A peony-leaves-derived liquid corrosion inhibitor: protecting carbon steel from NaCl

Abstract

A liquid mixture was developed from waste peony leaves through a zero-waste chemical/biological process. The inhibition effect of different concentrations of peony leaves derived solution (0-3 vol.%, PLS0-3) on C1010 carbon steel in 3.5 wt.% NaCl was investigated over time using electrochemical measurements. Chemical analyses were performed to reveal the main compounds of this inhibitor. Surface analyses together with water contact angle measurements were employed to study the characteristics of the steel surface affected. Semi-empirical calculations with PM3 method were used to find the relationship between molecular structure and inhibiting effect of PLS. The inhibitor was stable over time and its main active ingredients were C 19 H 27 N 4 O 10 P and C 17 H 16 N 3 O 9 P that adsorb onto the steel surface, block cathodic active sites, make the surface hydrophobic, decrease the surface free energy, and facilitate the formation of a passive layer. A good correlation was found between experimentally determined inhibition efficiency and theoretically calculated properties of PLS.ARTICLE HISTORY

Accelerated Laboratory Assessment of Discrete Sacrificial Anodes for Rehabilitation of Salt-Contaminated Reinforced Concrete

“…where ε = dielectric constant; ε o = vacuum permittivity; A = area of plate surface; and δ = distance between two plates. For S1-1, B1-1, and B2-2, the values of C dl decreased with the increase of the values of R ct after the connection of DSA, which was consistent with the findings of Nazari et al (2017b). The decrease of C dl corresponds to the decrease of the area of plate surface (A) or the increase of the distance between two plates (δ) caused by the repassivation of the rebar.…”

“…8, R o represents the offset resistance, the value of which was minor and negligible and which had no physical meaning; R c and Q c represent the resistance and constant phase element (CPE) of the concrete that covered the rebar, respectively; and R ct and Q dl represent the charge transfer resistance and the CPE of the double layer at the rebar-concrete interface, which were composed of passive film and corrosion product, respectively. The CPE often is used instead of a perfect capacitor when the semicircle of a Nyquist plot is displaced or depressed (Ribeiro and Abrantes 2016), which is caused by the roughness of the corrosion product at the surface of rebar or the heterogeneity of the specimen (Nazari et al 2017b). The impedance of CPE is expressed as follows (Nazari et al 2017b):…”

“…The CPE often is used instead of a perfect capacitor when the semicircle of a Nyquist plot is displaced or depressed (Ribeiro and Abrantes 2016), which is caused by the roughness of the corrosion product at the surface of rebar or the heterogeneity of the specimen (Nazari et al 2017b). The impedance of CPE is expressed as follows (Nazari et al 2017b):…”

“…The p-values of R ct were between 0.18 and 0.99, which statistically validates the effectiveness of all representative anodes except S2-1 and the different performance of cathodic protection of each type of anode. The values of C dl were calculated as follows (Nazari et al 2017b):…”

Mechanism of corrosion protection in chloride solution by an apple-based green inhibitor: experimental and theoretical studies

“…The major advantage of the chemicals prepared by this method over the commercial green chemicals used by the departments of transportation (e.g., beet juice) is that the former ones feature much lower chemical oxygen demand, which makes them more eco-friendly [31]. An example of inhibitors synthesized by the innovative method is a liquid extract made from peony leaf waste, exhibiting a corrosion inhibition efficiency of 65.8% for carbon steel in NaCl brine [51]. Due to relatively low corrosion inhibition efficiency (IE) of the peony leaf extract, the authors further explored a variety of other local agro-based wastes as feedstock (such as grass, dandelion leaf, blueberry pomace, cherry pomace, and apple pomace) to produce highefficiency "green" corrosion inhibitors.…”