Kinetics Study of Malachite Green Fading in the Presence of TX-100, DTAB and SDS

Abstract

The rate constants of alkaline fading of malachite green (MG + ) was measured in the presence of nonionic (TX-100), cationic (DTAB) and anionic (SDS) surfactants. This reaction was studied under pseudo-first-order conditions at 283∼303 K. The rate of fading reaction showed noticeable dependence on the electrical charge of the used surfactants. It was observed that the reaction rate constants were increased in the presence of TX-100 and DTAB and decreased in the presence of SDS. According to Hughs-Ingold rules for nucleophilic substitution reactions, the electric charge of MG/surfactant compound along with decrease in dielectric constant of MG + micro-environment in this compound varies the rate of fading reaction. Binding constants of surfactant molecules to MG + were calculated using cooperativity, pseudo-phase ion exchange and classical models and the related thermodynamic parameters were obtained by classical model. The results show that the binding of MG + to TX-100 is exothermic and binding of MG + to DTAB and SDS in some concentration ranges of the used surfactants is endothermic and in the other ones is exothermic.

Influence of Anions and Micelle and Submicellar Aggregates on the Alkaline Hydrolysis of Malachite Green: Tensiometric, Spectrophotometric, and Kinetic Investigations

“…13,14 There are reports of investigations into the interactions between carbocation dyes and oppositely charged surfactants both in the pre- 15−17 and postmicellar 15 region. The kinetic investigations of the alkaline fading of malachite green have been reported in the presence of micelles 18,19 and reverse micelle. 19 Spectral and surface tension measurement studies on the premicelle formation behavior of several carbocation dyes with different anionic surfactants such as sodium dodecyl sulfate (SDS), sodium dodecyl benzenesulfonate (SDBS), and sodium dodecyl sulfonate (SDSN) have been reported.…”

“…Microenvironments consisting of surfactants change the physicochemical behavior of the system and may either catalyze or inhibit the rates of different reactions. − Such catalysis or inhibition may occur by decreasing the entropy of the reactants either due to their association with the micelle or due to preferential interaction between the substrates and the micelle, thereby promoting or inhibiting the approach of the reactants toward themselves. − This type of rate modulation is also often observed in the submicellar concentrations of surfactant owing to the specific interaction between the reactant and the surfactant monomer resulting in the formation of premicellar aggregates. , There are reports of investigations into the interactions between carbocation dyes and oppositely charged surfactants both in the pre- − and postmicellar region. The kinetic investigations of the alkaline fading of malachite green have been reported in the presence of micelles , and reverse micelle . Spectral and surface tension measurement studies on the premicelle formation behavior of several carbocation dyes with different anionic surfactants such as sodium dodecyl sulfate (SDS), sodium dodecyl benzenesulfonate (SDBS), and sodium dodecyl sulfonate (SDSN) have been reported .…”

Alkaline Hydrolysis of Methyl Decanoate in Surfactant-Based Systems

“…A further increase of the surfactant concentration could lead to a decrease of the reaction rate since the methyl decanoate is diluted with higher amount of surfactant. This trend was also shown by other researchers, e.g., for the fading of dyes. , …”

Alkaline Fading of Malachite Green in β-Cyclodextrins

“…Different studies concluded the important fungal effect against oomycete fungus such as Saprolegnia [17], Haliphthoros [18] or Aphanomcyces invades [19]. Due to its effects on health, numerous studies in the literature analyze the physical-chemical properties of this compound [14,[20][21][22].…”