In this study, gallic acid (GA), tannic acid (TA) and sodium dodecyl benzene sulfonate (SDBS) were chosen as surrogates of natural organic matter (NOM) to investigate the effects of chemical structures on carbon nanotubes (CNTs) suspension. The critical micelle concentration (CMC) of TA (CMCTA) was 1.12mmol/L and the CMCSDBS was 0.24mmol/L. But GA could not form micelles in the range of tested concentration. Comparing the adsorption process of NOM on CNTs and the dispersion process of CNTs, it was showed that steric hindrance and micellar encapsulation were the two main mechanisms for promoting CNTs dispersion. The transmission electron microscopy (TEM) and average hydrodynamic diameter (DLS) of suspended CNTs were measured. Less adsorption (Se ≈ 0.01mmol/g) for the rigid structure of TA can lead to higher CNT suspension than SDBS with the flexible structure which was hardly dispersed due to the entanglement of alkane chain on CNTs surface. The suspension of CNT was the worst in the plane structure GA (Se > 0.2mmol/g) due to the poor steric hindrance. The semi-micelles and micelles of SDBS (Se > 0.13mmol/g) can be formed over CMC. The suspension of CNT can be increased by the micellar wrapping. This study highlighted that the steric hindrance and micellar wrapping were the main dispersion mechanisms of CNTs, depending on different the NOM structures.
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