Application of Ferrate(VI) on the Decomplexation of Cu(II)-EDTA

Abstract

See, stats, and : https : / / www . researchgate . net / publication / 255656171 Application (VI) on decomplexation (II) - EDTA Article DOI : 10 . 4491 / eer . 2008 . 13 . 3 . 131 CITATIONS 10 READS 52 4 , including : Some : Development - adsorbents Low - toxic - situ project Jae - Kyu Kwangwoon 139 , 784 SEE Seung - Mok Catholic 142 , 593 SEE All - Mok . The . Abstract In this study , Fe (VI) was employed as a multi - functional agent to treat the simulated industrial wastewater contaminated with Cu (II) - EDTA through oxidation of EDTA , decomplexation of Cu (II) - EDTA and subsequent removal of free copper through precipitation . The decomplexation of 10 - 4 M Cu (II) - EDTA species was performed as a function of pH at excess concentration of Fe (VI) . It was noted that the acidic conditions favor the decomplexation of Cu (II) - EDTA as the decomplxation was almost 100% up to pH 6 . 5 , while it was only 35% at pH 9 . 9 . The enhanced degradation of Cu (II) - EDTA with decreasing the pH could be explained by the different speciation of Fe (VI) . HFeO4 - and H2FeO4 , which are relatively more reactive than the unprotonated species FeO4 2 - , are predominant species below neutral pH . It was noted that the decomplexation reaction is extremely fast and within 5 to10 min of contact , 100% of Cu (II) - EDTA was decomplexed at pH 4 . 0 . However , at higher pH (i . e . , pH 10 . 0) the decomplexa - tion process was relatively slow and it was observed that even after 180 min of contact , maximum ca 37% of Cu (II) - EDTA was decomplexed . In order to discuss the kinetics of the decomplexation of Cu (II) - EDTA , the data was slightly fitted better for the second order rate reaction than the first order rate reaction in the excess of Fe (VI) concentration . On the other hand , the removal efficiency of free Cu (II) ions was also obtained at pH 4 . 0 and 10 . 0 . It was probably removed through adsorption / coagulation with the reduced iron i . e . , Fe (III) . The removal of total Cu (II) was rapid at pH 4 . 0 whereas , it was slow at pH 10 . 0 . Although the decomplexation was 100% at lower pH , the removal of free Cu (II) was relatively slow . This result may be explicable due to the reason that at lower pH values the adsorption / coagulation capacity of Fe (III) is greatly retarded . On the other hand , at higher pH values the decomplexation of Cu (II) - EDTA was partial , hence , slower Cu (II) removal was occurred .