Enhancement of Dispersion and Fluidity of Aqueous Carbon Slurry by Addition of Various Dispersants

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The dispersion and fluidity of aqueous carbon slurries were studied to elucidate the optimum preparation conditions to obtain well-dispersed and fluidized aqueous carbon slurries. The mean particle diameter of the carbon powder used was 13 nm. Styrene/maleic copolymer (SM), polystyrenesulfonic acid (HPSS), and naphthalene sulfonic acid formalin condensate ammonium salts (DEMOL-AS) were selected as dispersants. The rheological behavior of aqueous carbon slurries with various dispersants was examined and evaluated. The electrokinetic behavior of the carbon particles in the presence of DEMOL-AS, SM, or HPSS indicated that the surface properties of the carbon particles changed from hydrophobic to hydrophilic by adsorption of dispersants. The fluidity of aqueous carbon slurries was effectively enhanced by the addition of DEMOL-AS, as compared with the addition of SM or HPSS. DEMOL-AS containing a naphthalene nucleus was an effective dispersant to improve the surface of carbon particles. The dispersion and fluidity of the carbon slurries were dependent on electrokinetic and steric interactions. The carbon slurries with DEMOL-AS were well dispersed and fluidized over a wide range of pH. These observations indicated that DEMOL-AS is an effective dispersant for preparing aqueous carbon slurries.