Cucurbituril for water treatment. Part II: Ozonation and oxidative regeneration of cucurbituril

In Part I it was shown, that cucurbituril has high sorption capacities for the removal of reactive dyes from textile wastewater: despite the partial d issolution of this sorbent. Ozonation has been suggested as a regeneration step for loaded cucurbituril. Ozonation of loaded and pure cucurbituril was therefore evaluated. Dissolved cucurbituril reacts with ozone forming oxid ation products like nitrite, nitrate, formate, acetate and oxalate. Oxidati on is enhanced at alkaline pH. Dye-loaded cucurbituril suspended in water c an be decolorized by ozone, but the ozone consumption is up to seven times higher than for ozonation of the dissolved dyes without cucurbituril. Loade d columns can be regenerated by ozone gas, but dissolution of cucurbituril results in a higher DOC content than the initial one to be removed. Therefo re oxidative regeneration does not seem to be a feasible approach in this c ase. (C) 2001 Elsevier Science Ltd. All rights reserved.