Optimizing sonication parameters for dispersion of single-walled carbon nanotubes

► We study the optimization of sonication for the surfactant-based dispersion of SWCNTs. ► The absorption spectrum of SWCNT solution strongly depend on the sonication conditions. ► The sonication process has an important influence on the average length and diameters of SWCNTs in solution. ► Centrifugation mainly contributes to the decrease of nonresonant absorption background. ► Under the same sonication parameters, the large-diameter tip performs dispersion of SWCNTs better than the small-diameter tip.