Reaction of EDTA, oxalic acid and citric acid with Portland cement

Oxalic acid, citric acid and EDTA may occur as constituents of low-level radioactive waste streams. In the longer term, concern exists that these organic substances will remain water-soluble and able to complex and solubilize other toxic or radioactive species. The title study reports on the reaction between these organics and cement components. Citrate and oxalate are removed almost quantitatively from cement pore water. Oxalate is precipitated as calcium oxalate monohydrate, Ca(COO)₂·H₂O, the solubility of which is < 1 ppm in cement pore fluids. However, EDTA is less affected by the cement environment, and significant recovery from pore fluid is demonstrated after 6 months moist cure.