KINETICS, EQUILIBRIUM AND THERMODYNAMICS OF CONGO RED REMOVAL BY CATIONIZED CELLULOSE OBTAINED FROM CEREAL BY-PRODUCTS

Abstract

The present study deals with the removal efficiency towards Congo red dye of two cationized cellulose adsorbents prepared from cereal by-products. Rice and einkorn husks were used as raw materials to extract and separate the cellulose by alkali and bleaching treatments. The cellulose materials were modified with N,N-dimethyl-1-octadecylamine to prepare cationized adsorbents. Instrumental methods, such as XRD, DTA, FTIR and SEM, as well as low-temperature nitrogen adsorption, were used for their characterization. The results showed that the quaternary ammonium group was successfully grafted onto the cellulose structures. The survey mainly focused on the effect of process parameters on the adsorption capacity of the investigated materials, including contact time, initial Congo red concentrations, solution pH and temperature. The adsorption process was well described by the pseudo-second-order and Langmuir models. The values of entropy, enthalpy and Gibbs free energy for the Congo red removal were determined.