Influence of ultrasound modes on sonoelectrochemical degradation of Congo red and 2 palm oil mill effluent

Kalet, S. Z., Ismail, S. A., Ang, W. L. and Symes, M. D. (2023) Influence of ultrasound modes on sonoelectrochemical degradation of Congo red and 2 palm oil mill effluent. Results in Chemistry, 5, 100880. (doi: 10.1016/j.rechem.2023.100880)

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Sonoelectrochemical oxidation (SEO) treatment is a competitive technology for the degradation of organic pollutants in water. The operation modes of ultrasound (continuous and pulse) not only affect the pollutant degradation efficiency but also the energy consumption of SEO. In this study, the influence of ultrasound modes on SEO degradation of Congo red (CR) and real wastewater – palm oil mill effluent (POME) were investigated. The SEO was operated in two modes: continuous ultrasound throughout the whole process and intermittent ultrasound at a cycle of 15 min of ultrasound and 5 min without ultrasound. It was found that the intermittent SEO gave a higher degree of degradation of CR at 95% as compared to continuous SEO and electrochemical oxidation (EO) at 85% and 64%, respectively. The improved performance could be attributed to the supply of ultrasound that minimized electrode passivation and promoted mass transfer and production of hydroxyl radicals. The intermittent supply of ultrasound diminished the interference of ultrasound on the electrochemical process. A similar observation was also observed where the highest COD reduction of POME was recorded by intermittent SEO at about 65%. In terms of energy consumption, degradation of CR by SEO only required half of the energy consumed by the analogous purely electrochemical process at 250–265 kWh/kg dye removed. Surprisingly, the energy consumption for SEO degradation of POME only reduced from 32.82 (electrochemical) to 25.91 and 30.78 kWh/kg COD removed for continuous and intermittent SEO, respectively. Such contrast in energy saving highlights the need for further study as the complex constituents of real effluents will result in different SEO treatment performance. Nonetheless, the capability of SEO in reducing the COD indicates its potential to be used as pre- or post-treatment for other advanced processes in POME handling.

Item Type:Articles
Additional Information:The authors would like to thank the Universiti Kebangsaan Malaysia for funding this work through the research grant DPK-2021-014. This collaboration leading to this work was supported by the Royal Academy of Engineering under the Frontiers of Development scheme (FoE2122-10-6). MDS thanks the Royal Society for a University Research Fellowship (UF150104).
Glasgow Author(s) Enlighten ID:Symes, Professor Mark
Creator Roles:
Symes, M. D.Writing – review and editing
Authors: Kalet, S. Z., Ismail, S. A., Ang, W. L., and Symes, M. D.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Results in Chemistry
ISSN (Online):2211-7156
Published Online:06 March 2023
Copyright Holders:Copyright © 2023 The Author(s).
First Published:First published in Results in Chemistry 5:100880
Publisher Policy:Reproduced under a Creative Commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
173495Driving energetically uphill processes using metal-ligand coordination complexesMark SymesThe Royal Society (ROYSOC)UF150104Chemistry