Evaluation of pawpaw leaves extract as anti-corrosion agent for aluminium in hydrochloric acid medium

Abstract

Pawpaw leaves extract was examined as anti-corrosion agent for aluminium in hydrochloric acid medium. The extract and corrosion product were analyzed using Fourier transform infrared spectrophotometer (FTIR). Thermometric, gravimetric, potentiodynamic polarization and scanning electron microscopic methods were employed in the study. The inhibition efficiency was optimized using Response Surface Methodology (RSM) of Design Expert Software 9. Inhibitor concentration (0.2 g/l -1.0 g/l), temperature (303 K -333 K) and time (1hour -5 hours) were the considered factors. It was revealed that stretched C-H and O-H functional groups were predominantly responsible for the corrosion inhibition process. The adsorption of the extract on the aluminium surface adhered to the mechanism of physical adsorption. A quadratic model adequately described the inhibition process. Optimum inhibition efficiency of 80.58% was obtained at inhibitor concentration of 0.961 g/l, temperature of 311.459 K and time of 3.932 hrs. The extract is a mixed-type inhibitor that can control both cathodic and anodic corrosion.

Modeling the Corrosion Inhibition of Mild Steel in HCl Medium with the Inhibitor of Pawpaw Leaves Extract

“…Increase in concentration lowers the reaction number, but increases the inhibition efficiency of the inhibitor. It agrees with previous observations [2,5]. Results from the Gravimetric Method In Table 2, corrosion rate decreases with an increase in the extract concentration.…”

“…Leaves of pawpaw (Carica papaya) were collected from Akpugo, Enugu State, Nigeria. In the extraction of the pawpaw leaves extract and surface preparation of the mild steel, the method used in the previous study was adopted [2]. Standard method was used for the chemical analysis of the extract [3,4].…”

“…The inhibitor efficiency was determined using Equation (1), (1) where RN free and RN add are the reaction numbers for the metal dissolution in free and inhibited corrosive medium, respectively. The reaction number (RN) was evaluated using Equation (2), (2) where T m and T i are the maximum and initial temperatures (in ºC) respectively, and t is the time in minutes elapsed to reach T m . For the gravimetric measurements, the weight loss (∆w), corrosion rate (CR), inhibition efficiency (IE) and degree of surface coverage were determined using Equations (3), (4) and (5), respectively.…”

“…A is the total area of the mild steel sample and t is the immersion time. Considering the corrosion rates of the metal at T 1 and T 2 as CR 1 and CR 2 , the activation energy, E a , was obtained using Equation (7) [8][9][10]. (7) The heat of adsorption Q ads (kJmol -1 ) was calculated using Equation (8) [9,11],…”

Optimization of chicken nail extracts as corrosion inhibitor on mild steel in 2M H2SO4

“…The corrosion inhibitory effects of various plant extracts had been reported with promising inhibitory efficiency. Some of these plants are: Katemfe (Olawale et al, 2018a, Olawale et al, 2018b); Cashew waste (Olawale et al., 2015); Bamboo (Li et al., 2012, 2014); Gentiana olivieri (Evrim et al., 2016); Melon and Groundnut peels (Ita et al., 2016); Pawpaw leaves (Omotiowa and Onukwuli, 2017); Bitter kola leaf (Anadebea et al., 2018); Ocimum gratissium (Udunwa et al., 2017); Thevetia Peruvianna (Fouda et al., 2016); Mango extract (Onukwuli and Omotioma, 2016); phyllantus amarus extract (Okafor et al., 2008) Vernonia amygdalina (Loto et al., 2013), Katemfe fruit leaves (Olawale et al, 2018a, Olawale et al, 2018b) Almond fruit extract (Olawale et al, 2018a, Olawale et al, 2018b) Waterlemon (Odewunmi et al., 2015) Bitter leave root (Awe et al., 2015); Extract of Murraya koenigii Leaves (Quraishi et al., 2010); Gnetum Africana leaves (Nnanna et al., 2013); Gentiana olivieri extract (Evrim et al., 2016); Sida acuta (Umeron et al.,2016); Origanum majorana Extracts (Challouf et al., 2016) Nauclea latifolia (Uwah et al., 2013); Slavia aucheri mesatlantica (Znini et al.,2012); Pigeon pea leaf (Anadebe et al.,2019). The inhibiting activity of these plant/animal extracts is as a result of the phytochemical/physiochemical compositions such as tannins, alkanoids and amino acids.…”