Cation exchange capacity saponite

Cetylmethylammonium (CTMA) as the clay exchange cation and decylamine as the co-surfactant were used to form a PCH. A 1.0 wt % suspension of previously prepared saponite was allowed to react at 50°C with a 0.3 M aqueous cetylmethylammonium bromide solution in two fold excess of the clay cation exchange capacity. After a reaction time of 24h, the product was washed with ethanol and water to remove excess surfactant and... 

The cation exchange capacity (CEC) of the saponite was determined from the ammonium content in solution after exchange with NaOH using an ammonia selective electrode. 

Table XXXVIII). Brindley (1955) has suggested that stevensite is a mixed-layer talc-saponite however, Faust et al. (1959) considered it to be a defect structure with a random distribution of vacant sites in the octahedral sheets. A small proportion of domains with few or no vacancies would then be present having characteristics of talc. The layer charge in stevensite is due to an incompletely filled octahedral sheet (Faust and Murata, 1953). This deficiency is minor (0.05—0.10) and the resulting cation exchange capacity is only about one-third that of the dioctahedral montmorillonites (100 mequiv./lOO g.).

In the early work of Galarneau, a host clay with a high cation exchange capacity was considered essential for the PCH formation. However, more recent PCHs have been successfully synthesized from other clays of lower charge density. Cool and Ahenach reported the formation of PCHs from natural montmorillonite and synthetic saponite and laponite (25,104). The authors reported on the existence of two different heterostructures, depending on the origin of the host clay used (natural or synthetic) as well as on a combined micro- and mesoporosity for these materials. 

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