Boosting the Ni(II)-EDTA decomplexation and Ni(II) immobilization in a heterogeneous Fenton-like system with L-cysteine functionalized zero-valent iron

The remarkable stability and detrimental environmental impacts of nickel(II)-ethylenediaminetetraacetic acid (Ni(II)-EDTA) complexes originated from electroplating effluents have sparked a growing curiosity about their efficient remediation. In this study, L -cysteine functionalized zero-valent iron (C-ZVI bm ) was synthesized via a ball-milling method and employed as a heterogeneous Fenton-like catalyst to decomplex Ni(II)-EDTA and immobilize Ni(II) from wastewater. The results demonstrated that the pseudo-second-order kinetic rate constant (2.096 L·mol −1 ·min −1 ) for EDTA degradation in the C-ZVI bm /H 2 O 2 system was 123.3 times that in the ZVI bm /H 2 O 2 system (0.017 L·mol −1 ·min −1 ). The incorporation of L -cysteine onto the surface of ZVI significantly enhanced the H 2 O 2 activation, reactive oxygen species ( OH, O 2 − , and 1 O 2 ) generation, and the sequential Ni(II)-EDTA decomplexation and EDTA degradation. The results of capture experiments revealed that 1 O 2 played a crucial role in the degradation of EDTA in the C-ZVI bm /H 2 O 2 system. The optimization of the experimental variables indicated that the degradation of EDTA and the reduction/adsorption of Ni(II) were antagonistic in the C-ZVI bm /H 2 O 2 system, resulting in an efficient reduction/immobilization of Ni(II) and an inhibition of EDTA degradation at a higher dosage of C-ZVI bm . Our findings provide new insights into the promising heterogeneous Fenton-like process that enables the decomplexation of Ni(II)-EDTA, the degradation of EDTA, and the synchronous immobilization of Ni(II).