Facile fabrication of Artemisia sphaerocephala krasch gum hydrogels by radiation induced cross-linking polymerization and enhanced ultrahigh adsorption for methylene blue.

Although Artemisia sphaerocephala krasch gum (ASKG) has attracted growing attention in the field of medical engineering and food industries, however, there are few studies on the gelation of ASKG. In this paper, acrylic acid modified ASKG hydrogels were prepared by radiation induced grafting, cross-linking and polymerization technique for the first time. The semi-IPN structure was prepared by the cross-linked ASKG network and poly-AAc dispersed within the network. The effects of the adsorbed dose on the swelling ratio and gel fraction were investigated. The different acrylic acid content modified ASKG hydrogels (ASKGAAc1 and ASKGAAc2) for methyl blue (MB) adsorption were investigated, and the ASKG hydrogels was also studied for comparison. The influence of pH, contact time, initial concentration, temperature, ion strength on MB adsorption were tested. The results showed that acrylic acid can promote the formation of hydrogel and greatly enhanced the adsorption of ASKG. The adsorption isotherms were well obeyed the Langmuir model, and the maximum adsorption capacity for MB of ASKG, ASKGAAc1 and ASKGAAc2 were 571.43, 1517.8 and 1654.9 mg/g, respectively. Moreover, the MB adsorption by ASKG based hydrogels was exothermic, spontaneous, and more favorable at lower temperature. Furthermore, the adsorption-desorption experiments demonstrated a good reusability of these hydrogels.