Study On The Interaction Between Surfactant And Fluorescent Whitening Agent

The interactions between fluorescent whitening agent VBL with seven kinds of cationic surfactants, DHDAB, DDHAB, THDAB, TDHAB, CHDAB, CDHAB, Gemini were studied by using surface tension, UV-Vis spectroscopy and conductivity measurements.The interaction between fluorescent whitening agent with surfactants (DHDAB, Gemini) was studied by surface tension, at the same time curve ofγ-logc of seven cationic surfactant aqueous solutions were measured. The result show that the efficiency and the effectiveness of Gemini surfactant to decrease the surface tension of water is higher than single-chain cationic surfactants.UV-Vis absorption spectra and conductivities of various fluorescent whitening agent- surfactant aqueous solutions were measured. The strong interactions between fluorescent whitening agent and surfactants were also quantitatively checked and explained with different theoretical models from literature on the basis of the experimental absorbance and conductivity data. The equilibrium constants and some thermodynamic functions of the interactions between fluorescent whitening agent and surfactants were calculated from the experimental absorbance and conductivity data respectively.From the combination of the electrostatic and hydrophobic interactions and steric effects, it can be concluded that the order from strong to weak interaction between fluorescent whitening agent with surfactants is Gemini>CDHAB>CHDAB>TDHAB>DDHAB> THDAB>DHDAB.