Activation of persulfate by lanthanum modified activated coke for tetracycline degradation

Activated coke (ACO) has been applied in some wastewater treatment plants to advance the removal of micro-pollutants from secondary effluent. This work investigated the use of Lanthanum (La) to modify ACO (La-ACO) for enhancing the removal/degradation of micro-pollutants by activating peroxydisulfate (PDS). We report that the immobilization of La oxide on ACO significantly enhances the adsorption of tetracycline (TC) from aqueous solution as well as its persulfate-based catalytic oxidation. The pseudo-first-order K app value of the La-ACO/PDS process is 1.41 times that of adsorption and PDS oxidation alone, indicating an evident synergistic effect. Surface analysis confirms the introduction of La on ACO, while both La(OH) 3 and La 2 O 3 consist of La species on La-ACO. The pH values close to neutral are shown to improve the degradation of TC. Also, increasing reaction temperature improves the TC oxidation. The oxidizing species superoxide anion radical (O 2 ·− ) and active holes (h + ) prove the predominant oxidizing species, while the contribution percentages of O 2 ·− and h + achieve 51.3% and 84.2% of the total degradation capacity, respectively. The inhibiting effect of SO 4 2− and Cl − is insignificant, while the coexisting humic acid has actually improved the TC removal. Reusability test indicates the stable and continuable PDS catalytic ability.