21st Romanian International Conference on Chemistry and Chemical Engineering [602866]

21st Romanian International Conference on Chemistry and Chemical Engineering
Constanta- Mamaia, ROMANIA – September 4 – 7, 2019
-3-113
-800 -600 -400 -200
E/ mV vs. Ag/AgCllog i/ mA cm-2HCl blank 0.62 g/L PAcV
1 .24 g/L PAcV 1 .86 g/L PAcV
3.1 g/L PAcVa
0408012 0
0 1 00 200 300Zr/ Ω cm2-Zi/ Ω cm2HCl bank 0.62 g/L PAcV
1 .24 g/L PAcV 1 .86 g/L PAcV
3.1 g/L PAcVbPoly(vinyl acetate) performance on carbon steel corrosion control in
acid environment

Adriana Samide, Bogdan Tutunaru , Claudia Meri șanu, Cristian Tigae, Cezar Spînu

University of Craiova, Faculty of Sciences, Department of Chemistry
107i Calea Bucuresti, Craiova, Romania
[anonimizat]

Poly(vinyl acetate), further denoted as PVAc is an ecological, biodegradable and biocompatible
polymer, free of toxicity and without carcinogenic effects. It is readily accepted by the human body and is therefore used in biomedical applications [1], in the food industry [2] as well as precursor in the synthesis
of polyvinyl alcohol by hydrolysis [3, 4]. Vinyl acetate polymerization/electropolymerization in
emulsion/miniemulsion and solution represent the most common methods of PVAc synthesis [3, 4]. PVAc was obtained, under our laboratory conditions, by vinyl acetate polymerization in emulsion
using poly(vinyl alcohol) as emulsifier and Fenton reagent as reaction initiator, adjusting the environment
pH at 3.2 with acetic acid. A white and viscous emulsion was obtained containing 31% solids. PVAc emulsion was investigated as corrosion inhibitor for carbon steel in 1.0 mol L
-1 HCl solution
using volumetric method, potentiodynamic polarization (PP) and electrochemical impedance
spectroscopy (EIS) associated with optical microsco py. The results of electrochemical measurements and
optical microscopy images are presented in Figs. 1 and 2, respectively. As shown in Fig. 1a, PVAc acts as
a mixed inhibitor, predominantly anodic, merely blocking the active sites on the carbon steel surface. The
PVAc concentration increase leads to a corrosion current density (i corr) decrease and charge transfer
resistance (R ct) rising (Fig. 1b) and consequently, the inhibition efficiency (IE) follows an upward trend.
The microscopic images designed a specific surface morphology in the PVAc presence (Figs. 2c-f),
compared to that shown in its absence (Fig. 2b) confirming the change in coating characteristics.

Fig. 1 Electrochemical
results reco rded for
carbon steel corrosion in
1.0 mol L-1 in the absence
and presence of PVAc:
a – semilog-curves;
b – Nyquist diagram

Fig. 2 Microscopic images acquired for carbon steel before (a)
and after PP in the absence of PVAc (b) as well as in PVAc
presence in various concentrations:
c – 0.62 g L
-1; d – 1.24 g L-1; e – 1.86 g L-1; f – 3.1 g L-1

PVAc behaves as corrosion inhibitor of carbon steel corrosion in acid solution, acting by adsorption on the surface according to the Temkin isotherm model. The standard free adsorption energy ( ΔG
o
ads)
value of -43 kJ mol-1 indicates the PVAc spontaneous chemical adsorption of PVAc. High polymer
performance in carbon steel corrosion control, reaching a value around 90 %, was computed at PVAc concentration of 3.1 g L
-1 and room temperature.

[1] J. Aragón, R. González, G. Fuente s, L. Palin, G. Croce, D. Viterbo, Mater. Res ., 14 (2011) 25
[2] M. Jannesari, J. Varshosaz, M. Morshed, M. Zamani, Int. J. Nanomed. , 6 (2011) 993
[3] T. Segura, M. Menes-Arzate, F. León, A. Ortega, G. Burillo, R. D. Peralta, Polymer , 102 (2016) 183
[4] A. Samide, G. Bratulescu, C. Merisanu, N. Cioatera, J. Appl. Polym. Sci., 136 (2019) 47320