The effect of ionic strength and pH on the stability of tannic acid-facilitated carbon nanotube suspensions
The effect of ionic strength and pH on the stability of tannic acid-facilitated carbon nanotube suspensions
复制标题
离子强度和pH值对单宁酸促进碳纳米管悬浮液稳定性的影响
DOI：
10.1016/j.carbon.2009.06.036
复制
发表时间：
2009-10-01
期刊：
影响因子：
10.9
通讯作者：
Xing, Baoshan
中科院分区：
文献类型：
--
作者：
Lin, Daohui;Liu, Ni;Xing, Baoshan
碳纳米管由于其高的疏水性和长径比，在水中容易聚集和沉淀。然而，据报道，添加溶解的有机物（DOM）分散和稳定某些碳纳米管，这表明碳纳米管在自然水环境中的潜在运输和生物利用度。为了更好地理解CNT-DOM相互作用，使用外径为10（MWCNT 10）、10 - 20（MWCNT 20）、20 - 40（MWCNT 40）、40 - 60（MWCNT 60）和60 - 100 nm的五个多壁CNT，以多壁碳纳米管（MWCNT 100）为吸附剂，研究了它们在单宁酸溶液中的吸附和悬浮行为（TA，作为DOM替代物）溶液;检查了离子强度和pH对TA-CNT相互作用的影响。随着TA浓度的增加，MWCNTs的悬浮液急剧改善，并在TA初始浓度约为1000 μ g/L时趋于稳定。20 mg/L。MWCNT的悬浮顺序为MWCNT 40> MWCNT 60> MWCNT 20> MWCNT 100> MWCNT 10。TA稳定的CNT在pH 5 - 11内是稳定的，而它们在pH <5时快速沉淀。不同的离子（Na+，Mg2+，Ca2+，或La3+）聚集的稳定的碳纳米管，具有指数相关的离子价的临界凝聚浓度。空间排斥和静电相互作用的变化与TA的加入可以解释碳纳米管的稳定性的变化。(C)2009爱思唯尔有限公司保留所有权利。
Carbon nanotubes (CNTs) are prone to aggregation and precipitation in water due to their high hydrophobicity and aspect ratio. However, the addition of dissolved organic matter (DOM) has been reported to disperse and stabilize certain CNTs, suggesting the potential transport and bioavailability of CNTs in natural aqueous environments. For a better understanding of the CNT-DOM interaction, five multiwalled CNTs with outer diameters of 10 (MWCNT10), 10-20 (MWCNT20), 20-40 (MWCNT40), 40-60 (MWCNT60), and 60-100 nm (MWCNT100) were used to investigate their sorptive and suspension behavior in tannic acid (TA, as a DOM surrogate) solution; the effects of ionic strength and pH on the TA-CNT interaction were examined. Suspension of MWCNTs sharply improved with increasing TA concentration and leveled off at an initial TA concentration ca. 20 mg/L. Suspension of MWCNTs was in the order of MWCNT40 > MWCNT60 > MWCNT20 > MWCNT100 > MWCNT10. The TA-stabilized CNTs were stable within pH 5-11, while they quickly precipitated at pH < 5. Different ions (Na+, Mg2+, Ca2+, or La3+) aggregated the stabilized CNTs, with a critical coagulation concentration exponentially correlated to ionic valence. Changes of steric repulsion and electrostatic interaction with the added TA could account for the variation of CNT stability. (C) 2009 Elsevier Ltd. All rights reserved.