title: Electrophoresis of pH-regulated, zwitterionic particles: effect of self-induced nonuniform surface charge.
abstract: The electrophoresis of a pH-regulated, zwittterionic nanoparticle, taking account of its self-induced nonuniform surface charge, the presence of multiple ionic species, and the effect of double-layer polarization, is modeled. This extends previous models to a case closer to reality because the charged properties of a particle can be influenced by both its physicochemical nature and the solution conditions. We show that the nonuniform surface charge distribution induces a local electric field having the direction either opposite to or the same as that of the applied electric field, thereby either reducing or raising the particle velocity. This effect is most important when both the surface potential and the degree of nonuniformality are high. The competition of the effects of the position dependent double layer thickness, the surface proton distribution, and the double-layer polarization yields complicated and interesting behaviors. Depending upon the level of pH, the influence of the types of background salt on the particle mobility can be significant.
authors.affiliation: Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Yu-Yen
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan. Electronic address: jphsu@ntu.edu.tw.
authors.forename: Jyh-Ping
authors.initials: JP
authors.lastname: Hsu
authors.affiliation: Department of Mathematics, Tamkang University, Tamsui, Taipei 25137, Taiwan. Electronic address: topology@mail.tku.edu.tw.
authors.forename: Shiojenn
authors.initials: S
authors.lastname: Tseng
mesh_terms: D004586:Electrophoresis / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000302:isolation & purification*; D008962:Models, Theoretical; D013499:Surface Properties
chemical_list: D007477:Ions
keywords: Electrophoresis; Self-induced nonuniform surface charge; Types of background electrolytes; pH-regulated nanoparticles