Preparation of Cu(II)-Immobilized Chitosan (CIC) and Preliminary Urea Uptake Study

Abstract

In the present work, a new sorbent for urea removal was prepared by carrying out sorption of Cu(II) into chitosan particles at 293°K. Out of three model isotherms, namely, Freundlich, Temkin, and Langmuir, the Cu(II) uptake by chitosan was best interpreted in terms of Langmuir isotherm (R2 = 0.9715). The sorption mean free energy, as calculated from the Dubinin-Radushkevich isotherm, was 8.064 kJ mol−1, which indicates the chemical nature of the sorption process and which was also confirmed by Fourier transformation infrared (FTIR) spectral analysis. The Cu(II)-immobilized chitosan (CIC) so obtained was found to take up 22 mg urea per g sorbent in 4 h at 37°C. The linear plot between log (% removal) and log (time) indicates intraparticle diffusion of urea into CIC particles. The rate constant of pore diffusion, Kid, was found to be 1.02 × 10−2 min−1/2. The particles with diameter 297, 320, and 710 µm were found to remove 22.9, 14.2, and 6.0 mg urea per g sorbent, respectively. With increased initial concentration of urea, the urea uptake (mg g−1) also increased.