Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences , Post Office Box 1126, Hefei 230031, People's Republic of China.
Environ Sci Technol. 2011 Apr 15;45(8):3621-7. doi: 10.1021/es104047d. Epub 2011 Mar 11.
This paper examines the adsorption of Pb(II) and a natural organic macromolecular compound (humic acid, HA) on polyacrylamide (PAAM) -grafted multiwalled carbon nanotubes (denoted as MWCNTs/PAAM), prepared by an N(2)-plasma-induced grafting technique. The mutual effects of HA/Pb(II) on Pb(II) and HA adsorption on MWCNTs/PAAM, as well as the effects of pH, ionic strength, HA/Pb(II) concentrations, and the addition sequences of HA/Pb(II) were investigated. The results indicated that Pb(II) and HA adsorption were strongly dependent on pH and ionic strength. The presence of HA led to a strong increase in Pb(II) adsorption at low pH and a decrease at high pH, whereas the presence of Pb(II) led to an increase in HA adsorption. The adsorbed HA contributed to modification of adsorbent surface properties and partial complexation of Pb(II) with the adsorbed HA. Different effects of HA/Pb(II) concentrations and addition sequences on Pb(II) and HA adsorption were observed, indicating different adsorption mechanisms. After adsorption of HA on MWCNTs/PAAM, the adsorption capacity for Pb(II) was enhanced at pH 5.0; the adsorption capacity for HA was also enhanced after Pb(II) adsorption on MWCNTs/PAAM. These results are important for estimating and optimizing the removal of metal ions and organic substances by use of MWCNT/PAAM composites.
本文研究了聚丙酰胺（PAAM）接枝多壁碳纳米管（MWCNTs/PAAM）对 Pb(II)和天然有机大分子化合物（腐殖酸，HA）的吸附作用。采用 N(2)-等离子体诱导接枝技术制备了 MWCNTs/PAAM。研究了 HA/Pb(II) 对 MWCNTs/PAAM 上 Pb(II)和 HA 吸附的相互影响，以及 pH 值、离子强度、HA/Pb(II)浓度和 HA/Pb(II)添加顺序的影响。结果表明，Pb(II)和 HA 的吸附强烈依赖于 pH 值和离子强度。HA 的存在会导致低 pH 值下 Pb(II)吸附的强烈增加和高 pH 值下的减少，而 Pb(II)的存在会导致 HA 吸附的增加。吸附的 HA 有助于改变吸附剂表面性质和部分 Pb(II)与吸附的 HA 的络合。观察到 HA/Pb(II)浓度和添加顺序对 Pb(II)和 HA 吸附的不同影响，表明存在不同的吸附机制。在 HA 吸附到 MWCNTs/PAAM 上后，在 pH 值为 5.0 时，对 Pb(II)的吸附容量增强；在 MWCNTs/PAAM 上吸附 Pb(II)后，对 HA 的吸附容量也增强。这些结果对于估计和优化使用 MWCNT/PAAM 复合材料去除金属离子和有机物质非常重要。
