COLL 148 |
| John F Scamehorn, Institute for Applied Surfactant Research, University of Oklahoma, 100 E Boyd, Norman, OK 73019 and Chintana Saiwan, Petroleum and Petrochemical College, Chulalongkorn University, Phya Thai Road, Bangkok, 10330, Thailand. |
| Soap scum is fatty acids precipitated by hardness ions. In this work, calcium dodecanoate (CaC12) is used to represent soap scum and the wetting of solutions saturated in CaC12 and subsaturated in sodium dodecyl sulfate (SDS) is measured through the advancing contact angle. An unexpected result is that the soap scum generally has contact angles less than 40 degrees with these solutions despite being widely considered as hydrophobic due to their greasy feel and appearance. The Zisman equation is shown to be applicable for these solutions over a range of low contact angles, yielding a critical contact angle of 25.5 mN/m. However, the Zisman equation fails over a wider range of contact angles and this is explained through adsorption isotherms of the SDS onto the soap scum and calculated solid/liquid interfacial tensions. Arthur Adamson greatly expanded awareness of the colloid community to the Zisman equation through his book. |
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Symposium in Memory of Arthur W. Adamson
2:00 PM-5:40 PM, Monday, March 29, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |