A novel aqueous-phase route to synthesize hydrophobic CaCO3 particles in situ

Hydrophobic CaCO3 particles were prepared in situ by carbonation of Ca(OH)2 slurry in the presence of the ethanol solution of oleic acid by mimicking the process of biomineralization. The weight ratio of oleic acid to CaCO3 changed from 0.3 to 3 wt.%. By changing the weight ratio of oleic acid to CaCO3, the surface property of CaCO3 particles was changed from hydrophilic to hydrophobic. Floating test and contact angle analysis of the obtained product indicated that the final CaCO3 obtained was hydrophobic. From the floating test, the active ratio of the modified CaCO3 might reach 100%. The contact angle of the modified CaCO3 was 108.77. IR spectrums of the CaCO3 particles showed the appearance of the alkyl groups from the oleic acid. We have succeeded in surface modification of CaCO3 with the hydrophobic oleic acid.