Highly efficient and rapid adsorption of methylene blue dye onto vinyl hybrid silica nano-cross-linked nanocomposite hydrogel

Adsorption treatment of dyes from industrial effluent by hydrogel adsorbent has been a research hotspot, but few high-performance hydrogel adsorbents with high adsorption capacity have been reported. Previously reported poly (acrylic acid) PAA-based hydrogel adsorbents show a low swelling ratio due to the unsatisfactory cross-linked structure, which causes a passive impact on the exhibit of adsorptive sites and the penetration of water inside the hydrogel. Herein, we prepared a novel super-adsorbent nanocomposite (NC) hydrogel adsorbent by employing vinyl hybrid silica nanoparticles (VSNPs) with average diameter of 30 nm as crosslinking agent. The introduction of an optimal content of VSNPs effectively forms a well three-dimensional network structure. The structure system of our NC hydrogel effectively promotes the active sites on the polymer chains to be exposed to dye molecules. Thus, the NC hydrogel adsorbent achieved a high adsorption capacity of 1690 mg/g for adsorbing methylene blue and obtain a high removal ratio of 90 % within 40 min. Furthermore, the hydrogel exhibits excellent reusability after 4 repeated cycles of adsorption and desorption. The work confirmed that the VSNPs can build a well covalent hybrid cross-linked system of a PAA-based hydrogel without other organic crosslinkers and further provided a new method to develop novel hydrogel adsorbent with enhanced adsorption capacity for removing organic dyes from industrial wastewater.