Part I: Removing of Zn(II) from Polluted Water: Determination of Precipitation Limit Of Zn(II) Ion With 2-Hydroxy-1,2,3-Propanetricarboxylic Acid

Problem statement: The goal of this research was to investigate the condition for removing of Zn cation from water, through precipitation method with 2-hydroxy-1,2,3-propanetricarboxylic acid as ligand. Approach: In this study we examined the precipitation of Zn(II) ion in water solutions of ZnSO₄ × 7H₂O (1×10^-2 and 5×10^-3 mol L^-1) with 2-hydroxy-1,2,3-propanetricarboxylic acid (1×10^-1-1×10^-3 mol L^-1) in constant ionic strength of 0.6 mol L^-1 NaCl. We have determined the concentration region at which Zn(II) start to precipitate. Results: From precipitation diagrams of zinc with 2-hydroxy-1,2,3-propanetricarboxylic acid, in ionic force 0.6 mol L^-1 NaCl, we have found that during decreasing the concentration of 2-hydroxy-1,2,3-propanetricarboxylic acid, in case of constant concentration of Zn(II), the limit of precipitation is shifted to lower values of pH. The solid phase is analyzed by IR spectroscopy. Conclusion: From the IR spectroscopic analysis we can conclude that Zn(II) ion can precipitate with 2-hydroxy-1,2,3-propanetricarboxylic acid.