Effect of counter ion valence and pH on the aggregation and charging of oxidized carbon nanohorn (CNHox) in aqueous solution

Oxidized carbon nanohorn (CNHox) is one of nanomaterials and has attracted attention due to its unique material properties. To clarify the dispersion, aggregation, charging behaviors CNHox in aqueous solutions with different valences counter ions, K + , Ca 2+ La 3+ pH, stability ratio electrophoretic mobility were investigated by light scattering time-resolved dynamic techniques. The showed pH-dependent negative zeta potential probably de-protonation carboxylic groups on CNHox. Increasing electrolyte concentration ion valence decreased magnitude double layer screening adsorption. clear slow aggregation regime, fast critical coagulation (CCC). CCC increasing valence. That is, aggregation-dispersion follows Schulze-Hardy rule Derjaguin-Landau Verwey-Overbeek (DLVO) theory. Furthermore, relationship between ionic strength charge density reasonably agrees theoretical prediction DLVO theory for low surface potential. useful description irreversible aggregates colloidal size as found aggregate, once their potentials are evaluated. • Electrophoretic oxidized measured. Higher counter-ion induced reduction reversal. Critical Coagulation properties follow Schulze-Hardy's