A New Analytic Integration of the Rate Equation for Batch Dissolution of Salts in the Presence of Common Ion

Truesdale, Victor W.; Sebu, Cristiana

doi:10.1007/s10498-012-9177-0

Cited by 7 publications

(9 citation statements)

References 55 publications

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“…The programme is not rooted in one substance or its family, but seeks to describe dissolution as a universal physico-chemical process. Accordingly, biogenic silica (Kamatani et al 1980;Greenwood et al 2001Greenwood et al , 2005Truesdale et al 2005a, b), some simple salts (Truesdale 2007(Truesdale , 2008, sucrose (Truesdale 2009), silica gel (Truesdale 2010), and gypsum (Truesdale 2011a(Truesdale , b, c, 2012Truesdale and Sebu 2013) have been selected deliberately to challenge the model. Silica gel and gypsum comply with the model and hence operationally defines ideal dissolvers.…”

Section: Equation For Calcite Dissolutionmentioning

confidence: 99%

Evidence and Potential Implications of Exponential Tails to Concentration Versus Time Plots for the Batch Dissolution of Calcite

Truesdale

2015

Aquat Geochem

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Calcite batch dissolution kinetics behaviour has been described as complex for more than half a century. The dissolution of 100-to 250-lm particles of natural calcites at 20-35°C in Tris buffer or alkali at pHs 8-10.6 reveals that the non-ideal, long tails to the plot of calcium concentration versus time, are probably exponential. Equivalent alternative evidence from elsewhere for both calcite and gypsum is supplied. Inadequate kinetics templating of earlier results is believed to have obscured this exponential character, but rectification could induce a renaissance for batch dissolution study of calcite as well as for silicate and aluminosilicate minerals, too. The work extends a programme of study of the shrinking object (SO) model which has already considered a variety of substances such as sucrose, sodium chloride, gypsum, and silica gel, through which it has operationally defined ideal dissolution as an exponential rise in concentration with time, at high solids loadings. The SO model is limited to a constant surface area of the solid during dissolution. However, the possibility of explaining non-ideal dissolution of calcite by including a reduction in the apparent surface area during a dissolution, is explored here. In this the model shifts from an initial mode under one reaction rate constant to a terminal mode under a second rate constant, and by this the SO model is shown to share properties with a decelerating bolas-the South American hunting tool. The bolas model is consistent with earlier suggestions elsewhere that non-ideality arises from the surface being either poisoned or otherwise changed during dissolution. This current investigation derives from Empirical Kinetics, which is defined here as the wisdom of kinetics collected by the middle of the last half of the twentieth century. With the preliminary success gained with the exponential tails, the paper overcomes much confusion in the literature by differentiating direct measurements of rates of dissolution made for the purposes of chemical kinetics, from those needed for biogeochemical field purposes.

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Section: Equation For Calcite Dissolutionmentioning

confidence: 99%

Evidence and Potential Implications of Exponential Tails to Concentration Versus Time Plots for the Batch Dissolution of Calcite

Truesdale

2015

Aquat Geochem

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“…Morse and Arvidson 2002;Morse et al 2007). Turner's (2015) reservation that orders for m and n of and 1, respectively, would be problematic mechanistically was already appreciated in this laboratory (Truesdale 2012;Truesdale and Sebu 2013).…”

Section: On the Use Of X And C/c Sat In Rate Equationsmentioning

confidence: 87%

“…The hyperbolae also offer the possibility of reducing the dissolution properties of an entire substance to an array of hyperbolic constants (Truesdale 2009(Truesdale , 2010. The Shrinking-Object model was also validated in experiments where the reaction rate was kept pseudo-zero order in respect of surface area, when the amount of material stripped from the solid was \1 % of the mass present (Truesdale 2012;Truesdale and Sebu 2013;Truesdale 2015).…”

Section: Surface Areamentioning

confidence: 99%

“…Therefore, as the Shrinking-Object model was applied to salts (Truesdale 2007(Truesdale , 2008(Truesdale , 2011a(Truesdale , b, c, 2012 it was unclear firstly, whether this dependency should still apply to the total moles of salt added and, secondly, what power should be applied when the concentrations of the individual ions were used. The second point was crucial to the incorporation of the Common ion effect into the ShrinkingObject model (Truesdale and Sebu 2013). Because a rate equation is primarily a statement of the redistribution of molar amounts during a reaction, the Shrinking-Object equation for gypsum dissolution, with its stoichiometry of 1:1:1, was written in three parallel ways, for .…”

Section: On the Use Of X And C/c Sat In Rate Equationsmentioning

confidence: 99%

“…in Truesdale and Sebu (2013). Turner (2015) objected to the strong linear relationship between the initial dissolution rate and c sat reported by Truesdale (2015), claiming that it is inconsistent with the basic principle of the initial rate approach and that the forward reaction can be studied without interference from later parts of the reaction, that is, the back-reaction.…”

Section: On the Use Of X And C/c Sat In Rate Equationsmentioning

confidence: 99%

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