Abstract

Two sizes of particles have been employed from wood-derived biochar which produced by slow pyrolysis at 650°C under Ar gas flow to investigate size and dosage effects of biochar at cadmium (Cd) sorption via batch experiment in a sandy soil. The macro (MBC) (0.5–1 mm) and nano size (NBC) of biochar divided by sieving and milling by planetary ball mill processes from pristine biochar, respectively. X-ray diffraction analysis of NBC indicated the presence of magnesian-calcite mineral with turbostratic crystallites. Also, NBC differs from MBC by a higher intensity and different types of surface functional groups such as hydroxyl and carboxyl, and by more polarity, aromaticity and less C–C bands based on FTIR analysis. The zeta potential of NBC ranged from +16.2 to –71.8 mV which can be an effective factor in the agglomeration of particles. NBC particles have a higher specific surface area (approximately 210%) and total pore volume and external surface area, and greater mean pore diameter than MBC. Isotherm equations, namely, Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich were applied to evaluate which model provides the best fit predicted data with experimental results. The Langmuir isotherm provided the best fit according to adjusted R² and reduced chi-square parameters. By adding 2% (w/w) of MBC and NBC to sandy soil samples, maximum sorption of cadmium reached 328.9 and 1062.4 mg kg^–1 which were 58.6% and 412.2% more than control soil. The findings of the study confirmed that ball milling proposes nanobiochar which is more effective at cadmium sorption from contaminated solutions.

中文翻译：

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在沙土中使用球磨制得的生物炭纳米颗粒增强对镉的吸附

摘要

已通过在Ar气流下于650°C的慢速热解过程中产生的木材衍生生物炭使用了两种尺寸的颗粒，以通过在砂质土壤中进行分批实验研究生物炭在镉（Cd）吸附中的尺寸和剂量效应。生物炭的宏观尺寸（MBC）（0.5-1毫米）和纳米尺寸（NBC）分别通过行星式球磨工艺从原始生物炭中过筛和研磨而得到。NBC的X射线衍射分析表明存在镁铝方解石矿物和涡轮层晶。同样，NBC与MBC的区别还在于强度更高和不同类型的表面官能团（例如羟基和羧基），以及基于FTIR分析的更多极性，芳香性和更少的C–C谱带。NBC的ζ电位在+16.2至–71.8 mV的范围内，这可能是粒子聚集的有效因素。与MBC相比，NBC颗粒具有更高的比表面积（约210％），总孔体积和外表面积，以及更大的平均孔径。等温方程，即Freundlich，Langmuir，Temkin和Dubinin–Radushkevich被用于评估哪种模型可以提供最佳拟合预测数据和实验结果。Langmuir等温线根据调整后的R提供了最佳拟合^2，并减少卡方参数。通过在砂质土壤样品中添加2％（w / w）的MBC和NBC，镉的最大吸收量达到328.9和1062.4 mg kg ^-1，比对照土壤分别高58.6％和412.2％。该研究的结果证实了球磨技术提出了纳米生物炭，它对被污染溶液中的镉吸附更有效。