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The pH dependent surface charging and points of zero charge. XI. Update
1Lublin University of Technology, Nadbystrzycka 38, PL-20618 Lublin, Poland.
Advances in Colloid and Interface Science
|March 29, 2026
Summary
Reliable points of zero charge (PZC) data are scarce due to flawed experimental methods. This review compiles accurate PZC and isoelectric point (IEP) values for metal oxides, emphasizing rigorously determined results.
Area of Science:
- Surface Chemistry
- Materials Science
- Electrochemistry
Background:
- A concerning trend of unreliable points of zero charge (PZC) values reported in recent scientific literature.
- Prevalence of flawed methodologies leading to erroneous PZC data, which are frequently cited.
- Need for critical reviews to compile and disseminate accurately determined PZC and isoelectric point (IEP) values.
Purpose of the Study:
- To provide an updated compilation of reliable isoelectric point (IEP) data.
- To present PZC values for metal oxides derived from robust experimental approaches.
- To critically assess recent findings against established PZC data.
Main Methods:
- Electrokinetic and electroacoustic measurements for IEP determination.
- Surface charge versus pH curve analysis at varying ionic strengths for PZC determination.
- Inclusion of studies from 2023-2025 and previously overlooked literature.
Main Results:
- Compilation of updated IEP and PZC values based on properly conducted experiments.
- Comparison of recent data with historical PZC values.
- Focus on well-studied materials like alumina, silica, titania, and iron (hydr)oxides.
Conclusions:
- Highlighting the critical need for rigorous experimental design in PZC determination.
- Emphasizing the importance of relying on validated PZC and IEP data for scientific accuracy.
- Acknowledging the limited availability of reliable data for less-documented materials.
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