Hyperbranched Cellulose for Dye Removal in Aqueous Medium

Abstract

In recent decades, cellulose (Cel) and its modified forms have emerged as a new class of versatile adsorbents for removing dyes from aqueous solutions. This work reports the immobilization of macromolecules obtained from reactions between ethylenediamine (N) and ethylene sulfide (S) in three molar proportions (1:1, 1:2, and 1:4) on the surface of chlorinated cellulose (Cl-Cel), aiming to increase the adsorption capacity of dyes. The materials obtained (NS-Cel, N2S-Cel, and N4S-Cel) were characterized by elemental analysis, which demonstrated immobilization of macromolecules with a ratio of 12 ethylene sulfides to 1 ethylenediamine in the materials NS-Cel and N4S-Cel and a ratio of 10 ethylene sulfides to 1 ethylenediamine in NS-Cel. Intense C-H stretching bands of CH2 groups at 2900 cm−1 in the FT-IR spectra suggest a large amount of the functional group, corroborating the 13C NMR spectra, which presented a signal at 33 ppm referring to methylene carbons. The materials obtained had excellent performance in removing the dyes studied, with the adsorption capacity of the Remazol yellow GR dye being approximately 24 times greater than the raw material (87.70 ± 2.63 mg g−1) for the best-hyperbranched cellulose N4S-Cel and 3.60 ± 0.18 mg g−1 for Cel, and about ten times higher for the dye Remazol red RB (57.84 ± 1.73 mg g−1) for N4S-Cel compared to previously published work for Cel.