中文关键词
生物炭铁锰氧化物硝酸根吸附动力学等温吸附 | 英文关键词biochariron and manganese oxidesnitratesorption kineticadsorption isotherms |
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| 中文摘要 |
| 热解经过氯化铁和高锰酸钾浸渍的小麦秸秆，制备铁锰金属氧化物/生物炭复合材料，用以去除水中硝酸根.通过X射线光电子能谱和扫描电镜分析，发现复合材料表面形成了Fe（Ⅲ）/Mn（Ⅳ）二元金属氧化物颗粒.制备优化结果表明，复合材料比表面积可达153.116 m2 ·g-1，零电荷点可达9.76.同时，还调查了固液比、溶液初始pH值和共存阴离子等因素的影响.研究发现，复合材料在溶液pH值1.00~9.05时对NO3-的去除率维持在75.40%~78.70%，且以配位交换为主要吸附机制.共存阴离子对吸附NO3-竞争吸附的影响顺序为：Cl->SO42->PO43-.等温吸附实验数据符合Langmuir方程，且最大吸附量为37.3613 mg ·g-1.吸附动力学分析发现，吸附过程遵循二级动力学方程，且以化学吸附为主.热动力学分析表明，吸附过程为自发吸热过程.上述结果说明铁锰氧化物/生物炭复合材料对于去除水中NO3-具有潜在价值. |
| 英文摘要 |
| 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 m2·g-1 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- > SO42- > PO43-. 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-1 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. |
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