Simultaneous removal of tetracycline and arsenic(III) using copper-manganese composite oxide: Competition behaviors and removal mechanisms

The combined pollution of antibiotics and heavy metals/metalloids in the livestock industry wastewater has drawn considerable attention. In this study, a hybrid material of Cu-Mn binary oxide (CMBO) was used to activate persulfate (PS) for the enhanced co-removal of arsenite [As(III)] and tetracycline (TC) from water. Although the two pollutants posed a mutual impact on the removal efficiency of each other by using CMBO, the addition of PS could improve their co-removal performance remarkably. Sufficient experimental explorations confirmed the mechanism for TC removal was changed from adsorption to degradation, thus alleviating the impact effect of As(III) on TC removal. The by-products after TC degradation might compete for the oxidation and adsorption active sites with As species. The spectroscopic analysis and density function theory (DFT) results indicated that As(III) was directly adsorbed via inner-sphere complexation or removed through an “oxidation-adsorption” process with electrons transferred to Mn oxides or reactive oxygen species. The radicals played a dominant role in the co-removal process. Two possible pathways for TC degradation were proposed based on the HPLC–ESI–MS results assisted with DFT calculations. This contribution shed a new light on the technologies towards the co-removal of combined contaminants from water. • Cu-Mn binary oxide (CMBO) was designed for the co-removal of As(III) and TC from water. • The mutual impact between TC and As would depress their removal performance. • PS activation can alleviate the impact effect of As(III) on TC removal in the bi-pollutant system. • TC degradation intermediates competed for the oxidation/adsorption active sites with As(III/V). • Degradation pathways of TC were proposed based on HPLC-MS/MS analysis and DFT calculation.