Surface-Active Ionic Liquids and Surface-Active Quaternary Ammonium Salts from Synthesis, Characterization to Antimicrobial Properties.

The present work provides new evidence of the ongoing potential of surface-active ionic liquids (SAILs) and surface-active quaternary ammonium salts (surface-active QASs). To achieve this, a series of compounds were synthesized with a yield of ≥85%, and their thermal analyses were studied. Additionally, antimicrobial activity against both human pathogenic and soil microorganisms was investigated. Subsequently, their surface properties were explored with the aim of utilizing SAILs and surface-active QASs as alternatives to commercial amphiphilic compounds. Finally, we analyzed the wettability of the leaves' surface of plants occurring in agricultural fields at different temperatures (from 5 to 25 °C) and the model plant membrane of leaves. Our results show that the synthesized compounds exhibit higher activity than their commercial analogues such as, i.e., didecyldimethylammonium chloride (DDAC) and dodecyltrimethylammonium bromide (C12TAB), for which the CMC values are 2 mM and 15 mM. The effectiveness of the antimicrobial properties of synthesized compounds relies on their hydrophobic nature accompanied by a cut-off effect. Moreover, the best wettability of the leaves' surface was observed at 25 °C. Our research has yielded valuable insights into the potential effectiveness of SAILs and surface-active QASs as versatile compounds, offering a promising alternative to established antimicrobials and crop protection agents, all the while preserving substantial surface activity.

Quaternary ammonium salts based on caprylic acid as antimicrobial and surface-active agents.

In this work, amidequats and esterquats based on caprylic acid were investigated as promising compounds with surface properties and biological activity that are in harmony with the principles of green chemistry. Herein, caprylic acid, which is an essential component of the above compounds, is a noteworthy natural resource. Structural analysis was performed with the amphiphilic cations of the tested amidequats and esterquats, revealing two distinct factors, i.e., the elongation of the alkyl chain and the presence of two different functional groups; these factors undoubtedly affect the desired biological activity. These compounds were synthesized and characterized in terms of their physicochemical properties, among which surface activity is pivotal. In addition, the surfaces of the tested compounds were investigated through a detailed topographical analysis. The obtained results suggested that the esterquats exhibited higher surface activity, wettability and foamability than the amidequats. Antimicrobial studies, on the other hand, are not as conclusive. For shorter chains, esterquats are more active than amidequats, while for longer chains (over C12), the trend was the opposite. The amidequats and esterquats presented in this research may be a potential good replacement for antimicrobial formulations or as alternatives to surface-active agents used in industry.

Synthesis and Surface Properties of Piperidinium-Based Herbicidal Ionic Liquids as a Potential Tool for Weed Control.

A series of piperidinium-based herbicidal ionic liquids (HILs) were synthesized and investigated. The designed HILs, obtained with high yields, consisted of cation 1-alkyl-1-methylpiperidinium with surface activity and a commercially available herbicidal anion: (3,6-dichloro-2-methoxy)benzoates (dicamba). The above-mentioned compounds were characterized in terms of surface activity and phytotoxicity. Preliminary results were obtained at higher wettability for all HILs when compared to the wettability of commercial Dicash, with HIL having 18 atoms in the carbon chain being the best effectiveness in wetting surfaces (weeds and crop leaves), whereby a drop of HILs with short alkyl chains (C8-C10) could not slide down a leaf. Our findings present that wettability or mobility of HILs drops varied depending on the plant species. Moreover, in this study, by zeta potential and atomic force microscopy measurements, we provide conclusive evidence to demonstrate that alkyl chain elongation plays a significant role in the evolution of surface properties of HILs.

Spent Coffee as a Composite Filler for Wastewater Treatment.

Currently composites play an important role in all aspects of engineering and technology, with constantly growing applications. Recently, more attention was focused on natural fillers due to their suitability as reinforcement materials in thermo-plastic matrices which improve the mechanical properties of these polymers. Biofillers are used due to their low cost, high strength rigidity, non-toxicity, biodegradability, and availability. Currently, spent coffee grounds (SCG) are attracting more attention as a natural filler since high amounts of SCG are generated every day (food waste of coffee processing). This study allowed us to determine the long-term effect of activated sludge microorganisms with known technical and technological parameters on the mechanical properties of composites with spent coffee grounds filler. The fittings consisted of high-density poly-ethylene (PE-HD), which was used as the matrix, and a filler based on spent coffee grounds (SCG), which was used as a modifier. It was established that the composition of the composite and its residence time in the bioreactor directly influenced the contact angle value. The shift of the contact angle value is associated with the formation of the biofilm on the tested materials. An increase in the contact angle was observed in the case of all samples tested in the bioreactor, with the lowest values equal to approx. 76.4° for sample A (PE-HD) and higher values of approx. 90° for the remaining composite samples with a coffee grounds filler. The research confirmed that the increased ratio of coffee grounds in the composite results in the increased diversity and abundance of microorganisms. The highest number and the greatest diversity of microorganisms were observed in the case of the composite with 40% coffee grounds after more than a year of exposure in the bioreactor, while the composite with 30% SCG was second. Ciliates (Ciliata), especially the sessile forms belonging to the Epistylis genus, were the most common and the most numerous group of microorganisms in the activated sludge and in the biofilm observed on the samples after immersion in the bioreactor. The conducted research confirms that the use of polymer composite mouldings with a filler in the form of spent coffee grounds as a carrier allows the efficient increase in the population of microorganisms in the bioreactor.

Effect of 1-alkyl-1-methylpiperidinium bromides on lipids of fungal plasma membrane and lung surfactant.

This study aimed to investigate the potential of 1-alkyl-1-methylpiperidinium bromides as fungicides and evaluate their impact on the human respiratory system when spread in the atmosphere. We investigated the behavior of membrane lipids and model membranes in the presence of a series of amphiphilic 1-alkyl-1-methylpiperidinium bromides ([MePipCn][Br]), differing in the alkyl chain length (n = 4 - 18). The experiments were performed with the Langmuir monolayer technique using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and ergosterol (ERG)-the main components of lung surfactant and fungal plasma membrane, respectively and their mixtures with phospholipids and sterols. The mixtures were chosen as the representatives of target and non-target organisms. The surface pressure-area isotherms were obtained by compressing monolayers in the presence of [MePipCn][Br] in the subphase. The results were analyzed in terms of area expansion/contraction and compressibility. The surface activity of the studied organic salts was also studied. In addition, the monolayers were deposited on a solid surface and their topography was investigated using atomic force microscopy. This research implies that the studied compounds may destabilize efficiently the fungal plasma membrane. At the same time we demonstrated the significant impact of 1-alkyl-1-methylpiperidinium bromides on the lung surfactant layer. The interaction between [MePipCn][Br] and model membranes depends on the concentration and alkyl chain length of organic salt. The key role of contact time has been also revealed. The results may be helpful in the reasonable development of new agrochemical products aiming at the treatment of fungal infections in plants. In addition, our study indicates the significance of proper safety management while spreading the fungicides in the environment.

Antimicrobial and Cytotoxic Activity of Novel Imidazolium-Based Ionic Liquids.

In this study, a series of 10 novel 1-methyl-3-octyloxymethylimidazolium derivatives carrying various anionic moieties (4-hydroxybenzenesulfonate, benzenesulfonate, carvacroloxyacetate, chloride, formate, propionate, thymoloxyacetate, vanillinoxyacetate, eugenoloxyacetate and trimethylacetate) were synthesized. Compounds were tested for their antimicrobial activity against six microbe strains (Staph-ylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, and Candida albicans), cytotoxic activity against the mouse melanoma cell line (B16 F10), and surface active properties. All synthesized compounds exhibited antimicrobial activity (expressed as minimum inhibitory concentration; in range of 0.10-27.82 mM/L), especially against Gram-positive bacteria and fungi. In addition, all compounds demonstrated cytotoxicity on B16 F10 cells (IC50 values 0.0101-0.0197 mM/L). Surface properties defined as CMC values, ranged from 0.72 to 32.35 mmol L-1. The obtained results provide an insight into the promising activity of a novel group of quaternary imidazolium derivatives having ionic liquid properties. The most potent compounds, containing a thymoloxyacetate and eugenoloxyacetate moiety, could be candidates for new antimicrobial agents or surfactants.

Third-generation ionic liquids with N-alkylated 1,4-diazabicyclo[2.2.2]octane cations and pelargonate anions.

Ionic liquids that belong to the third-generation designs due to their intended biological activity are compounds with high potential applications as plant-protection products. The present study describes the synthesis and characterization of novel ionic liquids with cations based on the alkyl derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO) and an anion derived from naturally occurring pelargonic acid. The developed synthesis method allowed obtaining products with a high yield (≥96%), and the liquids were characterized as high-viscosity liquids at room temperature. This allowed classifying the products as ionic liquids (ILs). The structures of the obtained ILs were confirmed on the basis of their NMR and IR spectra as well as by elemental analysis. All the products exhibited surface activity and were capable of partially wetting a hydrophobic surface. The tested ionic liquids exhibited higher herbicidal activity against winter oilseed rape (Brassica napus L.) and common lambsquarters (Chenopodium album L.) at a lower dose compared to a commercial preparation in greenhouse studies. The studied ionic liquids also exhibited different effects as antifeedants on various insect species. The best results were obtained against beetles belonging to the granary weevil species (Sitophilus granarius L.). The relation between the surface-tension-reduction efficiency pC20 and biological activity was investigated. The herbicidal activity was also correlated with the value of the contact angles for the studied pelargonates. All the obtained results indicate that the designed and synthesized ionic liquids possess double biological functions: herbicidal activity and deterrent activity.

Clear distinction between CAC and CMC revealed by high-resolution NMR diffusometry for a series of bis-imidazolium gemini surfactants in aqueous solutions.

The aggregation behavior in the transition region was studied for a series of dicationic surfactants 3,3'-[α,ω-(dioxaalkane)]bis(1-dodecylimidazolium)dichlorides with varied spacer length from two to twelve carbon atoms. We employed Nuclear Magnetic Resonance diffusometry and Bayesian DOSY analysis to obtain the aggregate size distribution in the transition region. The critical concentrations CC were independently obtained from surface tension, electric conductivity, UV-Vis and NMR methods. The micelle aggregation numbers were estimated from the self-diffusion coefficients and were independently confirmed using steady-state fluorescence quenching. The morphology of the aggregates was characterized by small-angle scattering of synchrotron radiation and molecular dynamics simulations. The obtained CC values are identified as critical aggregation concentrations CAC. A broad transition region was observed, and stable micelles were obtained at much higher concentrations than CAC. The accurate CMC values could not be identified for the systems in the study. We indicated that the distribution of aggregate size becomes small and the system becomes homogeneous at much larger concentrations than CAC (typically 15-20 mM). The existence of a slow exchange between two environments, an aggregate and aqueous environment, was confirmed by 1H NMR and 2D HSQC NMR spectroscopy.

2-Ethylhexanol Derivatives as Nonionic Surfactants: Synthesis and Properties.

The synthesis and basic properties of 2-ethylhexanol based innovative nonionic surfactants are described in this paper. 2-Ethylhexanol as an available and relatively inexpensive raw material was used as the hydrophobe source modified by propoxylation and followed by polyethoxylation. As the result, six series of 2-ethylhexyl alcohol polyalkoxylates (EHP m E n ) were obtained with three steps of propoxylation, each followed by polyethoxylation and two series only with polyethoxylation (EHE n ). Two different catalysts were used, a dimetalcyanide and KOH. Values of average conversion rates and chemical content of the obtained products (GC, TG and GPC techniques) were compared. The influence of the applied catalyst and polyaddition degree on the homologue distribution, reactant conversion and amount of byproducts is discussed. The basic physicochemical parameters including refractive index, solubility in polar media, foaming properties and wettability were investigated and compared. Furthermore, surface activity parameters, i.e. surface tension (γCMC) and critical micelle concentrations were determined. Results are compared to C12-14 alcohol ethoxylates (LaE n ). Accordingly, it was found that the studied 2-ethylhexyl alcohol based compounds are effective, low foaming nonionic surfactants.

Comparative study on the biodegradability of morpholinium herbicidal ionic liquids.

This study focused on evaluating the toxicity as well as primary and ultimate biodegradability of morpholinium herbicidal ionic liquids (HILs), which incorporated MCPA, MCPP, 2,4-D or Dicamba anions. The studied HILs were also subjected to determination of surface active properties in order to assess their influence on toxicity and biodegradability. The study was carried out with microbiota isolated from different environmental niches: sediments from river channel, garden soil, drainage trench collecting agricultural runoff stream, agricultural soil and municipal waste repository. The obtained results revealed that resistance to toxicity and biodegradation efficiency of the microbiota increased in the following order: microbiota from the waste repository > microbiota from agricultural soil ≈ microbiota from an agricultural runoff stream > microbiota from garden soil > microbiota from the river sludge. It was observed that the toxicity of HILs increased with the hydrophobicity of the cation, however the influence of the anion was more notable. The highest toxicity was observed when MCPA was used as the anion (EC50 values ranging from 60 to 190 mg L(-1)). The results of ultimate biodegradation tests indicated that only HILs with 2,4-D as the anion were mineralized to some extent, with slightly higher values for HILs with the 4-decyl-4-ethylmorpholinium cation (10-31 %) compared to HILs with the 4,4-didecylmorpholinium cation (9-20 %). Overall, the cations were more susceptible (41-94 %) to primary biodegradation compared to anions (0-61 %). The obtained results suggested that the surface active properties of the studied HILs may influence their toxicity and biodegradability by bacteria in different environmental niches.

Solvothermal synthesis of hydrophobic chitin-polyhedral oligomeric silsesquioxane (POSS) nanocomposites.

Chitinous scaffolds isolated from the skeleton of marine sponge Aplysina cauliformis were used as a template for the deposition of polyhedral oligomeric silsesquioxanes (POSS). These chitin-POSS based composites with hydrophobic properties were prepared for the first time using solvothermal synthesis (pH 3, temp 80 °C), and were thoroughly characterized. The resulting material was studied using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetry. A mechanism for the chitin-POSS interaction after exposure to these solvothermal conditions is proposed and discussed.

Genetic and chemical analyzes of transformations in compost compounds during biodegradation of oiled bleaching earth with waste sludge.

Composting of oiled bleaching earth with waste sludge and corn straw was carried out to investigate the ability of microorganisms to synthesize biosurfactants that might decrease the surface tension of composts. Analytical results and changes in the surface tension suggest that biodegradation of fatty by-products was the consequence of emulsifying properties of higher fatty acids. The surface tension for isolates from all composting phases was between 37 and 43 mN m(-1). No substances synthesized by microorganisms that might be able to decrease the surface tension were detected in composts. Tensammetric, TLC and HPLC-MS results and changes in surface tension suggest that biodegradation of fatty by-products results from the emulsifying properties of higher fatty acids. A decrease in fatty content from 144 to 6 mg g(-1) dry matter was obtained.

Long-alkyl-chain quaternary ammonium lactate based ionic liquids.

A new group of quaternary ammonium lactate based ionic liquids have been prepared and characterized. Didecyldimethylammonium (DDA) and benzalkonium (BA) D,L- and L-lactates are air-stable, hydrophilic, surface-active salts. They are very effective antibacterial and antifungal agents, especially the DDA lactates, against Streptococcus mutants and Candida albicans. Their activities are comparable or more effective than the original benzalkonium chloride. In addition, they have been shown to be good insect-feeding deterrents. However, they are poor antifungal agents for wood preservation. The toxicity of the DDA and BA lactates has also been studied and the results are presented in this paper.

Cloud point extraction of direct yellow.

The cloud point separation of Direct Yellow from micellar solution of various nonionic surfactants, containing a polyoxyethylene chain, was studied. The separation of dyes is an important environmental problem. Moreover, such separation can also be considered as a preliminary step for further studies of biochemical recovery. Some dyes can be considered as affinity ligands, which form complexes with biochemicals. The use of dye enabled the observation of the dynamics of surfactant-rich phase separation by means of a color video. It was found that the separation of phases was incomplete. The aqueous phase contained some amounts of surfactant globules with the dye. The surfactant-rich phase was usually more heterogenic than the aqueous phase. The recovery of Direct Yellow was very effective in the presence of electrolyte (NaCl). The distribution coefficients were high and equal to a few hundreds in the presence of sodium chloride. Under optimum conditions 98-99.9% of the dye could be removed in the one step.

Dynamics of nonionic surfactant-rich phase separation and recovery of dyes.

Cloud point separation of selected dyes was studied. The use of dyes made possible observation of the dynamics of surfactant-rich phase separation by color video. The pictures were interpreted by means of ImageC software and degrees of whiteness were calculated. It was found that separation was slow and equilibrium was not achieved even after a period of more than 10 h. The separated surfactant-rich phase had a heterogeneous structure. The globules of the surfactant-rich phase were also observed in the micellar aqueous phase. The surfactant concentration could be as high as one or two orders of magnitude above the expected cmc values and was not decreased to critical micelle concentration by centrifugation. The presence of sodium chloride was important and improved separation. Separation of dyes was in the range 73-98% and depended upon the surfactant, the temperature, the electrolyte content, and the dye. In each system considered, appropriate conditions had to be selected to obtain high recovery of the dye. The presence of the electrolyte was the most important parameter and it improved the separation of dyes. However, addition of the electrolyte could also account for precipitation of the dyes, as observed for the systems containing Direct Pink. The best recoveries were observed for Direct Yellow and oxyethylated nonylphenol (98% at 55 degrees C in the presence of NaCl). Centrifugation gave recoveries similar to those for prolonged heating but it shortened the time of phase separation.

Cloud point of aqueous solutions containing oxyethylated methyl dodecanoates: effects of surfactant hydrophilicity, nature of added electrolyte, and water activity.

The aim of this work was to determine the cloud points of new oxyethylated methyl dodecanoates of various hydrophilicity (OMD-n, where n refers to the average degree of oxyethylation) and to correlate them with surfactant hydrophilicity and, for a given electrolyte, with water activity. Thus, it is shown that the cloud point in the absence of electrolyte (CP(0)) can be simulated by the following equation: CP(0)=165.5logn-112.0 (with R(2)=0.987). The effects of NaCl, NaHCO(3), and KSCN on the cloud point are also reported and discussed. The salting-out effect arising from the presence of NaCl or NaHCO(3) is explained by the existence of a hydration shell with enhanced water structure as well as a zone with decreased salt concentration around the -(OCH(2)CH(2))(n)- chain, as compared with the bulk. On the other hand, the salting-in effect is explained by depletion of water around the -(OCH(2)CH(2))(n)- chain. Thus, it is estimated that the number b of water molecules forced back into the bulk solution from the salt-deficient regions when the hydration shells of two -O-CH(2)-CH(2)- monomer units overlap ranges between 2 and 3 and 3 and 4 for NaCl and NaHCO(3), respectively, depending on the average degree of oxyethylation n of OMD-n. It is also shown that the water activity is a useful parameter to simulate the variation of cloud point in the presence of an electrolyte (CP) at low and moderate concentration (e.g., <1 M NaCl), CP(0)/CP approximately 1-(bR/alpha)lna(w), where R is the gas constant and alpha approximately 15 JK(-1)mol(-1). At high electrolyte concentration, the relationship between CP(0)/CP and lna(w) significantly deviates from linearity. In the particular case of KSCN, an inversion of the salt effect can be observed. The salting-in effect of KSCN increases up to about 2 M, but decreases at higher KSCN concentrations, so that KSCN can even act as a salting-out salt at high concentration (typically above 3.3 M for OMD-14).