| Carbon Nanotubes (CNTs) had been used in our daily life due to its excellent physical and chemical properties. With the force of environment, some CNTs would release into the environment, CNTs’ behavior in aqueous environment was an important problem which attracted many researchers’ attention. In aqueous environment, CNTs would aggregate and deposit to the sediment matrix because of hydrophobility, it could be affected by many factors such as agitation and lots of depositing CNTs would be suspended again. When DOM adsorbed on the surface of CNTs, CNTs suspension would promote. However, the mechanism that DOM enhanced CNTs suspension was not clear because the DOM’s structure and properties were very complex. What’s more, DOM was complex that consisted of lots of material. For different properties of DOM, the mechanism suspended CNTs might be different. Our paper used simply chemical models of DOM(Tannic Acid and Gallic Acid) and three CNTs which with different oxygen content, to investigate the effect of adsorbed molecular structure and properties of CNTs on CNTs suspension, and the next step was classified adsorption of HA on CNTs and classification of CNTs itself, aimed to understand the mechanism of HA and CNTs’ properties enhanced CNTs suspension. The main results were as follows:1. Ultrasonic wave could enhance CNTs suspension, and did not enhance adsorption of TA and GA on CNTs obviously. Adsorption capacity of TA was higher than of GA on CNTs, VDW and π-π bond are main adsorption mechanism. CNTs suspension could attribute to TA and GA adsorbed. At low adsorption capacity, TA presented stronger ability to enhance CNTs suspension due to TA’s high molecular weight and stero saptial structure. While at high adsorption capacity, ability of GA was higher than of TA because surface charge. Compared to MG, MH and MC which contained higher oxygen content suspension were better. The dispersion of CNTs by organic matter was not only controlled by the apparent adsorption of organic matter but also the molecular morphology and chemical properties of organic matter as good as chemical properties of CNTs.2. HA adsorbed on MH and MG presented classification, adsorption capacity increased with increasing classification. The adsorption process would be as follows, rigid and aromatic large molecular adsorbed on CNTs surface firstly, and then flexible and aromatic large molecular adsorbed, rigid and flexible aromatic small molecular adsorbed finally. The mechanism of HA adsorbed were π-π, hydrophobicity and hydrogen bond, π-π bond could be main. Classification of HA on MH was clearer than on MG, the reason might the MH with negative charge could reject some charged molecular. The effect of classified HA on CNTs suspension presented that stability of CNTs deceased with creasing classification. That would due to rigid and aromatic large molecular adsorbed firstly showed stronger steric hindrance than other molecules, it might present that steric hindrance was an important factor for CNTs suspension. Stability of MH with higher oxygen content was higher than of MG. Electrostatic repulsion contributed CNTs suspension could not as well as stories hindrance. The particle size of CNTs suspension, which could be good for CNTs suspension was75-85nm.3. CNTs in the HA solution presented that stability, increased before and reduced to the adsorption capacity increased. By analyzing, ruled out the distribution and confirmed the classification of CNTs itself. CNTs with shorter pipe, it stability was better than long one which could twine and aggregate. The oxygen content of CNTs was a factor that leaded classification of CNTs. The thermo-stability of MG was better than MH, it due to modified MH’s surface had more defects than MG. |
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