Removal of chlorophenols from aquatic systems with dye-affinity microbeads

Cibacron Blue F3GA carrying pHEMA microbeads were investigated as dye-affin ity sorbents for removal of chlorophenols (i.e. phenol, in-chlorophenol, p- chlorophenol and 2,4,6-trichlorophenol). PHEMA microbeads were prepared by modified suspension polymerization of HEMA in the presence of an initiator (azobisisobutyronitrile). These microbeads, with a swelling ratio of 55%, a nd carrying 16.5 mu mol Cibacron Blue F3GA/g polymer, were then used in the removal of chlorophenols from aqueous media. Adsorption rates of chlorophe nols were very high, and equilibrium was achieved in about 20 min. The maxi mum adsorptions of chlorophenols onto the Cibacron Blue-carrying microbeads were 88.8 mu mol/g for phenol, 94.6 mu mol/g for 2.4,6-trichlorophenol, 97 .6 mu mol/g for p-chlorophenol and 109.1 mu mol/g for in-chlorophenol. The affinity order was as follows: m-chlorophenol > p-chlorophenol > 2.4,6-tric hloro phenol > phenol. The adsorption of chlorophenols decreased with incre asing pH. Desorption of chlorophenols was achieved using methanol solution (30%, v/v). The Cibacron Blue F3GA-carrying microbeads are suitable for rep eated use for more than five cycles without any noticeable loss of adsorpti on capacity. (C) 2001 Elsevier Science B.V. All rights reserved.