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高锰酸钾改性椰壳生物炭对水中Cd(Ⅱ)和Ni(Ⅱ)的去除性能及机制
摘要点击 1240  全文点击 370  投稿时间:2022-07-24  修订日期:2022-08-16
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中文关键词  高锰酸钾改性  椰壳生物炭(MCBC)  Cd(Ⅱ)和Ni(Ⅱ)  吸附  去除性能及机制
英文关键词  potassium permanganate modification  coconut shell biochar(MCBC)  Cd(Ⅱ) and Ni(Ⅱ)  adsorption  removal performance and mechanism
作者单位E-mail
张凤智 桂林理工大学环境科学与工程学院, 桂林 541006 879400706@qq.com 
王敦球 桂林理工大学环境科学与工程学院, 桂林 541006
桂林理工大学岩溶地区水污染控制与用水安全保障协同创新中心, 桂林 541006
桂林理工大学广西环境污染控制理论与技术重点实验室, 桂林 541006 
 
曹星沣 桂林理工大学环境科学与工程学院, 桂林 541006  
刘桥京 桂林理工大学环境科学与工程学院, 桂林 541006  
岳甜甜 桂林理工大学环境科学与工程学院, 桂林 541006  
刘立恒 桂林理工大学环境科学与工程学院, 桂林 541006
桂林理工大学岩溶地区水污染控制与用水安全保障协同创新中心, 桂林 541006
桂林理工大学广西环境污染控制理论与技术重点实验室, 桂林 541006 
deanhenry_liu01@126.com 
中文摘要
      以高锰酸钾改性商业椰壳生物炭(MCBC)为吸附剂,探讨了它对Cd (Ⅱ)和Ni (Ⅱ)的去除性能及机制.当初始pH和MCBC投加量分别为5和3.0 g·L-1时,Cd (Ⅱ)和Ni (Ⅱ)的去除率均高于99%.Cd (Ⅱ)和Ni (Ⅱ)的去除更符合准二级动力学模型,表明它们的去除以化学吸附为主;Cd (Ⅱ)和Ni (Ⅱ)去除的控速步骤为快速去除阶段,而该阶段的速率取决于液膜扩散和颗粒内扩散(表面扩散).Cd (Ⅱ)和Ni (Ⅱ)主要通过表面吸附和孔隙填充附着在MCBC上,表面吸附的贡献更大;MCBC对Cd (Ⅱ)和Ni (Ⅱ)的饱和吸附量分别为57.18 mg·g-1和23.29 mg·g-1,约为前驱体(椰壳生物炭)的5.74倍和6.97倍.Cd (Ⅱ)和Ni (Ⅱ)的去除是自发的、吸热的,具有较为明显的化学吸附热力学特征.Cd (Ⅱ)通过离子交换、共沉淀、络合反应和阳离子-π相互作用附着在MCBC上;而Ni (Ⅱ)则是通过离子交换、共沉淀、络合反应和氧化还原反应被MCBC去除;其中,共沉淀和络合作用是Cd (Ⅱ)和Ni (Ⅱ)表面吸附的主要方式,且络合产物中无定形的Mn—O—Cd或Mn—O—Ni的占比可能会较高.研究结果将为商业生物炭在重金属废水处理中的实际应用提供重要的技术支持和理论依据.
英文摘要
      In this study, coconut shell biochar modified by KMnO4 (MCBC) was used as the adsorbent, and its removal performance and mechanism for Cd(Ⅱ) and Ni(Ⅱ) were discussed. When the initial pH and MCBC dosage were separately 5 and 3.0 g·L-1, respectively, the removal efficiencies of Cd(Ⅱ) and Ni(Ⅱ) were both higher than 99%. The removal of Cd(Ⅱ) and Ni(Ⅱ) was more in line with the pseudo-second-order kinetic model, indicating that their removal was dominated by chemisorption. The rate-controlling step for Cd(Ⅱ) and Ni(Ⅱ) removal was the fast removal stage, for which the rate depended on the liquid film diffusion and intraparticle diffusion (surface diffusion). Cd(Ⅱ) and Ni(Ⅱ) were mainly attached to the MCBC via surface adsorption and pore filling, in which the contribution of surface adsorption was greater. The maximum adsorption amounts of Cd(Ⅱ) and Ni(Ⅱ) by MCBC were individually 57.18 mg·g-1 and 23.29 mg·g-1, which were approximately 5.74 and 6.97 times that of the precursor (coconut shell biochar), respectively. The removal of Cd(Ⅱ) and Zn(Ⅱ) was spontaneous and endothermic and had obvious thermodynamic characteristics of chemisorption. Cd(Ⅱ) was attached to MCBC through ion exchange, co-precipitation, complexation reaction, and cation-π interaction, whereas Ni(Ⅱ) was removed by MCBC via ion exchange, co-precipitation, complexation reaction, and redox. Among them, co-precipitation and complexation were the main modes of surface adsorption of Cd(Ⅱ) and Ni(Ⅱ). Additionally, the proportion of amorphous Mn-O-Cd or Mn-O-Ni in the complex may have been higher. These research results will provide important technical support and theoretical basis for the practical application of commercial biochar in the treatment of heavy metal wastewater.

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