Malaysian Journal of Analytical
Sciences Vol 19 No 2 (2015): 291 – 299
Electrochemical Oxidation
of Glycerol Using Gold Electrode
(Pengoksidaan Elektrokimia Gliserol Secara
Elektrokimia Menggunakan Elektrod Emas)
Mohamed Rozali Othman* and Amirah Ahmad
School of Chemical Sciences
and Food Technology,
Faculty of Science and
Technology,
Universiti Kebangsaan
Malaysia, 43600 UKM Bangi, Selangor
*Corresponding author: rozali@ukm.edu.my
Received: 30
June 2014; Accepted: 2 December 2014
Abstract
Cyclic
voltammetry, potential linear V and chronocuolometry methods were carried out
to gain electrochemical behavior of glycerol at a gold electrode. Potassium
hydroxide and sulfuric acid were chosen to be the electrolyte for the
electro-oxidation of this organic compound. Besides gold plate electrode, gold
composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC
composite electrode was characterized by Scanning Electron Microscopy (SEM) to
determine its morphological aspects before and after used in electrochemical
oxidation of glycerol. In alkaline solution, the adsorption of hydroxide
species onto the surface of both gold plate and composite Au-PVC electrodes
occurs at potential around 500 mV vs SCE. However, at gold plate electrode,
there was a small, broad peak before the drastic escalation of current
densities which indicates the charge transfer of the chemisorbed OH-
anion. In acidic media, the gold oxide was formed after potential 1.0 V. From
the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide
at gold plate and Au-PVC composite electrodes, while in sulfuric acid,
oxidation reaction happened once for glycerol on the gold plate electrode.
Overall, electrochemical oxidation of glycerol was more effective in alkaline
media. Tafel graph which plotted from potential linear V method shows that Au-PVC
composite electrode is better than gold plate electrode for the
electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas
Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and
phenolic compounds.
Keywords: electrochemical
oxidation, glycerol, carboxylic acid, phenolic compounds
Abstrak
Kaedah
voltammetri kitaran, keupayaan linear V dan kronokuolometri telah dijalankan
bagi mengetahui kelakuan elektrokimia sebatian gliserol pada elektrod emas.
Kalium hidroksida dan asid sulfurik telah digunakan sebagai elektrolit bagi
pengoksidaan elektrokimia sebatian organik tersebut. Selain elektrod kepingan
emas, elektrod komposit emas polivinil klorida (Au-PVC) juga digunakan sebagai
elektrod kerja (anod). Morfologi elektrod komposit Au-PVC dicirikan dengan
Mikroskop Imbasan Elektron (SEM). Dalam larutan alkali, penjerapan
sebatian hidroksida pada elektrod kepingan emas dan elektrod komposit Au-PVC
berlaku pada keupayaan ±500 mV. Walau bagaimanapun, pada elektrod kepingan
emas, terdapat satu puncak lebar yang kecil sebelum peningkatan drastic arus
yang dikaitkan dengan pemindahan cas separa anion OH- yang terjerap
secara kimia. Dalam larutan berasid, oksida emas terbentuk selepas keupayaan
1.0 V. Berdasarkan voltammogram berkitar gliserol mengalami dua kali
pengoksidaan dalam larutan kalium hidroksida pada elektrod kepingan emas dan
elektrod komposit Au-PVC. Manakala dalam larutan asid sulfurik, tindak balas
pengoksidaan hanya berlaku sekali. Secara keseluruhannya, pengoksidaan
elektrokimia gliserol adalah lebih berkesan dalam larutan alkali. Graf Tafel
yang diplot melalui kaedah keupayaan linear V menunjukkan bahawa elektrod
komposit Au-PVC merupakan elektrod yang lebih baik berbanding elektrod kepingan
emas bagi pengoksidaan elektrokimia dalam medium beralkali. Hasil pengoksidaan
elektrokimia gliserol yang dianalisa menggunakan Kromatografi Gas-Spektrometer
Jisim mendapati produk yang terhasil adalah asid karboksilik dan sebatian fenol.
Kata
kunci:
pengoksidaan elektrokimia, gliserol, asid karbosilik,
sebatian fenol
References
1.
da
Silva, G.P., Mack, M. & Contiero, J. (2009). Glycerol: a promising and
abundant carbon source for industrial microbiology. Biotechnology Advances 27: 30 – 39
2.
Ullman’s
encyclopedia of industrial chemistry, electronic release, (2002). Wiley-VCH.
3.
Dumirel-Gülen,
S., Lucas, M. & Claus, P. (2005). Liquid phase oxidation of glycerol over
carbon supported gold catalysis. Catalysis
Today 102-103: 166-172.
4.
Claus,
P., Schimpf, S. & Önal,Y. (2003). in: Proceedings of 18th North
American Catalysis Meeting, Cancun/Mexico, June 1-6. pp. 365.
5.
Venancio, E.C.,
Napporn, W.T. & Motheo, A.J. (2001). Electro-oxidation of glycerol on
platinum dispersed in polaniline matrices. Electrochimica
Acta 47: 1495-1501.
6.
Pollington,
S.D., Dan, I.E., Landon, P., Meenakshisundaram, S., Dimitratos, N., Wagland,
A., Hutchings, G. J. & E. Hugh, E.S. (2009). Enhanced selective glycerol
oxidation in multiphase structured reactors. CatalysisToday 145: 169-175.
7.
Porta,
F. & Prati, L. (2004). Selective oxidation of glycerol to sodium glycerate
with gold-on-carbon catalyst: an insight into reaction selectivity. Journal of Catalysis 224:397-403.
8.
Pollington, N., Porta, F.
& Prati, L. (2005). Au, Pd (mono and bimetallic) catalysts supported on
graphite using the immobilization method Synthesis and catalytic testing for
liquid phase oxidation of glycerol. Applied
catalysis A: General 291:210-214
9.
Aguilar,
R., Davilla, M.M., Elizalde, M.P., Mattusch, J. & Weerich, R. (2004).
Capability of a carbon –polyvinylchloride composite electrode for the detection
of dopamine, ascorbic acid and uric acid. Electrochimica
Acta 49: 851-859
10.
Luque, M., Ríos, A.
& Valcárcel, M. (1999). A poly (vinyl chloride) graphite composite
electrode for flow-injection amperometric determination of antioxidants. Analytica Chimica Acta 395: 217-223.
11.
Riyanto and
Mohamed Rozali Othman. (2008). Characterization of Ni-Co-PVC and Ni-Cu-PVC Alloys Prepared By Mechanical
Alloying Technique (MAT). The Open
Materials Science Journal 2: 40 – 46.
12.
Riyanto,
Jumat Salimon & Mohamed Rozali Othman. (2007). Perbandingan Hasil
Pengoksidaan Elektrokimia Etanol dalam Larutan Alkali yang Menggunakan Elektrod
Platinum-Polivinilklorida (Pt-PVC) dan Kepingan Logam Pt Sains Malaysiana 36(2): 175-181.
13.
Riyanto, Mohamed Rozali Othman & Jumat Salimon.
(2007). Analysis of ethanol using copper and nickel sheet electrodes by cyclic
voltammetry. Malaysian Journal of Analytical Sciences 11 (2): 379 – 387.
14.
Kahyaoglu,
A., Beden, B. & Lamy, C. (1984). Oxydation
electrocatalitique du glycerol sur electrodes d'or et de platine en milieu
aqueux. Electrochimica
Acta 29: 1489-1492.
15.
Maljaei, A., Arami, M. & Mahmoodi, N M. (2009).
Decolorization and aromatic ring degradation of colored textile wastewater
using indirect electrochemical oxidation method. Desalination 249:1074–1078.
16.
Angerstein-Kozlowska,
H., Conway, B.E., Barnett, B. & Mozota, J. (1979). The role of ion adsorption in surface oxide formation and
reduction at noble metals: General features of the surface process. Journal of Electroanalytical Chemistry 100:
417-446.
17.
Chen, S., Wu, B.
& Cha, C. (1997). An EQCM investigation of oxidation of formic acid at gold
electrode in sulfuric acid solution. Journal
of Electroanalytical Chemistry 431: 243-247.
18.
Ketchie,
W.C., Fang, Y.L., Wong, M.S., Murayama, M. & Davis, R.J. (2007). Influence
of gold particle size on the aqueous-phase oxidation of carbon monoxide and
glycerol. Journal of Catalysis 250:
94-101.
19.
Ketchie,
W.C., Murayama, M. & Davis, R.J. (2007). Selective oxidation of glycerol
over carbon-supported AuPd catalysts. Journal
of Catalysis 250: 264-273.
20.
Prati, L. &
Rossi, M. (1998). Gold on Carbon as a New Catalyst for Selective Liquid Phase
Oxidation of Diols. Journal of Catalysis
176: 552-560.