Green Colloidal Composites from Local Agro-wastes for Inhibition of Mild Steel Corrosion in 1 M HCl

Aims: To investigate the corrosion inhibition efficiency of green colloidal water-soluble composites formulated from Thaumatococcus daniellii extract (TDE) and local agro-wastes as alternative oilfield chemicals using mild steel in 1 M HCl.

Study Design: Corrosion was monitored by Weight Loss (WL), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) techniques.

Place and Duration of Study: Materials and Oilfield Chemistry (MOC) laboratory, Department of Chemistry, Faculty of Science, University of Uyo, Nigeria, between December 2017 and March 2018.

Methodology: The standard procedures for thermo-gravimetric analyses (TGA), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) were exactly followed to evaluate corrosion efficiency.

Results: Inhibition efficiency of 91.7% was obtained with TDE 30℃ but this efficiency decreased as temperature increased. Increase in TDE concentration increased charge transfer resistance and decreased double layer capacitance. Adsorption isotherms and kinetic models were also used to describe the adsorption and activation processes. The presence of TDE increases the activation energy and reduces the rate of corrosive attack of the acid on the steel specimens. The adsorption of Thaumatococcus danielliiextract (TDE) on the mild steel surface was characteristic of inhibition by physisorption. Composites from TDE were up to 99% and 85% efficient at 30°C and 80°C respectively.

Conclusion: Adsorption of TDE molecules is by spontaneous physical adsorption mechanism and is best approximated by the Langmuir adsorption isotherm. TDE formulations and composites could be exploited to produce an effective alternative eco-friendly oilfield corrosion inhibitor.