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 重庆大学学报  2018, Vol. 41 Issue (12): 46-54  DOI: 10.11835/j.issn.1000-582X.2018.12.006 RIS（文献管理工具） 0

### 引用本文

AN Qiang, JIANG Yunqiu, WU Danqing, CHEN Xuanbing. Response surface methodology study on optimal modification conditions for Ni(Ⅱ) adsorption in the water by peanut shell carbon[J]. Journal of Chongqing University, 2018, 41(12): 46-54. DOI: 10.11835/j.issn.1000-582X.2018.12.006.

### 文章历史

Response surface methodology study on optimal modification conditions for Ni(Ⅱ) adsorption in the water by peanut shell carbon
AN Qiang , JIANG Yunqiu , WU Danqing , CHEN Xuanbing
College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045, P. R. China
Supported by Chongqing Technology Innovation and Application Demonstration (Social and Livelihood) Project(cstc2018jscx-msybX0308)
Abstract: To improve the removal efficiency of nickel in the water and obtain a kind of adsorbent with low-cost and high efficiency, peanut shell carbon derived from waste peanut shell was produced and modified by potassium permanganate (KMnO4) and potassium (KOH). Box-Behnken design and response surface methodology were used to optimize the modification conditions of the carbon. SEM and BET were employed to characterize the morphological and structural changes of the peanut shell carbon before and after the modification. The modified peanut shell carbon before and after Ni (Ⅱ) adsorption was analyzed by FTIR to preliminarily discuss its adsorption mechanism. The results show that the best modification conditions are:temperature 361℃, the mass ratio of KOH to carbon 2.5 and the concentration of KMnO4 0.76%. Under these best modification conditions, the maximum adsorption capacity of nickel is 85.02 mg/g, which is 15.6 times higher than that of the carbon without modification, proving its superior adsorption performance and pragmatic value. The results of FTIR show that -OH and -NH2 are the main functional groups in the Ni (Ⅱ) adsorption process and they participate in the co-precipitation and complexation reactions with Ni (Ⅱ). Besides, the effect of cation-π is also one of the adsorption mechanisms of modified peanut shell carbon to Ni (Ⅱ).
Keywords: peanut shell carbon    modification    adsorption    nickel    response surface methodology    adsorption mechanism

1 材料与方法 1.1 材料

1.2 方法 1.2.1 改性花生壳炭的制备

1.2.2 改性花生壳炭吸附Ni(Ⅱ)的方法

1.2.3 Ni(Ⅱ)含量的测定

1.2.4 响应面实验设计

 $Y{\rm{ = }}{\mathit{\beta }_{\rm{0}}} + \sum\limits_{i = 1}^4 {{\mathit{\beta }_\mathit{i}}{\mathit{x}_\mathit{i}}} + \sum\limits_{i = 1}^4 {{\mathit{\beta }_{\mathit{ii}}}x_i^2} + \sum\limits_{i = 1}^4 {\sum\limits_{j \ge i}^4 {{\mathit{\beta }_{\mathit{ij}}}{x_\mathit{i}}{\mathit{x}_\mathit{j}}} } ,$ (1)

1.2.5 表征测试方法

2 结果与讨论 2.1 响应面实验结果

 $\begin{array}{l} Y\left( {{\rm{吸附量}}} \right) = 9.38\mathit{A }+{\rm{0}}{\rm{.813\;8}}\mathit{B }+{\rm{0}}{\rm{.551\;2}}\mathit{C }-{\rm{2}}{\rm{.71}}\mathit{AB }-{\rm{1}}{\rm{.69}}\mathit{AC }+\\ {\rm{\;\;\;\;\;\;\;\;\;\;\;\;\;\;}}0.367\;5\mathit{BC }-{\rm{20}}{\rm{.29}}{\mathit{A}^{\rm{2}}} - 3.76{B^2} - 1.74{\mathit{C}^{\rm{2}}}。\end{array}$ (2)
2.2 回归方程方差分析

2.3 响应面分析

 图 1 热处理温度和氢氧化钾与炭的质量比对Ni(Ⅱ)吸附量的影响：高锰酸钾质量浓度(75%) Figure 1 Effects of temperature and the mass ratio of KOH to carbon at a constant concentration of KMnO4(75%) on the adsorption capacity of Ni(Ⅱ)

 图 2 热处理温度与高锰酸钾的浓度对Ni(Ⅱ)吸附量的影响：氢氧化钾与炭的质量比(2.5) Figure 2 Effects of temperature and the concentration of KMnO4 at a constant mass ratio of KOH to carbon (2.5) on the adsorption capacity of Ni(Ⅱ)

 图 3 氢氧化钾与炭的质量比与高锰酸钾的浓度对Ni(Ⅱ)吸附量的影响：热处理温度(350 ℃) Figure 3 Effects of the constant mass ratio of KOH to carbon and the concentration of KMnO4 at a constant temperature (350 ℃) on the adsorption capacity of Ni(Ⅱ)

2.4 改性花生壳炭SEM、BET及Zeta电位分析

 图 4 改性前后花生壳炭的电子扫描显微镜照片 Figure 4 SEM images of peanut shell carbon before and after modification

2.5 吸附反应机理

 图 5 改性花生壳炭吸附Ni(Ⅱ)前后的红外光谱图 Figure 5 FTIR spectra for modified peanut shell carbon before and after Ni(Ⅱ) adsorption

 $2{\rm{O}}{{\rm{H}}^ - } + {\rm{N}}{{\rm{i}}^{2 + }} \to {\rm{Ni}}\left( {{\rm{O}}{{\rm{H}}_{\rm{2}}}} \right) \downarrow ,$ (3)
 ${\rm{R}} - {\rm{OH + N}}{{\rm{i}}^{2 + }} \to {\rm{R - O - Ni}}{\rm{。}}\$ (4)

 $- {\rm{N}}{{\rm{H}}_{\rm{2}}} + {\rm{N}}{{\rm{i}}^{{\rm{2 + }}}} \to - {\rm{N}}{{\rm{H}}_{\rm{2}}} - {\rm{Ni}}{\rm{。}}$ (5)

3 结论

1) 通过响应面模型得到花生壳炭的最优改性条件为：热处理温度361 ℃，氢氧化钾与炭的质量比2.5，高锰酸钾的质量浓度0.76%。在该条件下制备的改性花生壳炭对Ni(Ⅱ)的吸附量为85.02 mg/g，是改性前的15.6倍，吸附性能得到较大改善，能够更高效的去除水中的重金属Ni(Ⅱ)，具有很好的实用价值。

2) SEM结果显示改性后花生壳炭的粒径相较改性前变小，表面更为粗糙，出现微孔结构。BET结果表明改性后材料的比表面积和平均孔容增加，平均孔径减小，更有利于吸附水中的Ni(Ⅱ)。中性条件下测得改性后的花生壳炭Zeta电位的绝对值大于改性前，说明改性提高了材料的分散度与稳定性。

3) 对吸附反应前后的改性花生壳炭进行FTIR分析，结果表明-OH、-NH2是参与吸附反应的主要官能团，这些官能团与Ni(Ⅱ)发生共沉淀反应与络合反应。除此之外，改性花生壳炭芳香环中的π共轭芳香结构可以作为电子供体与溶液中的Ni2+产生较弱的阳离子-π作用，从而将Ni2+吸附至碳材料的表面或孔中。