Effects of Carboxylic Acids on the Crystal Growth of Calcium Oxalate Nanoparticles in Lecithin−Water Liposome Systems

The effects of citric (H3cit), tartaric (H2tart), and acetic (HAc) acid on the growth of nanoparticles of calcium oxalate (CaOxa) were investigated in a lecithin−water ordered liposome system by means of X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The morphology of CaOxa particles grown in the presence of HAc was the same as that in the control test without additive. Both calcium oxalate monohydrate and calcium oxalate dihydrate (COD) were obtained in a ratio of about 1:1. However, CaOxa particles grown in the presence of H3cit and H2tart contained excess COD with a preferential growth of the (411) crystal face. The effectiveness of COD formation followed the order H3cit > H2tart > HAc. Possible reasons for this order are discussed.