Wang Bei, Ma Yayun, Cao Pan, Tang Xinde, Xin Junliang
School of Chemical and Environmental Engineering, Hunan Institute of Technology, Hengyang 421000, China.
School of Metallurgy and Environment, Central South University, Changsha 410083, China.
Molecules. 2024 Oct 30;29(21):5141. doi: 10.3390/molecules29215141.
Ball milling is a feasible and promising method of biochar modification that can significantly increase its adsorption ability to methylene blue (MB). This study synthesized nine biochars derived from water hyacinth under different pyrolysis temperatures and modified with ball milling and FeO. The structural properties of the pristine and ball-milled magnetic biochars were investigated and employed to adsorb MB. The results showed that ball milling significantly enhanced the specific surface area, total pore volume, and C-, N-, and O-containing groups of biochars, especially in low-temperature pyrolysis biochars. The Langmuir isotherm and the pseudo-secondary kinetic model fitted well with the MB adsorption process on biochars. After ball-milled magnetic modification, the adsorption capacity of biochar at 350 °C for MB was increased to 244.6 mg g (8-fold increase), owing to an increase in accessible functional groups. MB removal efficiencies by low-temperature pyrolysis biochars were easily affected by pH, whereas high-temperature pyrolysis biochars could effectively remove MB in a wide pH range. WQM1, with the high adsorption capacity and stability, provided the potential to serve as an adsorbent for MB removal. Based on DFT calculations, the chemisorption and electrostatic interactions were the primary mechanism for enhancing MB removal with ball-milled magnetic biochar at low-temperature pyrolysis, followed by H-bonding, π-π interaction, hydrophobic interaction, and pore filling.
球磨是一种可行且有前景的生物炭改性方法，能够显著提高其对亚甲基蓝（MB）的吸附能力。本研究合成了九种由水葫芦在不同热解温度下制备的生物炭，并通过球磨和FeO进行改性。对原始和球磨后的磁性生物炭的结构特性进行了研究，并用于吸附MB。结果表明，球磨显著提高了生物炭的比表面积、总孔体积以及含C、N和O的基团，特别是在低温热解生物炭中。Langmuir等温线和准二级动力学模型与生物炭对MB的吸附过程拟合良好。经过球磨磁性改性后，350℃下生物炭对MB的吸附容量提高到244.6 mg/g（增加了8倍），这归因于可及官能团的增加。低温热解生物炭对MB的去除效率容易受到pH值的影响，而高温热解生物炭能够在较宽的pH范围内有效去除MB。具有高吸附容量和稳定性的WQM1具有作为去除MB吸附剂的潜力。基于密度泛函理论计算，化学吸附和静电相互作用是低温热解球磨磁性生物炭增强MB去除的主要机制，其次是氢键、π-π相互作用、疏水相互作用和孔隙填充。
