The applied pressure and suspension height during consolidation of an aqueous suspension containing SiC (30 nm diameter, 5 vol% solid) or Al2O3 particles (150 nm diameter, 7 vol% solid) with and without phenylalanine (molecular weight 165) or polyacrylic ammonium (PAA, molecular weight 10,000) were continuously recorded using a developed pressure filtration apparatus at a constant crosshead speed. The dispersed SiC and Al2O3 particles at pH 7 and 3, respectively, changed to flocculated particles at an applied pressure of 0.24-0.63 MPa. The packing density of flocculated SiC and Al2O3 particles increased by the addition of dissociated PAA and phenylalanine. Since phenylalanine has two charged groups (-NH3+, -COO-) in one molecule, this dispersant can be used for surfaces of both positively and negatively charged particles

Keywords: Nanoparticles, Colloidal processing, Phenylalanine, Polyacrylic ammonium, Phase transition.