Insights into novel lignin-based magnetic carbon enabling peroxymonosulfate activation for tetracycline removal: Performance, mechanism and application

Abstract

Excellent and recyclable catalysts are essential for wastewater treatment by peroxymonosulfate (PMS)-based advanced oxidation processes. Herein, a novel lignin-based magnetic carbon Fe@CCL was fabricated as a heterogeneous catalyst to boost PMS activation in tetracycline (TC) degradation. Experiments collectively suggested that the TC removal efficiency could be achieved as 95.9% by Fe@CCL/PMS system in a wide value of pH 3–11. Among sundry reactive oxygen species (•OH, SO4•–, O2•– and 1O2) in reaction system, singlet oxygen 1O2 could be selectively generated and played a major contribution for TC degradation. Theoretical simulations demonstrated that the valence state transformation of Fe species distributed in carbon skeleton is the main reason for the generation of 1O2, while the Fe(Ⅱ)/Fe(Ⅲ) redox cycle and the electron transfer in Fe@CCL were evidently beneficial to the effective activation of PMS. In addition, Fe@CCL could be easily recovered by an external magnet from the reaction system, and the catalytic performance in TC removal could be well maintained after regeneration. This work proposes an approach in the construction of high-performance and sustainable magnetic catalysts for organic pollutants removal.