Preparation of a cellulose-based adsorbent with covalently attached hydroxypropyldodecyldimethylammonium groups for the removal of CI Reactive Blue 21 dye from aqueous solution

An adsorbent for the removal of C.I. Reactive Blue 21 (RB21) dye from aqueous solution was prepared by covalently attaching hydroxypropyldodecyldimethylammonium groups to microcrystalline cellulose. The adsorbent was characterized using FTIR, C-13 NMR spectroscopy, and SEM. Adsorption studies were conducted to evaluate the effects of adsorbent loading, contact time, dye concentration, pH, temperature, and ionic strength. Adsorption kinetics and isotherms were fitted to different models. FTIR and C-13 NMR studies indicated that the quaternary ammonium group had been successfully attached to the cellulose. SEM photographs showed that the surface became coarser after the modification. The cellulose-based adsorbent was shown to be very efficient for the removal of RB21 dye, with equilibrium being reached in 180min. Maximum adsorption of RB21 dye was achieved at pH 2. The adsorption of RB21 dye onto the adsorbent was a spontaneous endothermic process and satisfactorily fitted the pseudo-second-order kinetic model, the intraparticle diffusion model, and the Langmuir adsorption isotherm model. An adsorption capacity of 200mg/g was achieved, indicating an excellent adsorption performance.