Green surfactants for corrosion control: Design, performance and applications

Helmet-Roled Molecules Carrying Double Metronidazole Frameworks and Phenyl Ring for Strengthening Adsorption and Anticorrosion on Mild Steel

This study prepared new helmet-roled molecules (HMs) carrying metronidazole frameworks and a phenyl ring for strengthening adsorption and anticorrosion on mild steel. The adsorption of the HMs on the copper surface was understood by material simulation computation. Furthermore, the surface analysis experiments suggest that the studied molecules could be adsorbed to a mild steel surface through the chemical coordination bonding. The remarkable corrosion resistance of the HMs for mild steel in HCl was surveyed by potentiodynamic polarization and electrochemical impedance spectroscopy at 298 K. The HMs including two metronidazole skeletons displayed the stronger corrosion inhibition effect on mild steel than the HM1 bearing one single metronidazole part (the corrosion inhibition efficiency, HM3, 98.03%, HM2, 95.14%, HM1, 88.72%). The results presented in this study provided an efficient strategy to develop new clinical medicine-based corrosion inhibitors for metal in acid medium through molecular preconstruction.

Experimental and Theoretical Studies on Long Alkyl Chain-Bearing Dibenzotriazole Ionic Liquids as Eco-friendly Corrosion Inhibitors in Aqueous Hydrochloride Acid

Three long alkyl chain-bearing dibenzotriazole ionic liquids (BTA-R-BTA, R = 8, 12, and 16) were synthesized with high yield (>98%) through a simple and eco-friendly process. Their anticorrosion performance for Q235 carbon steel in 6 M hydrochloride acid was comprehensively evaluated by weight loss tests, electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy), and surface analysis techniques. As the length of the alkyl chain increased, the maximum corrosion inhibition efficiency enhanced from 55.02% (for BTA-8-BTA at 1.2 mM) to 97.10% (for BTA-12-BTA at 0.3 mM) and 98.84% (for BTA-16-BTA at 0.3 mM). Density functional theory calculation indicated that the alkyl chain length had little influence on the inhibitors' electronic structures, while molecular dynamics simulations revealed that the thickness, surface coverage, and compactness of adsorption films formed at the metal-electrolyte interface increased with the elongated alkyl chain. Corrosion inhibition efficiency is strongly correlated with the structures of the adsorption film.

Zwitterions and betaines as highly soluble materials for sustainable corrosion protection: Interfacial chemistry and bonding with metal surfaces

The primary requirements for interfacial adsorption and corrosion inhibition are solubility and the existence of polar functional groups, particularly charges. Traditional organic inhibitors have a solubility issue due to the hydrophobic moieties they incorporate. Most documented organic inhibitors have aromatic rings, hydrocarbon chains, and a few functional groups. The excellent solubility and high efficacy of zwitterions and betaines make them the perfect replacements for insoluble corrosion inhibitors. Zwitterions and betaines are more easily soluble because of interactions between their positive and negative charges (-COO-, -PO3-, -NH3, -NHR2, -NH2R, -SO3- etc.) and the polar solvents. The positive and negative charges also aid these molecules' physical and chemical adsorption at the metal-electrolyte interfaces. They develop a corrosion-inhibiting layer through their adsorption. After becoming adsorbed at the metal-electrolyte interface, they act as mixed-type inhibitors, slowing both cathodic and anodic processes. They usually adsorb according to the Langmuir adsorption isotherm. In this article, the corrosion inhibition potential of zwitterions and betaines in the aqueous phase, as well as their mode of action, are reviewed. This article details the advantages and disadvantages of utilizing zwitterions and betaines for sustainable corrosion protection.

Surfactants as biodegradable sustainable inhibitors for corrosion control in diverse media and conditions: A comprehensive review

BACKGROUND

Corrosion is a challenging and potentially harmful process that involves the continuing, impulsive deterioration of metallic structures via reactions involving environmental components and electro- or chemical processes. To inhibit corrosion, various additives are added. Traditional additives, on the other hand, contain environmentally hazardous substances. Surfactants are less expensive, easier to manufacture, and have high inhibitory efficacy and low toxicity compared to standard corrosion inhibitors. They are often employed as corrosion inhibitors to protect metallic materials against corrosion.

METHODS

Surfactant molecules' amphiphilic nature promotes adsorption at surfaces such as the metal/metal oxide-water interface. Surfactant adsorption on metals and metal oxides forms a barrier that can prevent corrosion.

SIGNIFICANT FINDINGS

This review of surfactants as corrosion inhibitors aims to offer a systemic evaluation of various surfactant physical and chemical properties, surfactant influence in corrosion inhibition, and surfactant used in corrosion inhibition that can be used to enhance the efficacy of surfactant use as corrosion inhibitors in a variety of environments. The effect of several parameters on the potential to suppress corrosion of surfactant molecule series is also discussed here.

Performance of volatile fatty acids production from food waste at the presence of alkyl ethoxy polyglycosides and sodium dodecyl sulfate

In the current context of technological and industrial development, strategies for sustainable development and resource utilization have become increasingly important. FW anaerobic fermentation (Fermentation of Wastes) is a process that utilizes organic waste for biotransformation and is widely used for the production of volatile fatty acids (VFAs). Volatile fatty acids (VFAs) are a kind of high value-added product generated from anaerobic fermentation process, and has extensive applications in chemical synthesis and electricity generation. This study investigated the performance of VFAs production from food waste at the presence of alkyl ethoxy polyglycosides (AEG) and sodium dodecyl sulfate (SDS). The highest yield of VFAs was obtained at 0.1 g AEG/g TS (14.53 g COD/L), which increased by 25.80% than the Blank. But inhibited phenomenon was observed at other reactors with relatively low yield and delayed fermentation time. The inhibition of lactate's production and bioconversion delayed the fermentation time, and SDS has changed the acidogenic fermentation type from lactate-butyrate fermentation to acetate fermentation. In addition, more organic matter dissolved in the fermentation liquor with the addition of AEG and SDS, but the hydrolysis and acidification of polysaccharide were inhibited to some extent. Microbial community analysis showed that the abundance of key bacteria Clostridium has significantly decreased from 82.71% (Blank) to 33.54% (AEG) and 23.72% (SDS), leading to low VFAs production performance.

Burning question: Are there sustainable strategies to prevent microbial metal corrosion?

The global economic burden of microbial corrosion of metals is enormous. Microbial corrosion of iron-containing metals is most extensive under anaerobic conditions. Microbes form biofilms on metal surfaces and can directly extract electrons derived from the oxidation of Fe0 to Fe2+ to support anaerobic respiration. H2 generated from abiotic Fe0 oxidation also serves as an electron donor for anaerobic respiratory microbes. Microbial metabolites accelerate this abiotic Fe0 oxidation. Traditional strategies for curbing microbial metal corrosion include cathodic protection, scrapping, a diversity of biocides, alloys that form protective layers or release toxic metal ions, and polymer coatings. However, these approaches are typically expensive and/or of limited applicability and not environmentally friendly. Biotechnology may provide more effective and sustainable solutions. Biocides produced with microbes can be less toxic to eukaryotes, expanding the environments for potential application. Microbially produced surfactants can diminish biofilm formation by corrosive microbes, as can quorum-sensing inhibitors. Amendments of phages or predatory bacteria have been successful in attacking corrosive microbes in laboratory studies. Poorly corrosive microbes can form biofilms and/or deposit extracellular polysaccharides and minerals that protect the metal surface from corrosive microbes and their metabolites. Nitrate amendments permit nitrate reducers to outcompete highly corrosive sulphate-reducing microbes, reducing corrosion. Investigation of all these more sustainable corrosion mitigation strategies is in its infancy. More study, especially under environmentally relevant conditions, including diverse microbial communities, is warranted.

Natural surfactant mediated bioremediation approaches for contaminated soil

The treatment of environmental pollution by employing microorganisms is a promising technology, termed bioremediation, which has several advantages over the other established conventional remediation techniques. Consequently, there is an urgent inevitability to develop pragmatic techniques for bioremediation, accompanied by the potency of detoxifying soil environments completely. The bioremediation of contaminated soils has been shown to be an alternative that could be an economically viable way to restore polluted soil. The soil environments have long been extremely polluted by a number of contaminants, like agrochemicals, polyaromatic hydrocarbons, heavy metals, emerging pollutants, etc. In order to achieve a quick remediation overcoming several difficulties the utility of biosurfactants became an excellent advancement and that is why, nowadays, the biosurfactant mediated recovery of soil is a focus of interest to the researcher of the environmental science field specifically. This review provides an outline of the present scenario of soil bioremediation by employing a microbial biosurfactant. In addition to this, a brief account of the pollutants is highlighted along with how they contaminate the soil. Finally, we address the future outlook for bioremediation technologies that can be executed with a superior efficiency to restore a polluted area, even though its practical applicability has been cultivated tremendously over the few decades.

Investigation of olive leaf extract as a potential environmentally-friendly corrosion inhibitor for carbon steel

Corrosion constitutes a significant issue in industries that handle metals. Corrosion inhibitors with a low impact on the environment provide a significant economic benefit in various engineering applications. In this work, the effectiveness of olive leaves extract is evaluated as a cost-effective and environmentally-friendly corrosion inhibitor. The corrosion of carbon steel in different concentrations of hydrochloric acid (0.1, 1.0, and 2.0 M) when protected by an aqueous solution of olive leaf extract of concentrations ranging from 10 to 60 ppm is investigated. A green extraction process based upon water extraction is used to ensure minimum impact on the environment. Results show that the corrosion inhibition efficiency increased as the concentration of the olive leaf extract increased. An analysis of variance showed a significant effect of acidic molarity, temperature, and inhibitor concentration on the corrosion rate. A significant statistical model indicates that the inhibitor exhibits higher efficiencies at higher acidic molarity. Results of SEM and EDX also demonstrated that a protective film of the inhibitor on the specimen surface plays a role in corrosion inhibition, suggesting that the inhibitor molecules are adsorbed at the interface between the carbon steel and the acid solution. The study provides an insight on the corrosion mechanism and highlights the potential of olive oil extract as an eco-friendly alternative to traditional corrosion inhibitors.

Lipid Membrane Remodeling by the Micellar Aggregation of Long-Chain Unsaturated Fatty Acids for Sustainable Antimicrobial Strategies

Antimicrobial fatty acids derived from natural sources and renewable feedstocks are promising surface-active substances with a wide range of applications. Their ability to target bacterial membrane in multiple mechanisms offers a promising antimicrobial approach for combating bacterial infections and preventing the development of drug-resistant strains, and it provides a sustainable strategy that aligns with growing environmental awareness compared to their synthetic counterparts. However, the interaction and destabilization of bacterial cell membranes by these amphiphilic compounds are not yet fully understood. Here, we investigated the concentration-dependent and time-dependent membrane interaction between long-chain unsaturated fatty acids-linolenic acid (LNA, C18:3), linoleic (LLA, C18:2), and oleic acid (OA, C18:1)-and the supported lipid bilayers (SLBs) using quartz crystal microbalance-dissipation (QCM-D) and fluorescence microscopy. We first determined the critical micelle concentration (CMC) of each compound using a fluorescence spectrophotometer and monitored the membrane interaction in real time following fatty acid treatment, whereby all micellar fatty acids elicited membrane-active behavior primarily above their respective CMC values. Specifically, LNA and LLA, which have higher degrees of unsaturation and CMC values of 160 µM and 60 µM, respectively, caused significant changes in the membrane with net |Δf| shifts of 23.2 ± 0.8 Hz and 21.4 ± 0.6 Hz and ΔD shifts of 5.2 ± 0.5 × 10^-6 and 7.4 ± 0.5 × 10^-6. On the other hand, OA, with the lowest unsaturation degree and CMC value of 20 µM, produced relatively less membrane change with a net |Δf| shift of 14.6 ± 2.2 Hz and ΔD shift of 8.8 ± 0.2 × 10^-6. Both LNA and LLA required higher concentrations than OA to initiate membrane remodeling as their CMC values increased with the degree of unsaturation. Upon incubating with fluorescence-labeled model membranes, the fatty acids induced tubular morphological changes at concentrations above CMC. Taken together, our findings highlight the critical role of self-aggregation properties and the degree of unsaturated bonds in unsaturated long-chain fatty acids upon modulating membrane destabilization, suggesting potential applications in developing sustainable and effective antimicrobial strategies.

Coco Monoethanolamide Surfactant as a Sustainable Corrosion Inhibitor for Mild Steel: Theoretical and Experimental Investigations

Recent studies indicate that surfactants are a relatively new and effective class of corrosion inhibitors that almost entirely meet the criteria for a chemical to be used as an aqueous phase corrosion inhibitor. They possess the ideal hydrophilicity to hydrophobicity ratio, which is crucial for effective interfacial interactions. In this study, a coconut-based non-ionic surfactant, namely, coco monoethanolamide (CMEA), was investigated for corrosion inhibition behaviour against mild steel (MS) in 1 M HCl employing the experimental and computational techniques. The surface morphology was studied employing the scanning electron microscope (SEM), atomic force microscope (AFM), and contact measurements. The critical micelle concentration (CMC) was evaluated to be 0.556 mM and the surface tension corresponding to the CMC was 65.28 mN/m. CMEA manifests the best inhibition efficiency (η%) of 99.01% at 0.6163 mM (at 60 °C). CMEA performs as a mixed-type inhibitor and its adsorption at the MS/1 M HCl interface followed the Langmuir isotherm. The theoretical findings from density functional theory (DFT), Monte Carlo (MC), and molecular dynamics (MD) simulations accorded with the experimental findings. The MC simulation's assessment of CMEA's high adsorption energy (-185 Kcal/mol) proved that the CMEA efficiently and spontaneously adsorbs at the interface.