Safranin-O dye removal from aqueous solution using superabsorbent lignin nanoparticle/polyacrylic acid hydrogel

Abstract

Alkali lignin (AL) modified by ethylene glycol and lignin nanoparticles (LN) was prepared through the acid precipitation technology. Lignin nanoparticle/polyacrylic acid (LN/PAA) hydrogel was prepared using copolymerization reactions. LN and LN/PAA hydrogel were investigated using GPC, SEM, FT-IR spectroscopy, and TGA-DTG analysis. The sizes of the nanoparticles were assessed using DLS. LN/PAA hydrogel was used to remove Safranin-O from an aqueous Solution. The optimal conditions for absorption provided at pH 7, an initial concentration of dye of 1.5 gr. L-1, and an adsorbent dosage of 0.1 gr. Also, the optimal time for LN and LN/PAA hydrogel were 100 min and 450 min, respectively. Both absorbent LN and LN/PAA hydrogel showed good agreement with the Langmuir isotherm. The maximum absorption capacities of LN and LN/PAA hydrogel were determined to be 100 mg.gr-1 and 1666.6 mg.gr-1, respectively. Both absorbent LN and LN/PAA hydrogel follow the pseudo-second kinetic model and the intraparticle diffusion model.