The point of zero charge of pseudoboehmite

Alwitt, Robert S.

doi:10.1016/0021-9797(72)90008-2

Cited by 33 publications

(22 citation statements)

References 6 publications

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“…Experimental observation of a shift of the zero potential charge (ZPC) following boron adsorption has been observed on boehmite (Fricke and Leonhardt, 1950), pseudoboehmite (Alwitt, 1972), aluminum hydroxide gel (Beyrouty et al, 1984) and magnetite (Blesa et aL, 1984) indicating specific adsorption on these minerals. It is within this context that boron adsorption on kaolinite has been investigated and surface reactions formulated to interpret the surface interactions from experimental observations.…”

Section: Boron Adsorptionmentioning

confidence: 99%

Modeling Boron Adsorption on Kaolinite

Singh¹,

Mattigod

1992

Clays and clay miner.

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Abstract--Boron adsorption at constant ionic strength [0.09 _+ 0.01 moles/liter of KC10, or Ca(C104)2] on 0.2-2 #m clay fraction of pretreated kaolinite was modeled using both phenomenological equations and surface complexation reactions. Phenomenological equations were expressed as linear relationships between the distribution coefficient and adsorption density or equilibrium concentration. The normalized form of the isotherms allowed the distribution coefficient to be predicted over a wide range of adsorption densities or equilibrium concentrations and pH. The Langmuir isotherm revealed a weak two-part linear trend supported by a similar behavior of the van Bemmelen-Freundlich isotherm. Potential adsorption mechanisms were assessed from these isotherms. The bases for the inner-sphere (surface coordination) and outer-sphere (ion-pair) surface reactions were postulated, and equations were developed and incorporated into the generalized triple-layer surface-complexation model [TL(g)-SCM]. Boron adsorption was best modeled using the inner-sphere complexes. The results confirm that the generalized triple-layer surface-complexation model can provide information regarding plausible reactions at the substrate/aqueous interface. Intrinsic constants for postulated surface reactions were derived as fitting parameters over a range of pH and initial boron concentrations.

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Section: Boron Adsorptionmentioning

confidence: 99%

Modeling Boron Adsorption on Kaolinite

Singh¹,

Mattigod

1992

Clays and clay miner.

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“…The increased anion adsorption at higher boric acid concentrations causes the pore wall charge density to be less positive, and hence the potential, which controls the compensating solution space charge concentration, is reduced. At the boric acid concentration of 0.075 M, the pH of zero charge is close to the bulk pH of 7.0 [32], and so the wall charge density is nearly zero. For this condition, the solution space charge concentration is small, and hence the potential on the pore axis is close to 0 V. Fig.…”

Section: Effects Of Ph Changes and Anion Adsorptionmentioning

confidence: 93%

“…Experimental data on anion adsorption to support the model were taken from measurements of the pH of zero charge of hydrous aluminum oxide (pseudoboehmite), as a function of the solution boric acid concentration [32]. Anion adsorption was manifested by a negative shift of the pH of zero charge (pzc) from 9.2 to 6 as the boric acid concentration was increased from zero to 0.3 M. In modeling the pzc vs. boric acid concentration data, adsorption of both B(OH) 4 À and B 3 O 3 (OH) 4 À , were considered, since these species predominate at pH near 9 and 6, respectively [33].…”

Section: Boundary Conditionsmentioning

confidence: 99%

The electrical double layer in a nanopore in a barrier surface film

Huang

Hebert

2004

Journal of Electroanalytical Chemistry

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“…In related experiments, others have reported that variations of pH on aging depend on the initial pH of the aluminum system studied [18][19][20][21]. The rate of change of mobility at a given pH also depended on the acid: the most rapid reaction took place with phosphoric acid, whereas with nitric or hydrochloric acid the changes were so slow that they were not completed within a month.…”

Section: Electrokinetic Datamentioning

confidence: 97%

Properties of aluminated silica sols

Katsanis

Matijević

1983

Colloid & Polymer Sci

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Abstract:The properties of colloidal dispersions of "Positive Sol 130M" (E. I. du Pont de Nemours and Co.), which contains silica particles coated with alumina, have been studied in detail. Drifts of pH, leaching of aluminum species, and changes of electrokinetic mobility occurred during aging at room temperature for periods of up to a month, and were attributed to surface reactions. Despite its name, the sol has a point of zero charge (PZC) at pH 9, and consequently the particles carry a positive charge only below this pH. The alumina of the coating dissolves in acidic environments; the extent of leaching of aluminum species is dependent upon pH and length of aging at room temperature. The effect of different anions on this process was examined by using various inorganic acids ; it was shown that phosphate and sulfate ions exhibit the strongest.effects. The removal of alumina changed the surface characteristics as well as the stability of the Sol 130M. The mobilities of the particles were found to be directly related to the composition of the particle surface, regardless of the time of aging or the pH.

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The point of zero charge of pseudoboehmite

Cited by 33 publications

References 6 publications

Modeling Boron Adsorption on Kaolinite

Modeling Boron Adsorption on Kaolinite

The electrical double layer in a nanopore in a barrier surface film

Properties of aluminated silica sols

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