Direct ethoxylation of a longer-chain aliphatic ester

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 (γ_CMC) and critical micelle concentrations were determined. Results are compared to C_12-14 alcohol ethoxylates (LaE _n ). Accordingly, it was found that the studied 2-ethylhexyl alcohol based compounds are effective, low foaming nonionic surfactants.

Comparison of Composition and Properties of Ethoxylated Dodecanoic acid obtained in the Presence of Various Catalysts

Oxyethylation of dodecanoic acid was performed in the presence of a conventional alkaline catalyst, a homogeneous alkaline earth metal catalyst and a heterogeneous rare earth metal catalyst, respectively. As the result, three series of products were obtained in a range of average polyaddition degrees from N = 3 up to N = 9. The content of the obtained products was determined analytically by different chromatographic techniques: Size Exclusion Chromatography (SEC) with dual detection, gradient Liquid Adsorption Chromatography (LAC) with evaporative light scattering detection (ELSD), and Liquid Exclusion Adsorption Chromatography (LEAC), a new technique, which allows quantitatively accurate determination of the oligomer distribution of ethoxylates.

It was found that the applied catalysts significantly influenced the obtained homologue distributions and the content of di-esters and polyethylene glycols as byproducts. Much more selective ethoxylation is observed in the presence of the multivalent metal catalysts. As the result, the equivalent product series exhibit significant differences of physicochemical properties and surface activity. The new capabilities in analytical determination of the complex mixture of ethoxylated acids and the detected substantial differences in their chemical content can give a new input for more detailed investigation of these products.

Partitioning behavior of petrodiesel/biodiesel blends in water

The partitioning behavior of six petrodiesel/soybean-biodiesel blends (B0, B20, B40, B60, B80, and B100, where B100 is 100% unblended biodiesel) in water was investigated at various oil loads by the 10-fold dilution method. Five fatty acid methyl esters (FAMEs), C10-C20 n-alkanes, and four monoaromatic compounds were targeted for analysis. Only the aromatic compounds were partitioned according to Raoult's law at all oil loads. The partitioning of the FAMEs and n-alkanes at higher oil loads was found to be orders of magnitude higher than the reported aqueous solubilities of these compounds, and directly correlated with the amount of oil load applied. Depth filtration of the water-accommodated fractions (WAFs) significantly reduced the observed concentrations of the FAMEs and n-alkanes, but did not appreciably affect the aromatic compounds. The FAMEs and n-alkanes concentrations in the filtered WAFs agreed with the aqueous solubilities of those compounds reported in the literature, but the n-alkanes showed progressive deviations from those solubilities with the increase in the amount of biodiesel in the blends. Further dilution experiments on pure n-hexadecane confirmed the presence of a metastable colloidal phase that seems to be controlled by hydrophobic interactions and surface phenomena. The addition of biodiesel to the oil blend appeared to have a positive impact on the dissolved concentrations and the colloidal accommodation of the n-alkanes. Autoxidation of the biodiesel constituents was found to be significant, and increased with increasing oil loads. Chemical products such as hexanal, n-butyl acetate, diethylene glycol monobutyl ether, and diethylene glycol monobutyl ether acetate were positively identified among the FAMEs' autoxidation byproducts. Our data suggest a positive enhancement for biodiesel on the formation of the oil in water colloidal phase, possibly by forming a surfactant-cosurfactant-like pair of the FAMEs and their autoxidation byproducts.

Separation of phenols from aqueous micellar solutions by cloud point extraction

The cloud point technique was used to recover phenol, 4-methylphenol, and 4-nitrophenol from aqueous solutions using oxyethylated methyl dodecanoates as nonionic surfactants. Oxyethylated methyl dodecanoates are convenient nonionic surfactants for such separations. Their cloud points can be easily modified by a change in surfactant hydrophilicity or by the addition of a second nonionic surfactant and/or an electrolyte. The use of the hydrophile lipophile balance is preferred to model the cloud point of oxyethylated methyl dodecanoates and their mixtures with other surfactants. The composition of the surfactant-rich phase depends on electrolyte type and the overheating. The phase can contain only 5-15% of water. Recovery of phenols changes in the order 4-nitrophenol >4-methylphenol > phenol and is increased in the presence of sodium chloride. The presence of salting-out electrolytes is preferred both to decrease the cloud point and to increase the efficiency of extraction.