Effect of ethylenediaminetetraacetic acid (di sodium salt) and aquasoft 330 on crystal growth and morphology of calcium oxalate

Calcium oxalate was synthesized from calcium chloride solution using oxalic acid in the presence of di sodium salt of ethylenediaminetetraacetic acid (EDTA) and commercially available1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aquasoft having chelating value 330 (AQ 330). The experiments were carried out at three different temperatures 60, 80 and 100 °C. The samples were characterized using scanning electron microscope (SEM), powder X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The morphological studies reveal that the tendency for agglomeration increases with increase in temperature. Interpretation of XRD pattern confirmed that whewellite with monoclinic structured is the most favored structure in the presence of EDTA where calcium oxalate hydrate having orthorhombic structure is most favored structure in the presence of AQ 330.

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► This paper reports the effect of two chelating agents on the morphology and structure of calcium oxalate.
► The structure is different with different chelating agents.
► The findings might be helpful to select the surfactants in industries using oxalic acid as mordent.