Effect Of Structurally-Specific Carboxylic Acids And Carboxyates On Crystallization Of Calcium Oxalate In Gel

The effects of structurally-specific carboxylic acids such as monocarboxylic acid(HAc), dicarboxylic acid (tartaric acid), tricarboxylic acid(citric acid), tetracarboxyllic acid (EDTA) and their sodiuiru potassium carboxylates on the crystallization of calcium oxalate (CaOx) were investigated in silica gel with a double diffusion technique.Monocarboxylic acid or carboxylates had no inhibition.Tartaric acid, citric acid and their sodium, potassium carboxylates can change the morphology of calcium oxalate monohydrate (COM) crystal, inhibit the aggregation of calcium oxalate monohydrate (COM) and induce the nucleation of calcium oxalate dihydrate (COD), and potassium tartrate can induce forming many calcium oxalate trihydrate phase (COT). EDTA and its sodiunu potassium carboxylates can not prevent the nucleation of COM, but can inhibit the growth of the aggregation of COM crystals, its sodiurcu potassium carboxylates can induce the nucleation of calcium oxalate dihydrate (COD). These inhibition abilities increased as prolonging the crystallization time and increasing the additives' concentration except sodium citrate. To sodium citrate, mid-concentration appears more stronger inhibition.Adding two sorts potassium carboxylates mixture show two carboxylates effects.Generally speaking, the ability of counter ions of inhibiting the growth and aggregation of CaOx crystal and inducing the formation of COD follows: potassium carboxylates > sodium carboxylates > carboxylic acid, but the ability of counter ions of tartaric acid of inhibiting the growth and aggregation of CaOx crystal is: tartaric acid> sodium tartrate>potassium tartrate, the ability of inducing formation of COD follows: sodium tartrate > potassium tartrate > tartaric acid, and potassium tartrate can induce formation of COT, there are no COT in other systems.The effects of the temperature on the crystallization of calcium oxalate (CaOx) were notability. The lower the temperature of crystallization, the longer the time for the appearance of CaOx in gel system, and the more the content of COD crystals, and more serious of the aggregation, but the size of the crystals are decrease.