| pH和Ni2+对人工纳米氧化硅吸附菲的影响 |
| 摘要点击 1700 全文点击 864 投稿时间：2011-10-10 修订日期：2012-01-11 |
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| 中文关键词 纳米氧化硅 菲 吸附 金属离子 pH 能量分布 |
| 英文关键词 nano-silica phenanthrene sorption metal ion pH energy distribution |
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| 中文摘要 |
| 为了揭示菲在人工纳米氧化硅上的吸附行为,采用批量平衡实验对比研究了灼烧前后纳米氧化硅对菲的吸附,考察了pH值和重金属离子(Ni2+)对吸附行为的影响,并应用位点能量分布模型分析了菲吸附行为的变化. 结果表明,吸附数据可用Freundlich模型较好地拟合,高温灼烧后纳米氧化硅对菲的吸附增加,lgKF由1.48增加到2.43; 吸附的非线性也增加,结合孔分布及表面积变化,说明纳米氧化硅对菲的吸附为孔填充与表面吸附共同作用,内部孔对菲的吸附起主要作用. pH值的变化没有显著改变原始纳米氧化硅对菲的吸附; 但是显著影响灼烧后纳米氧化硅对菲的吸附,吸附随着pH值的增加而降低,pH值由4.0增加到8.0,lgKF减少了73.7%. 主要因为提高pH值,可明显增加灼烧纳米氧化硅的表面电荷,降低孔的可及性. 不同浓度的Ni2+对菲吸附的影响不同,在Ni2+低浓度时(<5 mmol ·L-1),表现为吸附抑制; 在Ni2+高浓度时,对低浓度菲 (50 μg ·L-1) 表现为促进吸附,对高浓度菲 (500 μg ·L-1) 吸附的抑制程度不再增加. 这是多个机制共同作用的结果. |
| 英文摘要 |
| In order to reveal the sorption behavior of phenanthrene (PHE) on engineered nano-silica, batch equilibriums were conducted to study the effects of heating, solution pH, and heavy metal ion (Ni2+) on PHE sorption, and a site energy distribution model was used to analyze the changes of sorption behavior. The results demonstrated that the sorption isotherm of PHE could be fitted well by the Freundlich model. The sorption capacity of the original nano-silica (PNS) was enhanced by heating (heated nano-silica, HNS), with the Freundlich adsorption coefficient (lgKF) increasing from 1.48 to 2.43. The nonlinearity of sorption isotherm increased after heating. The sorption characteristics together with pore distribution and surface area analysis suggested that PHE sorption on nano-silica was a combination of pore-filing and surface sorption, with the microspores and mesopores of nano-silica playing a major role. While changes in solution pH did not show a significant effect on the sorption of PHE on PNS, the sorption of PHE on HNS decreased significantly with increasing pH, with lgKF reducing by 73.7% when pH increased from 4.0 to pH 8.0. The pH caused differences in sorption capacity could be mainly explained by zeta potentials of nanoparticles. High pH enhanced the charge of nanoparticles, and reduced the pore accessibility. The effect of Ni2+ on PHE sorption on HNS varied with its concentration. At low concentration (<5 mmol ·L-1), Ni2+suppressed PHE sorption, while at a higher concentration, Ni2+ enhanced the sorption of PHE at a lower concentration (50 μg ·L-1), and the inhibition on the sorption of PHE at a higher concentration (500 μg ·L-1) did not increase further. This complex pattern was a result of concurrence of multiple processes. |
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