SEM, XRD and FTIR Investigation on Crystal Growth of Calcium Oxalate Modulated by Sodium Tartrate
ZHENG Hui1, CHEN Cun-yuan1, OUYANG Jian-ming1, 2*
1. Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632, China 2. State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China
Abstract：Crystallization of calcium oxalate (CaOxa) was investigated in the presence of sodium tartrate (Na2tart) of different concentration in a gel system by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was found that in the presence of a low concentration of Na2tart (0.01 mol·L-1), calcium oxalate monohydrate (COM) is the dominant crystal phase. The percentage of calcium oxalate dihydrate (COD) is less than 5%. In the XRD pattern the main diffraction peaks are (101), (020), and (202) planes of COM crystals. In the FTIR spectrum, the main asymmetric carbonyl stretching band νas(COO-) and the metal-carboxylate stretch νs(COO-) of COM occur at 1 618 and 1 317 cm-1, respectively. With the concentration of Na2tart increasing to 0.10 and 0.50 mol·L-1, the percentage of COD crystals increases to 10% and 50%, respectively, and the surface area of COM crystals decreases. The diffraction peaks that assigned to the (200), (211), (411), and (213) planes of COD crystals become stronger and stronger. The temperature can influence the modulation of Na2tart in terms of the phase composition and morphology of CaOxa crystals. As the temperature decreases, the percentage of COD increases. At a higher temperature beyond 47 ℃, COM is the dominant phase; but COM is dominant when the temperature is lower than 27 ℃. The νas(COO-) and νs(COO-) of COD crystals occur at 1 647.6 and 1 327.7 cm-1, respectively.
Key words：Calcium oxalate;Sodium tartrate;SEM;XRD;Urinary stone
