dmqox to form 2D-sheets containing hexagonal 18-atom fused Cu₆(CN)₄(dmqox)₂ rings. The interwoven sheets along the a axis are close packed by extensive H-bonds developing 3D-network structure. The structures of 1 and 2 are investigated by elemental analysis IR, NMR and mass spectra. The ESI⁺ and ESI⁻ mass spectra of 2 support its polymeric nature while the ESI⁺ mass spectrum confirms the expected M. W. suggested by elemental analysis. The ¹³C-NMR spectrum of 2 supports the fact that the network structure of 2 contains the rhombic [Cu₂(μ₃-CN)₂] motif. The structure of 2 was compared with the structure of the reported prototype ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{qox}}} \right] as well as the other related structures.     

Soil nitrogen response to coupling cover crops with manure injection

Coupling winter small grain cover crops (CC) with manure (M) application may increase retention of manure nitrogen (N) in corn (Zea mays L.), -soybean [Glycine max (L.) Merr], cropping systems. The objective of this research was to quantify soil N changes after application of liquid swine M (Sus scrofa L.) at target N rates of 112, 224, and 336 kg N ha⁻¹ with and without a CC. A winter rye (Secale cereale L.)-oat (Avena sativa L.) CC was established prior to fall M injection. Surface soil (0–20 cm) inorganic N concentrations were quantified every week for up to 6 weeks after M application in 2005 and 2006. Soil profile (0–120 cm in 5, 20-cm depth increments) inorganic N, total N, total organic carbon and bulk density were quantified for each depth increment in the fall before M application and before the CC was killed the following spring. Surface soil inorganic N on the day of application averaged 318 \textmg  \textN  \textkg ^{- 1}_\textsoil 318\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in 2005 and 186 \textmg  \textN  \textkg ^{- 1}_\textsoil 186\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}} } in 2006 and stabilized at 150 \textmg  \textN  \textkg ^{- 1}_\textsoil 150\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in both years by mid-November. Surface soil NO₃-N concentrations in the M band were more than 30 times higher in the fall of 2005 than in 2006. The CC reduced surface soil NO₃-N concentrations after manure application by 32% and 67% in mid- November 2005 and 2006, respectively. Manure applied at 224 kg N ha⁻¹ without a CC had significantly more soil profile inorganic-N (480 kg N ha⁻¹) in the spring after M application than manured soils with a CC for the 112 (298 kg N ha⁻¹) and 224 (281 kg N ha⁻¹) N rates, and equivalent inorganic N to the 336 (433 kg N ha⁻¹) N rate. These results quantify the potential for cover crops to enhance manure N retention and reduce N leaching potential in farming systems utilizing manure.     

PWA/montmorillonite K10 catalyst for synthesis of coumarins under solvent-free conditions

12-Tungstophosphoric acid supported on montmorillonite K10 (PWA/mont-K10) catalysed Pechmann condensation reaction was reported. The catalyst was characterized by XRD, FTIR, UV–Vis DRS, surface area and pore size analysis, TGA and acidity by DRIFTS using pyridine. The morphology of the catalyst was studied by SEM. The activity of mont-K10, mont-KSF, \textSO ₄ ^{2 -} \mathord

The O<Subscript>2</Subscript> + NH<Subscript>3</Subscript> Reaction Over Rh(110): Steady State Kinetics and Oscillatory Behavior

Abstract  

The kinetics of ammonia oxidation with oxygen over a Rh(110) surface were studied in the pressure range 10⁻⁵–10⁻⁴ mbar. Nitrogen was found to be the preferred product at low partial pressures ratios \textp_{\texto 2} :\textp_{\textNH 3} {\text{p}}_{{{\text{o}}_{ 2} }} :{\text{p}}_{{{\text{NH}}_{ 3} }} , while the NO pathway was favored with oxygen rich gas mixtures and at high temperature. The reactive sticking coefficient of O₂ reaches up to 0.05 under steady state conditions. Pronounced hysteresis effects in the reaction rates were found in T-cycling experiments. Sustained oscillations in the reaction rates occurred under isothermal conditions at T = 620 K at a total pressure of 4 × 10⁻⁵ mbar.     

Structure and Biological Behaviors of Some Metallo Cationic Surfactants

In this study, different cationic surfactants were prepared by esterification with bromoacetic acid of different fatty alcohols, i.e., dodecyl, tetradecyl and hexadecyl species. The products were then reacted with diphenyl amine, and the resulting tertiary amines were quaternized with benzyl chloride to produce a series of quaternary ammonium salts. The metallocationic surfactants were prepared by complexing the cationic surfactants with nickel and copper chlorides. Surface tension of these surfactants were investigated at different temperatures. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ _max), minimum surface area (A _min), efficiency (PC₂₀) and effectiveness (π _CMC) were studied. The thermodynamic parameters such as the free energy of micellization ( $\Updelta G_{\text{mic}}^{^\circ }$ ) and adsorption ( $\Updelta G_{\text{ads}}^{^\circ }$ ), enthalpy ( $\Updelta H_{\text{m}}^{^\circ }$ ), ( $\Updelta H_{\text{ads}}^{^\circ }$ ) and entropy ( $\Updelta S_{\text{m}}^{^\circ }$ ), ( $\Updelta S_{\text{ads}}^{^\circ }$ ) were calculated. FTIR spectra and ¹H-NMR spectra were obtained to confirm the compound structures and purity. In addition, the antimicrobial activities were determined via the inhibition zone diameter of the prepared compounds, which were measured against six strains of a representative group of microorganisms. The results indicate that these metallocationic surfactants exhibit good surface properties and good biological activity on a broad spectrum of microorganisms.     

Investigation on conductivity of mixed surfactants reverse microemulsion

P-octyl polyethylene glycol phenyl ether (Triton X-100) and cetyltrimethylammonium bromide (CTAB) were mixed to be used as surfactant for preparing reverse microemulsion with n-hexane, n-hexanol and water. Effects of weight ratio of the two surfactants, temperature, concentrations of water and cosurfactant on the conductivity were studied. The results indicate that the conductivity of the mixed surfactants reverse microemulsion is greatly higher than that of the single surfactant system. The reverse microemulsion has been modified to be with good conductivity. The weight ratio of the two surfactants, temperature, concentrations of water and cosurfactant have obvious effects on the conductivity of the reverse microemulsion. Furthermore, the electrochemical behavior of potassium ferricyanide [K₃Fe(CN)₆] in the mixed surfactants reverse microemulsion was investigated by cyclic voltammetry. The result shows that the redox processes of \textFe( \textCN ) ₆ ^3- / \textFe( \textCN ) ₆ ^4- {{\text{Fe}}\left( {\text{CN}} \right)_{ 6}}^{ 3- } / {{\text{Fe}}\left( {\text{CN}} \right)_{ 6}}^{ 4-} present good reversibility and are controlled by diffusion in the system.     

Preparation of a New Oligomeric Surfactant: N,N,N′,N″,N″-Pentamethyl Diethyleneamine—N,N″-Di-[Tetradecylammonium Bromide] and the Study of its Thermodynamic Properties

A new oligomeric surfactant: N,N,N′,N″,N″- pentamethyl diethyleneamine—N,N″-di-[tetradecylammonium bromide] referred to as 14-2-N(CH₃)-2-14 was synthesized, purified and characterized by Elemental Analysis, ¹H and ¹³C NMR and Electrospray. The micellar properties of this compound were determined by electrical conductivity and surface tension methods. Optical microscopy was also employed to study the behavior of anhydrous surfactant and the binary water/surfactant system as a function of temperature. The critical micellar concentration (cmc), degree of counterion binding and thermodynamic parameters of micellization (standard molar Gibbs energy, enthalpy and entropy of micellization) were determined by electrical conductivity measurements in the temperature range [24–54 °C]. Surface tension measurements also provide information about the dependence of the surface tension at the cmc (γ_cmc), pC₂₀ (negative logarithm of the surfactant’s molar concentration C₂₀, required to reduce the surface tension by 20 mN/m, the surface excess (Γ_max) at air/solution interface, the minimum area per surfactant molecule at the air/solution interface (Amin), surface pressure at the cmc (П_cmc), critical packing parameter(CPP) and the standard free energies of micellization ( \Updelta G_m⁰\Updelta G_{m}^{0}) and of adsorption ( \Updelta G_\textads⁰ \Updelta G_{\text{ads}}^{0} ).     

Light-scattering studies on solutions of high and low molecular weight polystyrene mixtures used as models of microgel-containing solutions

Diluted solutions of linear polystyrene (PS) in toluene and dioxane were studied by the light-scattering method. The solutes were mixtures of high-M?_w and low M?_w PS. The dissolved PS mixtures were regarded as polymer solutions containing microgels, the high-M?_w PS being looked upon as the microgel counterpart. The calculation method as proposed by Strazielle¹ and Burchard² was used to evaluate the microgel percentage and particle size, whereby the method could be verified against mixtures with well-known weight composition and \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document}. The \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values evaluated for the mixtures from the experimental data were compared with those estimated from the molecular weights of the components, their weight concentrations, and their \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values. The method^1,2 was found to be useful for evaluating the microgel content in a sample, but not for \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values as calculated by Guinier's procedure nor those calculated by Zimm's procedure; the former were low and the latter were even incongruous. A comparative analysis of the theoretical function P^?1(θ)-versus-sin² (θ/2) and experimental (Kc/R(θ))_c=0-versus-sin² (θ/2) curves allowed to discuss the effect of the course of these curves at samll angles from 0° to 30° on M?_w and \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} as determined for the high and low molecular weight polystyrene mixtures in toluene as solvent.     

Surface and Biological Activity of Some Prepared Iminium Surfactants Based on Schiff Bases

A series of novel iminium surfactants were prepared through quaternization of different prepared fatty Schiff bases with benzyl chloride. The chemical structures were confirmed using FTIR, ¹H-NMR and mass spectroscopy. The surface properties and biological activity of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max) and minimum surface area (A _min), Efficiency (PC₂₀) and Effectiveness (π_CMC) as well as the free energy of micellization ( $ \Updelta G_{\text{mic}}^{\text{o}} $ ) and adsorption ( $ \Updelta G_{\text{ads}}^{\text{o}} $ ) were calculated. It was found that the prepared compounds have good surface and biological activity.     

Surface and Solution Properties of Amphiphilic Drug-Nonionic Surfactant Systems

A surface tension study was performed on mixed amphiphilic drug-nonionic surfactant systems. The drugs used were adiphenine hydrochloride and nortriptyline hydrochloride whereas surfactants were ethoxylated sorbitan esters and polyethylene oxide?Cpolypropylene oxide?Cpolyethylene oxide triblocks. The critical micelle concentration (CMC) and CMC^id (CMC at ideal mixing condition) values suggest nonideal and attractive interactions among the components. The micellar mole fraction $ (X_{ 1}^{\text{m}} ) $ values calculated using Rubingh??s model indicate predominance of the nonionic surfactant in micelle formation. The mole fraction of surfactant in mixed monolayer $ (X_{1}^{\sigma } ) $ values are greater than $ X_{ 1}^{\text{m}} $ values, indicating a greater contribution of surfactant in monolayer formation. Thermodynamic parameters, viz. Gibbs energy of micellization $ (\Updelta G_{\text{m}}^{\text{o}} ) $ , Gibbs energy of adsorption $ (\Updelta G_{\text{ad}}^{\text{o}} ) $ , and excess free energy of mixed micelles $ (\Updelta G_{\text{ex}}^{\text{m}} ) $ and monolayers $ (\Updelta G_{\text{ex}}^{\sigma } ) $ were also evaluated. All these values suggest stable mixed micelle and mixed monolayer formation.     

Micellization of Some Bile Salts in Binary Aqueous Solvent Mixtures

The micellization behavior of bile salts—sodium cholate and sodium deoxycholate was studied in aqueous methanol, ethanol and ethylene glycol mixtures (10–20 % v/v) over a temperature range (300–320 K) by surface tension and conductivity methods. Critical micelle concentration, extent of counter ion binding (α), interfacial property (A _min, ζ_max, π-CMC, $ \Updelta G_{\text{ad}}^{ \circ } $ ) and thermodynamic parameters ( $ \Updelta G_{\text{m}}^{ \circ } $ , $ \Updelta H_{\text{m}}^{ \circ } $ , $ \Updelta S_{\text{m}}^{ \circ } $ ) for the micellization process are reported and discussed.     

Thermodynamic characterization of poly (caprolactonediol) by inverse gas chromatography

Specific retention volumes, V _g ⁰, were determined for 21 solute probes on poly (caprolactonediol) (PCLD) in the temperature range 323.15–403.15 K by inverse gas chromatography. The retention diagrams drawn between ln V _g ⁰ versus 1/T are linear for all the solutes since PCLD with ten repeating units in its chain behaving like a non polymeric material under the conditions applied. The stationary phase with melting temperature ~321 K is in the liquid state in the GC column over the temperature range studied and hence found to be suitable to determine infinite dilution partial molar thermodynamic properties of mixing for solutes on PCLD. The V _g ⁰ values have been used to calculate weight fraction activity coefficients Ω^∞ and Flory–Huggins interaction parameters, χ ₁₂^∞. The average partial molar enthalpy of solution, [`(\Updelta H)]<sub>1</sub><sup>S</sup> , \overline{\Updelta H}_{1}^{S} , and partial molar enthalpy of mixing, [`(\Updelta H)]₁^￥ , \overline{\Updelta H}_{1}^{\infty } , are calculated using V _g ⁰ and Ω^∞ respectively. The average molar enthalpy of vaporization ΔH ₁ ^V for solutes have been calculated using [`(\Updelta H)]<sub>1</sub><sup>￥</sup> \overline{\Updelta H}_{1}^{\infty } and [`(\Updelta H)]₁^S \overline{\Updelta H}_{1}^{S} values and compared with the literature values at 363.15 K which is the average column temperature. The partial molar entropy of mixing, [`(\Updelta S)]<sub>1</sub><sup>￥</sup> \overline{\Updelta S}_{1}^{\infty } calculated at 363.15 K are in good correlation with the average [`(\Updelta H)]₁^￥ \overline{\Updelta H}_{1}^{\infty } values. The total solubility parameter due to Guillet and the Hansen solubility parameters (HSP) are calculated for PCLD using χ ₁₂^∞ values. In the present work the Hansen solubility parameters have been calculated using a new method following the Hansen theory and Huang method with less weight on polar and hydrogen bonding components. The errors in the solubility HSP are lower and the correlation coefficients are better in both the methods compared to unweighted three dimensional model.     

A dimensionless model for predicting the mass‐transfer area of structured packing

The mass‐transfer area of nine structured packings was measured in a 0.427 m ID column via absorption of CO₂ from air into 0.1 kmol/m³ NaOH. The mass‐transfer area was most strongly related to the specific area (125–500 m²/m³), and liquid load (2.5–75 m³/m²·h). Surface tension (30–72 mN/m) had a weaker but significant effect. Gas velocity (0.6–2.3 m/s), liquid viscosity (1–15 mPa·s), and flow channel configuration had essentially no impact on the mass‐transfer area. Surface texture (embossing) increased the effective area by 10% at most. The ratio of mass‐transfer area to specific area (a_e/a_p) was correlated within the limits of ±13% for the entire experimental database ${{a_{\rm{e}} } \over {a_{\rm{p}} }}= 1.34 \left[ {\left( {{{\rho _{\rm{L}} } \over \sigma }} \right)g^{1/3} \left( {{Q \over {L_{\rm{p}} }}} \right)^{4/3}} \right]^{\,0.116}$ . © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Thermodynamics of Micellization of Sulfobetaine Surfactants in Aqueous Solution

The thermodynamics of micellization of the sulfobetaine (SB) amphoteric surfactants, that is N-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and N-alkyl-N,N-dimethyl-3-ammonio-1-butanesulfonate (the carbon atom number of the alkyl chain is 12, 14 and 16 respectively) in aqueous solution, have been studied by surface tension measurements with the temperature range from 298.15 to 318.15?K. The critical micelle concentrations (CMC) of SB n-3 and SB n-4 surfactants were determined from the drop-volume methods at different temperatures. The obtained results indicated that the values of critical micelle concentration strongly depended on the surfactants species and temperatures. Thermodynamic parameters ( $ \Updelta G_{\text{mic}}^{ \circ } $ , $ \Updelta H_{\text{mic}}^{ \circ } $ and $ \Updelta S_{\text{mic}}^{ \circ } $ ) of the micelle formation were determined. The micellization was found to be enthalpy-driven at lower temperatures, while this process was entropy-driven at higher temperatures. The enthalpy?Centropy compensation were also investigated. The compensation temperature T _c and $ \Updelta H_{\text{mic}}^{*} $ decreased, while $ \Updelta S_{\text{mic}}^{*} $ increased with the increase in the hydrophobic chain length.     

Determination of equilibrium silver sulphate concentration in the system Cu-H2SO4-CuSO4-H2O-Ag2SO4-Ag as a function of composition

The value of the ratio \(\gamma _{{\text{Cu}}^{{\text{2 + }}} } /\gamma _{{\text{Ag}}^{\text{ + }} }^2 \) ( \(\gamma _{{\text{Cu}}^{{\text{2 + }}} } ,\gamma _{{\text{Ag}}^{\text{ + }} } \) -are the mean activity coefficients of copper and silver ions, respectively) was calculated from the measured emf of the cell $${\text{Cu(Hg)|H}}_{\text{2}} {\text{SO}}_{\text{4}} {\text{ (}}c_{\text{x}} {\text{)}} - {\text{CuSO}}_{\text{4}} {\text{ (}}c_{\text{y}} {\text{)|Hg}}_{\text{2}} {\text{SO}}_{\text{4}} {\text{, Hg}}$$ and the solubility of Ag₂SO₄ in H₂SO₄ (c _x) and CuSO₄ (c _y) solutions. The concentration of H₂SO₄ in the solution was varied from 0.5 to 2.1 mol dm^?3 that of CuSO₄ from 0.4 mol dm^?3 to saturation. The results were presented as a function: $$\frac{{\gamma _{{\text{Cu}}^{{\text{2 + }}} } }}{{\gamma _{{\text{Ag}}^{\text{ + }} }^2 }} = a_0 + a_1 c_{\text{x}} + a_2 c_{\text{y}} + a_3 c_{\text{x}}^{\text{2}} + a_4 c_{\text{x}} c_{\text{y}} + a_5 c_{\text{y}}^2 .$$ This function allows the estimation of the equilibrium silver ion concentration \(c_{{\text{Ag}}^{\text{ + }} }^{{\text{eq}}} \) in solutions containing both H₂SO₄ and CuSO₄ in the presence of metallic copper. The function is also very useful for the estimation of the \(c_{{\text{Ag}}^{\text{ + }} }^{{\text{eq}}} \) near a working copper electrode.