Carbon nanotubes could accumulate in organism and have a negative impact on the structure and function of the ecosystem when they were discharged into environment. Furthermore, it will affect the migration and fate of pollutants in the water body. The study is mainly to explore the adsorption behavior and mechanism of beta-blocker on multi-walled carbon nanotubes (MWCNTs). Propranolol (PRO) was selected as the representative of beta-blocker. The effects of different environmental factors such as pH, ionic strength and humic acid (HA) on the adsorption process were investigated. The adsorption results were characterized by Zeta potential. At the same time, the effects of different types of drugs on the adsorption process were explored and the possible adsorption mechanisms were analyzed. The experimental results showed that the adsorption behavior was significantly different under different pH conditions. π-π EDA interaction, hydrophobic interaction and hydrogen bonding were speculated to be the main adsorption mechanisms for PRO adsorption on MWCNTs. In recent years, with the large-scale industrialization of nanotechnology, carbon nanotubes (CNTs), as a new type of nanomaterial with large specific surface area and high surface energy, are widely used in biomedicine, electro-optics, smart sensors and catalytic degradation 1-5. However, CNTs are often discharged into the body of water without any treatment during production, application, and disposal, which may damage the balance of the ecosystem and seriously affect the normal ecosystem 6-8. At present, many studies have shown that CNTs can adversely affect many organisms. CNTs can cause delayed incubation of zebrafish embryos, which was ascribed to an interaction between a large number of functional groups on the surface of CNTs and the eggshell's hatching enzymes, inhibiting their activity and slowing the dissolution of the egg membrane 9. The normal physiological functions of the cell membrane were influenced due to the damage of cell integrity and the organelles because CNTs will directly enter the cell through the cell membrane 10-12. Furthermore, the strong adsorption capacity of CNTs will also change behaviors such as migration, transformation, and fate of other pollutants in the environment 13-15. At the same time, CNTs adsorbing environmental pollutants will form various types of composite pollutants, further causing greater harm to the environment. Therefore, more attention should be paid to the adsorption behavior of CNTs. Based on the interaction between CNTs and contaminants including heavy metals, antibiotics, and pesticides, some studies have pointed out that CNTs are important carriers or adsorbents to affect the migration and transformation of pollutants. The interaction mechanisms between CNTs and heavy metals are very complicated and may attributable to electrostatic attraction, sorption-precipitation and chemical interaction between the metal ions and the surface functional groups of CNTs 16,17. The adsorption of antibiotics on CNTs was affecte...