Physico-Chemical nanomaterials science

Spectroscopic studies of Tween surfactants
Szaniawska M.1, Szymczyk K.1
1 Department of Interfacial Phenomena, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland 
E-mail: magdalena.szaniawska@poczta.umcs.lublin.pl

Thus the objective of the presented studies was to determine the fluorescence emission spectra of pyrene (Py), ANS and Pyronin Y (PyY) in aqueous solutions of nonionic surfactants belonging to the Tween series (polysorbates), Tween 20 (T20), Tween 60 (T60) and Tween 80 (T80) as a function of surfactant concentration and temperature. Their structure includes 20 ethylene oxide groups attached to the sorbitan headgroup with different long-chain saturated carboxylic acids, that is lauric to stearic, and unsaturated oleic acid. Both the I1/I3ratio of pyrene fluorescence (concentration of pyrene, CPy = 2 × 10−6, 4 × 10−6 and 6 × 10−6M) in the surfactant solutions in the surfactant concentration ranging from 10−6 to 10−2 M and the Ie/I1 ratio were studied based on the Stevens-Ban plot [1]. The obtained spectra were used for the analysis of the CMC, micropolarity and microviscosity of T20, T60 and T80 and correlation with the temperature and concentration changes of a given surfactant as well as thermodynamic analysis of the dye-surfactant binding process. The performed investigations could be also important from the other, practical point of view that is possibility to uses of studied nonionic surfactants to removal of mentioned synthetic dyes from wastewater. 

1. Aoudia, M., Rodgers M.A.J., Wade W.H., Temperature dependence of excimer formation and excimer fluorescence polarization of micellar dispersions: surfactants as intrinsic probes // J. Phys. Chem.-1984.-88.-P. 5008-5012