Journal of Surfactants and Detergents最新文献

This work characterized the macroscopic thermodynamic properties of ionic micellar solutions. Formulation-composition studies were done along one dimension by varying the salinity (S) or oil–water ratio (WOR) in mixtures of sodium dodecyl sulfate, sodium sulfate, water, n-heptane, and 1-pentanol at 25°C and 1 atm. Material balance and multiple regression models were used to get the partial, mixed, and excess molar volumes. The UNIFAC local composition model, coupled with Debye–Hückel theory, was employed to calculate activity coefficients and dimensionless Gibbs energies (partial, mixed, and excess). The equilibrium SOW systems exhibited phase transitions (WI-WIII-WII), with micellar solubilization increasing as salinity increased at constant WOR. Solubilization peaked at the optimal formulation, and further increases in WOR enhanced solubilization up to the formation of a single-phase system. Deviations from ideal behavior, in the thermodynamic properties between aqueous and oil micellar solutions, were mainly due to chemical interaction of solutes ($��\gamma �\ne �1��$) respect to solvents ($��\gamma �\to �1��$). Negative values of the Gibbs energy of mixing confirmed the stability of the liquid phases and their extension to the liquid–liquid equilibrium. The response surfaces V = f(WOR, S) and G^E/RT = f(WOR, S) represent the macroscopic thermodynamic behavior of micellar solutions as a function of physicochemical formulation. These results can be extended to other colloidal systems for the design of formulations with surfactants and anionic salts, oriented to the diagnosis and resolution of problems in real systems, both at laboratory and industrial level.

This study is the first to explore the potential of distiller's corn oil (DCO) for rhamnolipid biosurfactant production. Two strains of Pseudomonas aeruginosa (ATCC9027 [higher relative mono-rhamnolipid content] and LFM1201 [higher relative di-rhamnolipid content]) were used to evaluate the best biosurfactant producer. The biosurfactants were characterized in terms of kinetic, structural parameters, tensoactive parameters, and stability at high temperatures and varied pHs. Obtained results in flasks using DCO as substrate were: ATCC9027 (P = 4.6 g L⁻¹, Y_P/S = 0.16 g g⁻¹, Q_p = 14.9 mg L⁻¹ h); LFM1201 (P = 5.9 g L⁻¹, Y_P/S = 0.20 g g⁻¹, Q_p = 13.7 mg L⁻¹ h). Surface tension, interfacial tension and critical micellar concentration were respectively: 25.9, 4.7 mN m⁻¹, 81.0 mg L⁻¹ for ATCC9027, and 28.5, 7.8 mN m⁻¹ and 121.1 mg L⁻¹ for LFM1201. The main congeners were: Rha-C₁₀C₁₀ (m/z 503.3) for ATCC9027 and RhaRha-C₁₀C₁₀ (m/z 649.4) for LFM1201. Biosurfactants showed stability at high temperature and diverse pHs. Posteriorly, the carbon: nitrogen ratio of the cultivation medium was optimized, with an optimal value of 28:1. Finally, the optimized medium was used in a bioreactor in different operating modes: simple batch, pulse-fed batch and continuous process. The best strategy for producing rhamnolipids using DCO as a carbon source was through a continuous process in a bioreactor. This method boosted rhamnolipid production, reaching 6.82 g L⁻¹ (Y_p/s = 0.35 g g⁻¹). The results showed that DCO was a new and interesting substrate for rhamnolipid biosurfactant production, with characteristics suitable for future application in the biorefinery context, forming part of the circular economy concept.

The utilization of sustainable feedstocks in surfactant production is crucial for reducing environmental impact, enhancing resource efficiency, and aligning with global efforts toward a circular economy and green chemistry. In this research, cellulose derivatives were synthesized by methylating cellulose fibers extracted from Guinea grass (Megathyrsus maximus) and their interfacial properties as surfactants were evaluated. The derivatives were characterized using Fourier-transform infrared spectroscopy (FTIR), which revealed distinct stretching vibration absorption bands indicative of methyl groups. Thermogravimetric analysis (TGA) identified a dual-stage decomposition process, consistent with reported behavior for methylcellulose. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) further confirmed the presence of methyl ether groups, with the H₅CO⁺ ion detected as the characteristic fragment of the methylated samples. Functional evaluations demonstrated that double-methylated cellulose derivatives exhibited a hydrophilic–lipophilic balance (HLB) of 12.7 and a surface tension of 55 dyne/cm when compared to mono or unmethylated fibers. Additionally, the double-methylated derivatives displayed enhanced foaming activity, emulsion stability, and water solubility. These cellulose-based surfactants exhibited interfacial properties comparable to their synthetic counterparts, emphasizing their potential for industrial applications and their role in advancing sustainable material development.

The hydrophilic–lipophilic difference (HLD) equation is being used extensively for designing oil-in-water based surfactant systems to maximize oil solubility and minimize oil–water interfacial tension. However, the equation was developed for and almost always presumes that the salt is sodium chloride. The work described in this paper extends the equation to other monovalent cations (Li, K) and divalent anions (CO₃). The equation was adjusted for molecular weight and the number of cations in the salt. For anionic surfactants, the Hofmeister series successfully qualitatively predicts that the salt concentration to reach HLD = 0 scales with Li > Na > K, that is, the surfactant with lithium requires more salt for the water to reach the hydrophobicity required. Although the exact salt concentration depends on the anionic surfactant headgroup, the difference in optimal salinity between two cations appears to not be dependent on headgroup. Also, CO₃ reduces the activity of the cation as compared to Cl. For narrow-range alcohol ethoxylates, there is little difference between Na and K; while Li requires more salt for a given increase in hydrocarbon number of carbons to reach HLD = 0. A broad-range ethoxylate gives inconsistent results, which we attribute to the finite solubility of some surfactant components in the oil.

Surfactant–oil–water (SOW) systems, particularly when packaged in metal containers, require chemical reagents with preservative and anticorrosive properties. This study aims to investigate the influence of sodium benzoate (NaBz) on fundamental interfacial properties of the surfactant lauryl ether sulfate (SLES) with two ethoxylation units (EO = 2). Using a combination of surface tension, electrical conductivity, and isothermal titration calorimetry (ITC) measurements, we evaluated SLES systems in the presence of NaCl, NaBz, and various mixtures of these salts using salinity scans, at room temperature. NaBz inhibits the formation of triphasic system in SOW formulation. The thermodynamic stability of SLES micelles followed the order: $�{�∆�G�}_{�\mathrm{mic}�,�\text{NaCl}�}^0�<�{�∆�G�}_{�\mathrm{mic}�,�\text{NaBz}�}^0�~�{�∆�G�}_{�\mathrm{mic}�,�1�:�1�}^0�<�{�∆�G�}_{�\mathrm{mic}�,�H_2�O�}^0$ with entropy being the primary driving force. The results suggest that NaBz acts as a potential interfacial structure decoupler. This novel behavior of NaBz may have important implications for its use in SOW systems, particularly in formulations requiring stability and integrity in aggregation state.

This study investigated the properties, namely: surface tension, foam, emulsion, and cloud point of a library of bio-based surfactants (represented as C_nEO_m where C is hydrophobic carbon chain and EO is ethylene oxide). The surfactants were derived from ring-opening alkyl oleate epoxides with polyethylene glycol (PEG) and monomethyl polyethylene glycol (MPEG) of varying chain lengths. Surfactants demonstrated good surface properties having surface tension at critical micelle concentration (CMC) between 35 and 38 mN/m, and recorded CMC values far lower than what was reported for most commercial ethoxylated surfactants. Foamability increased with over 30% foam increase upon increasing agitation speed from 6000 to 11,000 rpm. Branching, hydrophobic carbon chain length, and PEG chain length were seen to impact foamability and foam stability. Foam properties exhibited by the surfactants were found to be superior to those demonstrated by some known commercial nonionic surfactants. Emulsions formed by the oleate ester surfactants were stable over several weeks after formation. Surfactants showed high cloud points, which increased with increasing number of ethylene oxide units. However, the addition of co-solutes depressed the cloud point in the order Na₂SO₄ > NaCl > NaNO₂.

The laundering process is an essential routine for maintaining the cleanliness and freshness of textiles. Achieving an efficient deposition and retention of fragrances on different fabric types remains a complex challenge. This study provides a novel comparison of the impact on perfume deposition of different fabric types across wash cycle stages and wash conditions. The critical role of perfume redeposition during rinsing is examined, where micelles entrapped in the textile matrix break due to surfactant concentrations dropping below the critical micelle concentration (CMC), resulting in the release and subsequent redeposition on fabrics of perfume raw materials (PRMs) contained in the micelles. Our findings reveal that adsorption kinetics are faster on cotton compared with polyester. Cotton, due to its amphoteric nature, exhibits greater interaction with water molecules during rinsing, leading to more significant PRM loss. Conversely, polyester demonstrates a higher PRM retention capacity, which can be attributed to its hydrophobic nature. Surprisingly, however, we find that redeposition during the rinse steps of hydrophobic PRMs is more pronounced on cotton than polyester, which may be due to their respective water retention capacities and consequent effect on the micelle breaking mechanism.

Concerns about ultraviolet radiation (UV-R) are increasing due to climate change. The effects of UV-R on living organisms depend on exposure duration and intensity, making it crucial to monitor UV-R levels. In this study, we investigated the role of surfactants as photosensitizing or stabilizing agents in a colorimetric sensor based on a polymeric film doped with methyl green dye. The films were synthesized using the casting technique from a filmogenic solution containing either carboxylated polyvinyl alcohol (P1) or hydroxylated polyvinyl alcohol (P2). We evaluated the impact of surfactant structure (dodecylpyridinium chloride, C12; hexadecylpyridinium chloride, C16; or sodium dodecyl sulfate, SDS) and concentration on the colorimetric response of the films to UV-R. Color changes were monitored using the CIELab system. The results showed that, under UV-R exposure for up to 5 h, films without surfactants did not lose their blue hue (negative b* parameter in CIELab). While SDS stabilized the dye in the polymeric matrix, films containing pyridinium surfactants (C12 or C16) changed color from blue to pale yellow (positive b* parameter in CIELab). The color change, which was modulated by surfactant concentration, was attributed to radical reactions involving the pyridinium surfactants, influenced by their hydrophobicity and the polymer structure. These results represent a significant advancement in colorimetric sensors for UV-R, as they allow for the modulation of the sensor's response time through surfactant concentration in the polymeric film.

In the petroleum and petrochemical industries, oil sludge is a common contaminant that causes environmental pollution and resource wastage. Currently, recovering crude oil from oily sludge presents a significant challenge during processing. In this study, an amidinium bicarbonate-based CO₂-responsive microemulsion was developed to effectively treat sludge and recover crude oil. The microemulsion system demonstrates a strong capability for oil solubilization. After the microemulsion treatment, the residual oil contents in the sludge can be reduced to as low as 2.93% (ME-1, n-butanol as cosurfactant) and 1.44% (ME-2, n-hexanol as cosurfactant). Complete oil/water phase separation can be achieved by introducing N₂ at 65°C.

The phase behaviors of mixed systems comprising the amino acid surfactant potassium cocoyl glycinate (PCG) and soap-based surfactants, including potassium laurate (PL), potassium myristate (PM), potassium palmitate (PP), and potassium stearate (PS), were systematically investigated. The concentrations of the transition from spherical to rod-like micelles of the mixed system were determined using conductivity. The phase transition temperatures were determined using differential scanning calorimetry (DSC). The liquid crystal phases formed in the region of high surfactant concentration were initially investigated using polarized optical microscopy (POM), and the types of liquid crystal phases were further characterized using small-angle X-ray scattering (SAXS). Finally, the rheological behavior of different phase states was studied by varying the concentration and temperature. The results show that the mixed systems of PCG and soaps exhibit rich phase behavior, and the liquid crystal phases exhibit hexagonal and lamellar phase liquid crystals. The type of soap and the compounding ratio both affect phase behavior, specifically in terms of the extent of the phase region. Furthermore, the rheological properties of the sample are associated with the self-assembled structure of the surfactant. This study provides a reference for the application of the mixtures of amino acid surfactants and soaps in detergents and cosmetics.