Preparation and Application of Carboxymethylated Xylan as a Flocculant for Ethyl Violet Dye in Aqueous Systems

Hemicellulose is one of the most abundant renewable biopolymers on earth. Xylan is the main hemicellulose of hardwood species, but it is under utilized. In this work, carboxymethylated xylan (CMX) with the maximum degree of substitution (DS) of 0.95 and charge density of −4.57 mmol/g was produced. Fourier transmittance infrared (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the success of carboxylemthylation reaction. Thermogravimetric analysis confirmed that CMX was less thermo-stable than xylan. Furthermore, the CMX was applied as a coagulant for removing cationic ethyl violet dye from a simulated dye solution. The results showed that more than 95% of dye was removed from the solution. The theoretical and experimental values for the removal of the dye were close confirming that the charge neutralization was the main mechanism for interaction of dye and CMX. The impact of salt in the coagulation efficiency of CMX was also analyzed.