Boron Adsorption by Clay Minerals Using a Phenomenological Equation

Abstract

Abstract--Boron adsorption by Ca forms of montmorillonite, illite, and kaolinite was determined as a function ofpH and boron concentration in solution. Data from batch experiments were compared with results computed for each clay according to fitted adsorption coefficients (maximum boron adsorption and affinity constants related to the binding energy). The agreement between calculated values and experimental results indicates that a phenomenological equation can be used to predict boron adsorption on clays as a function of both of these variables. For the solution-to-clay ratios examined, the water content does not affect the boron-surface interaction as expressed by the above adsorption parameters. Because the affinity of clays for B(OHL-is much stronger than for B(OH) 3 , the adsorption maximum was obtained only under alkaline conditions at approximately pH 9.0 to 9.7. It is suggested that the pH of maximum adsorption is a function of the ratios of affinity coefficients of the three species B(OH)3, B(OH)4-, and OH-competing for the same adsorption sites. The adsorption coefficients indicate that in some cases the difference in the amount of adsorbed boron between montmorillonite and kaolinite could be either small or large, depending on the circumstances. The main factor that would affect this difference is the total amount of boron in the suspension. Estimated value of the adsorption maximum was 2.94, 11.8 and 15.1/zmole/g for Ca-kaolinite, Ca-montmorillonite, and Ca-illite, respectively.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

“…It should be noted that, unlike Sr 2+ , B behaves in a more conservative way and can hardly precipitate from the solution (Grew and Anovitz, 1996;Walker, 1975). Even admitting the presence of adsorption processes such as those detected in marine environments by Couch (1971), B would have been incorporated in clays' tetrahedral sheet structures at a very low rates (Keren and Mezuman, 1981) and it cannot be re-dissolved at the Ca' Lita site temperatures. Therefore, B tot contents linked to the deep water inflows could even be larger than those measured.…”

Surface complexation model of boron adsorption by calcareous soils

“…Although adsorption of B has been studied in numerous researches using empirical equations (Keren and Mezuman 1981;Elrashidi and O'Connor 1982;Goldberg and Forster 1991;Majidi et al 2010), B surface complexation modeling of soil constituent assemblages has less been investigated (Goldberg 1999;Goldberg et al 1993Goldberg et al , 2000Goldberg et al , 2004.…”

Effect of Exchangeable Ions and Ionic Strength on Boron Adsorption by Montmorillonite and Illite

“…The distribution of boron between the solid and liquid phase of soil is particularly important in view of the relatively small range between levels causing deficiency and toxicity symptoms in plants (Philipson, 1953). Important factors influencing the adsorption and removal of boron from the soil appear to be the pH of the system (Hingston, 1964;Mezuman and Keren, 1981;Sims and Bingham, 1967), the type of clay minerals (Hingston, 1964;Keren and Mezuman, 1981;Sims and Bingham, 1967), the type of exchangeable ions Parks and White, 1952), and wetting and drying cycles (Biggar and Fireman, 1960;. However, it is still not clear what specific role the clay minerals, the exchangeable cations, and the solution composition play in this process.…”

“…estimated a total boron adsorption capacity of 6.02/xmole/g for Na-montmorillonite. However, because Keren and Mezuman (1981) estimated different values for maximum boron adsorption for the Ca form of montmorillonite and illite (11.8 and 15.1/xmole/g, respectively), it is possible that additional factors influence boron adsorption. Pissarides et al (1968) showed that the exchangeable cations influenced the amount of phosphate that could be adsorbed on the edge sites of clay minerals.…”