School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China; Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Hefei, 230601, China.
School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China.
Chemosphere. 2023 Jul;330:138701. doi: 10.1016/j.chemosphere.2023.138701. Epub 2023 Apr 14.
Removal of heavy metals (e.g., Cd) from contaminated water using waste-converted adsorbents is promising, but the efficiency still needs to be improved. Here, we prepared a functional biochar composite as novel Cd adsorbents by co-pyrolysis of two typical solid wastes, i.e., agricultural corn straw and industrial fly ash. The adsorption behavior and mechanism were investigated using batch and column adsorption experiments and modern characterization techniques. Results showed that alkali-modified fly ash (AMFA) was loaded onto the surface of the corn straw biochar as some fine particle forms, with quartz (SiO) and silicate being the main mineral phases on the surface. The maximum sorption capacity fitted by Langmuir model for functionalized biochar composite (FBC700) was up to 137.1 mg g, which was 7.7 times higher than that of the original corn straw biochar (BC700). Spectroscopic analysis revealed that adsorption mechanisms of Cd onto the FBC700 included mainly precipitation and ion exchange, with complexation and Cd-π interaction also contributing. The AMFA could effectively improve the mineral precipitation with Cd. The adsorption columns filled with FBC700 exhibited a longer breakthrough time than that filled with BC700. The adsorption capacity calculated by Thomas model for FBC700 was also approximately 6.0 times higher than that for BC700, showing that FBC700 was more suited to practical applications. This study provided a novel perspective for recycling solid wastes and treating Cd-contaminated water.
利用废弃转化吸附剂从受污染的水中去除重金属（如 Cd）具有广阔的前景，但效率仍需提高。在这里，我们通过共热解两种典型的固体废物，即农业玉米秸秆和工业粉煤灰，制备了一种新型的 Cd 吸附剂功能生物炭复合材料。通过批量和柱吸附实验以及现代表征技术研究了吸附行为和机制。结果表明，碱改性粉煤灰（AMFA）以一些细颗粒的形式负载在玉米秸秆生物炭的表面上，表面的主要矿物相是石英（SiO）和硅酸盐。功能化生物炭复合材料（FBC700）的最大吸附容量符合 Langmuir 模型，达到 137.1 mg g，是原始玉米秸秆生物炭（BC700）的 7.7 倍。光谱分析表明，Cd 吸附到 FBC700 上的机制主要包括沉淀和离子交换，配合作用和 Cd-π 相互作用也有贡献。AMFA 可以有效地促进 Cd 的矿物沉淀。填充 FBC700 的吸附柱的穿透时间比填充 BC700 的吸附柱的穿透时间长。Thomas 模型计算的 FBC700 的吸附容量也比 BC700 高约 6.0 倍，表明 FBC700 更适合实际应用。本研究为回收固体废物和处理 Cd 污染水提供了新的视角。
