Abstract
Some artificial surfactants are not sufficiently decomposed and remain in the water of seas, rivers and lakes. The influence of the artificial surfactants on the Polymorphic forms of calcium carbonate was experimentally examined. The calcium carbonate contained in the sediment of seas, rivers and lakes has three polymorphic forms: calcite, aragonite, and vaterite. Sodium dodecylbenzene sulf onate and sodium dodecyl sulfate promoted calcite formation in the presence of magnesium ions. The promoting effect was observed at the concentrations > 5 mg/L. Polyoxyethylene sorbitan monolaurate and sorbitan monolaurate facilitated vaterite formation in a magnesium-free solution at the concentrations > 10 mg/L. The known concentrations of these surfactants in the Japanese coastal seas, rivers and lakes are much smaller than the our observation. Therefore, it seems that surfactant effects on the polymorphic crystallization of calcium carbonate in these aqueous environments are very small.
