Silva Teresa Cristina F, VergÜtz Leonardus, Pacheco Anderson A, Melo Larissa F, Renato Natalia S, Melo LeÔnidas C A
State University of Minas Gerais at Ubá, Ave. Olegário Maciel, 1427, Industrial, 36500-000 Ubá, MG, Brazil.
Federal University of Viçosa, Ave. PH Rolfs, s/n, Campus da UFV, 36570-900 Viçosa, MG, Brazil.
An Acad Bras Cienc. 2020 Nov 11;92(3):e20190440. doi: 10.1590/0001-3765202020190440. eCollection 2020.
Activated biochars were prepared from residues of medium density fiberboard (MDF) produced by the furniture industry. Biomass residue was pre-treated with FeCl3 in two different FeCl3:biomass ratios (0.5:1 and 1:1, w/w) aiming to produce a matrix embedded with iron oxide. The pyrolysis process produced maghemite on the biochar surface and its magnetic properties were confirmed by its attraction to a hand magnet and its magnetic susceptibility. Samples were also characterized using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), surface area by BET-N2, Fourier transform infrared (FTIR), X-ray diffraction, magnetic susceptibility, and cation exchange capacity (CEC). Magnetic biochar exhibited up to twelve-fold higher surface area than the non-magnetic biochar, which varies according the maghemite particles content. Iron oxide on biochar surface also contributed for increasing CEC around ten-fold compared to non-magnetic biochars. Phosphorus adsorption isotherms showed that these magnetic biochars have high capacity to sorb oxyanions like phosphate, especially at lower pH. Thus, these magnetic biochars could be used to clean water bodies contaminated with oxyanions in acidic conditions.
活性生物炭由家具行业生产的中密度纤维板（MDF）残渣制备而成。生物质残渣用两种不同的FeCl₃与生物质比例（0.5:1和1:1，w/w）的FeCl₃进行预处理，旨在制备嵌入氧化铁的基质。热解过程在生物炭表面产生了磁赤铁矿，通过其对手持磁铁的吸引力及其磁化率证实了其磁性。还使用带有能量色散光谱的扫描电子显微镜（SEM/EDS）、BET-N₂比表面积、傅里叶变换红外光谱（FTIR）、X射线衍射、磁化率和阳离子交换容量（CEC）对样品进行了表征。磁性生物炭的表面积比非磁性生物炭高多达12倍，这根据磁赤铁矿颗粒含量而变化。与非磁性生物炭相比，生物炭表面的氧化铁还使CEC增加了约10倍。磷吸附等温线表明，这些磁性生物炭具有高容量吸附磷酸根等含氧阴离子，尤其是在较低pH值下。因此，这些磁性生物炭可用于在酸性条件下净化被含氧阴离子污染的水体。
