Zheng Xiao-Qing, Wei An-Lei, Zhang Yi-Xuan, Shi Liang-Yu, Zhang Xiao
College of Urban and Environment Sciences, Northwest University, Xi'an 710127, China.
Huan Jing Ke Xue. 2018 Mar 8;39(3):1220-1232. doi: 10.13227/j.hjkx.201704216.
In this study, we synthesized Fe/Mn bimetallic oxide coated biochar sorbents by pyrolysis of wheat straw impregnated with ferric chloride and potassium permanganate and investigated their potential to adsorb nitrate in water. X-ray photoelectron spectroscopy and scanning electron microscopy analysis suggests that Fe(Ⅲ)/Mn(Ⅳ) bimetallic oxide particles emerge on the sorbents. The optimized sorbent could achieve a specific surface area of 153.116 m·g and a point of zero charge of 9.76. Batch nitrate adsorption experiments were carried out to investigate the influence of various factors, such as sorbent dosage, initial solution pH, and co-existing anions. Results show that the sorbent maintained a high adsorption capacity of 75.40%-78.70% over a wide range of pH from 1.00 to 9.05, and the sorption mechanism was interpreted as ligand exchange. The effects of co-existing anions on the nitrate sorption followed the decreasing order of Cl > SO > PO. Furthermore, the adsorption isotherms were well described by the Langmuir model, and the sorbent could exhibit a quite competitively high capacity of 37.3613 mg·g for nitrate removal. In addition, the accordance of sorption kinetics with the pseudo-second order model implied that the sorption could be a multi-stage controlled chemical process. In addition, the thermodynamic parameters suggested that the sorption reaction could be a spontaneous and endothermic process. The results demonstrated that the Fe/Mn bimetallic oxide coated biochar could serve as a promising agent for nitrate removal from water.
在本研究中，我们通过对浸渍有氯化铁和高锰酸钾的小麦秸秆进行热解，合成了铁/锰双金属氧化物包覆的生物炭吸附剂，并研究了它们对水中硝酸盐的吸附潜力。X射线光电子能谱和扫描电子显微镜分析表明，吸附剂上出现了Fe(Ⅲ)/Mn(Ⅳ)双金属氧化物颗粒。优化后的吸附剂比表面积可达153.116 m²·g，零电荷点为9.76。进行了批量硝酸盐吸附实验，以研究各种因素的影响，如吸附剂用量、初始溶液pH值和共存阴离子。结果表明，该吸附剂在1.00至9.05的较宽pH范围内保持75.40%-78.70%的高吸附容量，吸附机理被解释为配体交换。共存阴离子对硝酸盐吸附的影响顺序为Cl＞SO＞PO。此外，吸附等温线能用Langmuir模型很好地描述，该吸附剂对硝酸盐去除的吸附容量可达37.3613 mg·g，具有相当高的竞争力。此外，吸附动力学与准二级模型的一致性表明吸附可能是一个多阶段控制的化学过程。此外，热力学参数表明吸附反应可能是一个自发的吸热过程。结果表明，铁/锰双金属氧化物包覆的生物炭可作为一种有前景的从水中去除硝酸盐的试剂。
