Cationic Surfactant Adsolubilization of 2-Naphthol and Naphthalene with Titanium Dioxide Having Dodecyl Chain

Naphthalimide-Based Fluorescent Probe for Profiling of Aldehydes during Oxidation of Unsaturated Lipids

A lipophilic naphthalimide hydrazine fluorescent probe was successfully developed in this study for profiling aldehyde oxidation products. Dodecyl amine was applied to afford lipophilicity of the fluorescent probe for lipids. Investigation of fluorescence properties of the probe and condensation products with typical aldehydes including MDA and hexanal revealed significant enhancement of fluorescence intensity after condensation due to the inhibition of photo-induced electron transfer. MDA and hexanal could be differentiated by the probe through emission of different fluorescence colors (blue, MDA; green, hexanal). Eight major oxidation components including seven aldehydes were detected by the fluorescent probe coupled with high-performance liquid chromatography-mass spectrometry during aerobic oxidation of typical unsaturated lipids. Formation of these aldehyde oxidation products was rationalized through the radical oxidation mechanism. Detection of representative aldehyde products demonstrated the generality in the application of this fluorescent probe for profiling of aldehydes after lipid oxidation.

Organic polyaromatic hydrocarbons as sensitizing model dyes for semiconductor nanoparticles

The study of interfacial charge-transfer processes (sensitization) of a dye bound to large-bandgap nanostructured metal oxide semiconductors, including TiO(2), ZnO, and SnO(2), is continuing to attract interest in various areas of renewable energy, especially for the development of dye-sensitized solar cells (DSSCs). The scope of this Review is to describe how selected model sensitizers prepared from organic polyaromatic hydrocarbons have been used over the past 15 years to elucidate, through a variety of techniques, fundamental aspects of heterogeneous charge transfer at the surface of a semiconductor. This Review does not focus on the most recent or efficient dyes, but rather on how model dyes prepared from aromatic hydrocarbons have been used, over time, in key fundamental studies of heterogeneous charge transfer. In particular, we describe model chromophores prepared from anthracene, pyrene, perylene, and azulene. As the level of complexity of the model dye-bridge-anchor group compounds has increased, the understanding of some aspects of very complex charge transfer events has improved. The knowledge acquired from the study of the described model dyes is of importance not only for DSSC development but also to other fields of science for which electronic processes at the molecule/semiconductor interface are relevant.

Partitioning of hydrophobic organic chemicals (HOC) into anionic and cationic surfactant-modified sorbents

Surfactant-modified sorbents have been proposed for the removal of organic compounds from aqueous solution. In the present study, one cationic (HDTMA) and three anionic (DOWFAX-8390, STEOL-CS330, and Aerosol-OT) surfactants were tested for their sorptive behavior onto different sorbents (alumina, zeolite, and Canadian River Alluvium). These surfactant-modified materials were then used to sorb a range of hydrophobic organic chemicals (HOCs) of varying properties (benzene, toluene, ethylbenzene, 1,2-dichlorobenzene, naphthalene, and phenanthrene), and their sorption capacity and affinity (organic-carbon-normalized sorption coefficient, K(oc)) were quantified. The HDTMA-zeolite system proved to be the most stable surfactant-modified sorbent studied because of the limited surfactant desorption. Both anionic and cationic surfactants resulted in modified sorbents with higher sorption capacity and affinity than the unmodified Canadian River Alluvium containing only natural organic matter. The affinities of the surfactant-modified sorbents (K(oc)) for most HOCs are lower than octanol/water partition coefficient (K(ow)) normalized to the organic carbon content (f(oc)) and the density of octanol (K(oc) octanol); naphthalene and phenanthrene are the exceptions to this rule.

Use of the BET adsorption isotherm equation to examine styrene adsolubilization by nonionic surfactants at the water–silica interface

A modified BET adsorption isotherm equation was used to explain adsolubilization at the water-silica interface, producing a method for understanding adsolubilization that is independent of admicelle structure. The two constants k1 and k2 provide a measure of the surfactant-solute and solute-solute interactions, respectively. As predicted, k1 changed with various factors including surfactant structure, the presence and quantity of added lipophilic linker and hexane. On the other hand, k2 was fairly constant for all examined systems having the same solute. Commonly used partition coefficients can be easily related to the model and adsolubilization isotherms may be reproduced by the developed equation. Inferences about solute distribution at the interface and its location within the admicelle may be extracted from the results. The model is useful in explaining trends in adsolubilization and in predicting adsolubilization behavior for similar systems.

Interactions between Surfactants and Particles: Dispersion, Surface Modification, and Adsolubilization

Interactions of surfactants and polymers at solid-liquid interfaces can be correlated with many interfacial processes. In this study, we discuss dispersion of particles, surface modification of particles, and adsolubilization using various surfactants and particles. Copyright 2001 Academic Press.