Competition between sodium oleate and sodium silicate for a silicate/oleate modified magnetite surface studied by in situ ATR-FTIR spectroscopy

Abstract

Competition between sodium oleate and sodium silicate for a silicate/oleate modified magnetite surface studied by in situ ATR-FTIR spectroscopy Attenuated Total Reflection (ATR) IR spectroscopy was utilized to monitor adsorption of sodium oleate and sodium silicate onto synthetic magnetite at pH = 8.5, both individually and in a competitive manner.Oleate was adsorbed within a concentration range of 0.01-0.5 mM. It was observed that adsorption of oleate increased linearly with increasing concentration of oleate in solution up to a concentration of 0.1 mM. The infrared spectrum of oleate showed a broad single band at 1535 cm À1 assigned to the asymmetric stretching vibration of carboxylate, implying chemisorption of oleate to the magnetite surface. The kinetics of oleate adsorption followed a pseudo first-order reaction with an apparent rate constant of k 1 = 0.030 ± 0.002 min À1. Competitve adsorption of silicate and oleate was performed either by adding silicate solution to a magnetite film initially equilibrated with 0.1 mM oleate or adding oleate solution to magnetite treated with silicate solutions in the concentration range 0.1-5 mM. It was shown that silicate, within reasonable time, had only minor effect on the amount of oleate already adsorbed on magnetite. On the other hand, oleate did not efficiently compete with silicate if the latter substance was already adsorbed on the iron oxide.

Adsorption in Biodiesel Refining - A Review

“…The system could be modeled by a LDFM with an overall coefficient of mass transfer, K LDF =0.013-0.035 min -1 (see Table 5). These values compare well with those obtained for the adsorption of sodium oleate over magnetite, 0.002-0.03 min -1 (Roonasi et al, 2010 Table 5. Values of the LDF overall mass transfer coefficient for the silica adsorption of free fatty acids from biodiesel at different temperatures .…”

The flotation separation of scheelite from calcite using acidified sodium silicate as depressant

“…While the observance of these peaks on the scheelite indicates the presence of adsorbed sodium oleate, it does not provide any information as to the nature of the adsorption. The band at 1699 cm À1 indicates the presence of the carbonyl mode (C@O) of oleic acid, and is generally considered to indicate physically adsorbed species (Rao andForssberg, 1991a, 1991b;Roonasi et al, 2010). The new bands are also observed at 1544.2 and 1461.2 cm À1 which are the results of chemical adsorption of sodium oleate on scheelite.…”

Effect of Al (III) Ions on the Separation of Cassiterite and Clinochlore Through Reverse Flotation

“…Sodium oleate (NaOL), a fatty acid, is widely used in silicate and oxide minerals flotation. It has shown more advantages in reverse flotation such as lower cost and strong collecting capability [21][22][23][24]. However, selective problem arises between cassiterite and clinochlore with NaOL as a collector because of its low selective performance.…”