Development of Magnetic Bio-Activated Carbon for Water Treatment

Yanghao Jin, Ziyi Shi, Tong Han, Pär G. Jönsson, Weihong Yang Department of Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm, 114 28, Sweden Development of Magnetic Bio-Activated Carbon for Water Treatment Ensuring safe drinking water requires efficient removal of dissolved organic matter (DOM) from source water and disinfection by-products (DBPs) formed during chlorination. Powdered activated carbon is effective but difficult to recover due to its fine particle size, leading to high operational costs. Magnetic activated carbon enables rapid separation, but most studies rely on commercial activated carbon and lack optimized synthesis strategies that balance porosity, iron loading, and magnetic performance. This study focused on synthesizing Magnetic Bio-Activated Carbon (MBAC) from sawdust, an abundant biomass resource in Sweden. The synthesis involved combining bio-activated carbon with iron nanoparticles to produce a composite with enhanced adsorption capacity and facile magnetic separability. KOH activation produces 1419 m²/g specific surface area (SSA) and 0.58 cm³/g micropore volume (higher than K₂CO₃ activation: 673 m²/g ), forming a welldeveloped microporous network essential for adsorption. Background Sample ABET (m2/g) Amicro (m2/g) Vtotal (cm3/g) Vmicropore (cm3/g) MBAC 1:1 1214.53 588.40 0.69 0.28 MBAC 2:1 890.17 412.22 0.58 0.20 MBAC 3:1 662.84 273.99 0.44 0.13 1 um Activation Magnetization Wet impregnation ensures deep penetration and uniform deposition of Fe nanoparticles (clear Fe peaks in XRD). Process order Magnetization→Activation:Activation blocked by Fe particles with SSA of 259 m²/g. Activation→Magnetization:KOH creates open micropores first; Fe added afterward preserves porosity, giving a high SSA of 1250 m²/g. MBAC SSA decreases with increasing Fe ratio, as more nanopores become filled by Fe nanoparticles. Adsorption Performance Results MBAC with Fe:C=3:1 ratio have the best removal ability of organica matter. It can removal 90% organic matter (10ug/L) within 2h, under loading amount at 0.1g/L. Organic MatterAdsorption At 2 g/L, MBAC can removes 90% Bromodichloromethane (BDCM, 500ug/L) within 10 min. MBAC1:1 and MBAC2:1 show slightly better performance for BDCM, suggesting surface area plays a greater role than Fe content. DBP Adsorption MBAC maintains >70% removal after 8 adsorption tests. Low-temperature regeneration can restores initial BDCM removal capacity. After 5 regeneration cycles, SSA slightly increases to 776 m²/g due to partial Fe release from micropores. Regeneration Methodology Conclusion & Acknowledgement This work establishes a synthesis route of MBAC from sawdust through optimized pyrolysis, KOH activation, and FeSO₄ wet impregnation. The resulting MBAC materials showed strong adsorption performance toward DOM and DBPs, rapid magnetic separability, and good regeneration stability. This research was supported by the European Union’s Horizon Europe Programme, under the H2OforAll Project, whose financial and collaborative support is gratefully acknowledged. https://h2oforall.eu/