Interaction of methyl orange with cationic surfactant (DTAB) under the influence of anionic polyelectrolyte (NaCMC) in ethanol/water solvent mixtures: A UV–visible spectroscopic investigation

Abstract

The purpose of this novel investigation is to thoroughly examine and assess the spectral properties of methyl orange (MO) and its impact on the micellization behavior of dodecyl trimethylammonium bromide (DTAB) in sodium carboxymethyl cellulose (NaCMC) solution in various volume (vol.) fractions of ethanol in water (0, 0.1, 0.2, and 0.3) at 298.15 ± 0.2 K. According to the findings, the CMC* values calculated using spectroscopic data increase in the order listed below: (CMC*$=$ 0.0200)_0.3$>$ (CMC*$=$ 0.0182)_0.2 $>$ (CMC*$=$ 0.0163)_0.1 $>$ (CMC* $=$0.0145)_water. The Gibbs energy of micellization ($∆G_{\text{m}}^{\text{o}}$)has a less negative value $(∆G_{\text{m}}^{\text{o}}=$ -19.07 kJ mol⁻¹)_0.3. $>$ $(∆G_{\text{m}}^{\text{o}}=$ -19.51 kJ mol⁻¹)_0.2 $>$ $(∆G_{\text{m}}^{\text{o}}=$ -19.98 kJ mol⁻¹)_0.1. $>$ $(∆G_{\text{m}}^{\text{o}}=$ -20.45 kJ mol⁻¹)_waterwith increasing ethanol contents in the solvent mixture, which also validates that raising the ethanol concentration inhibits micellization. On the other hand, the overall value of the binding constant increases in the trend: ($K_{\text{b}}=$119.41)_water $<$($K_{\text{b}}=$1152.71)_0.1 $<$ ($K_{\text{b}}=$1248.55)_0.2 $<$ ($K_{\text{b}}=$1304.05)_0.3$,$ and $∆G_{\text{b}}^{\text{o}}$drops in the order: ($∆G_{\text{b}}^{\text{o}}=$−11.85 kJ mol⁻¹)_water $>$ ($∆G_{\text{b}}^{\text{o}}=$-17.48 kJ mol⁻¹)_0.1 $>$($∆G_{\text{b}}^{\text{o}}=$-17.67 kJ mol⁻¹)_0.2 $>$($∆G_{\text{b}}^{\text{o}}=$-17.78 kJ mol⁻¹)_0.3$.$ A higher binding constant (K_b) value indicates enhanced MO-DTAB-NaCMC interactions in the after-micellar region. This is validated by the feasibility of the processes, as indicated by a drop in the standard Gibbs binding energy ($∆G_{\text{b}}^{\text{o}}$). Variation of $∆G_{\text{m}}^{\text{o}}$ with various solvents and solvophobic parameters additionally offers important insights into the thermodynamic stability, solvent polarity, fluidity, micellization, and strength of DTAB-NaCMC interaction in ethanol-water mixture solvent with MO. The blue spectral shifts indicate that the interaction mechanism was primarily influenced by the solvent composition. The results of this study will shed light on our knowledge of intricate molecular interactions between dye, surfactant, polyelectrolyte, and the impacts of other co-solvents/additives and also have the consequences throughout numerous domains of science, ecology, cosmetics, pharmaceutics, drug delivery, and wastewater treatment.