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Title

Na/Pb, Na/Cd and Pb/Cd exchange on a low iron Texas bentonite in the presence of competing H+ ion

AuthorsBreen, C.; Bejarano Bravo, M.; Madrid, Luis ; Thompson, G.; Mann, B. E.
Issue Date1999
PublisherElsevier
CitationColloids and Surfaces A: Physicochemical and Engineering Aspects 155(2-3): 211-219 (1999)
AbstractThe competitive sorption of Pb2+, Cd2+, and H+ ions onto a low iron Texas bentonite (BL) has been studied under conditions where the quantity of Pb2+ and Cd2+ ions was equivalent to the cation exchange capacity (CEC) of the clay and the amount of added acid ranged from 0 to 1 mmol H+ (g clay)-1. Clay concentrations were in the range 25-50 g dm-3 and [M2+] ranged from 0.02 to 0.04 mol dm-3. The adsorption of both Pb2+ and Cd2+ ions onto Na+-BL was reduced as the amount of H+ was increased to values equivalent to the CEC (1 mmol H+ (g clay)-1). Increasing the quantity of Pb2+ to the clay either by increasing the aqueous Pb2+ concentration or reducing the clay content in the suspension had little influence on the shape of the uptake curves for Pb2+ and H+. Cd2+ ions were less able to compete with aqueous H+ ions for exchange sites on Na+-BL than Pb2+ ions. Pb2+ competed more effectively with H+ for the exchange sites on Cd2+-BL than Cd2+ was able to compete with protons for the sites on Pb2+-BL. Protons were less able to compete for exchange sites on both Pb2+- and Cd2+-BL when the aqueous phase contained 1 CEC of Pb2+or Cd2+, respectively. Copyright (C) 1999 Elsevier Science B.V. | The competitive sorption of Pb2+, Cd2+, and H+ ions onto a low iron Texas bentonite (BL) has been studied under conditions where the quantity of Pb2+ and Cd2+ ions was equivalent to the cation exchange capacity (CEC) of the clay and the amount of added acid ranged from 0 to 1 mmol H+ (g clay)-1. Clay concentrations were in the range 25-50 g dm-3 and [M2+] ranged from 0.02 to 0.04 mol dm-3. The adsorption of both Pb2+ and Cd2+ ions onto Na+-BL was reduced as the amount of H+ was increased to values equivalent to the CEC (1 mmol H+ (g clay)-1). Increasing the quantity of Pb2+ to the clay either by increasing the aqueous Pb2+ concentration or reducing the clay content in the suspension had little influence on the shape of the uptake curves for Pb2+ and H+. Cd2+ ions were less able to compete with aqueous H+ ions for exchange sites on Na+-BL than Pb2+ ions. Pb2+ competed more effectively with H+ for the exchange sites on Cd2+-BL than Cd2+ was able to compete with protons for the sites on Pb2+-BL. Protons were less able to compete for exchange sites on both Pb2+- and Cd2+-BL when the aqueous phase contained 1 CEC of Pb2+ or Cd2+, respectively.
URIhttp://hdl.handle.net/10261/64966
DOIhttp://dx.doi.org/10.1016/S0927-7757(99)00030-8
Identifiersdoi: 10.1016/S0927-7757(99)00030-8
issn: 0927-7757
Appears in Collections:(IRNAS) Artículos
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