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Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants
(Wiley, 2012) Akbas, Halide; Elemenli, Aylin; Boz, Mesut
In 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.
Aggregation behavior and intermolecular interaction of binary surfactant mixtures based on cationic Geminis and nonionic surfactants
(Springer, 2015) Akbas, Halide; Kasapoglu, Sinem; Boz, Mesut
The 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.
CI Reactive Orange 16-dodecylpyridinium chloride interactions in electrolytic solutions
(Pergamon-Elsevier Science Ltd, 2006) Akbas, Halide; Kartal, Cigdem
The effect of electrolytes on the interaction between an anionic dye and a cationic surfactant was investigated spectrophotometrically in submicellar concentration range at certain temperature. The spectral change of the azo dye C.I. Reactive Orange 16 (RO16) exhibits a high sensitivity to the polarity of dye's environment. Dodecylpyridiniurn chloride (DPC) affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results formation of complex and therefore a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte cations cause an increase of the absorbance of DPC-RO16 ion-pair complex in the following order: Ca2+ > Na+ > NH4+ > K+ > Mg2+, also for electrolyte anions Br- > Cl- > SO42-. Furthermore, this order can be changeable with increasing electrolyte concentration. The increase on absorbance value with increasing electrolyte concentration is explained as charge screening. The increase or decrease on absorption spectra of RO16-DPC solution depends on concentration range of the electrolyte added. As an increase on absorbance value with increasing electrolyte concentration is explained as charge screening, a decrease in this value for higher concentration of electrolyte is attributed as the charge of micelle shape. (c) 2005 Elsevier B.V. All rights reserved.
A COMPARATIVE STUDY ON THE SIGNIFICANCE OF LEAD, NICKEL AND CADMIUM ON ROOT GROWTH, THE KINETICS OF METAL ION TRANSPORT AND pH CHANGES IN ONION (ALLIUM CEPA) ROOT
(Parlar Scientific Publications (P S P), 2016) Akbas, Halide; Dane, Feruzan; Meric, Ciler
In this study, the effect of different concentrations of lead (0.25, 0.50, 1.00 and 2.00 mM) uptake by roots, on root growth of Allium cepa, and the transport of lead ion (Pb2+), iron ion (Fe2+), manganese ion (Mn2+) and hydrogen ion (H+) were investigated spectrophotometrically. The uptake of Pb2+, Fe2+ and Mn2+ by Allium cepa were monitored by a Unicam model 929 flame atomic absorption spectrophotometer (AAS) and pH values were measured by a Jenway 3040 Ion Analyzer with a combination glass electrode. The mineral content of the solution was measured instead of the mineral content of the root material. Lead ions had inhibitory effect on the root growth in all concentrations during the entire treatment. The EC50 was found at 0.50 mM Pb2+. A large amount of Pb2+ was translocated into A. cepa roots. The kinetics of metal ion transport was described by a pseudo-first order reaction at 1.00 and 2.00 mM metal ion concentrations. Pb2+, Fe2+ and H+ ions transfer into plant from solution but Mn2+ ion transfer to the solution from the plant. The amount of H+ in the solution is increased at all Pb+2 concentrations except 0.25 mM Pb+2 concentration. The results of this study are compared with previous studies with nickel and cadmium treatment.
Conductometric studies of the interaction of CI Reactive Orange 16 with cationic alkyltrimethylammonium bromide surfactants
(Elsevier Sci Ltd, 2007) Akbas, Halide; Kartal, Cigdem
The interactions between an anionic dye, C.I. Reactive Orange 16 (RO16) and the cationic surfactants, dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) were studied using a conductometric method. The specific conductance of dye-surfactant mixtures was measured at five different temperatures. The equilibrium constants and other thermodynamic functions for the process of dye-surfactant ion pair formation were calculated on the basis of two theoretical models. The results showed that an increase in temperature reduces the tendency for ion pair formation as equilibrium constants decrease with increasing temperature. According to results, the surfactant which contained the longer hydrophobic chain had a stronger tendency to associate with the dye and the equilibrium constants were considerably higher than those measured for the surfactant with the shorter hydrophobic chain. These results indicate that short range, non-electrostatic interactions have a significant influence on dye-surfactant ion pair formation as well as long range electrostatic forces. (c) 2005 Elsevier Ltd. All rights reserved.
The Effect of Electrolytes on the Interaction of C. I. Reactive Orange 16-Tetradecyltrimethylammonium Bromide
(Carl Hanser Verlag, 2013) Akbas, Halide; Taner, Tanzer
The aim of this study is to investigate the interaction of a cationic surfactant tetradecyltrimethyl ammonium bromide (TTAB) on the electronic absorption spectra of azo dye Reactive Orange 16 (RO16) and to observe the effects of the kind and concentration of electrolytes on these interactions by means of UV-Vis spectroscopy in submicellar and micellar concentration range at a certain temperature (303 K). TTAB affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results into formation of complex and therefore, a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte anions cause an increase on the absorbance of TTAB-RO16 ion-pair complex in the following order: Br- > Cl- > SO42- > NO3- > CN- and also for cations; Na+ > K+ > NH4+ > Mg2+. The increase or decrease on absorption spectra of RO16-TTAB solution depends on concentration range of the electrolyte added.
Effect of nickel on root growth and the kinetics of metal ions transport in onion (Allium cepa) root
(Natl Inst Science Communication-Niscair, 2009) Akbas, Halide; Dane, Feruzan; Meric, Ciler
The effect of different concentrations of nickel nitrate (0.25, 0.50, 1.00 and 2.00 mM) uptake by the roots, on root growth of onion (Allium cepa) and the transport of Ni2+, Fe2+, Mn2+, Zn2+, K+, Na+ and H+ ions were investigated spectrophotometrically. The uptake of Ni2+, Fe2+, Mn2+ and Zn2+ was monitored by flame atomic absorption spectrometry with a 24-h period for 7 days and the amounts of K+ and Na+ were determined in solutions by flame photometer, The mineral content of the solution, instead of the root material was measured. Ni2+ ions showed inhibitory effect oil the root growth at all concentrations during the entire treatment. The EC50 (effective concentration that reduced root growth by 50%) was found at 0.25 mM Ni2+. No significant change in inhibitory effect was observed after at 0.50 mM Ni2+ concentrations. A large amount of Ni2+ was translocated into the roots. The kinetics of metal ion transport followed a pseudo-first order reaction in all metal ion concentrations. Ni2+, Zn2+ Fe2+ Mn2+ and H+ ions transferred together into plant, but Na+ and K+ ions transferred to the solution from the plant. The amount of H+ in the solution decreased at all Ni2+ concentrations.
Interaction between cationic gemini surfactant and related single-chain surfactant in aqueous solutions
(Elsevier, 2014) Akbas, Halide; Boz, Mesut; Elemenli, Aylin
In 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.
Interfacial and micellar properties of anionic azo dye-surfactant binary systems
(Pleiades Publishing Inc, 2008) Akbas, Halide; Aydemir, Melike
The association of an anionic dye C.I. Reactive Orange 16 (RO16) and different types of surfactants, i.e., anionic surfactant sodium dodecylsulfate, nonionic surfactants poly(oxyethylene) ethers (C (m) POE10, m = 12, 16, and 18; C12POEn , n = 4, 10, and 23), was investigated using tensiometry in a certain micellar concentration range. RO16 was shown to aggregate in water when its concentration is above the threshold value. The surface tension lowering and critical micellar concentration (CMC) values were interpreted on the same grounds as those for surfactants mixtures. The tensiometric measurements of dye-surfactant systems are carried out as a function of the molar concentration of solution at 25 degrees C. Using Rubingh's regular solution theory, the values of interaction parameters were found to be negative for all studied binary mixtures. These negative values indicate that there is an attractive interaction of the surfactants in mixed micelles and reflect synergistic behavior of a mixture. In all studied systems, deviations from ideal behavior were observed depending on the type of surfactant. Interaction parameters calculated using regular solution theory are changed from -2.62 to -12.43. The smallest deviation from ideal behavior is obtained for the RO16-C12POE4 mixed system; i.e., in the case when nonionic surfactant has the shortest alkyl chain and the smallest number of ethylene oxide units.
Investigation of Mixing Behavior of both a Conventional Surfactant and Different Inorganic Salts with a Cationic Gemini Surfactant in Aqueous Solution
(Wiley, 2019) Sarikaya, Ikbal; Bilgen, Selcuk; Akbas, Halide
N,N '-bis [3-(dodecanoylamino)propyl]-N,N,N ',N '-tetramethylhexane-1,6-diaminium dibromide is a cationic Gemini surfactant including quaternary ammonium salt with amide groups. Critical micelle concentration (CMC) and some thermodynamic parameters of the cationic Gemini surfactant were investigated using surface tension and conductivity methods. Mixed micellization of binary mixtures of the cationic Gemini surfactant with a conventional surfactant cetyl trimethylammonium bromide (CTAB) was investigated using the conductometric method at five different temperatures ranging from 303.15 to 323.15 K. CMC, micellar ionization degree (alpha(m)), counterion binding constant (g(1)), interaction parameter (beta), and activity coefficients (f1M and f2M) of mixed systems were found out from data of conductivity at different mole fractions for all studied temperatures. Additionally, the effects of some inorganic salts with different concentrations on the surface properties of cationic Gemini surfactant were examined by surface tension measurements. Some surface properties of the pure cationic Gemini surfactant and mixed salts systems were calculated using the data of surface tension.
The investigation of thermodynamic parameters of kinetic reaction between o-phenylenediamine and gold (III)
(Academic Press Ltd Elsevier Science Ltd, 2007) Altun, Ozlen; Akbas, Halide
A visible spectrophotometric method has been developed for the reaction kinetics of o-phenylenediamine in the presence of gold (III). The method is based on the measurement of the absorbance of the reaction o-phenylenediamine and gold (III). Optimum conditions for the reaction were established as pH 6 at lambda=466 nm. When the reaction kinetic of o-phenylenediamine by gold (III) was investigated, it was observed that the following rate formula was found as In (A/A(0)) = -kt, according to absorbance measurements. The activation energy E-a and Arrhenius constant A were calculated from the Arrhenius equation as 1.009 kJ center dot mol(-1) and 3.46 center dot 10(-2) s(-1), respectively. Other activation thermodynamic parameters, entropy, Delta S (J center dot mol(-1) center dot K-1), enthalpy, Delta H (kJ center dot mol(-1)), Gibbs free energy, Delta G (kJ center dot mol(-1)) and equilibrium constant, K-e were calculated at T = (283.2, 303.2, 323.2, and 343.2) K. The study was exothermic due to the decrease of entropy and was a non-spontaneous process during activation. (c) 2007 Published by Elsevier Ltd.
Kinetic spectrophotometric method for o-phenylenediamine in the presence of gold(III)
(Pergamon-Elsevier Science Ltd, 2007) Altun, Ozlen; Akbas, Halide; Dolen, Emre
From the color developing reactions of o-phenylenediamine oxidizing agent and gold(III), the kinetic reactions between both of them in aquaeous solutions were studied using spectrophotometric and differential method. Light absorbances in the visible spectral range are measured as a function of mole fractions of phenylenediamine at a fixed gold(III) concentration and as a function of mole fraction of gold(III) at a fixed o-phenylenediamine concentration at periodic time internal. In the differential method, which was suggested by van't Hoff, one deals with the actual rates of reactions as determined by measuring the slopes of absorbance-time curves. Optimum condition of the reaction were established as pH 6 at lambda = 466 nm and room temperature. When the oxidation of o-phenylenediamine by gold(III) was investigated, it was observed that the following rate formula and rate constant were found: v = k[Au+3](1/2) [o-phenylenediamine](1/2), k = 2.33 x 10(-2) s(-1) (c) 2006 Elsevier B.V. All rights reserved.
Micellization and Related Behaviours of Polyoxyethylene-Type Non-ionic Surfactants on Root Elongation of Allium cepa L.
(Asian Journal Of Chemistry, 2012) Yilmaz, Gulden; Akbas, Halide; Dane, Feruzan; Leventer, Sinem; Ozturk, Fatmanur
In this study, polyoxyethylenated fatty alcohol ether (POE) nonionic surfactants polyoxyethylene (23) lauryl ether (C12E23) (Brij 35); polyoxyethylene (10) cetyl ether (C16E10) (Brij 56); polyoxyethylene (10) stearyl ether (C18E10) (Brij 76); polyoxyethylene (10) lauryl ether (C12E10) (POE 10). A large proportion nonionic surfactants are made hydrophilic by the presence of a polyethylene glycol chain obtained by the polycondensation of ethylene oxide. They are called polyethoxylated nonionics. In this study the effects of polyoxyethylene-type nonionic surfactants on root elongation of Allium cepa L. were determined for a week under laboratory conditions in the concentration ranges of 5.00, 2.50 and 1.25 g/L (w/v) at 16 +/- 0.5 degrees C. It was determined that the stimulatory effect on root elongation becomes stronger when the number of ethylene oxide group (C2H4O) was increased in the POE surfactant. The stimulatory effect decreases in the order C18E10 > C16E10 > C12E23 > C12E10 due to the decreasing of the number hydrocarbons in the series.
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, Mesut
The 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.
Micellization of dodecylpyridinium chloride in water-ethanol solutions
(Pleiades Publishing Inc, 2008) Akbas, Halide; Batigoec, Cigdem
Micellar properties of dodecylpyridinium chloride (DPC) were investigated by means of electrical conductometry with emphasis on the influences of cosolvent-water content and temperature. Ethanol was used as a cosolvent. Conductivity measurements gave information about critical micelle concentration and micellar ionization degree of the water-ethanol micellar solutions at different temperatures. In all solvent mixtures, it was observed that the critical micelle concentration of DPC and the degree of the counterion dissociation increase with an increasing concentration of ethanol and increasing temperature. Micellar and thermodynamics data were obtained from the temperature dependence of critical micelle concentrations in various aqueous mixtures of ethanol. In order to explain the effect of the cosolvent, the differences in the Gibbs energies of micellization of DPC between water and binary cosolvent were determined. The standard free energy (Delta G degrees(mic)) of micellization was found to be negative as the concentration of the solvent increases, but it is roughly independent of temperature. Although the enthalpic contribution was found to be larger than the entropic one, in particular at lower temperatures, an entropy-enthalpy compensation effect was observed for all systems. Also, enthalpy (Delta H degrees(mic)) and entropy (Delta S degrees(mic)) of micellization are strongly temperature dependent and decrease with increasing temperature and cosolvent content.
Micellization, aggregation, interaction, and solubilization behaviors of mixed solutions of cationic gemini and nonionic surfactants
(Wiley, 2024) Sarikaya Yildiz, Ikbal; Bilgen, Selcuk; Akbas, Halide
The micellization properties of mixed aqueous solutions of a cationic gemini surfactant (CGS) and Triton X-100, a conventional non-ionic surfactant, with various mole fractions, were determined by measuring the surface tension at different temperatures. Various theoretical models were used to analyze the behavior of this mixed system. The interactions between CGS and Triton X-100 were determined to be non-ideal and synergistic. The calculated interaction parameters (beta M) have negative values at all temperatures and for all mole fractions, showing attractive interactions. It was found that increasing the mole fraction of Triton X-100 significantly increased the synergistic effect (more negative values). Micellar aggregation number (Nagg) values of pure surfactants and their mixtures in different ratios were obtained with the steady-state fluorescence quenching method. Furthermore, the molar solubilization ratio of Sudan III organic dye in all surfactants aqueous systems was obtained using UV-Visible spectrophotometry. At concentrations above critical micelle concentration, the solubility of Sudan III in water was substantially increased linearly for all systems and it was observed that the enhancement was even more significant for mixed surfactant systems.
A novel cationic Gemini surfactant with amide group: synthesis and micellization behavior in aqueous solutions
(Springer, 2016) Akbas, Halide; Kocaoglu, Semra; Boz, Mesut; Dikmen, Alper
Novel 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.
Phytotoxic Effects of Non-ionic Surfactant Octylphenol Series (Triton X-100, Triton X-114, Triton X-405) on Onion
(Asian Journal Of Chemistry, 2012) Dane, Feruzan; Yilmaz, Gulden; Akbas, Halide; Ozturk, Fatmanur; Leventer, Sinem
In this study, three widely used octylphenol series non-ionic surfactant Triton X-114, Triton X-100 and Triton X-405 were selected to I examine their phytotoxic effects. They were evaluated under laboratory conditions using onion (Allium cepa L.) as a test material. The phytotoxic effects on root were determined after 7th days. Surfactants used in study were tested at three different surfactant concentrations, 5.00, 2.50 and 1.25 g/L (w/v) concentrations. The phytotoxicity results were based on the effective concentration that reduced root growth I I by 50 % (EC50). Some differences were observed between the effects of three types of surfactants. Stimulatory effects only occurred in I Triton X-405 while inhibitory effects occured in Triton X-100 and Triton X-114 at all concentrations. It was observed that inhibitory effects increased with increasing concentrations of Triton X-114 and Triton X-100.
PHYTOTOXIC EFFECTS OF SIX SURFACTANTS ON Allium cepa L. PLANTLETS
(Parlar Scientific Publications (P S P), 2012) Akbas, Halide; Dane, Feruzan; Yilmaz, Gulden; Ozturk, Fatmanur; Leventer, Sinem
In this study, the effects of two anionic surfactants, sodium dodecyl benzene sulfonate (DBSNa) and sodium dodecyl sulfate (SDS), one meric and one dimeric cationic surfactant, cetyltrimethylammonium bromide (CTAB) and gemini surfactant (16-2-16), and two non-ionic surfactants, polyoxyethylene tert-octylphenyl ether (Triton X-100) and polyoxyethylene (23) lauryl ether (Brij 35) were evaluated under laboratory conditions using onions (A Ilium cepa L.) as test material. The phytotoxic effects of surfactant solutions were observed. The phytotoxic effects on roots were determined by measuring root elongations of onions for each day in a week under laboratory conditions at 16.0 +/- 0.5 degrees C, after treated them by different surfactants. All surfactants used in this study were tested at three different concentrations, 5.00, 2.50 and 1.25 g/L (w/v), and some differences were observed between the effects of them. The phytotoxic effects were observed on onions which treated by anionic, cationic surfactants and nonionic surfactant Triton X-100. Stimulatory effects only occurred on onions treated by Brij 35 while inhibitory effects were observed on onions treated by all concentrations of Triton X-100. It was observed that inhibitory effects increased with increasing concentrations of Triton X-100.
The production of fuel from, and the thermal stability of, sunflower oil, corn oil, and canola oil
(Taylor & Francis Inc, 2016) Sarikaya, Ikbal; Bilgen, Selcuk; Akbas, Halide
Frying of sunflower, corn, and canola oils was carried out for seven running days at 175 degrees C in this study. Fatty acid composition, free fatty acid, viscosity, iodine value, peroxide value, density, pH, saponification value, refractive index, average molecular weight, color, and the higher heating value of these oils have been analyzed. While the contents of free fatty acid, viscosity, saponification value, peroxide value, and colors (red and yellow) increase with the frying times, the contents of average molecular weight, iodine value, pH, and the higher heating value decreased for all oils in this work. However, reduction in the higher heating value is relatively low. This work indicated that recycling as a fuel of these oils can make a major economic contribution.

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