Imperative Role of Oxidation of Diethylthiourea in Dye Wastewater Treatment | Chapter 7 | Current Strategies in Biotechnology and Bioresource Technology Vol. 1
Several properties of thiourea and its derivatives are
reported in biological, electrochemical, photochemical and radio-protective
fields. This article proposed the use of thiourea derivative in the field of
dye wastewater management where the color of the dye was reduced by the application
of Diethylthiourea (DETU). For this purpose basic dye methylene green (MG) was
selected at laboratory scale to monitor its color reduction by the addition of
DETU. It was observed that DETU reacts with methylene green (MG) and reduced it
into leuco dye where it oxidized into smaller fragments like urea, nitrate and
sulphate. The reaction was favorable in acidic condition. A direct relation in
between oxidation of DETU and MG to the concentration of H+ ions was observed
through typical kinetics in two acids like HCl and H2SO4. The second order
kinetics with respect to HCl and the first order with respect to H2SO4
indicated the protonation of the dye leading to reduction. In alkaline medium,
the decline in the rate of reaction may be due to the suppressing effects of
alkali on oxidation/degradation of DETU into smaller fragments or may be
attributed with the de-protonation of DETU. Influence of addition of dye into
reaction mixture retarded the bleaching process and follows zero order kinetics
while rate of reaction enhanced by the addition of DETU in the reaction mixture
and shows ¾th order with respect to DETU. Negative effect of added different
electrolytes reflects that change of ionic strength of reaction mixture have
some bearing on redox reaction of MG and DETU. Reaction was monitored at
elevated temperature and activation parameters were computed. The mechanisms of
oxidation of DETU with reduction of dye MG were discussed. Reduction of MG into
leuco dye with the fragmentation of DETU was observed in acidic condition at
elevated temperature.
Author(s) Details
Dr. Tehseen Ahmed
Department of Chemistry, University of Karachi, Karachi-75270, Pakistan.
Department of Chemistry, University of Karachi, Karachi-75270, Pakistan.
Dr. Rafia Azmat
Department of Chemistry, University of Karachi, Karachi-75270, Pakistan.
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