Determination of sorbent point zero charge: usefulness in sorption studies
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Potentiometric mass titration (PMT) technique has been adapted to determine the pHpzc of four vegetable wastes: grape stalks, cork, yohimbe bark and olive stones wastes used for Cu(II) removal. The pH at the point zero charge (pHpzc), determined by PMT, are compared with that obtained by two classical techniques: mass titration (MT) and immersion technique (IT). PMT has been found to be an easy and appropriate technique to determine pHpzc of the studied materials. From the results, the knowledge of sorbents pHpzc provides information about the possible attraction and repulsion between sorbent and sorbate but in any case enables to ensure that electrostatic force is one of the mechanisms that takes place in metal sorption.
KeywordsPotentiometric mass titration Immersion technique Mass titration pHpzc Cu(II) sorption Vegetable wastes
This research was supported by the Ministerio de Educación y Ciencia, Spain (project CTM2005-07342-C02-01/TECNO).