Molecular mechanism of anionic dyes adsorption on cationized rice husk cellulose from agricultural wastes

Cationized rice husk cellulose (CRHC) were designed and synthesized by introducing hydroxypropyloctadecyldimethylammonium group onto rice husk cellulose (RHC) molecular structure. Structure and morphology of samples were characterized by FTIR, XRD and SEM. The characterization results showed that the molecular structure and morphology of RHC have changed and the quaternary ammonium group was successfully grafted onto the RHC molecular structure. Adsorption studies were conducted to evaluate the adsorption performance and related mechanism of Diamine Green B (DG-B), Acid Black 24 (AB-24) and Congo Red (CR) onto CRHC. The adsorption process was well described by Pseudo-second-order and Langmuir models. The Langmuir maximum adsorption capacity of DG-B, AB-24 and CR on the CRHC was found to be 207.15, 268.88 and 580.09 mg g(-1) at 303.15 K, respectively. The possible adsorption mechanism might be due to the combination of molecular structure characteristics of adsorbents and adsorbates, electrostatic attraction, hydrogen bonding, and the competition of OH- ions. CRHC has a good reusability and high adsorption performance for dye removal. The thermodynamic parameters indicated the adsorption process is a spontaneous and feasible purification process, increasing the temperature is conducive to the adsorption process. (C) 2018 Elsevier B.V. All rights reserved.