| The effects of structurally-specific carboxylic acids such as monocarboxylic acid ( HAc), dicarboxylic acid ( tartaric acid ), tricarboxylic acid ( citric acid ), tetracarboxylic acid ( EDTA ) and their sodium, potassium carboxylates on the crystallization of calcium oxalate ( CaOxa ) were investigated in ordered unilamelar vesicles by X-ray powder diffraction (XRD), transmission electron microcopy (TEM), Dyanmic Light Scattering Spectroscopy (DLS), atomic absorption Spectroscopy (ABS), and so on.The size of the CaOxa crystals grown in vesicles (about 80-150 nm) is much smaller than that in aqueous solution (about 1500 nm). It can be mainly attributed to the micro-space limitation of vesicles.Monocarboxylic acid or its salts had no inhibition on the crystallization of CaOxa crystals in vesicles and in aqueous solution.But tartaric acid (Hatart), citric acid (tbcit), EDTA and their sodium, potassium carboxylates can change the crystal habits of CaOxa crystals. These changes increase as their increasing concentrations.The promotion effectives to COD followed this order: Najcit > Na2tart; Hscit > H2tart.The promotion effectives to COD followed this order: Kscit > Kaedta >> K2tart~KAc. The promotion effectives to COT followed this order: K2tart > Kacit > K2edta >> KAc.The effect of different counterions of carboxylic acids on the crystallization of CaOxa crystals follows this order: Naacit > Kscit > Hscit.The morphology of COM, COD and COT were carefully studied by combination of XRD and SAED. |
