Removal of reactive dyes by sorption/complexation with cucurbituril

Color removal is an important task in textile wastewater treatment. Cucurbi turil, a cyclic hexamer with internal hydrophobic cavity, has been studied as sorbent for removal of reactive dyes. Loadings as high as 1 g/g and more were obtained, making the method seem interesting for technical applicatio n. A minimum of 1 to 5 mmol/L calcium is needed for efficient sorption. How ever, salt concentrations of 100 mmol/L and above decrease sorption efficie ncy due to increased solubility of cucurbituril in salt solutions. The pH h as little influence between 4 and 7.5, higher pH-values can result in decre ased sorption, The salt influences are similar for most of the tested dyes whereas the pH-effect differs from dye to dye. (C) 1999 IAWQ Published by E lsevier Science Ltd. All rights reserved.