Ultrasonic Intensification of the Chemical Degradation of Methyl Violet: An Experimental Study

Authors: N. P. Dhanalakshmi, R. Nagarajan

Abstract:

The sonochemical decolorization and degradation of azo dye Methyl violet using Fenton-s reagent in the presence of a high-frequency acoustic field has been investigated. Dyeing and textile effluents are the major sources of azo dyes, and are most troublesome among industrial wastewaters, causing imbalance in the eco-system. The effect of various operating conditions (initial concentration of dye, liquid-phase temperature, ultrasonic power and frequency and process time) on sonochemical degradation was investigated. Conversion was found to increase with increase in initial concentration, temperature, power level and frequency. Both horntype and tank-type sonicators were used, at various power levels (250W, 400W and 500W) for frequencies ranging from 20 kHz - 1000 kHz. A 'Process Intensification' parameter PI, was defined to quantify the enhancement of the degradation reaction by ultrasound when compared to control (i.e., without ultrasound). The present work clearly demonstrates that a high-frequency ultrasonic bath can be used to achieve higher process throughput and energy efficiency at a larger scale of operation.

Keywords: Fenton oxidation, process intensification, sonochemical degradation of MV, ultrasonic frequency.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1082051

References:

[1] C. Chang-qi, C. Jian-ping, T. Zhiguo, "Degradation of Azo Dyes by Hybrid Ultrasound-Fenton Reagent," IEEE, pp. 3600-3603, 2008.
[2] C. Walling, Fenton's reagent revisited, Acc. Chem. Res., vol. 8, no. 5, pp. 125-131, Apr. 1975.
[3] K. Okitsu, K. Iwasaki,Y. Yobiko, H. Bandow, R. Nishimura and Y. Maeda, "Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration of OH radicals and azo dyes," Ultrasonics Sonochemistry , vol. 12, no.4, pp. 255-262, Mar. 2005.
[4] C. Bouasla, M. El-Hadi Samar, and F. Ismail, "Degradation of methyl violet 6B dye by the Fenton process," Desalination, vol. 254, no.1-3, pp. 35-41, May 2010.
[5] P. R. Gogate, S. Mujumdar, and A. B. Pandit, "Sonochemical reactors for waste water treatment: comparison using formic acid degradation as a model reaction," Advances in Environmental Research, vol. 7, no. 2, pp. 283-299, Jan. 2003.
[6] X. K. Wang, G. H. Chen, and W. L. Guo, "Sonochemical Degradation Kinetics of Methyl Violet in Aqueous Solutions," Molecules, vol. 8, no.1, pp. 40-44, Jan. 2003.
[7] C. Little, M. J. Hepher, and M. El-Sharif, "The sono-degradation of phenanthrene in an aqueous environment," Ultrasonics, vol. 40, no. 1-8, pp. 667-674, May 2002.