Adsorption of cationic and anionic dyes by ethylenediamine-modified carboxymethyl cellulose

A novel amphoteric adsorbent, ethylenediamine-modified carboxymethyl cellulose (EDA-CMC,) with various CMC amounts, was prepared to eliminate toxic methylene blue (MB) and orange II (ORII) dyes from wastewater. The modification and adsorption onto EDA-CMC1 was analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, and zeta potentials. At 293 K, the maximum adsorption capacities of 82.06 and 63.72 mg g-1- for 250 mg L-1 MB and ORII, respectively, were obtained at pH 11 (MB) and pH 3 (ORII) within 30 min. Various zeta potentials were obtained (+10 mV at pH 3 and-30 mV at pH 11) and pH-sensitive properties of EDA-CMC1 were exhibited during the adsorption process. The adsorption of ORII followed the Langmuir isotherm, while MB adsorption could be described better by Freundlich model. For adsorption kinetics, both of them followed the pseudo-second-order kinetics equation. These results indicated that EDA-CMC1 could serve as a potential material for textile wastewater treatment.