Kinetic study of adsorption of some biocompounds at the oil/water interface

Abstract

The adsorption kinetics of some local anesthetics, like dibucaine and tetracaine, and of stearic acid from bulk solutions at the oil/water interface was studied by using the pendent drop and ring methods. The anesthetics were dissolved in aqueous solutions (pH 2), and the fatty acid was dissolved in benzene, each biocompound at several different concentrations in bulk solutions. Kinetic equations for Langmuir mechanism of adsorption at oil/water interface were tested. The kinetic analysis shows that Langmuir kinetic approach describes the dynamic interfacial pressures within the limits of the experimental errors over a wide range of time and for different surfactant concentrations in bulk solutions. It is also concluded that this approach allows the calculation of the ratio of the adsorption and desorption rate constants of these biocompounds at the oil/water interface. Obtained results are in substantial agreement with earlier reported data for the surfactant adsorption as well as with their molecular structure.

Behavior of Doped Hydroxyapatites During the Heat Treatment

“…Atomic force microscopy (AFM) images were obtained using the AFM JEOL 4210 equipment, operated in tapping mode [25][26][27][28], using standard cantilevers with silicon nitride tips (resonant frequency in the range of 200-300 kHz, and spring constant 17.5 N/m). The particles were adsorbed from their aqueous dispersion for 20 s on optically polished glass support.…”

A kinetic description of how interfaces accelerate reactions in micro-compartments

“…It is assumed that the amine and aldehyde react in the surface compartment only aer they adsorb; consistent with a Langmuir-Hinshelwood mechanism. Adsorption/desorption rate constants (k ads and k des ) for the aldehyde and amine synthesized by Fallah-Araghi et al 1 are not available, so rate coefficients are used that are consistent with, though not identical to, those reported by Tomoaia et al 45 for structurally similar molecules adsorbing to the benzene/water interface. For the three molecules in that study, 45 dibucaine, tetracaine, and stearic acid, k ads is measured to be 0.1204, 0.0831 and 0.0035 M À1 s À1 , respectively.…”

In vitro Response of Human Osteoblasts Cultured on Strontium Substituted Hydroxyapatites

“…These substrates showed good stability in cell culture, since a significant lost of scaffold material was not observed by dissolution in cellular medium during three weeks of experiments. The surface morphology of these substrates was examined by SEM and AFM [31][32][33][34][35][36][37][38]. Then, after the traditional sterilization in ethylene oxide [6,8] these substrates were investigated in cell culture for at least 21 days (21d).…”