Cellulose/biopolymer/Fe3O4 hydrogel microbeads for dye and protein adsorption

Abstract

Cellulose-based magnetic hydrogel microbeads were prepared through sol–gel transition using a 1-ethyl-3-methylimidazolium acetate-in-oil emulsion. Surface properties of the microbeads were altered by blending cellulose with chitosan, carrageenan, lignin, or starch. The adsorption capacity of the cellulose microbeads for crystal violet was 1.3 times higher after blending cellulose with carrageenan, while that for methyl orange was 2.0 times higher after blending cellulose with chitosan. As a model study, kinetics and isotherms for the adsorption of crystal violet on the cellulose/carrageenan microbeads were investigated to understand the effect of the biopolymer on the adsorption properties. Adsorption capacities of the cellulose microbeads for pepsin and bovine serum albumin were 1.6 and 1.2 times higher after blending cellulose with chitosan, respectively. The adsorption capacity of the cellulose/carrageenan microbeads for lysozyme was 1.2 times higher than that of the cellulose microbeads. The cellulose/alkali lignin and cellulose/starch magnetic microbeads were found to be efficient supports for immobilization of lipase. Specific activities of lipase immobilized on the cellulose/alkali lignin and cellulose/starch magnetic microbeads were 1.2- and 1.4-fold higher than that of free lipase, respectively. Under denaturing thermal conditions, the half-life of lipase immobilized on the cellulose/alkali lignin and cellulose/starch magnetic microbeads was 47- and 56-fold higher than that of free lipase, respectively. Thus, owing to their biocompatibility, biodegradability, and controllability, the cellulose/biopolymer/Fe3O4 hydrogel microbeads may have many potential applications in biocatalytic, biomedical, and environmental fields.