A stopped-flow electric dichroism study on adsorption of metal chelates by a colloidal clay

An apparatus for measuring stopped-flow electric dichroism is constructed. The instrument enables one to measure electric dichroism as a function of time after two solutions are mixed within 6 ms. The adsorption of enantiomeric or racemic [Ru(phen) 3 ] 2+ (phen=1,10-phenanthroline) by colloidally dispersed montmorillonite is studied with this instrument. As a result, it is confirmed that the adsorption of racemic [Ru(phen) 3 ] 2+ occurs by way of two successive paths: first the chelate binds with a clay rapidly within the cation-exchange capacity (CEC) and then it is adsorbed slowly in excess over the CEC