Removal of caffeine from aqueous solution by indirect electrochemical oxidation using a graphite-PVC composite electrode

A role of hypochlorite ion as an oxidising agent

Fouad F. Al-Qaim, Zainab H. Mussa, Mohamed Rozali Othman, Md. Pauzi Abdullah

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl<sup>-</sup>) loading, presence of hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23min<sup>-1</sup> depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H<inf>2</inf>O<inf>2</inf> to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.

Original languageEnglish
Pages (from-to)387-397
Number of pages11
JournalJournal of Hazardous Materials
Volume300
DOIs
Publication statusPublished - 1 Dec 2015

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Vinyl Chloride
Caffeine
Hypochlorous Acid
Graphite
Electrochemical oxidation
Oxidants
graphite
Electrodes
electrode
aqueous solution
chloride
Ions
oxidation
ion
Composite materials
Byproducts
Chlorides
Nonprescription Drugs
Oxidation
Kinetics

Keywords

  • Caffeine removal
  • Combined NaCl/H<inf>2</inf>O<inf>2</inf> effect
  • Elecrochemical oxidation process
  • Graphite-PVC composite electrode
  • Identification of chlorinated by-products
  • Pseudo-first order kinetic
  • Toxicity

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Pollution
  • Waste Management and Disposal
  • Environmental Chemistry
  • Environmental Engineering

Cite this

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title = "Removal of caffeine from aqueous solution by indirect electrochemical oxidation using a graphite-PVC composite electrode: A role of hypochlorite ion as an oxidising agent",
abstract = "The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl-) loading, presence of hydrogen peroxide (H2O2), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23min-1 depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H2O2 to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.",
keywords = "Caffeine removal, Combined NaCl/H<inf>2</inf>O<inf>2</inf> effect, Elecrochemical oxidation process, Graphite-PVC composite electrode, Identification of chlorinated by-products, Pseudo-first order kinetic, Toxicity",
author = "Al-Qaim, {Fouad F.} and Mussa, {Zainab H.} and Othman, {Mohamed Rozali} and Abdullah, {Md. Pauzi}",
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T1 - Removal of caffeine from aqueous solution by indirect electrochemical oxidation using a graphite-PVC composite electrode

T2 - A role of hypochlorite ion as an oxidising agent

AU - Al-Qaim, Fouad F.

AU - Mussa, Zainab H.

AU - Othman, Mohamed Rozali

AU - Abdullah, Md. Pauzi

PY - 2015/12/1

Y1 - 2015/12/1

N2 - The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl-) loading, presence of hydrogen peroxide (H2O2), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23min-1 depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H2O2 to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.

AB - The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl-) loading, presence of hydrogen peroxide (H2O2), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23min-1 depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H2O2 to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.

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KW - Pseudo-first order kinetic

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