Functionalized fibrous materials for the removal of dyes

Wastewater effluents from textile industry mainly contain dyes used in the dyeing or printing of textiles yarns or fabrics. A lot of technologies can be adopted for dye removal from wastewaters, including biological treatments based on activated sludge, adsorption on activated carbon, or membrane processes. Nevertheless, none of these methods is performing toward all classes of dyes; treatment plants of great dimensions and difficult handling can be required, while cost can be prohibitive. In the present study, dye adsorption was performed on low-cost fibrous cellulose materials, submitted to a cationization process using a quaternary ammonium reagent. These materials were characterized by FTIR–ATR spectroscopy, while the treatment efficiency was investigated through exhaustion and kinetic adsorption tests toward anionic dyes, such as acid, direct, reactive, and a cationic dye. Comparisons were carried out between treated and untreated samples, and with activated carbon. Best results were obtained with cationized cotton, both in linters or “tulle” fabric form, showing good performance toward all the investigated dyes. Tests in continuous flow confirmed the good behavior of these materials, but tulle fabric was better as filtration medium for a lower pressure drop. Finally, regeneration tests by bleaching were carried out finding that regenerated material maintained good adsorption power.