ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Kinetics of metribuzin degradation by colloidal manganese dioxide in absence and presence of surfactants

Qamruzzaman and Abu Nasar

Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh, 202 002, India

E-mail: abunasaramu@gmail.com

Abstract: The kinetics of the degradation of metribuzin by water-soluble colloidal MnO₂ in acidic medium (HClO₄) were studied spectrophotometrically in the absence and presence of surfactants. The experiments were performed under pseudo-first-order reaction conditions in respect of MnO₂. The degradation was observed to be of the first order in respect of MnO₂ while of fractional order for both metribuzin and HClO₄. The rate constant for the degradation of metribuzin was observed to decrease as the concentration of MnO₂ increased. The anionic surfactant, sodium dodecyl sulphate (SDS), was observed to be ineffective whereas the non-ionic surfactant, Triton X-100 (TX-100), accelerated the reaction rate. However, the cationic surfactant, cetyltrimethyl ammonium bromide (CTAB), caused flocculation with oppositely-charged colloidal MnO₂; hence further study was not possible. The catalytic effect of TX-100 was discussed in the light of the available mathematical model. The kinetic data were exploited to generate the various activation parameters for the oxidative degradation of metribuzin by colloidal MnO₂ in the absence as well as the presence of the non-ionic surfactant, TX-100.

Keywords: kinetics – metribuzin – manganese dioxide – degradation – pseudo-first-order – surfactants

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0424-7

Chemical Papers 68 (1) 65–73 (2014)