Organic Corrosion Inhibitors

Organic corrosion inhibitors are one of the five ways, besides material selection, design, cathodic protection and coatings, to protect materials against corrosion. Corrosion is an ubiquitous phenomena that deteriorates all materials, metals, plastics, glass and concrete. The costs of corrosion are tremendous and amounts to 4.0% of gross domestic product (GDP) in USA. The similar losses of GDP are noted in all countries around the world. At this point of time, there is no way to completely stop the corrosion processes. Some new solutions can only slow this process. Organic corrosion inhibitors are widely used in industry because of their effectiveness at wide range of temperatures, compatibility with protected materials, good solubility in water, low costs and relatively low toxicity. Organic corrosion inhibitors adsorb on the surface to form protective film which displace water and protect it against deteriorating. Effective organic corrosion inhibitors contain nitrogen, oxygen, sulfur and phosphorus with lone electron pairs as well can contain structural moieties with π-electrons that interact with metal favoring the adsorption process. This review presents mechanisms and monitoring of corrosion, laboratory methods for corrosion study, relationship between structure and efficacy of corrosion inhibitions, theoretical approach to design new inhibitors and some aspects of biocorrosion

Multifunctional Gemini Surfactants: Structure, Synthesis, Properties and Applications

Gemini cationic surfactants are compounds which are composed of two hydrophilic head groups and two hydrophobic tails linked by a spacer at the head groups or closed to them. The spacer can be either hydrophobic or hydrophilic. It can be rigid or flexible. The neutral charge of the molecule is retained by the presence of organic or inorganic counterions. Critical micelle concentrations (CMCs), surface tension (γ) and minimal inhibitory concentration (MIC) are dozen times lower than corresponding parameters of monomeric surfactants. The unique properties of gemini surfactants with a wide range of hydrophilic-lipophilic balance (HLB) make them a very useful, innovative material in detergents, cosmetics, personal care products, additives for paints and coatings, biocides, material science, organic synthesis, pharmacy, textiles, enhanced oil recovery, nanotechnology, petroleum and many other branches of life. A large number of papers concerning gemini surfactants have been published so far. This review presents a synthetic look at current work devoted to structure, synthesis and applications of gemini surfactants

Synthesis, physicochemical properties, biological and anticorrosion activity of new oligomeric alkylammonium surfactants

Wydział ChemiiPrezentowana praca doktorska zawiera badania interdyscyplinarne łącząc chemię organiczną, chemię analityczną, elektrochemię oraz mikrobiologię. W pierwszym etapie badań zsyntezowano nowe oligomeryczne surfaktanty oraz przedstawiono charakterystykę spektroskopową. Drugi etap badań przedstawia właściwości fizykochemiczne badanych surfaktantów. Wyznaczono CMC oraz zbadano korelację pomiędzy strukturą a agregacją w roztworach wodnych. Na podstawie zebranych wyników wybrane surfaktanty poddano testom korozyjnym wobec stali węglowej oraz stali nierdzewnej. Czas imersji w roztworze elektrolity z oraz bez dodatku surfaktantu wynosił 24 h oraz tydzień. Wszystkie testowane surfaktanty wykazały znaczną efektywność hamowania korozji. Wyznaczono MIC (Minimalne Stężenie Hamujące) wobec bakterii, drożdży oraz grzybów. Biorąc pod uwagę znaczną aktywność antykorozyjną oraz biologiczną, kolejnym aspektem badań było badanie hamowania biokorozji przez surfaktanty. W ostatnim etapie badań immobilizowano surfaktanty w kaspuły silikonowe oraz żelatynowe w celu modyfikacji powłok antykorozyjnych.The presented doctoral dissertation includes interdisciplinary research combining organic chemistry, analytical chemistry, electrochemistry and microbiology. In the first stage of research, new oligomeric surfactants were synthesized and spectroscopic characteristics were presented. The second stage of research presents the physicochemical properties of the surfactants tested. CMC was determined and the correlation between structure and aggregation was examined in aqueous solutions. Based on the collected results, selected surfactants were subjected to corrosion tests against carbon steel and stainless steel. The immersion time in the solution of electrolytes with and without the addition of surfactant was 24 hours and a week. All tested surfactants showed significant corrosion inhibition efficiency. The MIC (Minimum Inhibitory Concentration) was determined against bacteria, yeast and fungi. Given the significant anti-corrosive and biological activity, another aspect of the study was the study of inhibition of biocorrosion by surfactants. In the last stage of research, surfactants were immobilized into silicone and gelatin capsules to modify anti-corrosion coatings

Synthesis, physicochemical properties, biological and anticorrosion activity of new oligomeric alkylammonium surfactants

Wydział ChemiiPrezentowana praca doktorska zawiera badania interdyscyplinarne łącząc chemię organiczną, chemię analityczną, elektrochemię oraz mikrobiologię. W pierwszym etapie badań zsyntezowano nowe oligomeryczne surfaktanty oraz przedstawiono charakterystykę spektroskopową. Drugi etap badań przedstawia właściwości fizykochemiczne badanych surfaktantów. Wyznaczono CMC oraz zbadano korelację pomiędzy strukturą a agregacją w roztworach wodnych. Na podstawie zebranych wyników wybrane surfaktanty poddano testom korozyjnym wobec stali węglowej oraz stali nierdzewnej. Czas imersji w roztworze elektrolity z oraz bez dodatku surfaktantu wynosił 24 h oraz tydzień. Wszystkie testowane surfaktanty wykazały znaczną efektywność hamowania korozji. Wyznaczono MIC (Minimalne Stężenie Hamujące) wobec bakterii, drożdży oraz grzybów. Biorąc pod uwagę znaczną aktywność antykorozyjną oraz biologiczną, kolejnym aspektem badań było badanie hamowania biokorozji przez surfaktanty. W ostatnim etapie badań immobilizowano surfaktanty w kaspuły silikonowe oraz żelatynowe w celu modyfikacji powłok antykorozyjnych.The presented doctoral dissertation includes interdisciplinary research combining organic chemistry, analytical chemistry, electrochemistry and microbiology. In the first stage of research, new oligomeric surfactants were synthesized and spectroscopic characteristics were presented. The second stage of research presents the physicochemical properties of the surfactants tested. CMC was determined and the correlation between structure and aggregation was examined in aqueous solutions. Based on the collected results, selected surfactants were subjected to corrosion tests against carbon steel and stainless steel. The immersion time in the solution of electrolytes with and without the addition of surfactant was 24 hours and a week. All tested surfactants showed significant corrosion inhibition efficiency. The MIC (Minimum Inhibitory Concentration) was determined against bacteria, yeast and fungi. Given the significant anti-corrosive and biological activity, another aspect of the study was the study of inhibition of biocorrosion by surfactants. In the last stage of research, surfactants were immobilized into silicone and gelatin capsules to modify anti-corrosion coatings

Functionalised novel gemini surfactants as corrosion inhibitors for mild steel in 50 mM NaCl: experimental and theoretical insights

Novel gemini surfactants functionalised with oxygen atom and ester groups were synthesized and characterised by NMR methods. The corrosion inhibiting properties of the synthesized compounds were investigated by potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). The results show that inhibition efficiency depends on concentration and the ability to create micelles in aqueous environment, with the highest inhibition efficiency being at around critical micelle concentration (CMC). Furthermore, their inhibition effect was compared against a well-known, commercially available, corrosion inhibitor (benzotriazole) and found to be better for the novel compounds under study in this work. Moreover, the Langmuir adsorption isotherm was found to be suitable for correlating the experimental results with the proposed mechanism of protection. Theoretical studies were based on Density Functional Theory (DFT) and correlation between experimental and theoretical results was determined. These results open perspectives for the application of these new compounds in corrosion protection.publishe

Antimicrobial Activity of Gemini Surfactants with Azapolymethylene Spacer

A series of 21 azapolymethylene gemini surfactants were obtained. The synthesis of the title surfactants in one- or two-step reaction proceeds with good yields. The structure and the purity of the synthesized compounds were determined by 1H and 13C NMR, ESI-MS spectra, and elemental analysis. Moreover, 2D COSY, HMBC, and HSQC spectra were performed. The minimal inhibitory concentrations (MIC) of the synthesized compounds were determined against fungi: Candida albicans, Aspergillus niger, Penicillium chrysogenum and bacteria: Escherichia coli,Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. Also, the critical micelle concentrations (CMC) were determined. The relationship between antimicrobial and surface activity and surfactant structure has been determined

Biodegradability and aquatic toxicity of new cleavable betainate cationic oligomeric surfactants

New cleavable oligomeric cationic surfactants containing ester groups susceptible to hydrolysis between the hydrocarbon tails and the hydrophilic moiety have been synthesized and their biodegradability and aquatic toxicity examined. Aerobic biodegradability was evaluated by applying a standard method for ready biodegradability, the CO2 Headspace test. Aquatic toxicity was assessed by means of the acute toxicity test with Daphnia. Cleavable oligomeric cationic surfactants undergo a significant biodegradation extent (31-52%) as compared to dimeric surfactants without ester groups that showed null degradation in previous works. However, they do not attain the threshold of ultimate degradation required (60%) to be classed as easily biodegradable chemicals. On the other hand, the introduction of cleavable groups in the surfactant hydrophobic chains reduces the toxic effects on the microorganisms responsible for degradation observed for conventional alkyl ammonium dimeric surfactants. Acute toxicity values of betainate cationic oligomeric surfactants to Daphnia magna, IC50-48 h, varies from 1.5 to 50 mg/L. Aquatic toxicity of oligomeric cationic surfactants depends on their hydrophobicity and increases regularly with the alkyl chain length. However, whether the surfactant is a dimeric or a trimeric betaine ester does not affect their acute toxicity to crustaceanThis work was supported by National Centre for Research and Development (Poland; TANGO1/266340/NCBR/2015) and the Spanish Ministry of Economy and Competitiveness (CTQ2017-88948-P)Peer reviewe