Reusable magnetic microspheres for efficient removal of atrazine in aqueous media

• Q150 exhibited higher adsorption capacity and better reusability than 1240AC.
• A small dose of Q150 was needed to reach a high atrazine removal efficiency.
• Q150 prevented fouling more than 1240AC due to its weak direct site competition.
• The micromolecular DOM accumulated inside Q150 and cause pore blockage.
• NDMP pretreatment improved the performance of Q150 for atrazine adsorption.

In this study, a magnetic hypercrosslinked microsphere (Q150) was prepared and used for organic micropollutants (OMPs) removal. Q150 has a high surface area (1103.6 m2/g) with a narrow particle size distribution (10–30 μm). The high saturation magnetization (9.6 emu/g) of Q150 demonstrates its excellent separation ability. The adsorption behaviors of a typical OMPs, atrazine, were studied and a commercial powdered activated carbon, 1240AC, was selected as comparison. Q150 and 1240AC both displayed fast adsorption kinetics, and the adsorption followed a pseudo-second-order equation (R2 > 0.99). Q150 exhibited a slightly larger adsorption capacity (107.1 mg/g) for atrazine than 1240AC (101.8 mg/g). The most cost-effective adsorbent dose was 0.06 g/L at an initial atrazine concentration of 20 μg/L, resulting in an atrazine removal efficiency that was higher than 99.5%. Q150 could treat 600 ml more of the atrazine solution than 1240AC in a single batch before reaching a breakthrough point (3 μg/L). In the presence of dissolved organic matter (DOM), the water treatment volume of Q150 decreased by 29.2%, which is less than that observed for 1240AC (47.6%). 1240AC completely lost its adsorption capability after 3 adsorption–desorption cycles, whereas Q150 maintained approximately 50% of the initial adsorption capacity after 6 repeated uses. NDMP (magnetic anion exchange resin) pretreatment removed 45.2% of DOM, which improved the atrazine treatment capability of Q150 by 20.8% and enhanced the reusability.