Bicol University R&D Journal

Official Refereed Journal of Bicol University

4500 Legazpi City,Philippines

Print ISSN: 0016-4139       Online ISSN: 2719-082X

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Vol 26, Issue 1
August 2023

CHED-JIP Recognized Journal as per CMO NO. 50, s. 2018.

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Chemistry

Copper-Activated In Situ Chemical Oxidation of Cyanide in Water Using Persulfate

Publisher: Bicol University
Abstract

Cyanide is found commonly in effluents coming from metallurgical processes. Cyanide toxicity poses a serious environmental threat. In this study, the stoichiometry, kinetics, and mechanism of the in situ chemical oxidation of cyanide in the presence of copper-activated persulfate were investigated. Ion selective electrode (ISE) was used to monitor the concentration of cyanide. Chemical and spectroscopic analyses were employed to characterize the products formed upon oxidation. An accelerated reaction using S2 O8 2- to destroy cyanide can be achieved via chemical activation with copper (II) ions to generate reactive sulfate radicals (SO4 ˙-). Cu2+ improved the percent removal of cyanide at room temperature. Under the optimum copper to persulfate ratios (1:1 and 1.5:1), 98% of the initial cyanide concentration was degraded at t = 90 minutes. They also obey pseudo-second order kinetics and their forward reactions are relatively favorable based on reaction coefficient values. The [Cu]:[S2 O8 2-] ratio of 1.5:1 resulted in rapid degradation of cyanide in the first half of the reaction but was accompanied by a decrease afterwards. In contrast, the [Cu]:[S2 O8 2-] ratio of 1:1 has a longer lasting degradation effect. Unlike other activation methods, Cu2+ does not exert 100% oxidative capacity on cyanide, only around 75%. IR spectroscopic analysis and qualitative test also suggest the formation of thiocyanate and copper (I) cyanide complex, respectively. Thus, persulfate activation by Cu2+ ions improved the cyanide oxidation process.


Trina B. Estrada
Querubin P. Gapas
Ma. Crispina P. Baltazar

kinetics
mechanism
degradation
environment

April 23, 2024
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CHED-JIP Recognized Journal as per CMO NO. 50, s. 2018.

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Higher Education Regional Research Center, Bicol University East Campus, Legazpi City, Albay, Philippines

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