Inhibitive Corrosion Performance of the Eco-Friendly Aloe Vera in Acidic Media of Mild and Stainless Steels

Abstract

The inhibitive behaviour of aloe vera as an eco-friendly inhibitor was studied in the corrosion of mild and stainless steel in 0.5 M H2SO4 medium. The varied aloe vera inhibitor concentrations were studied using weight loss (gravimetric) and linear polarization methods. The methods showed that the inhibition efficiency increased with an increase in the concentration of the inhibitor (up to 10 vol/vol%) for both the mild and stainless steels. Stainless steel was found to exhibit a lower corrosion rate compared to mild steel. The results showed that Langmuir adsorption isotherm was obeyed by the inhibition of mild and stainless steel using aloe vera in 0.5 M H2SO4 with the values of the regression coefficients near unity. The negative values of ∆Gads show the spontaneous adsorption of inhibitor on the mild and stainless steel surfaces and a physisorption adsorption mechanism of the aloe vera inhibitor since the values of ∆Gads obtained are more than − 20 kJ/mol, that is, aloe vera is an efficient corrosion inhibitor with mixed-type inhibition property.

Unveiling green corrosion inhibitor of Aloe vera extracts for API 5L steel in seawater environment

“…The study discovered that A. vera extracts could act as inhibitors, with efficiency of up to 77.32% 40 . The investigation of A. vera at different times (in 3-day intervals) in H 2 SO 4 solution also showed that the weight loss of mild steel decreased as the activity of A. vera decreased over time 48 .…”

“…Furthermore, based on several previous literature reports, if the difference in corr corrosion potential (E corr ) between the absence and presence of a corrosion inhibitor is less than 85 mV, then the inhibitor could be classified as a mixed-type inhibitor 40 , 41 , 48 . Otherwise, it will be categorized as either anodic or cathodic, as stated in reference 49 , 50 .…”

“…9 c and cʹ). Soaking times have a significant effect on corrosion phenomena on metal surfaces, and consequently, several studies have evaluated the performance of inhibitors based on exposure time 12 , 19 , 40 , 48 .…”

“… S/N Inhibitor study (years) Metal/medium Inhibitor concentration Inhibitor efficiency Ref 1 Aloe vera (2015) Iron metal sheets/1 M HCl 200 mg kg −1 83.59% 69 2 Aloe vera gel (2016) Mild steel/1 M HCl 200 ppm 87.4% 57 3 Aloe vera gel (2017) Mild steel/0.5 M CH 3 COOH 1.0 g L −1 82.35% 45 4 Aloe vera (2018) Mild steel/0.1–0.5 M HCl-HNO 3 0.03 g L −1 77.32% 40 5 Aloe vera (2019) Aluminium alloys/3% NaCl 0.08 mg mL −1 93.25% 39 6 Aloe vera (2020) Mild steel/0.5 M H 2 SO 4 10% (vol.) 88.9% 48 7 Aloe polysaccharide (APS) (2020) Mild steel/15% HCl 800 ppm 96.61% 59 8 Aloe vera gel (2021) Carbon steel/1.0 M HCl …”

Effect of Aloe Vera Extract as Green Corrosion Inhibitor on Medium Carbon Steel in Sulphuric Acid Environment

“…In 2002, the USA, civil administration, and National Association of Corrosion Engineers (NACE) collectively researched corrosion cost, and they estimated that around $276 billion are being spent on over corrosion prevention techniques every year in the USA, which is almost 3.1 per cent of the US gross domestic product (GDP) [5]. Thereby, it can be said that corrosion affects different areas of life directly or indirectly.…”