Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing 100083, China; Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA.
Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA.
Sci Total Environ. 2020 Jun 20;722:137972. doi: 10.1016/j.scitotenv.2020.137972. Epub 2020 Mar 16.
Magnetic carbonaceous adsorbents were synthesized by ball-milling biochar (BC) or activated carbon (AC) with FeO nanoparticles, and their capacities to sorb methylene blue (MB) from water were evaluated and compared. Ball milling with magnetite not only improved the surface properties of the carbonaceous adsorbents, especially BC, but also introduced magnetic properties through mechanical extrusion. Furthermore, ball-mill extrusion increased the MB adsorption capacity of BC at all pH values by 14-fold, on average, but BC ball milled with magnetite had even greater MB adsorption capacity (27-fold, greater, on average). While ball milling of AC also improved its MB adsorption capacity (by almost 3-fold, on average), ball milling with magnetite did not further improve its MB adsorption capacity. All the magnetic adsorbents showed fast MB adsorption kinetics, reaching equilibrium within about 8 h. The Langmuir maximum MB adsorption capacity of the magnetic ball-milled BC (MBM-BC) was the highest (500.5 mg/g) among all the samples including the ones derived from AC. After five adsorption-desorption cycles, MBM-BC maintained about 80% MB removal capacity. The high MB adsorption capacity of MBM-BC was attributed to its increased surface area, opened pore structure, functional groups and aromatic CC bonds, which promoted π-π and electrostatic interactions. Findings from this study indicate that the magnetic ball-milled BC is a promising adsorbent due to its environmentally friendly synthesis, high efficiency, low cost, and convenience in operation.
磁性碳质吸附剂是通过将生物炭（BC）或活性炭（AC）与 FeO 纳米颗粒球磨合成的，评估并比较了它们从水中吸附亚甲基蓝（MB）的能力。与磁铁矿一起球磨不仅改善了碳质吸附剂的表面性质，尤其是 BC，而且通过机械挤压引入了磁性。此外，球磨挤压平均将 BC 在所有 pH 值下的 MB 吸附能力提高了 14 倍，但经磁铁矿球磨的 BC 的 MB 吸附能力更高（平均增加 27 倍）。虽然 AC 的球磨也提高了其 MB 吸附能力（平均提高近 3 倍），但磁铁矿的球磨并没有进一步提高其 MB 吸附能力。所有磁性吸附剂均表现出快速的 MB 吸附动力学，在 8 小时内即可达到平衡。所有样品中，包括源自 AC 的样品，磁性球磨 BC（MBM-BC）的最大 MB 吸附容量最高（500.5mg/g）。经过五次吸附-解吸循环后，MBM-BC 仍保持约 80%的 MB 去除能力。MBM-BC 具有较高的 MB 吸附容量，这归因于其增加的表面积、开放的孔结构、官能团和芳族 CC 键，这些促进了π-π 和静电相互作用。本研究结果表明，由于其环保合成、高效、低成本和操作方便，磁性球磨 BC 是一种很有前途的吸附剂。
