INTERACTIONS BETWEEN CALCITE, NADBS, PB(II) AND CD(II) IONS IN SEAWATER

It was demonstrated by a Coulter counter method in combination with ph otomicrographs that the commercially used anionic surfactant sodium do decylbenzene sulfonate (NaDBS) forms solid crystals with major seawate r cations as Na+, Mg2+, Ca2+ and Sr2+ and thus can be removed from sea water to sediments. In the presence of calcite particles suspended in seawater with variable concentrations of NaDBS, complicated mutual int eractions occur resulting in partial calcite dissolution, and conseque ntly in surface area diminuation. Namely, from Coulter counter kinetic measurements simultaneous decrease of the total number and total volu me of particles was observed. Partial dissolution of calcite was also confirmed by the weight loss in the presence of c(t)(NDBS) = 1.6 x 10( -3) mol l(-1). Remobilization of lead and cadmium ions from calcite pa rticles occurs up to c(t)(NaDBS) = 1 x 10(-3) mol l(-1). At concentrat ions above that value, an increased removal of these ions can be expla ined with their adsorption on a reprecipitated calcium salt (either wi th DBS- or with SO42- from SW).