Carboxylate-functionalized hollow polymer particles modified polyurethane foam for facile and selective removal of cationic dye

Abstract

As an efficient technique for treatment of dye contaminated water, adsorption process has drawn wide research attention. However, conventional sorbents are mainly powdery and difficult to separate, which severely limited their practical application. Herein, a series of polyurethane foam (PUF) modified with carboxylate-functionalized hollow polymer particles (HPPs-COO-) were specially designed and synthesized. Combining the advantages of both open-cell foams and functional HPPs, the as-prepared HPPs-COO-/PUF can be utilized as advanced adsorbents towards cationic dyes (i. e., methylene blue b-MB). Batch adsorption experiments were performed to evaluate and optimize various parameters affecting the adsorption performance of HPPs-COO-/PUF, including the content (mass ratio) of HPPs-COO-, initial b-MB concentration, and solution pH. The experimental data demonstrated that the adsorption isotherm results fitted well with Langmuir model, possessing maximum sorption capacity of 125 mg/g at pH = 10 (25 °C). Furthermore, the adsorption process was better described by the pseudo-second order kinetic equation. Besides, the HPPs-COO-/PUF exhibit a remarkable pH-sensitive sorption capacity. When the pH value changed from 10.0 to 2.0, the sorption capacity of HPPs-COO-/PUF dropped sharply from 115.6 mg/g to 26 mg/g. Hence, regeneration of b-MB containing HPPs-COO-/PUF can be effectively realized. The recovered HPPs-COO-/PUF show > 90% b-MB removal efficiency during five adsorption–desorption processes, demonstrating excellent recyclability. With advantages of facile preparation, high adsorption capacity, and outstanding reusability, the HPPs-COO-/PUF showed great potential for dye wastewater treatment.