title: Effect of electrostatic interactions on rejection of capsular and spherical particles from porous membranes: theory and experiment.
abstract: OBJECTIVE
  Particle rejection from porous membranes will increase when particle and membrane carry like charges. The influence of charge on particle rejection can be modeled by first solving the Poisson-Boltzmann equation for the electrostatic particle-pore wall interaction energy, enabling one to predict the cross sectional particle concentration in a pore. Rejection coefficients can then be predicted by combining the Boltzmann factor with a hydrodynamic lag coefficient.
  
  
  METHODS
  Rejection experiments were conducted with three different spherical colloidal silica particles, a spherical virus (PRD1) and gold nanorods of two different aspect ratios (ratio of length to diameter). Track-etched polycarbonate microfiltration and ultrafiltration membranes having nearly parallel pores of cylindrical cross-section were used. Experiments were conducted under conditions where both particle and membrane carried a negative charge as well as under conditions where surface charges had minimal impact. Experiments were designed to cover a broad range of dimensionless particle sizes under conditions when convection dominated particle transport.
  
  
  RESULTS
  Model predictions and experimental measurements demonstrate that particle rejection can be enhanced significantly when particle and pore carry like charges.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Clarkson University, Potsdam, NY 13699-5705, USA.
authors.forename: Basavaraju
authors.initials: B
authors.lastname: Agasanapura
authors.affiliation: Department of Chemical and Biomolecular Engineering, Clarkson University, Potsdam, NY 13699-5705, USA. Electronic address: baltus@clarkson.edu.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Baltus
authors.affiliation: Department of Civil and Environmental Engineering, University of Houston, Houston, TX 77204-4003, USA.
authors.forename: Charan Tej
authors.initials: CT
authors.lastname: Tanneru
authors.affiliation: Department of Civil and Environmental Engineering, University of Houston, Houston, TX 77204-4003, USA; Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA.
authors.forename: Shankararaman
authors.initials: S
authors.lastname: Chellam
keywords: Electrostatics; Microfiltration; Nanoparticles; Ultrafiltration; Virus removal