engleski

ELECTROCHEMICAL CHARACTERISATION OF OIL PIPELINE INTERNAL CORROSION PRODUCTS BY VOLTAMMETRY OF IMMOBILIZED MICROPARTICLES

Laboratory analysis of corrosion products from inside the pipeline can provide the information that enable determination of cause of corrosion damage. Researchers may apply a range of analytical techniques, like XRD, HPLC, AAS, GC, MS, or the range of spectroscopic analysis of surface, like SEM/EDS, TEM, AES, SIMS, FTIR if available. In this study we have tried to apply a simple electrochemical method of voltammetry of immobilized microparticles that has been used for the identification of microsampled corrosion products from historical and archaeological bronzes, to analysis of corrosion products from inside of oil pipeline. The methodology is simple, cheap and quick way to obtain the information on very small amount of sample. Corrosion products from inside the oil pipeline were analyzed by cyclic voltammetry at the carbon paste electrode. The microparticles of corrosion products were immobilized to carbon paste by gently pulling the electrode over the sample. The electrode was transferred into the electrochemical cell where direct oxidation or reduction of electroactive species was performed. Measurements conducted on brown and black corrosion products confirmed the difference in the composition of samples. Constituent phases were determined by comparing the cyclic voltammograms and electrochemical parameters to those of reference compounds. The reduction peak at negative potentials attributed to reduction of Fe(III) species and oxidation peak attributed to oxidation of Fe(II) species were identified. The electrode processes differed for the two samples and different media. Cyclic voltammograms were measured in 0.5 M HCl and oxalic acid solution to determine behavior of corrosion products in different complexing media. Cyclic voltammograms measured in oxalic acid revealed more pronounced peaks and better resolved measurements.

carbon paste; voltammetry; immobilized microparticels; corrosion products

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