Determination of surface zeta-potential and isoelectric point of carbon surfaces using tracer particle suspensions

0506639 - ÚFCH JH 2020 RIV GB eng J - Journal Article
Vasconcelos, J.M.T. - Zen, F. - Stamatin, Serban - Behan, J.A. - Colavita, P.E.
Determination of surface zeta-potential and isoelectric point of carbon surfaces using tracer particle suspensions.
Surface and Interface Analysis. Roč. 49, č. 8 (2017), s. 781-787. ISSN 0142-2421. E-ISSN 1096-9918
Institutional support: RVO:61388955
Keywords : biomedical applications * thin-films * diamond * charge * termination * adsorption * interfaces * nanotubes
OECD category: Physical chemistry
Impact factor: 1.263, year: 2017
Method of publishing: Limited access

Carbon materials are widely used in a range of applications from biomaterials to sensing and electronics. Many of these applications rely on the ability to control carbon/water interfacial properties, in particular, surface charge density. This work reports a study of the electrokinetic properties of amorphous carbon thin films as a function of pH and surface chemistry. Surface zeta-potential (SZP) and isoelectric point were determined using the tracer particle method. Initially, the use of sulfonated and amine-terminated latex bead suspensions as tracer particles for the determination of SZP of reference polymer surfaces was validated. The tracer particle method was then applied to the determination of SZP and isoelectric point of macroscopic carbon surfaces with different surface chemistry. Highly graphitic and sp(3)-rich hydrogenated carbon surfaces were found to display negative SZP, as expected for hydrophobic surfaces. The isoelectric point of the most highly graphitic surface was found to be pH(iso) = 3.7. Surface oxidation of these films resulted in a decrease of SZP at all pH values and in a downshift of pH(iso) to values lower than 1.5, consistently with the presence of surface acidic groups arising from oxidation. Results indicate that the specific choice of acid/base chemistry for the tracer particles does not significantly affect either SZP or pH(iso) determinations. These results show that the tracer particle method in combination with widely available latex beads as tracers can be applied for the determination of carbon SZP as a function of pH.
Permanent Link: http://hdl.handle.net/11104/0297846