Interactions in calcium oxalate hydrate surfactant systems

Phase transformation of calcium oxalate dihydrate (COD) into the thermodyna mically stable monohydrate (COM) in anionic (sodium dodecyl sulfate (SDS)) and cationic (dodecylammonium chloride) surfactant solutions has been studi ed. Both surfactants inhibit, but do not stop transformation from COD to CO M due to their preferential adsorption at different crystal faces. SDS acts as a stronger transformation inhibitor. The general shape of adsorption is otherms of both surfactants at the solid/liquid interface is of two-plateau -type, but differences in the adsorption behavior exist. They originate fro m different ionic and molecular structures of crystal surfaces and interact ions between surfactant headgroups and solid surface. (C) 1999 Academic Pre ss.