Vol.:(0123456789) 1 3 Journal of Bio- and Tribo-Corrosion (2020) 6:13 https://doi.org/10.1007/s40735-019-0312-y Mathematical Modeling and Electrochemical Behavior for Corrosion Inhibition of Steel by Kiwi Juice Extract Khalid H. Rashid 1 · Anees A. Khadom 2 Received: 1 September 2019 / Revised: 10 October 2019 / Accepted: 20 November 2019 © Springer Nature Switzerland AG 2019 Abstract The inhibition inﬂuence of kiwi juice extract (KJE) for corrosion of steel in 2.5 M hydrochloric acid has been studied by polarization technique at various temperatures and inhibitor concentrations. The maximum inhibition eﬃciency was 87% at 45 °C and 55 cm 3 /L concentration of inhibitor, while the minimum value was 81% at 45 °C and 5 cm 3 /L concentration of inhibitor. Polarization curves showed that KJE is a mixed-type inhibitor but the cathode is more polarized than the anode. The polarization curve curvature region near the potential of corrosion can be investigated depending on the overvoltage data as a function of current densities. These data can be analyzed by suggesting a mathematical model to take into account the inﬂuence of diﬀusion on the charge transfer process. The results obtained from electrochemical technique and mathematical model are in good agreement. Keywords Low-carbon steel · Corrosion inhibition · Mass transfer · Green inhibitor 1 Introduction Steel and its alloys are commonly utilized in the equipment of petroleum reﬁneries, pipelines, tank constructions, etc. [1]. The principal issue of utilizing alloys of steel is the aggressive reaction in acidic solution [2]. Acidic solutions are generally used for clearing of rust, undesirable scale and oil-well acidizing in numerous industrial cleaning processes [3]. Corrosion can be controlled by diﬀerent methods, such as coating [4], cathodic protection [5], inhibitors [6], etc. Inhibitors are added in small amount and widely used to prevent or reduce the corrosion rates in acidic solutions [7]. Corrosion inhibitors can be classiﬁed as inorganic [8] and organic materials [9]. Consequently, organic corrosion inhibitors can be subdivided to artiﬁcial synthesis [10] and natural extracts [11]. Natural extracts have recently been used as environmentally friendly, non-toxic, safely used and economic anticorrosion materials [12–14]. Inhibi- tion performance cannot be predicated without the use of a comprehensive experimental work. Several methods are available for corrosion rate evaluation. Weight loss [15], electrochemical polarization [ 16] and electrochemical impedance spectroscopy [17] are the most common tech- niques. An electrochemical polarization technique based on Tafel extrapolation was widely used for the calculation of corrosion parameters, such as corrosion current density, corrosion potential and Tafel slopes [3]. Tafel extrapolation technique assumed linear regions in the anodic and cathodic curves. In other words, this technique neglects the eﬀect of mass transfer on the activation process. It has been reported that plant extracts own signiﬁcant inhibitive performance and limited ecological hazards [18, 19]. Several previous studies are available about the suitabil- ity of plant extracts as corrosion inhibitors of steel in hydro- chloric acid, such as Ficus tikoua leaf extract with eﬃciency of 95.8% for carbon steel [20], bitter kola leaf extract with eﬃciency of 90% [21], Glycyrrhiza glabra leaf extract with eﬃciency of 88% [22], Xanthium strumarium extract with eﬃciency of 94.8% [23], peach juice with eﬃciency of 91% [24], kiwi juice with eﬃciency of 96.1% [25], etc. The aim of this study is to investigate the inhibition inﬂuence of extracted kiwi juice as a cheap, raw and non- toxic corrosion inhibitor on low-carbon steel corrosion in 2.5 M HCl at various temperatures. Mathematical modeling was suggested to investigate the eﬀect of mass transfer on * Anees A. Khadom aneesdr@gmail.com 1 Department of Chemical Engineering, University of Technology, Baghdad, Iraq 2 Department of Chemical Engineering, College of Engineering, University of Diyala, Baquba, Iraq