Removal of transition metals from alkaline suspensions of cellulose pulp using CDTA as chelating agent

Removal of transition metals (Fe, Mn, and Cu) from oxygen delignified alkaline cellulose pulp slurry was carried out using CDTA (trans-cyclohexane-1,2-diaminetetraacetic acid) as chelating agent. After simple treatment in alkaline solutions the initial natural concentrations of the metals above-mentioned can by reduced by ca. 50% for Fe and Mn and by ca. 70% for Cu, whereas the lowering of concentration of Ca varies in the range from 30% to 60%, depending on solution pH and concentration of chelating agent.