Preparation of Polyurethane and Carbon Nanotube Foam and Its Adsorption Properties for Sulfonamides in Water

Abstract

At present, the problem of antibiotic contamination has become a global crisis. Some methods on the removal of antibiotics have been reported, and the adsorptive process was an effective approach to the disposal of antibiotics in water. Under mild conditions, carbon nanotubes (CNTs) were synthesized using fallen willow (Salix matsudana Koidz.) leaves as raw materials in this work. Polyurethane (PU)/CNT foams were synthesized using a comixing method. The adsorptive properties of PU/CNT foams for sulfonamides in water were investigated. The results showed that intraparticle diffusion was not the only rate control step, and adsorption was controlled jointly by membrane diffusion and internal diffusion. The adsorption equilibrium time was 8 h. The optimum adsorption conditions of PU/CNT foams for sulfanilamide were as follows: the pH of the sulfanilamide solution was 7, the dosage of PU/CNT foam was 0.02 g, and the initial concentration of sulfanilamide solution was 40 mg·L−1. In addition, adsorption was affected by electrostatic force, the π-π effect, hydrophobic interaction, and hydrogen bond. Moreover, adsorption was heterogeneous in a certain range, and there was an interaction between adsorbent and adsorbate molecules in the adsorption process. Subsequently, the adsorption of PU/CNT foams for sulfonamide was a preferential, spontaneous, and exothermic reaction. In the process of desorption, sulfonamide tended to be retained in the PU/CNT foams.