Asian Journal of Chemistry; Vol. 28, No. 2 (2016), 335-338
A
SIAN
J
OURNAL OF HEMISTRY
C
Degradation of Azo Dye, Acid Red-14 by Hexacyanoferrate(III)
Using Iridium Nanoclusters: A Kinetic Study
*
RAJNI LASYAL and ANJALI GOEL
Department of Chemistry, Kanya Gurukul Campus, Gurukul Kangri Vishwavidyalaya, Haridwar-249 407, India
*Corresponding author: E-mail: lasyal.rajni@gmail.com
Received: 30 April 2015;
Accepted: 1 July 2015;
Published online: 3 November 2015;
AJC-17603
In the present work, a novel method for the treatment of wastewater containing an azo dye, acid red-14 by hexacyanoferrate [HCF(III)] in
presence of iridium nanoclusters has been proposed. The effect of some important operational parameters such as pH, temperature and
catalyst concentration (iridium nano) has been investigated by kinetic spectrophotometric method at λmax 515 nm of the reaction mixture.
The results reveal that degradation kinetics of acid red-14 follows first order kinetic model with respect to [HCF(III)], [acid red-14] and
Ir nano concentration. Iridium nanoclusters were recovered with the help of centrifugation and reused for three consecutive cycles.
Thermodynamic parameters Ea, ∆S#,∆F#,∆H# and ‘A’have been calculated by studying the reaction rate in the range of temperatures 40 to
55 °C. The formation of degradation products was characterized by chromatographic and spectroscopic techniques after the extraction
with ethyl acetate. 1-Hydroxy-2-amino naphthalene and naphthalene sodium sulphate were identified as major degradation products. The
results can provide fundamental knowledge for the treatment of wastewater containing acid red-14/other azo dyes.
Keywords: Kinetics, Degradation, Acid Red-14, HCF(III), Iridium nanoclusters.
nanoclusters) on the degradation of acid red-14. These are the
major variables governing the degradation process. Acid red-
14 is the common dye for fiber dyeing, especially for woolen
fibers [9]. Furthermore, the kinetics and mechanism of the
degradation of acid red-14 has also been elucidated based on
the experimental data.
INTRODUCTION
Fiber dyeing produces a great deal of wastewater [1]. The
effluent from the dyeing process is colourful and the release
of the associated wastewater to natural stream and rivers poses
severe problems to aquatic life and humans [2]. Considerable
efforts have been made by many researchers to find appropriate
treatment systems to remove pollutants and impurities of waste-
waters from the textile industries. The conventional treatment
techniques applied to textile wastewaters, such as chemical
coagulation/flocculation, membrane separation or elimination
by activated carbon adsorption, are costly and result in phase
transfer of pollutants [3-5]. Recently nanotechnology has been
extended to waste water treatments. Degradation of dye-stuffs
using nanoparticles has gained prominence due to their low
cost, easy availability and effectiveness [5-7]. Among the
different transition metals as catalyst the interest in iridium
based nanocatalyst is increasing due to their high activity,
stability and selectivity under different reaction conditions [8].
The aim of the present study is to develop a new method for
the treatment of wastewater containing, acid red-14 (AR-14)
by hexacyanoferrate(III) ions in presence of iridium nano-
cluster by kinetic spectrophotometric method in alkaline
medium and to investigate the effect of operational parameters
such as pH, temperature and catalyst concentration (iridium
EXPERIMENTAL
All the chemicals used in the study were of analytical
grade. Acid red-14 dye (chemical structure shown in Fig. 1.)
and IrCl3·3H2O were purchased from Loba Chemie Pvt. Ltd,
Mumbai, India and Sisco Research Laborateries Pvt. Ltd., India
respectively. pH of solution was kept constant by using KH2PO4
and NaOH solutions as buffer. Measurements of pH of solution
were carried out with a digital pH meter (Systronics µ pH
system 361). Iridium-nanoclusters (particle size 4.5 0.5 nm)
were synthesized by wet reduction method using polyvinyl-
pyrrolidone (PVP) as protecting agent after the reduction of
precursor salt, (IrCl3·3H2O), by methanol as reported earlier
by Goel et al. [10].
The kinetic experiments were carried out at pH (7.5) and
constant temperature (40 0.1 °C). The appropriate quantities
of all reactants except substrate were mixed in a 100 mL iodine
flask and kept at 40 1 °C. The reaction was initiated by