BACKGROUND: Beta-cyclodextrin (beta-CD) has a hydrophilic exterior and a hydrophobic internal cavity which gives it the ability to form a host-guest complex. Sodium alginate (NaAlg) is a natural polysaccharide which can form a hydrogel in the presence of divalent cations. RESULTS: The degree of substitution (DS) of the resulting beta-CD grafted alginate was 12%. The adsorption ratio of beta-CD to methylene blue (MB) was close to 2: 1 which agreed with the theoretical value. The inclusion property of the Alg-beta-CD/MB-Ca hydrogel was excellent and stable. The hydrogel could be disintegrated easily with the aid of Na2CO3, and the Alg-beta-CD sol obtained could be reused. CONCLUSION: This study indicated that the method of aggregation-disintegration of the prepared hydrogel used to adsorb MB from water was effective and could be reused. (C) 2014 Society of Chemical Industry