Ultrasound regeneration of multi wall carbon nanotubes saturated by humic acid

The main purpose of this study was to evaluate the efficiency of ultrasound technique for regeneration of multi wall carbon nanotubes exhausted by humic acid. Carbon nanotubes (CNTs) were prepared by chemical vapor deposition method in the presence of Co-Mg/MgO as the catalyst. Results of ultrasound regeneration (in frequencies of 130 and 35 kHz) showed higher regeneration efficiency at 130 kHz after five cycles of regeneration. The slight decrease in adsorption capacity after each regeneration cycle may be due to the deposition of decomposed residues in CNT pores, which blocked carbon porosity and decreased specific surface area. In conclusion, ultrasonic regeneration showed the possibility as an alternative to chemical and thermal regeneration of CNTs.