Screening of commercial sorbents for the removal of reactive dyes

摘要

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) 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 of 200-1200 #mu#mol g~(-1) (230-900 mg g~(-1)) and complete regeration 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 H_2O_2.