ASSESSMENT OF ASPARTAME AS A GREEN AND EFFECTIVE CORROSION INHIBITOR FOR T95 CARBON STEEL IN STRONG HCl SOLUTIONS
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Date
2022
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Abstract
Oil well acidizing, although a stimulation process, induce the corrosion of metallic
equipment and well tubings. It is a necessity to use an effective corrosion inhibitor
during oil well acidizing. However, current acidizing inhibitors, although effective are
toxic to the natural environment and in some cases, very expensive. There is therefore,
at present a high demand of effective, low-cost, and less toxic corrosion inhibitor for
acidizing process. This work was thus designed to formulate a green and low-cost
inhibitor formulation based on Aspartame (ASP) that can compete favourably with
the commercially available acidizing corrosion inhibitors. The inhibitive effect of ASP
for T95 CS in 15 and 28 wt.% HCl solution at 60, 70, 80, and 90oC was investigated
using the weight loss, electrochemical impedance spectroscopy (EIS),
potentiodynamic polarization (PDP), scanning electron microscope (SEM), energy
dispersive spectroscopy (EDX), and optical profilometry (OP) techniques. Results
from the weight loss and the electrochemical techiniques show that the retardation
efficacy of ASP enhances with increase in concentration and temperature. At 90oC
and 2000 ppm of ASP, inhibition efficiency of 85% and 88% is obtained in 15 wt.%
and 28 wt.% HCl solution, respectively. Following the variation of inhibition
efficiency of ASP with temperature, chemisorption mechanism is proposed for the
adsorption of ASP onto the T95 CS surface in both 15 wt% and 28 wt.% HCl solution.
In order to enhance the inhibitive performance of ASP, studies were undertaken to
ascertain whether or not there is synergistic effect between ASP, potassium iodide
(KI), and sodium dodecylsulfate (SDS). Results from weight loss studies reveal that
synergistic effect existed between ASP, KI, and SDS especially at 90oC. Based on the
synergistic studies, ASP-based cocktail was formulated in a ratio of 2 (ASP): 0.1 (KI):
0.1 (SDS). The formulation performed outstandingly at the studied corrosive media.
At 90oC, 2000 ppm of the formulation exhibits inhibition efficiency of 92% and 96%
in 15 wt% and 28 wt.% HCl solution, respectively from EIS technique. A comparison
of the performance of the formulation with that of a commercially available acidizing
inhibitor reveals that, the formulation perform better than the commercial inhibitor
in 28 wt.% HCl solution but compete considerably in 15 wt% solution. The PDP
results reveal that ASP alone and in combination with additives acted as a mixed-type
corrosion inhibitor in the studied environment and inhibited both the anodic
oxidation and cathodic reduction reactions. The SEM, OP, and EDX results
confirmed the adsorption and high inhibitive performance of ASP-based inhibitor.
The ASP-based formulation is a potential inhibitor for oil well acidizing process.