Treatment of malachite green dye-contaminated wastewater via photolysis treatment process

Collin G. Joseph and Teo Siow Hwa and Nurul Najiha Datu Masjidin 1,2 , and Sitti Nurazida Maruja and Nur Ammarah Affandi and S M Anisuzzaman (2025) Treatment of malachite green dye-contaminated wastewater via photolysis treatment process. Malaysian Journal of Chemistry,, 27. pp. 1-17.

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Abstract

A photodegradation experiment was performed in a batch photoreactor, and concentration reduction and degradation efficiency were calculated from absorbance values obtained using an ultraviolet-visible (UV-Vis) spectrophotometer. The effects of different operational parameters were studied. The effects of various UV wavelengths were investigated using different types of UV irradiation, UV-A, UV-B, and UV-C. UV-C, which has the shortest wavelength and therefore the highest energy, was the most effective UV irradiation to degrade malachite green (MG) molecules, resulting in 88% degradation after 3 h of irradiation. Increasing the dye's initial concentration resulted in reduced degradation rates. The highest degradation was at 20 ppm (92.2%), while the lowest was at 100 ppm (61.9%). The photodegradation rate was better at neutral pH (95.6%) compared to acidic pH (84.2%). Longer irradiation time resulted in increasing degradation efficiency of MG. Due to the incomplete mineralisation of the dye after photolysis, COD and TOC content decreased only by 3.7% and 8%, respectively. Meanwhile, BOD analysis increased after photolysis, proving that photolysis is an efficient pre-treatment method before biological treatment. Reaction kinetic studies indicated that all experiments conformed to first-order kinetics, and the degradation rate constants were between 0.0054 min-1 and 0.0171 min-1 , with correlation coefficients ranging between 0.9286 to 0.9938.

Item Type:	Article
Keyword:	Photolysis; malachite green; UV irradiation; photodegradation; degradation efficiency
Subjects:	T Technology > TD Environmental technology. Sanitary engineering > TD1-1066 Environmental technology. Sanitary engineering > TD201-500 Water supply for domestic and industrial purposes T Technology > TD Environmental technology. Sanitary engineering > TD1-1066 Environmental technology. Sanitary engineering > TD895-899 Industrial and factory sanitation > TD896-899 Industrial and factory wastes
Department:	FACULTY > Faculty of Science and Natural Resources
Depositing User:	ABDULLAH BIN SABUDIN -
Date Deposited:	11 Jun 2025 12:01
Last Modified:	11 Jun 2025 12:01
URI:	https://eprints.ums.edu.my/id/eprint/44045

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