Resumo

ARELLANO-CARDENAS, Sofía; GALLARDO-VELAZQUEZ, Tzayhrí; OSORIO-REVILLA, Guillermo  e  LOPEZ-CORTEZ, Ma. del Socorro. Study of the Surface Charge of a Porous Clay Heterostructure (PCH) and Its Adsorption Capacity of Alkaline Metals. J. Mex. Chem. Soc [online]. 2010, vol.54, n.2, pp.92-97. ISSN 1870-249X.

A Porous Clay Heterostructure (PCH) was prepared by chemical modification of a natural clay, by intercalation of a cationic surfactant. Its surface charge properties as well as its adsorption capacity for alkali metals were studied using a potentiometric titration method. The PCH developed a pH-dependent charge (σ_H), probably due to the presence of amphoteric silanol groups (SiO₂) coming from the pillars of silica interlayered during the pillared process. The PCH presented a region of zero charge in the range of pH of 4.0 to 7.7. The σ_H acquired by the PCH was adjusted with good correlation to the electric double layer model of Gouy-Chapman (r² = 0.9925). The surface charge conferred the PCH ion exchange capacity for the studied metals (Li, Na, K, Rb and Cs) at high pH values (10 < pH), in comparable quantities (3.5 to 6 meq/g) to some Dowex resins. The results of this study suggest that PCH could have applications in the recovery of toxic metals from waste waters.

Palavras-chave : clay; PCH; metal adsorption; surface charge.

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