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Öğe Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants(Wiley, 2012) Akbas, Halide; Elemenli, Aylin; Boz, MesutIn this study, the gemini surfactants of the alkanediyl-alpha-omega-bis(alkyl dimethyl ammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as m-2-m (m = 10, 12 and 16) and, on the other hand, with n-C-16 alkyl groups and different spacers containing s carbon atoms, referred to as 16-s-16 (s = 2, 6, 10 and Ar (8)) have been synthesized, purified and characterized. The critical micelle concentration (CMC), micelle ionization degree (alpha) and Gibbs free energy of micellization (a dagger G (mic)) of these surfactants and the monomeric cationic surfactants DTAB and CTAB have been determined by means of electric conductivity measurements. In addition, the temperature dependence of the CMC was determined for the 10-2-10 gemini surfactant. The CMCs of the gemini surfactants are found to be much lower than those of the corresponding monomeric surfactants and the effect of the hydrophobic alkyl chain length is more important than that of the spacer. The CMC of 16-s-16 passes through a maximum of (or around) s = 6 and then decreases for s = 10. The presence of a maximum CMC is explained by the contribution of a change of conformation of the surfactant with increasing spacer chain length. The changes of alpha with s and m are found qualitatively similar to those found for CMC values. The values of a dagger G (mic) are more negative for the dimers than for the monomers and also change with an increasing spacer carbon number, as CMC values do. The thermodynamic parameters of micellization indicate that the micellization of 10-2-10 is enthalpy driven.Öğe Aggregation behavior and intermolecular interaction of binary surfactant mixtures based on cationic Geminis and nonionic surfactants(Springer, 2015) Akbas, Halide; Kasapoglu, Sinem; Boz, MesutThe Gemini surfactants of type alkylediyl-alpha-omega-bis(alkyldimethylammonium) dibromide with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred as m-2-m [C (m) H2m + 1(CH2)(2) N+(CH2)(2) N+(CH2)(2) C (m) H2m + 1, 2Br(-)] (m = 12 and 16), have been synthesized, purified, and characterized in our laboratory. The interactions between cationic Geminis and nonionic surfactants polyoxyethylene (23) lauryl ether (Brij35) and polyoxyethyleneoctyl phenyl ether (TX-100) have been studied by conductivity and steady-state fluorescence quenching techniques at a certain micellar concentration range and certain temperature. Rubingh's theory is used to evaluate the micellar interaction parameters (beta) for the mixed systems. It has been observed that mixed micelle formation in all the binary mixtures exhibited negative synergism (antagonism) or ideal behavior due to positive beta values. It was observed that contribution of conventional surfactants was always more than that of the Geminis. By using the ratio of peak intensities, micro-polarity, dielectric constant (D), and binding constant (K (sv)) of mixed systems have been found.Öğe Bazı sikloalkenlerden sentezlenen geminal dibromosiklpropan halkasının AgNO3 ile DMF-asetikasit çözücü sisteminde açılma reaksiyonları ve halka genişlemesi(Trakya Üniversitesi, 1999) Boz, Mesut; Zaim, ÖmerÖZET Karbenler yüksüz, oldukça reaktif ara ürünlerdir. Verdikleri pekçok önemli reaksiyondan biri de katılma reaksiyonudur. Karben türevleri çift bağlara katılarak substitue siklopropan halkasını oluştururlar. Bu halkanın gerilimi çok yüksek olduğu için açılarak rahatlama istemindedir. Siklopropan halkasının sikloalkenler üzerinde oluşturulup açılmasıyla siklo yapıdaki karbon sayısı bir artırılarak, halka genişletilebilir. Daha önce yapılan çalışmalarda siklopropan halkası trietilamin kullanılarak açılmaya çalışılmış fakat sonuç olarak halkanın açılmadığı görülmüştür. Bu sebeple halka Ag* elektrofili ile H2O-CH3OH çözücü sisteminde açılmış hem suyun hemde metanolün nükleofilik karakter göstermesi yüzünden ürün karmaşası oluşmuş ve saflaştırma problemi ortaya çıkmıştır. Bu çalışmada ürün karmaşasından kurtulmak amacıyla tek nükleofil olarak CH3COOH kullanılmıştır, ilk planda siklopenten, sikloheksen, siklohepten, siklookten, siklododesen olmak üzere beş adet basit yapılı sikloalken üzerinde reaksiyonların nasıl yürüdüğü gözlenmiştir. Bu amaçla alkenlerin çift bağları üzerinde bromoform ve potasyum tert-bütoksit ile heksan içerisinde dibromosiklopropan halkası oluşturulmuştur. Siklopropan halkası Ag* elektrofili ile asetikasit-DMF çözücü sisteminde açılarak halka genişlemesi sağlanmıştır. Sonraki aşamada 1 -alkil sikloheksenler sentezlenerek aynı reaksiyonlar bu alkenlere uygulanmıştır. Bu çalışmanın bir özelliği de bu reaksiyonların a-pinene ilk defa uygulanmış olmasıdır. Reaksiyonların yürüyüşü TLC ile kontrol edilmiş ürünler kolon kromatografisi ile saflaştırılmıştır. Yapı belirlemede İR ve NMR spektroskopilerinden faydalanılmıştır.Öğe A Convenient Synthesis of 2-Azido and 2-Thiocyanato-2,3-Unsaturated Cyclic Ketones(Tubitak Scientific & Technological Research Council Turkey, 2009) Boz, Mesut; Zaim, Oemer; Esen, Hilal2-Azido and 2-thiocyanato-2,3-unsaturated ketones were synthesized by utilizing functionalization of 5- or 6-membered cycloalkane-1,2-diones, namely diosphenols, with dimethylthiocarbomoyl chloride, which activates the system towards reaction with nucleophiles in acidic conditions. Replacement of the enolic oxygen of the diosphenols with azide and thiocyanate may be achieved by treating their dimethylthiocarbamates with sodium azide or potassium thiocyanate in boiling acetonitrile/acetic acid.Öğe Diosfenollerde yeni reaksiyonlar: a) Diosfenol tiyo karbamatların Cı, Br, I dışındaki nükleofillerle yer değiştirme reaksiyonları b) Dallanmış diosfenol w-haloalkil eterlerde radikalik halka kapanma(Trakya Üniversitesi, 2005) Boz, Mesut; Zaim, ÖmerDoktora TeziDiosfenollerde Yeni Reaksiyonlar: a) Diosfenol Tiyo Karbamatların -Cl, -Br, -IDışındaki Nükleofillerle Yer Değiştirme Reaksiyonları. b) Dallanmış Diosfenolω−Haloalkil Eterlerde Radikalik Halka Kapanma Reaksiyonları ve Bölge Seçiciliğinncelenmesi.Trakya ÜniversitesiFen Bilimleri EnstitüsüKimya Anabilim DalıÖZETAktive edici grup olarak dimetil tiyo karbomoil grubu kullanılarak,diosfenollerin enolik hidroksilinin -Cl ve -Br nükleofilleriyle yer değiştirmereaksiyonları bilinmektedir. Dimetil tiyo karbomoil oksi grubu asidik ortamda birmoleküliçi halka oluşumu ile nükleofilik yerdeğiştirmeye uygun bir yapı oluşturur. Buyöntem kullanılarak α-kloro ve α-bromo-α,β-doymamış ketonlar'ın sentezi daha önceyapılmıştır. Çalışmanın birinci kısmında üç farklı diosfenol ve dört farklı diosfenoldimetil tiyo karbamat'ın sentezi gerçekleştirilmiş, diosfenol dimetil tiyo karbamatlarındört farklı nükleofille (-N3, -SCN, -OCN, -CN) yer değiştirme reaksiyonlarıincelenmiştir. Bu nükleofillerle yapılan reaksiyonlar sonucunda α-azido ve α-tiyosiyanato-α,β-doymamış ketonların sentezi gerçekleştirilmiş, -CN ve -OCNnükleofilleriyle yerdeğiştirme gerçekleşmemiştir.Çalışmanın ikinci kısmında ise dallanmış diosfenol ω-haloalkil eterlerinradikalik halka kapanması ve reaksiyonun bölge seçiciliği incelenmiştir. Bu amaçlaöncelikle üç farklı dallanmış diosfenol ω-haloalkil eterin sentezi planlanmış, fakatbunlardan sadece ikisinin sentezi yapılabilmiştir. Daha sonra ise bu eterlerin halkakapanma reaksiyonları gerçekleştirilmiştir. Halka kapanma reaksiyonlarından spiroyapılı bileşikler ve bir indirgenme ürünü elde edilmiş, altı üyeli halka oluşumugözlenmemiştir.Anahtar Sözcükler: Diosfenol, diosfenol tiyo karbamat, nükleofilik yer değiştirme,diosfenol ω-haloalkil eter, moleküliçi radikalik halka kapanma, bölge seçicilik,heterosiklik bileşikler2005141 sayfaÖğe Experimental Investigation of Cationic Gemini Surfactants: Self-Assembly, Corrosion Inhibition, Foaming and Dye Solubilization Properties(Wiley-V C H Verlag Gmbh, 2023) Kasapoglu, Sinem; Batigoc, Cigdem; Boz, Mesut; Tetik, OvulIn this study, two cationic gemini surfactants 12-3-12 and 12-3(OH)-12 were synthesized in our labrotory. The critical micelle concentration (CMC) values of synthesized surfactants were determined by conductivity measurements. The aggregation number (Nagg) of micelles was calculated using the pyrene probe fluorescence method. It was been investigated the corrosion effect of cationic gemini surfactants were denoted as 12-3-12 and 12-3(OH)-12 for carbon steel in 1 M HCl. The inhibition effect was investigated using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and scanning electron microscopy (SEM) techniques. It has been determined that both surfactants showed the best inhibitory effect at low concentrations. The foaming capacity (FC) and the foam stability (FS) of gemini surfactants were studied by measuring the foam volume for 0.5 % (w/v) surfactant solutions and it was observed that the foaming properties of 12-3(OH)-12 gemini surfactant were better. The solubility capability of both surfactants was tested with the water-insoluble dye Sudan Red B and it was observed that the solubility increased significantly over the CMC value of the cationic gemini surfactants. Finally, the corrosion effect, foam capacity and foam stability and effects on paint solubility of the synthesized surfactants were obtained at very low concentrations.Öğe Interaction between cationic gemini surfactant and related single-chain surfactant in aqueous solutions(Elsevier, 2014) Akbas, Halide; Boz, Mesut; Elemenli, AylinIn this paper, the gemini surfactants of type alkanediyl-a-co-bis (alkyldimethylammonium) dibromide with different spacers containing s carbon atoms, referred to as 16-s-16 [C16H33(CH2)(2)N+(CH2)sN(+)(CH2)(2)C16H33.2Br-], (s=2, 6, 10 and Ar (8)) have been synthesized, purified and characterized in our laboratory. The interactions between geminis and their conventional monomeric surfactant hexadecyltrimethylammonium bromide (CTAB) have been studied using the conductivity and steady-state fluorescence quenching techniques at a certain micellar concentration range and certain temperature. Using the conductance data, the values of critical micelle concentrations (CMC) of the binary gemini-conventional mixtures having different compositions have been obtained. The micellar interaction parameters, (beta), were determined from the critical micelle concentration values using the approach of Rubingh's regular solution theory. Mixed systems were exhibited negative synergism due to positive beta values. The beta values were found as close to zero. This indicates that the mixed micelle formation is ideal for all studied mixtures. The micelle aggregation numbers (N-agg evaluated using steady-state fluorescence quenching at a total concentration of 2 mM for CTAB/16-s-16 (s= 2, 6, 10 and Ar (8)) systems. It was observed that contribution of conventional surfactants was always more than that of the geminis. Using the ratio of peak intensities, the micro-polarity, dielectric constant and binding constant (K-sv) of mixed systems were determined. (C) 2014 Elsevier B.V. All rights reserved.Öğe Micellization behaviour and thermodynamic parameters of 12-2-12 gemini surfactant in (water plus organic solvent) mixtures(Academic Press Ltd- Elsevier Science Ltd, 2011) Batigoc, Cigdem; Akbas, Halide; Boz, MesutThe effect of organic solvents on micellization behaviour and thermodynamic parameters of a cationic gemini (dimeric) surfactant, C12H25(CH3)(2)N+-(CH2)(2)-N+(CH3)(2)C12H25 center dot 2Br(-), (12-2-12) was studied in aqueous solutions over the range of T = (293.15 to 323.15) K using the conductometric technique. Ethylene glycol (EG), dimethylsulfoxide (DMSO) and 1,4-dioxan (DO) were used as organic solvents with three different contents. The critical micelle concentration (cmc) and the degree of counter ion dissociation (a) of micelles in the water and in the (water + organic solvent) mixtures including 10%, 20%, and 30% solvent contents were determined. The standard Gibbs free energy (Delta G degrees(m)), enthalpy (Delta H degrees(m)) and entropy (Delta S degrees(m)) of micellization were estimated from the temperature dependence of the cmc values. It was observed that the critical micelle concentration of the gemini surfactant and the degree of counter ion dissociation of the micelle increased as the volume percentage of organic solvent, and temperature increased. The standard Gibbs free energy of micellization was found to be less negative with the increase in the organic solvent content and temperature. (C) 2011 Elsevier Ltd. All rights reserved.Öğe A novel cationic Gemini surfactant with amide group: synthesis and micellization behavior in aqueous solutions(Springer, 2016) Akbas, Halide; Kocaoglu, Semra; Boz, Mesut; Dikmen, AlperNovel cationic Gemini surfactant with amide group, N (1),N (10)-bis(3-dodecanamidopropyl)-N (1),N (1),N (10),N (10)-tetramethyldecan-1,10-diammonium bromide (abbreviated as 2C(12)enAm) has been synthesized by two-step reactions, purified and characterized in our laboratory. The critical micelle concentration (CMC) values of this Gemini surfactant were determined using electrical conductivity and surface tension measurements in the range of temperatures from 298.15 to 328.15 K. It was observed that the CMC value of Gemini surfactant has a much lower value compared with monomeric ones and shows a slight increase with an increase in the temperature. The interactions between Gemini and conventional monomeric surfactant hexadecyltrimethylammonium bromide (CTAB) have been studied using the conductivity at a certain micellar concentration and temperature range. Rubingh's theory is used to evaluate the micellar interaction parameters (beta) for the mixed systems. It has been observed that mixed micelle formation in all the binary mixtures exhibited negative synergism (antagonism) or ideal behavior due to positive beta values. Thermodynamics parameters were also obtained from the temperature dependence of the CMC values. From the surface tension measurements, CMC, maximum surface excess concentration at the solution/air interface (I(max)), minimum area per surfactant molecule (A (min)), the surface pressure at CMC (I (CMC)), the surfactant concentration required to reduce the surface tension of solvent by 20 mN m(-1) (pC(20)), and thermodynamic parameters have been evaluated at same temperatures.Öğe THE Pd(II) COMPLEX INVOLVING A NEW PYROLE-BASED LIGAND: SYNTHESIS, SPECTRAL ANALYSIS, AND ANTIMICROBIAL ACTIVITY(Soc Chemists Technologists Madeconia, 2022) Boz, Mesut; Tetik, Ovul; Altun, OzlenIn the current study, firstly, a new pyrrole-based ligand (3,4-(ethylenedimercaptodiacetoxy)-N-(benzyl)-diethyl-2,5-pyrroledicarboxylate (L) was synthesized in the presence of diethyl-N-benzyl-3,4-dihydroxy-1H-pyrrole-2,5-dicarboxylate and 2,2'-(ethane-1,2-diylbis(sulfanediyl))diacetylchloride. Then, the palladium(II) complex of the synthesized ligand was obtained, and its structural features were examined by spectral (HRMS, ESI-MS, UV-Visible, FTIR, H-1 NMR, C-13 NMR, XRD-POWDER, SEM, EDX) and thermogravimetric (TG-DTA) techniques. The spectral and thermal measurements of the ligand and its Pd(II) complex show that the ligand is coordinated to the Pd2+ ion. Antimicrobial activities of both the ligand and its palladium complex were examined. It was determined that whereas the ligand indicated modest antimicrobial activity against Staphylococcus aureus and Candida albicans at a concentration of 6.25 mu g/ml, the palladium complex was significantly effective against C. albicans at a concentration of 6.25 mu g/ml.Öğe Phase Transfer Catalysis with Quaternary Ammonium Type Gemini Surfactants: O-Alkylation of Isovanillin(Springer Heidelberg, 2016) Boz, Mesut; Basturk, Sedat SemihIn this paper, O-alkylation of isovanillin with unusual phase transfer catalysts alkandiyl-a,omega-bis(dimethylalkyl-ammonium bromide) dimeric surfactants (also known as gemini surfactants) is described. Some dimeric surfactants with simple hydrophobic alkyl chains and others with hydrophobic alkyl chains containing ester functionalities with different lengths were synthesized and characterized in our laboratory. The alkylation of isovanillin with alkyl halide was successively carried out in the presence of potassium carbonate and a phase transfer catalyst in tetrahydrofuran. The same reactions were also performed with both the traditional phase transfer catalyst tetrabutylammonium bromide and without any catalyst. The results were compared with those of dimeric surfactants. Consequently, it was expressed that alkandiyl-alpha,omega-bis(dimethylalkylammonium bromide) dimeric surfactants successively exhibit the character of phase transfer catalysts through environmentally friendly procedures undermild conditions. The most significant feature of this work is that dimeric surfactants have been determined to act as phase transfer agents.Öğe Silver Ion-Assisted Ring Expansions in Different Solvent Systems(Tubitak Scientific & Technological Research Council Turkey, 2009) Boz, Mesut; Caliskan, Hafize; Zaim, OemerSeveral ring expansion products carrying vinylic bromo functionality were synthesized by opening of the geminal dibromobicyclo[n.1.0]alkanes ring. Dibromocarbene was formed from bromoform and potassium tert-butoxide in hexane. Its reaction with various cyclic alkenes was the resultant dibromobicyclo[n.1.0]alkanes. Then, opening was performed using AgNO3 in various solvent systems, such as acetic acid/DMSO, acetic acid/DMF, CH3OH/acetone, and H2O/DMF.Öğe Study on cloud points of Triton X-100-cationic gemini surfactants mixtures: A spectroscopic approach(Pergamon-Elsevier Science Ltd, 2010) Akbas, Halide; Boz, Mesut; Batigoc, CigdemThis study investigates the effects of various cationic surfactants on the cloud point (CP) of the nonionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The values of CPs for Triton X-100 can be measured directly because TX-100 has an average number of oxyethylene units per molecule of p approximate to 9.5 and a CP = 66.0 degrees C. Quaternary ammonium dimeric surfactants (m-s-m, m = 10, 12, and 16, and s = 2, 6, and 10) were synthesized and used. The melting temperature T-M and the Krafft temperature T-K were measured for 1 wt% aqueous solutions of these synthesized surfactants. The melting temperature of the solid gemini surfactants increased with the carbon number of the alkyl chain. The results showed that additions of the gemini surfactants (which are infinitely miscible with water) to Triton X-100 increased the cloud point of the TX-100 solutions. All salts tested in these studies had a large effect on the CPs of nonionic surfactants due to their effect on water structure and their hydrophilicity. The effect of the alkyl chain length of the gemini surfactant on the CP of Triton X-100 is therefore more important than the spacer chain length. (C) 2009 Elsevier B.V. All rights reserved.Öğe Synthesis and Biological Activity of a New Pt(II) Complex Involving 4-bromo-2,6-bis-hydroxymethyl-phenol and Nicotinamide(Jihad Daneshgahi, 2022) Altun, Ozlen; Yoruc, Zeliha; Boz, MesutIn the present study, a Pt(II) complex including 4-Bromo-2,6-bis-hydroxymethylphenol (BBHMP) and nicotinamide (NA) was synthesized and structurally analyzed by using spectral and thermal analysis methods. BBHMP and its Pt(II) complex in the presence of BBHMP and NA were investigated for their antimicrobial, cytotoxicity, gene expression, and antioxidant properties. The antimicrobial activity results showed that the platinum complex displayed a significant effect against Staphylococcus aureus and Candida albicans. The cytotoxicity of BBHMP and platinum complex were determined against human prostate adenocarcinoma (DU145) and breast (MCF7) cancer cell lines by applying the MTT assay. Cytotoxicity results suggested that the Pt(II) complex exhibited moderate cytotoxicity against the growth of these cancer cell lines when compared with the reference drug cisplatin is more effective than free BBHMP and NA. Gene expression results proved that the Pt(II) complex is a special bioactive chemical constituent and potential anticancer agent. The results obtained showed that the complex had highly inhibitory effects on gene expression. In addition, Pt(II) complex also displayed effective antioxidant activity.Öğe Synthesis and Physicochemical Properties of Double-Chain Cationic Surfactants(Amer Chemical Soc, 2016) Ozdil, Sinem Engin; Akbas, Halide; Boz, MesutIn this study two types cationic surfactants were synthesized, purified, and characterized in our laboratory. One them is a series of cationic surfactants, a two tail-one head surfactant, N,N-dialkyl-N,N-diethylammonium bromide, abbreviated as m-0-m (m = 10, 12, and 16). The other type is N,N'-dialkyl-N,N,N',N'-tetramethyl-N,N'-ethanediyl-diammonium dibromide, two tail-two head surfactants, abbreviated as m-2-m (m = 12 and 16). Once NMR spectra (1(H) NMR, C-13 NMR) for all the gemini surfactants that were synthesized were taken, then the melting temperatures (T-M) were measured. These surfactants have very high surface activity. The main goal of our study was to examine some properties of these two tail cationic surfactants by manipulating their dimeric structure. The effects of alkyl chain length and headgroup on surfactant self-assembly in solution were investigated. Critical micelle concentrations (CMC), degree of micelle ionization (alpha), and Krafft temperatures (T-K) of 1 wt % aqueous solutions of these surfactants were determined by conductance measurements. Krafft points were found to be dependent on the number of carbon atoms in the alkyl chain and decreased by the addition of the electrolytes. The absence of the spacer group, peculiar to these twin tail cationic surfactants, may confer relatively low flexibility to the molecules, with potential implications on the interfacial properties, namely, on micellization.Öğe Thermodynamic Study of the Interaction Between CI Reactive Red180 with Cationic Gemini Surfactant in Aqueous Solution(Asian Journal Of Chemistry, 2012) Akbas, Halide; Elemenli, Aylin; Batigoc, Cigdem; Boz, MesutInteractions between Reactive Red 180 and cationic gemini surfactant solutions were investigated by means of electrical conductivity measurement:, at different temperatures ranging from 298.15 to 323.15 K. Gemini surfactant of the type N,N'-didecyl-N,N,N',N'-tetramethyl-N,N'-ethanediyl-diammonium dibromide referred as (10-2-10) was synthesized in our laboratory. It was observed that a decrease in the measured specific conductance of dye-gemini surfactant mixtures was caused by the formation of nonconducting or less conducting dye-surfactant associates. The aggregation of surfactant and dye takes place at a surfactant concentration far below the critical micelle concentration of the individual surfactant. The long-range electrostatic forces and short-range hydrophobic interactions are very important factors at the dye-surfactant aggregation in aqueous solutions. From conductivity data for dyes-gemini surfactant interaction such as micellar ionization degree, counterion binding, equilibrium constant and thermodynamic parameters of interaction were calculated. Thermodynamic parameters of interaction indicate that interaction of dye-(10-2-10) is enthalpy driven.Öğe Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point(Academic Press Ltd- Elsevier Science Ltd, 2011) Batigoc, Cigdem; Akbas, Halide; Boz, MesutThis study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-alpha-omega-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as m-2-m (m = 10, 12, and 16) and, on the other hand, with -C-16 alkyl groups and different spacers containing s carbon atoms, referred to as 16-s-16 (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (Delta G(cp)(o)), the enthalpy (Delta H-cp(o)) and the entropy (Delta S-cp(o)) of the clouding phenomenon were found positive in all cases. The standard free energy (Delta G(cp)(o)) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration. (C) 2011 Elsevier Ltd. All rights reserved.
