Behavior of papain in mixed micelles of anionic-cationic surfactants having similar tails and dissimilar head groups

Perfluorooctanoic acid (PFOA) removal by flotation with cationic surfactants

Perfluorooctanoic acid (PFOA) was separated and recovered using a foam flotation process aided by cationic surfactants. The PFOA removal efficiency was in the following decreasing order: OTAB (C₈TAB) > DTAB (C₁₀TAB) > CTAB (C₁₆TAB) > TBAB, which indicates that cationic surfactants with an alkyl chain that had a similar length to that of PFOA had higher affinities to PFOA. PFOA removal slightly decreased with increasing ionic strength of the surfactant but did not change with the pH. PFOA could be completely removed in 20 min with 1.25 mM of OTAB in actual wastewater. The energy yield value of foam flotation with a cationic surfactant was much higher than those of other methods, which means that using foam flotation with a cationic surfactant as the collector is a simple, fast, and energy-efficient method to separate and recover PFOA from dilute water solutions.

Determination of iron(III) by room temperature ionic liquids/surfactant sensitized fluorescence quenching method

A new method for the determination of iron (III) has been described. The analytical procedure was based on the fluorescence quenching of salicylfluorone (SAF) by iron (III) and the fluorescence quenching value (ΔF) could be increased in the medium of room temperature ionic liquids (RTILs) (1-ethyl-3-methylimidazolium ethyl sulfate)/SDS (sodium dodecyl sulfate). The main factors influencing the fluorescence quenching (ΔF) were investigated in detail. Under the optimal conditions, the linear equation was [Formula: see text](c:μg·mL(-1), r = 0.9936). The linear range of calibration curve was 0.2-1.1 μg·mL(-1) and the detection limit was 8.3 ng·mL(-1). The preliminary sensitized mechanism was discussed with distribution coefficient and fluorescence quantum yield in different media. The method has been applied to the determination of Fe (III) in water samples with satisfactory results.