Surface Properties and Critical Coagulation Concentration of TiO2 Particles in Organic Solutions

• Main Authors: Chang, Yeun-Tsong, 張允聰
• Other Authors: Hsu Jyh-Ping
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/83467164631447188904

碩士 === 國立臺灣大學 === 化學工程學系研究所 === 86 === The critical coagulation concentration (CCC) and the mobility of TiO2 colloida l particles in organic solutions, including pure water, ethanol, acetone, and mixed water-organic solvent solutions, are examined experimentally. The fo rmer is estimated by turbidity measurement, and the latter by microelectrophor esis. It is found that the 50% organic solvent-water colloidal dispersion lead s to the greatest turbidity, or the most stable dispersion. The turbid ity for the case of methanol-water is greater than that for the case of aceton e-water, in general.Mono- (NaCl), bi- (CaCl2), and tri-valent (AlCl3) electrol ytes, are all capable of coagulating most of the colloidal dispersions. R estabilization may occur, however, for the case of trivalent electrolyte.The r esult obtained from the microelectrophoresis experiment reveals that, for the case of methanol-water solvent, the higher the concentrationof methanol, the s maller the mobility of TiO2 particles. This is not observed for the case of ac etone-water solvent. The addition of NaCl has a negligible effect on the mobil ity of TiO2 particle.On the other hand, the absolute mobility decreases wit h the increase in the amount of CaCl2 added Also, charge reversal may occur fo r the case the solution is richer in organic solvent.For the case of AlCl3 ,ch arge reversal is observed. The results of turbidity a nd microelectrophoresis measurements all suggest that the coagulation mechanis m for the case of a water-rich solvent is mainly the double-layer compression for both NaCl and CaCl2. For the case of AlCl3, adsorpt ion and charge reversal seems to be the coagulation mechanism. This is consis tent with the value of parameter Qc estimated.