Cotton Filter Fabrics Functionalized by Chitosan UV-grafting for 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 costs can be prohibitive. [1]. In the present work, a cotton tulle fabric functionalized by chitosan UV grafting was used as dyes adsorbent. The process parameters for the fabric finishing were optimized in terms of chitosan weight-on, impregnation time, temperature and pH, radiation time and intensity for curing. The as prepared material was then tested towards different dye classes: acid, reactive and direct dyes. Batch, kinetics as well as continuous flow assessment tests were carried out evaluating the adsorption capacity by spectrophotometrical measurements. Moreover the influence of liquid pH as well as temperature on the adsorbant capacity of the functionalized cotton were investigated. The material showed good adsorption capacity and very high rate of adsorption kinetics toward all the investigated dyes. Moreover, by assembling the functionalized cotton in a filter form, good adsorption capacity is ensured even at 25°C, with good behavior in terms of filter exhaustion and pressure drop. A positive influence on adsorption capacity was displayed in acid conditions. The chitosan weighted cotton was finally characterized by SEM and FTIR-ATR analysis to evidence the deposition of chitosan on the single fibers surface and the grafting reactions occurred. [1] F. Ferrero, M. Periolatto, Clean Techn Environ Policy, DOI 10.1007/s10098-011-0442-