Recyclable polyurethane foam loaded with carboxymethyl chitosan for adsorption of methylene blue

Novel composite foam (CMCTS-PUF-s) was prepared by immobilizing carboxymethyl chitosan (CMCTS) on polyurethane foam (PUF) in which amino groups in CMCTS reacted with isocyanate groups in polyurethane prepolymer. The adsorption capacity of the optimal composite foam (CMCTS-PUF-5) reached to 118.2 mg/g with 5% CMCTS loading. The removal rate to methylene blue (MB) was up to 97.1%, which was obviously higher than 18.9% of PUF. After recycling for five times, the removal rate still reached 83.2%, which strongly proved the excellent reusability of immobilizing CMCTS modified PUF. The characterization results of FTIR and TG showed that CMCTS was well loaded on PUF by covalent bond. The Young's modulus and tensile strength of CMCTS-PUF5 were increased by 252% and 97% compared with that of PUF. MIP characterization result showed the porosity of CMCTS-PUF-5 was 73.99% and the pore sizes were mainly distributed between 50 and 150 mu m, which provide sufficient diffusion channels and active sites for MB dyes. The adsorption kinetics and isotherm proved pseudo second-order kinetic model and Langmuir isotherm model could well describe the adsorption process of CMCTSPUF-5. Therefore, CMCTS-PUF-s presents excellent recoverability, high stability and attractive adsorption efficiency, shows the potential application in future treatment of dye wastewater.

Automated summary

The novel composite foam CMCTS-PUF-s showed excellent adsorption efficiency for methylene blue, with a high adsorption capacity of 118.2 mg/g and a removal rate of 97.1%. Even after recycling five times, it still maintained a removal rate of 83.2%, demonstrating its excellent reusability. Additionally, the CMCTS-PUF-s exhibited increased elasticity and tensile strength compared to PUF, making it a promising candidate for future treatment of dye wastewater.