Ferrate(VI) in wastewater treatment contaminated with metal(II)-iminodiacetic acid complexed species

•Green treatment proposed using Ferrate(VI) in the remediation of Cu(II)-IDA and Zn(II)-IDA contaminated water.•Mineralization of IDA along with M(II) was removed simultaneously.•Kinetics of degradation was proposed.

The aim of this investigation is to assess the suitability and applicability of ferrate(VI) in the treatment of wastewaters contaminated with the Cu(II)-IDA and Zn(II)-IDA (IDA: iminodiacetic acid) complexed species in an attempt to provide safe and environmentally benign treatment process. The study was conducted for the degradation of metal(II)-IDA, followed by the oxidation of IDA and simultaneous removal of metal(II) species by the coagulation/flocculation process obtained by the reduced Fe(VI) into Fe(III). The high purity of ferrate(VI) was synthesized by the wet oxidation process in the laboratory and a regulated dose was imparted to the water contained with metal(II)-IDA species in solution. The batch reactor operations were performed for various parametric studies viz., effect of solution pH and metal(II)-IDA concentration for a fixed dose of ferrate(VI). The pH dependence data obtained from varying pH from 8.0 to 12.0 showed that higher efficiency of degradation of Fe(VI) was occurred at lower pH value i.e., at pH 8.0. Similarly, the total organic carbon (TOC) values showed in accordance to the UV–Vis data that the lower pH values (i.e., pH at 8.0) favored an enhanced degradation/mineralization of IDA since low TOC values were obtained at low pH values. The simultaneous removal of Cu(II) and Zn(II) was obtained through the process showed that insignificant percent of metal (Cu(II) or Zn(II)) was removed by the process which was significantly enhanced at pH 12.0. The UV–Vis data recorded at different time intervals for the reduction of Fe(VI) at varied metal(II)-IDA concentrations was utilized to demonstrate the kinetics of degradation. Further, this was employed in obtaining the overall rate constant of the degradation. These kinetic data revealed that an efficient degradation of IDA was achieved using the Fe(VI) treatment.