Efficient removal of Cu(II) organic complexes by polymer-supported, nanosized, and hydrated Fe(III) oxides through a Fenton-like process

In this study, a polymer-supported, nanosized, and hydrated Fe(III) oxide (HFOD) was developed as a Fenton-like catalyst for the efficient removal of metal complexes in water. HFOD was prepared through the irreversible impregnation of hydrated iron(III) oxide (HFO) nanoparticles into cation exchange resin and characterized through X-ray photoelectron spectroscopy (XPS) and ion chromatography. The mechanism of Cu(II) ion removal and the degradation pathway of Cu(II)-citrate were analyzed through UV-vis spectrophotometry (UV) and liquid chromatography-mass spectrometry (LC-MS). The optimal removal rate of Cu(II) and TOC by a Fenton-like reaction at pH 4 and 40 mM H₂O₂ reached 81.6 % and 75.6 %, respectively. The removal efficiency of Cu(II)-citrate was remarkably affected with the addition of humic acid. However, the addition of competitive ions did not significantly reduce the removal rate of Cu(II)-citrate, thereby proving that the Fenton-like reaction by HFOD had a certain salt tolerance. Simultaneously, hydroxyl radical (•OH) was verified as the main free radical for Cu(II)-citrate degradation in a Fenton-like reaction, and citrate degradation was a process decarboxylation. HFOD recycling experiments and stability experiments showed that HFOD had high stability with good acid/alkali resistance and showed remarkable potential in the practical application of fixed-bed as catalysts for Fenton-like reactions.