The surface properties of commercial TiO2 and samples synthesized by the thermal decomposition procedure using several precursor salts were investigated by a microelectrophoresis technique. The iep was determined as a function of the ionic strength which was controlled with KNO3 or KCl. The experimental results showed: 1) The commercial sample and the ones synthesized from the chloride salt dissolved in HCl 1:1 (v/v) show low iep’s due to chloride inclusion; 2) The purification methods explored (oxide suspension at pH~12 and dialysis) are inefficient; 3) TiO2 samples synthesized from an organic precursor salt under totally chloride-free conditions furnished an iep of 5.9 in excellent agreement with literature data; 4) Chloride specific adsorption on TiO2 is weak.
electrocatalysis; surface properties; titanium dioxide; chloride specific adsorption
