Team:ITB Indonesia/Data


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Ethylene Glycol Assay using Chromic Acid

Poly(ethylene terephthalate) (PET) is a plastic that is a polymer of ethylene terephthalate (C10H8O4) units (Sarker et al., 2010). Polyethylene terephthalate (PET) can be degrade via limited enzymatic hydrolysis of the ester bond of the polymer backbone, one enzyme that have been assesed for this purpose is cutinase (Ribitsch et al., 2012). When polyethylene terephthalate degraded, it will produce terephthalic acid and ethylene glycol (Venkatachalam et al., 2012). Ethylene glycol is one of alcohol compound. Oxidation of alcohols by strong oxidants such as chromic acid (K2Cr2O7) in suphuric acid(H2SO4) is possible, but differs depending on the degree of alcohol. If a reaction has occurred using chromic acid in sulphuric acid, there is a color change from orange to green. In our project we use chromic acid to detect ethylene glycol as product of the PET degradation by LC cutinase enzyme.figure 1 shown the result of ethylene glycol assay using chromic acid.

Figure 1. Ethylene Glycol Concentration LC ITB and LC UC Davis

Each sample used for measure the absorbance contain a fixed amount of chromic acid. The absorbance of the chromic acid will represent the total amount of ethylene glycol inversely. It means that if the absorbance is high, the amount of ethylene glycol in solution is low, and if the absorbance is low, the amount of ethylene glycol in solution is high. If the absorbance is high, the amount of chromic acid is high, which means that the amount of ethylene glycol being oxidized by chromic acid is low and vice versa. Both of LC Cutinase UC Davis and OmpA-LC Cutinase ITB_Indonesia shown the degrading activity of PET become ethylene glycol as once of the product.The optimum time to produce ethylene glycol is on the fourth hour after inoculation.


Ribitsch D, Enrique HA, Katrin G, Anita D, Sabine Z, Annemarie M, Rosario DR, Georg S, Karl G, Helmut S and Georg MG. 2012. A New Esterase from Thermobifida halotolerans Hydrolyses Polyethylene Terephthalate (PET) and Polylactic Acid (PLA). Polymers. 4: 617-629

Sarker M, Aminul K, Mohammad MR, Mohammed M and ASMD Mohammad. 2011. Waste Polyethylene Terephthalate (PETE-1) Conversion into Liquid Fuel. Journal of Fundamentals of Renewable Energy and Applications. 1

Venkatachalam S, Shilpa GN, Jayprakash VL, Prashant RG, Krishna R and Anil KK. 2012. Degradation and Recyclability of Poly (Ethylene Terephthalate). Intech