Performance evaluation and mechanism analysis of potassium permanganate used for simultaneous removal of tetracycline and Cu(II)

The coexistence of tetracycline (TTC) and Cu(II) in various water bodies has been frequently detected, but their simultaneous removal efficiency is far from satisfactory. In this study, potassium permanganate (KMnO4) was utilized to remove TTC and Cu(II) simultaneously from the aqueous solution. The removal efficiency of TTC (10 mu M) and Cu(II) (10 mu M) was 92.8% and 78.5%, respectively, after 30 mins reaction under the condition of pH 6.0 and KMnO4 dose at 50 mu M. TTC was mainly removed by KMnO4 oxidation and Cu(II) was removed by adsorption on MnO2 formed in situ. Afterward, the effects of initial concentrations of TTC and Cu(II), KMnO4 dose, solution pH, temperature, and water matrix on simultaneous removal of TTC and Cu(II) were comprehensively evaluated. The increase of KMnO4 dose and reaction temperature is more favorable to the improved removal efficiency of TTC and Cu(II). Specifically, TTC was almost 100% removed at pH 4.0, while the highest Cu(II) removal efficiency was 84.9% obtained at pH 7.0. The removal efficiency of TTC and Cu(II) in surface water remained higher than 79% and 80%, respectively. The molecular orbital calculations supported that the complexation of TTC with Cu(II) inhibited the oxidation of TTC by KMnO4. X-ray photoelectron spectroscopy and X-ray diffraction confirmed that the solid product formed from the reduction of KMnO4 was amorphous MnO2. Furthermore, the plausible transformation pathways of TTC were proposed based on the identified intermediates. This work provides a cost-effective approach for the simultaneous removal of TTC and Cu(II) from water.

Automated summary

This study utilized potassium permanganate (KMnO4) to simultaneously remove tetracycline (TTC) and Cu(II) from water. The removal efficiency of TTC and Cu(II) was 92.8% and 78.5%, respectively, after 30 minutes of reaction under pH 6.0 and 50 μM of KMnO4. The factors affecting the simultaneous removal of TTC and Cu(II), such as initial concentrations, KMnO4 dose, solution pH, temperature, and water matrix, were comprehensively evaluated. Increasing the KMnO4 dose and reaction temperature improved the removal efficiency. This work provides a cost-effective approach for the simultaneous removal of TTC and Cu(II) from water.