Effects of carbon nanotubes on phosphorus adsorption behaviors on aquatic sediments
Effects of carbon nanotubes on phosphorus adsorption behaviors on aquatic sediments
复制标题
碳纳米管对水生沉积物磷吸附行为的影响
DOI：
10.1016/j.ecoenv.2017.04.017
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发表时间：
2017
影响因子：
6.8
通讯作者：
Lu Bianhe
中科院分区：
文献类型：
--
作者：
Qian Jin;Li Kun;Wang Peifang;Wang Chao;Shen Mengmeng;Liu Jingjing;Tian Xin;Lu Bianhe
水生沉积物被认为是碳纳米管（CNTs）的重要汇。碳纳米管具有新颖的性质，可能会干扰沉积物中共存污染物的命运和流动性。以前只研究了有毒污染物，据我们所知，没有关于碳纳米管如何影响水生沉积物对磷（P）吸附的数据。在这项研究中，多壁碳纳米管（MWCNTs）被选为模型碳纳米管。实验结果表明，与准一级模型和颗粒内扩散模型相比，准二级模型更适合描述沉积物和多壁碳纳米管污染沉积物的吸附动力学.吸附等温线的研究表明，Langmuir模型拟合的等温线数据。随着碳纳米管与沉积物比例从0.0%增加到5.0%，理论最大单分子层吸附容量（Qmax）从0.664增加到0.996 mg/g。然而，Langmuir等温线系数（KL）从4.231 L/mg显著降低到2.874 L/mg，表明多壁碳纳米管污染后沉积物对磷的吸附自由能降低。结果表明，沉积物再悬浮后，磷更容易释放到上覆水中。此外，沉积物和沉积物-多壁碳纳米管混合物的吸附是吸热和物理性质。结果表明，沉积物的比表面积和zeta电位的变化与多壁碳纳米管的污染有关，多壁碳纳米管的大吸附量可能是导致沉积物对磷吸附量变化的主要因素。
Aquatic sediments are believed to be an important sink for carbon nanotubes (CNTs). With novel properties, CNTs can potentially disturb the fate and mobility of the co-existing contaminants in the sediments. Only toxic pollutants have been investigated previously, and to the best of our knowledge, no data has been published on how CNTs influence phosphorus (P) adsorption on aquatic sediments. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as model CNTs. Experimental results indicated that compared to pseudo-first order and intraparticle diffusion models, the pseudo-second-order model is better for describing the adsorption kinetics of sediments and MWCNT-contaminated sediments. Adsorption isotherm studies suggested that the Langmuir model fits the isotherm data well. With the increase in the MWCNT-to-sediment ratio from 0.0% to 5.0%, the theoretical maximum monolayer adsorption capacity (Qmax) for P increased from 0.664 to 0.996 mg/g. However, the Langmuir isotherm coefficient (KL) significantly decreased from 4.231 L/mg to 2.874 L/mg, indicating the decrease in the adsorption free energy of P adsorbed on the sediments after MWCNT contamination. It was suggested that P was released more easily to the overlying water after the re-suspension of sediments. Moreover, the adsorption of sediments and sediment-MWCNT mixture was endothermic and physical in nature. Results obtained herein suggested that the change in the specific surface area and zeta potential of sediments is related to MWCNT contamination, and the large adsorption capacity of MWCNTs is probably the main factor responsible for the variation in the adsorption of P on aquatic sediments.