Comparative study on the removal of organic pollutants by magnetic composite and pre-magnetized zero-valent iron activated persulfate

The rapid development of global logistics has led to the overuse of packaging cartons, causing problems for municipal solid waste disposal. Diverse methods of exploiting the potential value of waste cartons are needed. Herein, we fabricated a magnetic composite (MC) from waste cartons via a one-step hydrothermal treatment and characterized. Using methylene blue (MB) as a model organic pollutant, tests of the activation of persulfate (PS) via the MC for the removal of MB were performed. Meanwhile, a comparison with activation with pre-magnetized zero-valent iron (Pre-ZVI/PS) was made. The comparative results show that the removal of MB was successfully accomplished with both Pre-ZVI/PS and MC/PS. Specifically, MC/PS could remove almost 100 % of MB, with the COD removal efficiency reaching over 70 % when the MB concentration was 50 mg/L at 80 min under different pH conditions. Even when reused twice, the MC still displayed robust activation performance. Additionally, we evaluated the lifetime of magnetic memory for Pre-ZVI, and first found its consecutive loss of pre-magnetization over 30 days, corresponding to the incremental attenuation of reaction rate constants in the Pre-ZVI-activated PS process. Overall, activating PS using the MC is a promising advanced oxidation technology and also provides a valuable reference on the valorization of lignocellulosic biomass.