Department of Chemical and Biological Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 34158, Republic of Korea.
Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 700000, Vietnam.
Sci Total Environ. 2020 May 15;717:137091. doi: 10.1016/j.scitotenv.2020.137091. Epub 2020 Feb 3.
This study developed a green and novel magnetic biochar via the co-pyrolysis of firwood biomass pre-treated with 10% (w/w) of either solid-phase (admixing; G10BC) or liquid-phase (impregnation; G10BC) goethite mineral (α-FeOOH). Newly fabricated magnetic biochars were characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES), Brunauer-Emmett-Teller (BET) equipment, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), proximate and elemental analyzer, and vibrating sample magnetometry. The effects of magnetic precursor, iron loading, and aqua-treatments on recoverability, magnetic property, and stability (resistance to α-FeOOH reconstructive crystallization/dissolution reactions) were explored and compared to those of magnetic biochar derived from conventional ferric chloride precursor (F10BC). Results confirmed a direct correlation between biochar yields and ash contents with iron loading, irrespective of the used types of magnetic precursors (α-FeOOH or FeCl). Although FeCl can generate magnetic biochar (F10BC) with higher total carbon content (83.6%) and surface area (299 m/g), α-FeOOH proved to be more effective at yielding magnetic biochars with nanostructured surfaces, lower water extractable components (thus green; G10BC = 0.21 mg/mL and G10BC = 0.16 mg/mL), higher magnetic saturation (G10BC = 10.0 emu/g and G10BC = 20.8 emu/g), higher ferromagnetic susceptibility, and excellent recoverability. α-FeOOH was undetected on the surface of G10BC, post-aqua-treatments (over 30 days), and this demonstrated its stability in the face of demagnetization via α-FeOOH reformation reactions. Consequently, this study demonstrated that the admixing solid-phase α-FeOOH (10%) with firwood biomass offered a green, facile, and efficient way to thermochemically produce magnetic biochar. The produced biochar exhibited a superb stability to α-FeOOH reconstructive crystallization/dissolution reactions in aquatic (aqua) media, green attributes, good magnetic properties, and great potential applications in many areas of the economy.
本研究通过共热解经 10%（质量比）固相（混合；G10BC）或液相（浸渍；G10BC）预处理的冷杉木生物质，开发了一种绿色新颖的磁性生物炭。新制备的磁性生物炭通过电感耦合等离子体发射光谱（ICP-OES）、BET 设备、X 射线粉末衍射（XRD）、扫描电子显微镜（SEM）、能量色散光谱（EDS）、元素分析和振动样品磁强计进行了表征。研究了磁性前体、铁负载量和水热处理对可回收性、磁性和稳定性（抵抗α-FeOOH 重构结晶/溶解反应的能力）的影响，并与传统三氯化铁前体（F10BC）衍生的磁性生物炭进行了比较。结果证实，生物炭产率与铁负载量之间存在直接关系，而与使用的磁性前体（α-FeOOH 或 FeCl）类型无关。虽然 FeCl 可以生成具有更高总碳含量（83.6%）和表面积（299 m/g）的磁性生物炭（F10BC），但α-FeOOH 更有效地生成具有纳米结构表面、更低水可提取成分（因此更环保；G10BC=0.21mg/mL 和 G10BC=0.16mg/mL）、更高磁饱和（G10BC=10.0 emu/g 和 G10BC=20.8 emu/g）、更高铁磁性和出色可回收性的磁性生物炭。在 G10BC 经过水热处理（超过 30 天）后，表面未检测到α-FeOOH，这表明它在面临通过α-FeOOH 再形成反应导致的退磁时具有稳定性。因此，本研究表明，将 10%的冷杉木生物质与固相α-FeOOH（混合）共热解提供了一种绿色、简便、高效的方法来热化学制备磁性生物炭。所制备的生物炭在水介质中对α-FeOOH 重构结晶/溶解反应具有极好的稳定性，具有绿色属性、良好的磁性和在经济许多领域的巨大潜在应用。
