CHROMATOGRAPHIC CHARGE-DENSITY DETERMINATION OF MATERIALS WITH LOW SURFACE-AREA

A new method is presented for the determination of the charge density as a function of pH for oxides. From measured pH-breakthrough curves t hrough a chromatographic column filled with the sorbent, one can obtai n the charge density by a simple integration. This method is specially interesting when classical titration experiments cannot be applied, f or example, if the sorbent has a low surface area with not enough site s to be detected by common potentiometric titrations. The feasibility of the technique is demonstrated by measuring charge densities of sili ca and iron oxides and comparing with known data.