School of Civil & Environmental Engineering, National International Cooperation Base on Environment and Energy, University of Science and Technology Beijing, 30 Xueyuan Road, 100083 Beijing, PR China.
Environ Pollut. 2013 Sep;180:1-6. doi: 10.1016/j.envpol.2013.04.035. Epub 2013 May 25.
The environmental behavior of carbon nanotubes (CNTs) and humic acid (HA) is a prominent concern, but effect of functionalities on their sorption is not clear yet. Functionalized multi-walled CNTs (MCNT15) and HA were used to study their sorption behavior. Sorption rate of HA to MCNTs was dominantly controlled by its diffusion from liquid-MCNT boundary to MCNT surfaces. The sorption is in the sequence of MCNT15 > MCNT15-NH2 > MCNT15-OH > MCNT15-COOH > MCNT15-Ni, which was dependent on their surface area and meso- and macro-pore volume. The functionalities of MCNTs regulated the sorption by affecting their interaction mechanisms (i.e., H-bonding, π-π, and hydrophobic interaction). Additionally, the amount of these functionalities on the MCNT surface reduced indirectly the sorption sites due to the steric hindrance. Electrostatic repulsion deceased the sorption of HA by MCNTs with increasing pH. This study demonstrated the importance of functionalities on the MCNTs for the sorption of HA.
碳纳米管（CNTs）和腐殖酸（HA）的环境行为是一个突出的关注点，但功能对它们吸附的影响尚不清楚。本文使用功能化多壁 CNT（MCNT15）和 HA 来研究它们的吸附行为。HA 对 MCNTs 的吸附速率主要受其从液体-MCNT 边界扩散到 MCNT 表面的控制。吸附顺序为 MCNT15 > MCNT15-NH2 > MCNT15-OH > MCNT15-COOH > MCNT15-Ni，这取决于它们的表面积和中孔和大孔体积。MCNTs 的功能通过影响它们的相互作用机制（即氢键、π-π 和疏水相互作用）来调节吸附。此外，由于空间位阻，MCNT 表面上这些功能团的数量减少了吸附位点的数量。随着 pH 的增加，静电排斥会降低 HA 被 MCNTs 吸附的程度。本研究表明了 MCNTs 上功能团对 HA 吸附的重要性。
