Removal of Anionic Dyes from Aqueous Solutions by Cellulose-Based Adsorbents: Equilibrium, Kinetics, and Thermodynamics

A novel cellulose (CE)-based adsorbent was synthesized by polyacrylamide grafted quaternized cellulose (PAM-g-QC) to remove anionic dyes. The elemental analysis results showed that there were abundant amino groups on adsorbents and scanning electron microscopy indicated the structure was porousproperties that were a benefit to increase the adsorption ability. The adsorption ability was specifically investigated in different temperatures. Adsorption isotherms including the Langmuir, Freundlich, and Temkin isotherm models were studied at different temperatures (303323 K), and the maximum theoretical adsorption capacity of the adsorbents was 380.084 mg g(1) for Congo red (CR) and 349.284 mg g(1) for Eriochrome blue SE (EBSE) at 323 K by the Langmuir isotherm model. The adsorption data was fitted to the adsorption kinetics (pseudo-first-order kinetic, pseudo-second-order kinetic, and intraparticle diffusion models), and the pseudo-second-order kinetic model showed a better fit for the adsorption of CR and EBSE. Thermodynamic parameters (Delta H degrees, Delta S degrees, and Delta G degrees) showed that the adsorption of EBSE and CR was feasible, endothermic, and spontaneous from 303 to 323 K. The adsorption and desorption mechanism of CR and EBSE also was investigated in this study, which verified that electrostatic adsorption played a main role between adsorbents and adsorbates. A comparison with other cellulose-based adsorbents confirmed that the CE/PAM-g-QC adsorbent possessed excellent potential and practical value in dye wastewater treatment.