Biodegradability and aquatic toxicity of new cleavable betainate cationic oligomeric surfactants

Adsorption, Aggregation, and Application Properties of Green Pluronic Aliphatic Alcohol Ether Carboxylic Acids and Nonionic/Amphoteric Surfactants in Water

In the realm of colloid and interface science, new types of green surfactants, including anionic Pluronic alcohol ether carboxylate (AEC), branched alkyl glucoside (IG), and zwitterionic coconut oil amide propyl betaine (CAB), have been identified and merit further exploration. AEC, characterized by its inclusion of 5 EO and 3.5 PO units, was synthesized, and its behavior in aqueous solutions with IG and CAB was meticulously examined. Their performance in applications such as foam generation, wetting, and the dispersion and stabilization of graphene was also evaluated. At αAE5P3C = 0.5, AE5P3C/CAB exhibited superior surface and interfacial properties compared to AE5P3C/IG. In these hybrid systems, the self-assembly of micelles is predominantly influenced by hydrogen bonding, electrostatic interactions, and hydrophobic forces. Kinetic analysis further confirmed that the driving force for micelle formation in these hybrid systems is enthalpy, with the adsorption process involving a mixed diffusion-kinetic adsorption mechanism. AE5P3C/CAB demonstrated enhanced foaming ability, foam stability, and wetting properties compared to AE5P3C/IG. Intriguingly, the optimal dispersion and stabilization of graphene were achieved with AE5P3C/IG at αAE5P3C = 0.2, providing a foundational basis for its potential application in graphene-based systems. A thorough examination of the synergistic mechanisms and application potential of these three distinct surfactants in aqueous solutions was presented, taking into account various charged ions and the specific hydrophilic and hydrophobic groups of EO and PO. This study not only provides fundamental insights into their intrinsic properties but also offers a fresh perspective for the ongoing exploration of green surfactants.

Biosurfactant production by Bacillus cereus GX7 utilizing organic waste and its application in the remediation of hydrocarbon-contaminated environments

The use of biosurfactants represents a promising technology for remediating hydrocarbon pollution in the environment. This study evaluated a highly effective biosurfactant strain-Bacillus cereus GX7's ability to produce biosurfactants from industrial and agriculture organic wastes. Bacillus cereus GX7 showed poor utilization capacity for oil soluble organic waste but effectively utilized of water- soluble organic wastes such as starch hydrolysate and wheat bran juice as carbon sources to enhance biosurfactant production. This led to significant improvements in surface tension and emulsification index. Corn steep liquor was also effective as a nitrogen source for Bacillus cereus GX7 in biosurfactant production. The biosurfactants produced by strain Bacillus cereus GX7 demonstrated a remediation effect on oily beach sand, but are slightly inferior to chemical surfactants. Inoculation with Bacillus cereus GX7 (70.36%) or its fermentation solution (94.38%) effectively enhanced the degradation efficiency of diesel oil in polluted seawater, surpassing that of indigenous degrading bacteria treatments (57.62%). Moreover, inoculation with Bacillus cereus GX7's fermentation solution notably improved the community structure by increasing the abundance of functional bacteria such as Pseudomonas and Stenotrophomonas in seawater. These findings suggest that the Bacillus cereus GX7 as a promising candidate for bioremediation of petroleum hydrocarbons.

Selective biodegradation of octylphenol polyethoxylates with different ethoxylate length chains by aerobic bacterial culture

Octylphenol polyethoxylates (OPEOn) are composed of a hydrophobic octylphenol (OP) group and a hydrophilic polyethylene oxide (EO) chain and are widely used in commercial products. Shorter EO chains and OPEOn biometabolites have been identified as endocrine-disrupting contaminants and can threaten biotic factors in the ecosystem. In this study, OPEOn at three EO lengths (TX-45, TX-114, and TX-165) were selected in monomer (MN) or micelle (MC) state for batch experiments under aerobic conditions, with results showing biodegradation rates of 90 % within 35-70 h. The pseudo-first-order constant (k) of OPEOn biodegradation was observed in the order TX-45 (0.1414 h-1) > TX-114 (0.0556 h-1) > TX-165 (0.0485 h-1), with biomineralisation reaching at least 80 % for all OPEOn. The selective biodegradation of EO chains was also measured, with initial accumulation of OPEO3 observed along with the depletion of longer EO chains for TX-45 and TX-114 in both the MN and MC states. A similar trend was observed for the MN state of TX-165, with OPEO3-OPEO9 observed to accumulate and reduced after 70 h. MC biodegradation was accomplished via the initial accumulation of OPEO3-OPEO9. The amounts of OPEO3 increased and others reduced; however, OPEO3 remained high at the end of biodegradation for TX-165. Bacterial community analysis indicated that the genera Sphingobium spp., Pseudomonas spp., Flavobacterium spp., Comamonas spp., and Sphingopyxis spp. dominate OPEOn biodegradation, and they have their roles during biodegradation, and the community-level physiological profile (CLPP) was also changed by biodegradation in both the MN and MC states.

Rethinking the Esterquats: Synthesis, Stability, Ecotoxicity and Applications of Esterquats Incorporating Analogs of Betaine or Choline as the Cation in Their Structure

Esterquats constitute a unique group of quaternary ammonium salts (QASs) that contain an ester bond in the structure of the cation. Despite the numerous advantages of this class of compounds, only two mini-reviews discuss the subject of esterquats: the first one (2007) briefly summarizes their types, synthesis, and structural elements required for a beneficial environmental profile and only briefly covers their applications whereas the second one only reviews the stability of selected betaine-type esterquats in aqueous solutions. The rationale for writing this review is to critically reevaluate the relevant literature and provide others with a "state-of-the-art" snapshot of choline-type esterquats and betaine-type esterquats. Hence, the first part of this survey thoroughly summarizes the most important scientific reports demonstrating effective synthesis routes leading to the formation of both types of esterquats. In the second section, the susceptibility of esterquats to hydrolysis is explained, and the influence of various factors, such as the pH, the degree of salinity, or the temperature of the solution, was subjected to thorough analysis that includes quantitative components. The next two sections refer to various aspects associated with the ecotoxicity of esterquats. Consequently, their biodegradation and toxic effects on microorganisms are extensively analyzed as crucial factors that can affect their commercialization. Then, the reported applications of esterquats are briefly discussed, including the functionalization of macromolecules, such as cotton fabric as well as their successful utilization on a commercial scale. The last section demonstrates the most essential conclusions and reported drawbacks that allow us to elucidate future recommendations regarding the development of these promising chemicals.

Injectable hydrogels as promising in situ therapeutic platform for cartilage tissue engineering

Injectable hydrogels are gaining prominence as a biocompatible, minimally invasive, and adaptable platform for cartilage tissue engineering. Commencing with their synthesis, this review accentuates the tailored matrix formulations and cross-linking techniques essential for fostering three-dimensional cell culture and melding with complex tissue structures. Subsequently, it spotlights the hydrogels' enhanced properties, highlighting their augmented functionalities and broadened scope in cartilage tissue repair applications. Furthermore, future perspectives are advocated, urging continuous innovation and exploration to surmount existing challenges and harness the full clinical potential of hydrogels in regenerative medicine. Such advancements are crucial for validating the long-term efficacy and safety of hydrogels, positioning them as a promising direction in regenerative medicine to address cartilage-related ailments.

Self-Aggregation, Antimicrobial Activity and Cytotoxicity of Ester-Bonded Gemini Quaternary Ammonium Salts: The Role of the Spacer

Five ester-bonded gemini quaternary ammonium surfactants C₁₂-E_n-C₁₂ (n = 2, 4, 6), with a flexible spacer group, and C₁₂-B_m-C₁₂ (m = 1, 2), with rigid benzene spacers, were synthesized via a two-step reaction and analyzed. Furthermore, the effects of the spacer structure, spacer length and polymerization degree on the self-aggregation, antimicrobial activity and cytotoxicity of C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ and their corresponding monomer N-dodecyl-N,N,N-trimethyl ammonium chloride DTAC were investigated. The results showed that C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ had markedly lower critical micellar concentration (CMC) values and lower surface tension than DTAC. Moreover, the CMC values of C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ decreased with increasing spacer length. In the case of equivalent chain length, the rigidity and steric hindrance of phenylene and 1,4-benzenediyl resulted in larger CMC values for C₁₂-B_m-C₁₂ than for C₁₂-E_n-C₁₂. The antibacterial ability of C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ was assessed using Escherichia coli (E. coli) and Staphylococcus albus (S. aureus) based on minimum inhibitory concentrations (MICs). Furthermore, C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ exhibited higher antimicrobial activity than DTAC and had stronger function toward S. aureus than E. coli. The antimicrobial activity was enhanced by increasing the spacer chain length and decreased with the increased rigidity of the spacers. The cytotoxic effects of C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ in cultured Hela cells were evaluated by the standard CCK8 method based on half-maximal inhibitory concentration (IC₅₀). The cytotoxicity of C₁₂-E_n-C₁₂ and C₁₂-B_m-C₁₂ was significantly lower than alkanediyl-α,ω-bis(dimethyldodecylammonium) bromide surfactants and DTAC. The spacer structure and the spacer length could induce significant cytotoxic effects on Hela cells. These findings indicate that the five ester-bonded GQASs have stronger antibacterial activity and lower toxicity profile, and thus can be used in the pharmaceutical industry.

Effects of tea saponin on the foaming properties of pea protein

Plant proteins are becoming increasingly important for foam formation as an alternative to animal proteins. Consumers, however, are unsatisfied with the foaming properties of pea protein isolates. Recent research on proteins and surfactants has primarily concentrated on chemically synthesized surfactants. In this study, foams were prepared by complexing pea protein isolates with a natural small molecule surfactant tea saponin. This study investigates the mechanisms responsible for the formation and stability of foams prepared from pea protein isolates (PPIs) complexed with tea saponins. Analyses of foaming performance were carried out by analyzing the morphology of foam, foaming properties, foam's rheological properties, and the microstructure of the pea protein-tea saponin complex system. Compared to the pea protein isolate alone, the pea protein-tea saponin complex significantly improved foaming capacity and foaming stability. As shown by light microscopy analysis, the size of the foam decreased and became more homogeneous, probably because of the altered aggregate state of the protein. In this study, natural surfactants and mixtures of plant proteins are studied in order to better understand their properties. The mixed system has excellent prospects for application in the industries related to foam.

UV aging of microplastic polymers promotes their chemical transformation and byproduct formation upon chlorination

The presence and accumulation of microplastics (MPs) in water and wastewater is a growing concern. When released to the water bodies, microplastics can be subject to surface weathering due to ultraviolet (UV) exposure. In this study, the effects of UV aging of six MP polymers from three groups (e.g., polyamide, polyester, and polyolefin) on their chlorine reactivity, chemical transformation, and formation of disinfection byproducts (DBPs) were studied. Polyamide (e.g., polyamide 6) in both virgin and UV-aged forms showed significantly higher chlorine demands than other MP polymers (915.5-947.9 versus 7.0-21.1 μmol/g MP in 24 h), and polyolefins were relatively inert to chlorine. UV aging enhanced the destructions of functional groups of polyamide and polyester upon chlorination, promoting the chlorine demands and leaching of organics by up to 1.7- and 2.4-fold, respectively. Polymer monomer and oligomers of polyamide 6 and toxic or endocrine disrupting additives (e.g., dimethyl phthalate and butyl octyl phthalate) were identified in leachates from chlorinated MP polymers by mass spectrometry. Meanwhile, up to >10-fold increases in the yields of trihalomethane, haloacetic acid, haloacetaldehyde, haloacetonitrile, and haloacetamide were observed from 30-day UV-aged MP polymers as compared to their virgin counterparts. Overall, this study reveals that UV aging can promote the reactivity and chemical transformation of MP polymers during chlorination, especially for polyamide and polyester, increase the release of polymer monomers, oligomers, and additives, and aggravate the role of MP polymers as DBP precursors.

A new class of quaternary ammonium compounds as potent and environmental friendly disinfectants

Quaternary ammonium compounds (QACs) are inexpensive and readily available disinfectants, and have been widely used, especially since the COVID-19 outbreak. The toxicity of QACs to humans has raised increasing concerns in recent years. Here, a new type of QACs was synthesized by replacing the alkyl chain with zinc phthalocyanine (ZnPc), which consists of a large aromatic ring and is hydrophobic in nature, similar to the alkyl chain of QACs. Three ZnPc-containing disinfectants were synthesized and fully characterized. These compounds showed 15-16 fold higher antimicrobial effect against Gram-negative bacteria than the well-known QACs with half-maximal inhibitory (IC50) values of 1.43 μM, 2.70 μM, and 1.31 μM, respectively. With the assistance of 680 nm light, compounds 4 and 6 had much higher bactericidal toxicities at nanomolar concentrations. Compound 6 had a bactericidal efficacy of close to 6 logs (99.9999% kill rate) at 1 μM to Gram-positive bacteria, including MRSA, under light illumination. Besides, these compounds were safe for mammalian cells. In a mouse model, compound 6 was effective in healing wound infection. Importantly, compound 6 was easily degraded at working concentrations under sunlight illumination, and is environmentally friendly. Thus, compound 6 is a novel and promising disinfectant.

Growth Inhibition of Sulfate-Reducing Bacteria during Gas and Oil Production Using Novel Schiff Base Diquaternary Biocides: Synthesis, Antimicrobial, and Toxicological Assessment

Upstream crude oil production equipment is always exposed to destruction damagingly which is caused by sulfate-reducing bacterium (SRB) activities that produce H2S gas, which leads to increased metal corrosion (bio-fouling) rates and inflicts effective infrastructure damage. Hence, oil and gas reservoirs must be injected with biocides and inhibitors which still offer the foremost protection against harmful microbial activity. However, because of the economic and environmental risks associated with biocides, the oil and gas sectors improve better methods for their usage. This work describes the synthesis and evaluation of the biological activities as the cytotoxicity and antimicrobial properties of a series of diquaternary cationic biocides that were studied during the inhibition of microbial biofilms. The prepared diquaternary compound was synthesized by coupling vanillin and 4-aminoantipyrene to achieve the corresponding Schiff base, followed by a quaternization reaction using 1,6-bromohexane, 1,8-bromooctane, and 1,12-bromododecane. The increase of their alkyl chain length from 6 to 12 methylene groups increased the obtained antimicrobial activity and cytotoxicity. Antimicrobial efficacies of Q1-3 against various biofilm-forming microorganisms, including bacteria and fungi, were examined utilizing the diameter of inhibition zone procedures. The results revealed that cytotoxic efficacies of Q1-3 were significantly associated mainly with maximum surface excess and interfacial characteristics. The cytotoxic efficiencies of Q1-3 biocides demonstrated promising results due to their comparatively higher efficacies against SRB. Q3 exhibited the highest cytotoxic biocide against the gram +ve, gram -ve, and SRB species according to the inhibition zone diameter test. The toxicity of the studied microorganisms depended on the nature and type of the target microorganism and the hydrophobicity of the biocide molecules. Cytotoxicity assessment and antimicrobial activity displayed increased activity by the increase in their alkyl chain length.

Cationic gemini surfactant properties, its potential as a promising bioapplication candidate, and strategies for improving its biocompatibility: A review

Gemini surfactants consist of two cationic monomers of a surfactant linked together with a spacer. The specific structure of a cationic gemini surfactant is the reason for both its high surface activity and its ability to decrease the surface tension of water. The high surface activity and unique structure of gemini surfactants result in outstanding properties, including antibacterial and antifungal activity, anticorrosion properties, unique aggregation behaviour, the ability to form various structures reversibly in response to environmental conditions, and interactions with biomacromolecules such as DNA and proteins. These properties can be tailored by selecting the optimal structure of a gemini surfactant in terms of the nature and length of its alkyl substituents, spacer, and head group. Additionally, regarding their properties, comparison with their monomeric counterparts demonstrates that gemini surfactants have higher performance efficacy at lower concentrations. Hence, less material is needed, and the toxicity is lower. However, there are some limitations regarding their biocompatibility that have led researchers to develop amino acid-based and sugar-based gemini surfactants. Owing to their remarkable properties, cationic gemini surfactants are promising candidates for bioapplications such as drug delivery systems, gene carriers, and biomaterial surface modification.

Self-Assembling Drug Formulations with Tunable Permeability and Biodegradability

This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed.

Experimental Research on the Performance of a Wetting Agent Based on Compound Acidification in Low-Porosity and Hard-to-Wet Coal Seams

To improve the wetting performance of the composite acid solution in the deep coal seam, in this paper, the surface tension and contact angle characteristics of the compound acid wetting agent are studied, then the composition of the wetting agent is developed and evaluated based on nuclear magnetic resonance. The research indicates that surfactants can reduce the surface tension of water, and the surface tension tends to decrease with the increase in the surfactant concentration. The critical micelle concentration of the anionic surfactant sodium dodecyl sulfate (SDS) solution is only 0.025%, and the corresponding critical surface tension is 30.63 mN/m. The wetting agent material based on the composite acid solution includes the acid HCl, HF, the anionic surfactant SDS, and the inorganic salt NaCl, the composition of which is 8%, 8%, 0.025%, and 0.6 mol/L, respectively. The total wetting rate of the composite acid-containing HCl + HF + SDS + NaCl is the largest, reaching 64.30%, which has good wettability inside the coal and can be a comprehensive intrusion into the internal structure of coal pores.

Antimicrobial Activity of Gemini Surfactants with Ether Group in the Spacer Part

Due to their large possibility of the structure modification, alkylammonium gemini surfactants are a rapidly growing class of compounds. They exhibit significant surface, aggregation and antimicrobial properties. Due to the fact that, in order to achieve the desired utility effect, the minimal concentration of compounds are used, they are in line with the principle of greenolution (green evolution) in chemistry. In this study, we present innovative synthesis of the homologous series of gemini surfactants modified at the spacer by the ether group, i.e., 3-oxa-1,5-pentane-bis(N-alkyl-N,N-dimethylammonium bromides). The critical micelle concentrations were determined. The minimal inhibitory concentrations of the synthesized compounds were determined against bacteria Escherichia coli ATCC 10536 and Staphylococcus aureus ATCC 6538; yeast Candida albicans ATCC 10231; and molds Aspergillus niger ATCC 16401 and Penicillium chrysogenum ATCC 60739. We also investigated the relationship between antimicrobial activity and alkyl chain length or the nature of the spacer. The obtained results indicate that the synthesized compounds are effective microbicides with a broad spectrum of biocidal activity.

The Process of Binding and Releasing of Genetic Material from Lipoplexes Based on Trimeric Surfactants and Phospholipids

Nonviral vectors for gene therapy such as lipoplexes are characterized by low toxicity, high biocompatibility, and good transfection efficiency. Specifically, lipoplexes based on polymeric surfactants and phospholipids have great potential as gene carriers due to the increased ability to bind genetic material (multiplied positive electric charge) while lowering undesirable effects (the presence of lipids makes the system more like natural membranes). This study aimed to test the ability to bind and release genetic material by lipoplexes based on trimeric surfactants and lipid formulations of different compositions and to characterize formed complexes by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). The cytotoxicity of studied lipoplexes was tested on HeLa cells by the MTT cell viability assay and the dye exclusion test (trypan blue). The presence of lipids in the system lowered the surfactant concentration required for complexation (higher efficiency) and reduced the cytotoxicity of lipoplexes. Surfactant/lipids/DNA complexes were more stable than surfactant/DNA complexes. Surfactant molecules induced the genetic material condensation, but the presence of lipids significantly intensified this process. Systems based on trimeric surfactants and lipid formulations, particularly TRI_N and TRI_IMI systems, could be used as delivery carrier, and have proven to be highly effective, nontoxic, and universal for DNA of various lengths.

Soybean-Oil-Based CO2-Switchable Surfactants with Multiple Heads

Oligomeric surfactants display the novel properties of low surface activity, low critical micellar concentration and enhanced viscosity, but no CO2 switchable oligomeric surfactants have been developed so far. The introduction of CO2 can convert tertiary amine reversibly to quaternary ammonium salt, which causes switchable surface activity. In this study, epoxidized soybean oil was selected as a raw material to synthesize a CO2-responsive oligomeric surfactant. After addition and removal of CO2, the conductivity analyzing proves that the oligomeric surfactant had a good response to CO2 stimulation. The viscosity of the oligomeric surfactant solution increased obviously after sparging CO2, but returned to its initial low viscosity in the absence of CO2. This work is expected to open a new window for the study of bio-based CO2-stimulated oligomeric surfactants.

Biological activity of quaternary ammonium salts and resistance of microorganisms to these compounds

Quaternary ammonium salts (QASs) are ubiquitous in nature, being found in organisms ranging from microorganisms to vertebrates (e.g., glycine betaine, carnitine) where they have important cellular functions. QASs are also obtained by chemical synthesis. These compounds, due to their diverse chemical structure (e.g. monomeric QAS or gemini) and their biological properties, are widely used in medicine (as disinfectants, drugs, and DNA carriers), industry, environmental protection and agriculture (as preservatives, biocides, herbicides and fungicides). Discussed chemical compounds reduce the adhesion of microorganisms to various biotic and abiotic surfaces and cause the eradication of biofilms produced by pathogenic microorganisms. The properties of these chemicals depend on their chemical structure (length of the alkyl chain, linker and counterion), which has a direct impact on the physicochemical and biological activity of these compounds. QASs by incorporation into the membranes, inhibit the activity of proteins (H⁺-ATPase) and disrupt the transport of substances to the cell. Moreover, in the presence of QASs, changes in lipid composition (qualitative and quantitative) of plasma membrane are observed. The widespread use of disinfectants in commercial products can induce resistance in microorganisms to these surfactants and even to antibiotics. In this article we discuss the biological activity of QASs as cationic surfactants against microorganisms and their resistance to these compounds.

Gemini Surfactant as a Template Agent for the Synthesis of More Eco-Friendly Silica Nanocapsules

Silica mesoporous nanocapsules are a class of “smart” engineered nanomaterials (ENMs) applied in several fields. Recent studies have highlighted that they can exert deleterious effects into marine organisms, attributed to the use of the toxic cationic surfactant N-hexadecyl-N,N,N-trimethylammonium bromide (CTAB) during the synthesis of ENMs. The present study reports the successful synthesis and characterization of novel gemini surfactant-based silica nanocapsules. The gemini surfactant 1,4-bis-[N-(1-dodecyl)-N,N-dimethylammoniummethyl]benzene dibromide (QSB2-12) was chosen as a more environmentally-friendly replacement of CTAB. Nanocapsules were characterized by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), dynamic light scattering (DLS), thermogravimetric analysis (TGA) and N2 adsorption-desorption isotherms. Short-term exposure effects of new ENMs were evaluated in four marine species (Nannochloropsis gaditana, Tetraselmis chuii and Phaeodactylum tricornutum) and the microcrustacean (Artemia salina). The replacement of the commercial cationic surfactant by the gemini surfactant does not change the structure nor the environmental behaviour in seawater of the newly synthesised silica nanocontainers. Additionally, it is demonstrated that using gemini surfactants can reduce the toxicity of novel silica nanocapsules towards the tested marine species. As a result, environmentally-friendly ENMs can be obtained based on a safe-by-design approach, thereby fitting the concept of Green Chemistry.

Synthesis, Characterization, and Computational Chemical Study of Aliphatic Tricationic Surfactants as Corrosion Inhibitors for Metallic Equipment in Oil Fields

Aliphatic tricationic surfactants were prepared by the esterification reaction, followed by a quaternization reaction to protect oil well facilities from corrosion problems. Microelemental analysis and Fourier transform infrared and ¹H NMR spectroscopic techniques were performed to explore the obtained motifs. The performance of these amphiphiles as inhibitors for metallic S90 steel corrosion in formation water was investigated through electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy). The results revealed significant inhibition effectiveness improvement with increasing concentrations of these amphiphiles. Its maximum inhibition efficiency reaches 93.07% at 250 ppm for the compound (AED). Potentiodynamic polarization graphs demonstrated that tricationic amphiphiles behave as mixed-type inhibitors. In addition, the adsorption of the tricationic surfactant at the S90 steel surface followed Langmuir isotherm. Atomic force microscopy revealed that a protective layer formed at the surface of S90 steel caused the inhibition of corrosion. During the inhibition procedure of S90 steel corrosion, theoretical research has been performed to validate electrochemical experiments and to clearly demonstrate the mechanism of these amphiphiles. Finally, quantum chemical calculations were calculated to achieve the justification for the obtained empirical results.

Environmental behaviour and ecotoxicity of cationic surfactants towards marine organisms

Cationic surfactants are surface-active compounds that can be found in many products, including household and cleaning agents. As a consequence, they tend to be discarded into water streams, ultimately ending up in the aquatic environment. In spite of this environmental issue, studies describing their effects towards marine species are lacking. The aim of this study was therefore to evaluate the short-term exposure effects of two commercial cationic surfactants and three novel gemini surfactants on four marine species, the green microalgae Nannochloropsis gaditana and Tetraselmis chuii, the diatom Phaeodactylum tricornutum, and the crustacean Artemia salina. Furthermore, biodegradation and size distribution of the cationic surfactants in artificial seawater were also studied by UV-vis spectrophotometry and dynamic light scattering, respectively. Ecotoxicity tests revealed that the commercial cationic surfactant N-cetyl-N,N,N-trimethylammonium bromide is toxic to all tested marine species while N-dodecyl-N,N,N-trimethylammonium chloride and 1,4-bis-[N-(1-dodecyl)-N,N-dimethylammoniummethyl]benzene dibromide showed the lowest toxicity among the tested cationic surfactants. Besides the novel insights regarding the effects caused by these five cationic surfactants, this work opens prospects for the replacement of commercially available surfactants by more environmentally friendly alternatives.

Cationic Surfactants: Self-Assembly, Structure-Activity Correlation and Their Biological Applications

The development of biotechnological protocols based on cationic surfactants is a modern trend focusing on the fabrication of antimicrobial and bioimaging agents, supramolecular catalysts, stabilizers of nanoparticles, and especially drug and gene nanocarriers. The main emphasis given to the design of novel ecologically friendly and biocompatible cationic surfactants makes it possible to avoid the drawbacks of nanoformulations preventing their entry to clinical trials. To solve the problem of toxicity various ways are proposed, including the use of mixed composition with nontoxic nonionic surfactants and/or hydrotropic agents, design of amphiphilic compounds bearing natural or cleavable fragments. Essential advantages of cationic surfactants are the structural diversity of their head groups allowing of chemical modification and introduction of desirable moiety to answer the green chemistry criteria. The latter can be exemplified by the design of novel families of ecological friendly cleavable surfactants, with improved biodegradability, amphiphiles with natural fragments, and geminis with low aggregation threshold. Importantly, the development of amphiphilic nanocarriers for drug delivery allows understanding the correlation between the chemical structure of surfactants, their aggregation behavior, and their functional activity. This review focuses on several aspects related to the synthesis of innovative cationic surfactants and their broad biological applications including antimicrobial activity, solubilization of hydrophobic drugs, complexation with DNA, and catalytic effect toward important biochemical reaction.