Cui Zhi-Wen, Ren Yan-Fang, Wang Wei, Zhang Li-Ming, Zhang Lu-Yun, Wang Xi-Yue, He Jun-Yu
School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
Jiangsu Petrochemical Safety and Environmental Engineering Research Center, Changzhou 213164, China.
Huan Jing Ke Xue. 2020 Jul 8;41(7):3315-3325. doi: 10.13227/j.hjkx.201912025.
Wheat straw biochar (BC) was modified by KOH and magnetics to generate composited modified biochar (FKC). Based on characterization by scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and magnetic (VSM) techniques, the adsorption characteristics and mechanisms of Cd in water and the effects of temperature, pH value, and dosage on the adsorption characteristics of FKC were studied. The results showed that the modified biochar was loose and porous. The specific surface area of FKC increased by 19.11 times, the number of aromatic and oxygen-containing functional groups such as O-H, C=O, and C=C increased, and a new functional group Fe-O formed compared to the BC. FKC is magnetic, and its magnetization is 8.43 emu·g, which can be recycled and reused. The adsorption of Cd by FKC fitted well with the pseudo-second-order kinetic model and the Langmuir model, indicating that chemical adsorption is the main adsorption mechanism. The theoretical maximum equilibrium adsorption capacity of FKC is 23.44 mg·g, which is 1.47 times that of BC. The thermodynamic parameters suggested the adsorption of Cd by FKC was a spontaneous and endothermic process. The adsorption capacity increased with an increase of pH in the region 2-8, and a biochar dosage of 10 g·L was used. After three cycles of adsorption-desorption-adsorption, the adsorption capacity of Cd by FKC still reached 17.71 mg·g, indicating that FKC has good reusability. These results can provide a theoretical basis for the application of KOH and magnet-modified biochar from wheat straw to remove heavy metals from contaminated wastewater.
通过KOH和磁性物质对小麦秸秆生物炭（BC）进行改性，制备了复合改性生物炭（FKC）。基于扫描电子显微镜-能谱仪（SEM-EDS）、布鲁诺尔-埃米特-泰勒（BET）、傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）和磁性（VSM）技术表征，研究了FKC对水中Cd的吸附特性及机理，以及温度、pH值和投加量对FKC吸附特性的影响。结果表明，改性生物炭结构疏松、多孔。与BC相比，FKC的比表面积增大了19.11倍，O-H、C=O和C=C等芳香族和含氧官能团数量增加，且形成了新的官能团Fe-O。FKC具有磁性，其磁化强度为8.43 emu·g，可回收再利用。FKC对Cd的吸附符合准二级动力学模型和朗缪尔模型，表明化学吸附是主要吸附机制。FKC的理论最大平衡吸附量为23.44 mg·g，是BC的1.47倍。热力学参数表明，FKC对Cd的吸附是一个自发的吸热过程。在pH值为2-8的范围内，吸附量随pH值升高而增大，生物炭投加量为10 g·L。经过三次吸附-解吸-吸附循环后，FKC对Cd的吸附量仍达到17.71 mg·g，表明FKC具有良好的重复使用性。这些结果可为利用KOH和磁性改性小麦秸秆生物炭去除污染废水中重金属的应用提供理论依据。
