Screening of commercial sorbents for the removal of reactive dyes

Sorption filters could be a relatively simple treatment step to remove reactive dyes from textile wastewater. Activated carbon is already used in some treatment plants (loadings approx. 100 mg g(-1)), and many non-regenerable products have been tested. This study aimed at identifying suitable sorbents for on-site regeneration. Zeolites, polymeric resins, ion exchangers and granulated ferric hydroxide (GEH) were tested with different reactive dyes (M 600-1500 g mol(-1)). Zeolites and microporous resins were not suitable due to extremely low sorption capacities. The macroporous resins without functional groups showed moderate maximum loadings (100-400 mu mol g(-1) or 100-400 mg g(-1)) but low affinity and were not suitable for large dyes (> 1000 g mol(-1)). loadings on anion exchangers were high but regeneration was difficult for the strong basic type (S6328a. Bayer). The weak basic type (MP62, Bayer) showed the most favorable profile: max. loadings or 200-1200 mu mol g(-1) (230-900 mg g(-1)) and complete regeneration using alkaline methanol (10% water). With GEH moderate loadings of about 150 mu mol g(-1) were achieved. Catalytic oxidative regeneration of GEH is possible using H2O2. (C) 2001 Elsevier Science Ltd. All rights reserved.