Comparison of different methods for the point of zero charge determination of NiO

Tahira Mahmood, Muhammad Tahir Saddique, Abdul Naeem, Paul Westerhoff, Syed Mustafa, Absar Alum

Research output: Contribution to journalJournal articlepeer-review

204 Scopus citations


Four methods, fast titration, salt addition, mass titration, and Χ potentiometry, were employed to determine the point of zero charge (PZC) and isoelectric point (IEP) of NiO. However, this work mainly focuses on the fast titration method because it limits the release of Ni from the substrate. Furthermore, the fast titration is simple, rapid, and accurate and requires a small quantity of substrate as compared to the salt addition and mass titration techniques. The similarity between the PZC and IEP values rules out the specific adsorption of the bulk electrolyte onto the NiO surface. However, the PZC values shift downward with the increase in Cd ion concentration, which indicates the specific adsorption of Cd onto the NiO. In addition, temperature has a mild effect on the deprotonation constants and PZC of NiO. It was also observed that the thermodynamic parameters favor the deprotonation of NiO.

Original languageEnglish
Pages (from-to)10017-10023
Number of pages7
JournalIndustrial & Engineering Chemistry Research
Issue number17
StatePublished - 7 Sep 2011
Externally publishedYes


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