Color removal is an important task in textile wastewater treatment. Cucurbituril, 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 application. A minimum of 1 to 5 mmol/L calcium is needed for efficient sorption. However, salt concentrations of 100 mmol/L and above decrease sorption efficiency due to increased solubility of cucurbituril in salt solutions. The pH has little influence between 4 and 7.5, higher pH-values can result in decreased sorption. The salt influences are similar for most of the tested dyes whereas the pH-effect differs from dye to dye.

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