Cationic surfactants interaction with azo dye in mixed solvent media and anti-corrosion ability of surfactants

Abstract

Due to modernization, researchers are in search of efficient compounds which must be easy to synthesis in large volume at low cost, durable, reliable, cheap for commercial applications for enhancement in dyeing and for corrosion control. In this context, surfactants are the best chemical compounds due to their aggregating nature at critical micelle concentration and such form is called micelle. The present study is dealt to its interaction with additives azo dye possessing typical dyeing features as it can be utilized for enhancing the quality of colourful substances in mixed solvent system along with its anti-corrosion ability. The aim of the present study is to investigate the interaction between cationic surfactants dodecyl trimethyl ammonium bromide (DTAB) and cetylpyridinium chloride (CPC) with azo dye methyl red (MR) in mixed solvent media and study the anti-corrosion ability of surfactants. The interaction study is performed with the studies of UV-Vis. spectra, conductivity, surface tension, viscosity, pH, and anti-corrosion study with weight loss and potentiodynamic polarization measurements. The interactional and anticorrosion analysis has been compared at three different temperatures (298.15 K, 308.15 K and 318.15 K). CMCs are identified at lower absorbance using UV-visible spectrophotometric techniques. From the spectral data, azo form of MR is best for interaction with cationic surfactants.The binding as well as partition parameters have been determined using Benesi-Hildebrand equation and pseudo-phase model respectively. All the spectral analysis are analysed at 0.1, 0.2, 0.3 and 0.4 volume of methanol in room temperature. Conductometric measurements are performed to determine the CMCs both in absence and presence of MR at three different temperatures in mixed methanol media. The interaction of surfactants DTAB and CPC with MR has been identified separately through the dye-surfactant aggregation process with suppressed CMC values due to the architectural flexibility of MR in the systems. Micellization becomes more likely with MR due to the formation of a molecular complex in mixed systems. The calculated thermodynamic properties both in the absence and presence of methyl red are the standard Gibbs free energy of micellization (∆G_m^o), the standard enthalpy of micellization (∆H_m^o), the standard entropy of micellization (∆S_m^o), the standard free energy of transfer (∆G_trans^o) and heat capacity of micellization (〖∆mC〗_p^0). In accordance with ∆G_m^o values, the mixtures show the spontaneous nature of micellization of DTAB and CPC. CMCs are determined from the plots of surface tension and log[surfactant] in presence of MR with surface tension measurement. Surface properties are determined using CMCs to study the interaction of DTAB with MR and CPC with MR. Such surface properties are dγ/(d log⁡C ) , Γ_max, A_min, π_CMC, P, ∆G_ads^o and pC_20 of CPC in the presence of methyl red with respect to volume fractions of methanol at 298.15 K, 308.15 K and 318.15 K. Viscosities in presence of MR of surfactant solution in mixed methanol system are determined at three temperatures and CMCs are obtained. Using the increased CMCs with increase in mixed volume, viscosity coefficient is determined with Jones-Dole equation. Along with this pH of surfactant solutions in presence of MR are determined at room temperature. Anti-corrosion study of DTAB and CPC are studied to find the inhibition efficiency using weight loss method and potentiodynamic polarization method. Weight loss is obtained at three different temperatures (298.15 K, 308.15 K and 318.15 K). All the reported sample solutions were maintained at three different temperatures (298.15 K, 308.15 K and 318.15 K) of concentrations range below, above and at optimum critical micelle concentration (CMC) of the cationic surfactants. Results showed that inhibition efficiency decreases with increase in temperatures and increases with addition of concentrations of cationic surfactants. The highest inhibition efficiency of both surfactants was determined at around CMC. Both CPC and DTAB follow isotherm of Langmuir adsorption and represent as mixed type of corrosion inhibitor with predominance of cathodic reaction.