engleski

A Spectrophotometric Studies of Interaction Between Xylenol Orange and Cationic Surfactant in Aqueous solution

Xylenol orange (XO) is polybasic weak acid and belongs to the triphenylmethane dyes. Depending on the pH value, the several possible different forms of XO can be present in aqueous solutions. The absorption spectra of XO in aqueous solution at pH< 6 show a characteristic absorption at 434 nm and at pH > 6 at 580 nm, respectively.[1] The addition of small amounts of the cationic surfactant to the deeply coloured solutions of the xylenol orange at pH 10 -11 causes a marked colour change.[2] This work presents spectrophotometric studies of the interaction between xylenol orange and two cationic surfactants cetyltrimethylammonium bromide (CTMA) and cetylpyridinium chloride (CPC) in aqueous solution. The absorption spectra of the dye were measured at various pH values in the presence of various amounts of surfactant and compared with the spectra of the dye alone. The presence of studied cationic surfactants in aqueous solution of xylenol orange influences the absorption intensities and causes the spectral shift of the absorption maximum of a xylenol orange solution. The observed changes in the absorption spectra of the dye are dependent on pH values of the solution as well as on concentration ratio of the surfactant to xylenol orange. When optimal ratio has been exceeded, the absorbance of XO remains unaltered even if excess of surfactant has been added. The optimal ratio of XO to surfactant is different for both absorption maximum at various pH values. Following observed interactions between anionic dye and cationic surfactant in acidic solution of XO, new spectrophotometric methods for quantitative determination of cationic surfactants can be elaborated. Literature: [1] M.B.Gholivand, F.Bamdad and J.Ghasemi, Talanta 1998, 46, 875 [2] V.Svoboda and V.Chromy, Talanta 1965, 12, 431.

cationic surfactants ; cetyltrimethylammonium bromide ; cetylpyridinium chloride ; spectrophotometry ; xylenol orange

nije evidentirano