Cucurbituril for water treatment. Part I: Solubility of cucurbituril and sorption of reactive dyes

Cucurbituril was investigated regarding its potential as a sorbent for the removal of reactive dyes from model solutions and authentic wastewaters. Th e solubility of cucurbituril is low in pure water but increases in the pres ence of salts. When dyes sorbing onto cucurbituril are present, solubility is drastically decreased compared to dye-free media. Sorption efficiency de pends on salt concentration and salt species. Moderate salt concentrations favor sorption, high concentrations lead to cucurbituril dissolution. Dival ent, ions have a stronger effect than monovalent ions and larger ions more than smaller ones. In tests with authentic wastewaters cucurbituril was par tially (20-100%) dissolved and contaminant removal was inefficient. Because of its,solubility, cucurbituril is not feasible as a sorbent in wastewater treatment unless it could be covalently fixed onto a suitable support mate rial. (C) 2001 Elsevier Science Ltd. All rights reserved.