Adsorption of Acid Dyes from Aqueous Solution on a Chitosan-cotton Composite Material Prepared by a New Pad-dry Process

Abstract

In this paper, we developed a method that may be considered as an easy and economical way to prepare chitosan-cotton composite (CH-cotton) materials using an electrolytes-free pad-dry process in which the cure step was performed in an oven microwave to provide a cotton fabric with greatly enhanced affinity for acid dyes. Evidence of successful interaction between cotton and CH through formation of hydrogen bonding and/or ion dipole interactions was analysed by FTIR spectroscopy. Influence of cure time onto the weight per surface unit of samples has been studied and five CH-cotton composite materials with different %CH content (I-V) were prepared. Crosslinking of cellulosic chain molecules of cotton fiber through CH segments was confirmed by Wrinkle Recovery Angle (WRA) and Tensile properties measurements. CH-cotton samples were then tested as adsorbent of four acid dyes from no-electrolytes aqueous solution [Indigo Carmine (AB74), Acid Red 183 (AR183), Acid Blue 161 (AB161) and Acid Yellow 17 (AY17)]. Results were monitored using, reflectance spectro-colorimeter and spectrophotometer analyses. Data obtained with treated cotton showed better dye exhaustion than obtained with untreated one. The modelling of the adsorption isotherms was performed by Langmuir equation and the thermodynamic parameters were evaluated. Globally, the lack of affinity of cotton for acid dyes is widely overcome by the use of low %CH content ranging from 0.079 to 0.515