Compared solubilisation properties of bulk micelles and confined surfactant phases

Titania/CnTAB Nanoskeleton as adsorbent and photocatalyst for removal of alkylphenols dissolved in water

We report here on the removal of alkylphenols (phenol, 4-n-propylphenol, 4-n-heptylphenol and 4-nonylphenol) dissolved in water using the composite particles of nanocrystalline titania and alkyltrimethylammonium bromide (CnH2n+1N(CH3)3Br, CnTAB; n=12, 14, 16 and 18) (named as TiO2/CnTAB Nanoskeleton) as adsorbents and photocatalysts. In particular, the adsorption of alkylphenols onto TiO2/CnTAB Nanoskeleton in water was investigated in terms of hydrophobic interaction between alkylphenols and CnTAB, surface area, pore structure and crystal size of TiO2/CnTAB Nanoskeleton. We revealed that CnTAB incorporated in the TiO2/CnTAB Nanoskeleton promotes the adsorption of alkylphenols onto TiO2/CnTAB Nanoskeleton due to the hydrophobic interaction between alkylphenols and CnTAB. On the other hand, the surface area, pore structure and crystal size of TiO2/CnTAB Nanoskeleton did not affect the adsorption of alkylphenols onto TiO2/CnTAB Nanoskeleton. We also found that the alkylphenols dissolved in water were completely removed by the combination of adsorption and photocatalytic degradation by the TiO2/CnTAB Nanoskeleton under UV irradiation. These results prove that the TiO2/CnTAB Nanoskeleton acts as in tandem an adsorbent and a photocatalyst for removal of alkylphenols dissolved in water.

Sorption of 1-hydroxy-2-naphthoic acid to goethite, lepidocrocite and ferrihydrite: batch experiments and infrared study

The adsorption of naphthoic acids to iron oxides and hydroxides influences strongly their mobility in soils and sediments. Sorption of 1-hydroxy-2-naphthoic acid (HNA) to three iron oxides was examined over a wide range of conditions (pH, ionic strength, sorbate and sorbent concentrations). In the examination of HNA sorption, Tempkin model was performed to fit sorption data of HNA onto all iron oxides. The adsorption in the Henry law range increases in the order: goethite<lepidocrocite<ferrihydrite, while at high sorbate equilibrium concentration, the trend is opposite. Structure of the HNA surface complexes was examined by infrared spectroscopy at different surface coverages and pH conditions. The variation of HNA sorption with solid-to-solution ratio (SSR) in batch experiments exhibited a solid effect for tested oxides except goethite. The role of hydrophobicity in HNA sorption and an eventual formation of solute aggregation on the solid surface have been particularly highlighted on goethite. These results indicate that the mineralogy of the iron oxides and pH value should be considered when predicting HNA sorption in iron oxides and its fate in soil and environment.