Cobalt particles encapsulated and nitrogen-doped bamboo-like carbon nanotubes as a catalytic and adsorptive bifunctional material for efficient removal of organic pollutants from wastewater

Bifunctional materials having both good catalytic and adsorptive performances are promising in the field of wastewater treatment. Cobalt-encapsulated and nitrogen-doped bamboo-like carbon nanotubes (Co/N-CNTs) were prepared by a simple method of calcination and acid treatment with Co3[Co(CN)6]2 as a precursor. Based on a series of characterization and performance studies, Co/N-CNTs were confirmed to be able to function as both a catalyst and an adsorbent for oxidative degradation of organic pollutants in the presence of peroxymonosulfate (PMS). When rhodamine B was used as a typical dye pollutant, it was found that all the added pollutant (10 mg L−1) was completely removed in 7 min by using 0.1 g L−1 Co/N-CNTs and 0.2 g L−1 PMS. The fast and efficient degradation of the pollutant was attributed to the synergistic effect between adsorption and catalysis on the surface of Co/N-CNTs. It was confirmed that this bifunctional material provided good performances in a wide range of operation conditions, such as a wide temperature range and a wide pH range. Co/N-CNTs also exhibited a good recyclability. A mechanism study indicated that the main active species in the catalytic oxidation process was surface-bound SO4− and OH.