Polysaccharide self-crosslinking and refrigerated air-drying interfacial modification: A new approach for konjac glucomannan-guar gum thin film loaded with NZVI for enhanced Cr(VI) removal

For facile fabrication of environmentally friendly nanoparticle film carriers, the present study utilized sodium periodate to oxidize and induce the self-crosslinking of konjac glucomannan (KGM) and guar gum (GG). Innovatively, the film preparation process involves refrigerated air-drying technique to simultaneously achieve interface modification. The dendritic structure and swelling characteristics produced by the refrigerated air-drying technique significantly increased the specific surface area and improved the dispersion and loading of NZVI. The biodegradable and swell-hydrolyzable characteristics of KGM-GG enabled the green treatment of the carriers. To evaluate the performance of the film, a composite material with highly dispersed nanoscale zero-valent iron (NZVI) was prepared to remove Cr(Ⅵ) in a wide pH range, especially under strongly acidic media. At room temperature and pH 2.0, Fe 0 /KGM-GG loaded with 1.2 mg of NZVI could completely remove Cr(Ⅵ) within 60 min. By characterization analysis, this rapid removal may be achieved by synergistic interactions such as adsorption, reduction, co-precipitation, and formation of bidentate-mononuclear complexes. The results showed that Fe 0 /KGM-GG had a good anti-interference ability in the presence of HA and coexisting ions. In this study, a new method for preparing environmentally friendly nanoparticle carriers with high loading and high dispersion through polysaccharide self-crosslinking and refrigerated air-drying film-making technology has been proposed, which provides a new way for green and sustainable synthesis of nanoparticle carrier materials.