The Influence of Fluoride, Temperature, Calcium, and Alcohol on the Reaction of Cobalt With Montmorillonite

Abstract

Pretreatment of montmorillonite with F interferes with the adsorption of Co by montmorillonite. Since the effect is reversible with base, the F is thought to replace surface hydroxyl groups that serve as the adsorption sites for Co. The Co reaction with these sites increases with temperature, indicating that the reaction is endothermic. Therefore, either heat is required to form the Co‐to‐surface bond or the cation is replacing more strongly bound surface hydrogens such as those associated with the hydroxyls mentioned above. While certain other heavy metal cations were previously shown to exchange with adsorbed Co, Ca is found to have no effect on the reaction, except to alter the activity coefficient of Co in solution. This is interpreted as indicating the absence of any charge associated with the bonding site. Alcohol is found to enhance the reaction of Co with montmorillonite in contrast to what would be expected if hydrolysis played a role in the reaction.

Synthesis and characterization of an analogue of heulandite: Sorption applications for thorium(IV), europium(III), samarium(II) and iron(III) recovery from aqueous waste

“…In addition changing the temperature will change the equilibrium capacity of the sorbent for particular sorbate [80]. This could also be due to acceleration of some originally slow sorption steps or due to thermal agitation of the system, processes such as association of ions, aggregation of molecules, ion pairing and complex formation are discouraged in the system [81][82][83]. According to Barrow, temperature also affect the rate of approach to equilibrium and position or state of equilibrium [84].…”

Diel behavior of rare earth elements in a mountain stream with acidic to neutral pH

“…Although the pH dependence of sorption processes is well known (e.g., Dzombak and Morel, 1990), it is less widely recognized that sorption reactions also are sensitive to changes in temperature, despite numerous experimental studies that have quantified this effect (Hodgson et al, 1964;Foda et al, 1982;Johnson, 1990;Machesky, 1990;Barrow, 1992;Rodda et al, 1996;Angove et al, 1998;Axe, 2000, 2001;Scheckel and Sparks, 2001). In the case of Fisher Creek, the diel pH change at any one location was very small (only 0.06 log units at F3), whereas the diel temperature change was large (11.7°C at F3).…”

Studies on manganese-nodule leached residues

“…10 as a function of temperature. The percentage of adsorption of nickel onto WMNLR increases slightly with increased temperature from 30 to 50 • C, which may be explained as follows: (1) if the sorption of metal ions is endothermic, which is the case for many divalent metal cations [20,21], then adsorption is favored at higher temperatures; (2) at a given pH the surface charge of MnO 2 /goethite is decreased and the extent of hydrolysis of the metal cation is increased [22][23][24]. Both these factors will reduce the electrostatic repulsion between the surface and the adsorbing species, leading to higher adsorption.…”