Influence of Cissus populnea stem extract on kinetics and thermodynamics of mild steel corrosion in acidic medium

Abstract

The inhibition of mild steel corrosion in 1.0 M HCl and 0.5 M H2SO4 by Cissus populnea stem extract was investigated using weight loss measurements in the temperature range of 303 – 333 K. Results from the study revealed that Cissus populnea stem extract inhibited the corrosion of mild steel in both acid media. Inhibition efficiency of the stem extract increased with increase in the extract concentration but decreased with immersion time. The kinetics of the reaction aligned with a first order type. Thermodynamics investigations showed that Cissus populnea extract is adsorbed on the steel surface through physical interactions, and the adsorption process was endothermic and spontaneous. Langmuir, Freundlich and Temkin isotherm models best described the adsorption mechanism of the stem extract on the steel surface.

Lepidagathis alopecuroides methanol extract as corrosion inhibitor for mild steel in HCl

“…A plot of log CR/T versus 1/T is a straight-line graph with a slope of(− ] (Figure 5b) from which the values of ∆ * ∆ * were calculated respectively and presented on Table 2 [21][22][23]. The negative entropies of activation suggest the association mechanism of the corrosion process whereby a decrease in disorder takes place ongoing from the reactants to the activated complex as reported in other studies [12,22,23].…”

“…Weight loss measurements were done as described elsewhere [12,19,20]. Already cleaned and preweighed mild steel (MS) coupons were immersed in duplicates in 100 mL of 1.0 M solution of HCl in the absence and presence of different concentrations of L. alopecuroides extract and left for the period of 3, 6, 9, 12, 24, 48, 72, 96 and 120 h. The coupons were removed from the test solutions each time, washed in water, cleaned with ethanol, dried with acetone, and reweighed.…”

“…where inh and blank are the weight loss (g) of the mild steel in the presence and absence of the inhibitor respectively [12,20].…”

“…Plant materials are promising green corrosion inhibitors for steel as revealed by several studies [11][12][13][14][15]. Plant materials are not only organic but eco-friendly and pose less health concerns in respect of their toxic effects to man and animals compared to inorganic corrosion inhibitors like the salts of vanadium and chromium, and some toxic synthetic organic compounds [16].…”

“…Plant materials are not only organic but eco-friendly and pose less health concerns in respect of their toxic effects to man and animals compared to inorganic corrosion inhibitors like the salts of vanadium and chromium, and some toxic synthetic organic compounds [16]. Plant materials are rich sources of heterocyclic compounds like tannins, saponins, flavonoids and alkaloids [11,12] which also contain heteroatoms.…”