Zuhair M. Gasem

Performance evaluation of pectin as ecofriendly corrosion inhibitor for X60 pipeline steel in acid medium: experimental and theoretical approaches.

The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was investigated using weight loss, electrochemical, water contact angle measurements, and scanning electron microscopy techniques. The results obtained show that pectin acts as a good corrosion inhibitor for X60 steel. Inhibition efficiency increased with increase in pectin concentration and temperature. Potentiodynamic polarization results reveal that pectin could be classified as a mixed-type corrosion inhibitor with predominant control of the cathodic reaction. The effective corrosion inhibition potential of pectin could be related to the adsorption of pectin molecules at the metal/solution interface which is found to accord with the Langmuir adsorption isotherm model and a protective film formation. Quantum chemical calculations provided insights into the active sites and reactivity parameters governing pectin activity as a good corrosion inhibitor for X60 steel.

Fabrication of nitrogen doped graphene oxide coatings: experimental and theoretical approach for surface protection

In this work, we present a simple strategy of fabricating an N-doped graphene oxide (N-GO) coating on stainless steel (SS) for protective applications. Electrochemical, surface analytical and quantum chemical techniques were employed to characterize the synthesized coatings on the SS surface. Graphene oxide (GO) and reduced graphene oxide (rGO) coatings on SS were adopted for comparison. The downshift of the G band in the Raman spectra of N-GO corroborated the incorporation of N atoms and the deconvoluted spectra of N1s revealed that N-GO coatings retain three types of nitrogen. The influence of N doping on the surface roughness and hydrophobicity of GO was investigated using surface topographic and contact angle measurements. An electrochemical corrosion study on the coatings indicated that N doping of GO enhances the corrosion resistance of SS in 3.5% NaCl solution more than GO and rGO. In order to describe the underlying mechanism, the adsorption energies of GO coatings with SS were computed using molecular dynamics simulation (MDS). The MDS results revealed that all the coating systems adsorbed in a parallel orientation on the Fe surface. N-GO coating exhibited the strongest and the most stable chemisorbed interaction on SS when compared to GO and rGO.

Multi-functional ceramic hybrid coatings on biodegradable AZ31 Mg implants: electrochemical, tribological and quantum chemical aspects for orthopaedic applications

Application of biodegradable implants has received increasing attention for the treatment of bone damage due to their low adverse effects. To achieve better biocompatibility and enhanced corrosion resistance of biodegradable implants with improved wear resistance, multifunctional coatings need to be developed. Herein, a ceramic hybrid coating has been fabricated by a plasma electrolytic oxidation (PEO) technique using Ta2O5 nanoparticle inclusion on AZ31 Mg alloy in order to attain superior corrosion, wear behavior, and surface porosity that enable improved bioactivity. X-ray diffraction analysis of PEO coatings showed that the surface coating is mainly composed of Mg3(PO4)2, MgO and Ta2O5 in different quantities based on PEO processing. Furthermore, scanning electron microscopy (SEM) analysis was employed to observe the surface of the resultant PEO hybrid coatings after and before wear tests. With Ta2O5 nanoparticles, PEO coatings showed excellent wear compared with pure PEO coatings. The efficiency of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements in simulated body fluid. Furthermore, in vitro cell culture studies were performed on MG-63 human cells to evaluate the biocompatibility of PEO coatings. A quantum chemical approach and force-field molecular dynamics simulation were employed to evaluate the interaction between the AZ31 Mg surface and PEO hybrid coatings. All of the observations evidently showed that the ceramic hybrid PEO coating provides improved wear and corrosion protection performance with superior biocompatibility with Ta2O5 nanoparticles, when compared to pure PEO coatings, due to its synergistic beneficial effect.

An electrochemical, in vitro bioactivity, and quantum chemical approach to nanostructured copolymer coatings for orthopedic applications

Conducting polymers represent a promising platform toward coating materials for implant technologies in recent years. In this investigation, copolymers based on pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) were electrodeposited on 316L SS with various feed ratio of Py/EDOT through cyclic voltammetric technique. The surface and chemical structure of the synthesized copolymers were analyzed by SEM, AFM, FT-IR, and 1H NMR spectroscopic analysis. The influence of comonomer feed ratio on electrochemical corrosion behavior was investigated in stimulated body fluid. A significant lower corrosion current with nobler shift in corrosion potential and higher charge transfer resistance values of copolymer-coated 316L SS were obtained and the comparisons were made with uncoated as well as their homo polymers. Furthermore, in vitro cell culture studies were performed on MG63 osteoblast human cells to confirm the biocompatibility of copolymer coatings. Quantum chemical approach was employed to verify the obtained experimental outcomes. As a result of this investigation, it was concluded that the performance of coatings was strongly dependent to the monomer feed ratio and the copolymer synthesized with 50:50 feed ratio showed high corrosion protection efficiency with improved cell growth on MG63 osteoblast cell.

Effect of degree of hydrolysis of polyvinyl alcohol on the corrosion inhibition of steel: theoretical and experimental studies

Two grades of polyvinyl alcohol (PVA) namely partially hydrolyzed (designated as PVA-I) and fully hydrolyzed (designated as PVA-II) were studied with the aim of determining the influence of PVA degree of hydrolysis on the corrosion inhibition effect of mild steel in HCl medium. The investigation was carried out using weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization (PDP), and linear polarization resistance techniques. Results obtained indicate that the two grades of PVA inhibited the acid-induced corrosion of mild steel. Inhibition efficiency increased with increase in the PVAs concentration but decreased with increase in temperature. Results from all the techniques employed were in close agreement and revealed that corrosion inhibition effect followed the order PVA-I > PVA-II. PDP data show that both grades of PVA act as a mixed-type inhibitor. Impedance spectra show a high frequency capacitive loop related to the charge-transfer process of the metal corrosion and the double-layer behavior. Corrosion inhibition by the PVAs is assumed to occur by virtue of adsorption of PVA molecules on the mild steel surface which can be approximated by Langmuir adsorption isotherm model. Quantum-chemical calculations and molecular dynamic simulation approaches were also employed in the study and they have provided useful insights into the active centers of the two grades of PVA as well as the nature of interaction between the mild steel surface and the PVAs.

Date palm (Phoenix dactylifera) leaf extract as an eco-friendly corrosion inhibitor for carbon steel in 1M hydrochloric acid solution

– The purpose of the paper was to investigate the use of aqueous extract of date palm (Phoenix dactylifera) leaf as a green inhibitor for corrosion of carbon steel in 1M hydrochloric acid (HCl) solution. , – Extracts from the date palm were used as the main component of an environmentally friendly corrosion inhibitor for use in HCl pickling processes. Inhibition behavior on carbon steel in HCl was investigated using weight loss measurements, linear and potentiodynamic polarization curves, electrochemical impedance spectroscopy and scanning electron microscopy. , – The results show that the extract exhibited good inhibition performance in 1M HCl. The inhibition efficiency increased with increase in the concentration of the inhibitor but decreased with increase in temperature. Inhibition efficiency also was found to increase as immersion time increased. The inhibitive action was due to adsorption of the date palm leaf components on the steel, which was consistent with the Langmuir isotherm. , – Date palm leaf extract (DPLE) is an effective inhibitor at room temperature and can be used to protect plain carbon steel from corrosion in HCl solution. , – This study provides new information on the inhibiting characteristics of DPLE under specified conditions. The environmentally friendly inhibitor could find possible applications in metal surface anodizing and acid pickling processes.

Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants.

The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings.

Influence of Molecular Weight on Mild Steel Corrosion Inhibition Effect by Polyvinyl Alcohol in Hydrochloric Acid Solution

The corrosion inhibition of mild steel in hydrochloric acid solution in the presence of three different molecular weights of polyvinyl alcohol (PVA) designated as PVA-I, PVA-II, and PVA-III corresponding to 14,000, 72,000, and 125,000 g mol−1, respectively, was investigated using electrochemical impedance spectroscopy, linear polarization resistance (LPR), and potentiodynamic polarization techniques at 25°C. It was found that PVA of different molecular weights inhibited the corrosion of mild steel in the acid environment. Inhibition efficiency (η%) increases with increase in concentration of the polymers. LPR measurements clearly show that inhibition efficiency increases with increasing molecular weight in the order PVA-III > PVA-II > PVA-I. Polarization curves indicate that PVA functions as a mixed inhibitor affecting both the anodic metal dissolution and cathodic hydrogen evolution partial reactions of the corrosion process. The experimental data obtained fitted well into Langmuir adsorption isotherm model. Physical adsorption mechanism is proposed from the thermodynamic (free energy of adsorption) parameters obtained.

A promising nanocomposite from CNTs and nano-ceria: nanostructured fillers in polyurethane coatings for surface protection

The balanced combination of nanostructured carbon materials and metal oxide nanoparticles has been considered as an efficient reinforcement material in developing next-generation multifunctional coatings. Herein, we demonstrate a general approach to fabricate a CNT based nanocomposite with the inclusion of CeO2 nanoparticles that can be effectively implemented as a reinforcement material in surface protective coatings. The synthesized CNT/CeO2 nanocomposite was characterized by spectral and surface morphological analyses, which indicated that the CeO2 nanoparticles were successfully deposited onto the surface of the CNTs. The XRD pattern shows the semi-crystalline nature of the CNTs and the face centered cubic structure of the CeO2 nanoparticles. The prepared nanocomposite has subsequently been used as a nanofiller in polyurethane (PU) coatings for surface protection of steel substrates and a remarkable synergistic effect of nano-ceria and CNTs has been observed. The corrosion resistance of steel coated with a PU coating containing CNT/CeO2 was pointedly higher than with a pure PU coating and a PU coating with CNTs alone. This result suggests a new prospect for solving the corrosion issues encountered on steel structures in industrial applications by using multifunctional hybrid coatings with nanostructured reinforcements.

Experimental and Theoretical Studies of Red Apple Fruit Extract as Green Corrosion Inhibitor for Mild Steel in HCl Solution

The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild steel in hydrochloric acid was investigated by gravimetric and electrochemical methods at 30–60°C. Inhibition efficiency increased with the increase in concentration and temperature. Polarization curves indicate that the extract functions as mixed-type inhibitor. The adsorption of the extract onto mild steel surface followed Langmuir adsorption isotherm model. Chemisorption mechanism is proposed based on the trend of inhibition efficiency with temperature. Quantum chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of the major extract components with mild steel. GRAPHICAL ABSTRACT