Poly(vinyl alcohol)/graphene oxide nanocomposite hydrogel with catalytic activity: the removal behavior and dual adsorption/catalytic degradation mechanism for dye wastewater

The treatment of dye wastewater with traditional adsorption materials usually proceeds slowly with low removal efficiency and without completely eliminating dye molecules, leading to secondary pollution. In this work, poly(vinyl alcohol)/graphene oxide@tetraamino iron phthalocyanine (PVA/GO@TAFePc) nanocomposite hydrogels with catalytic activity were prepared via an in situ crosslinking method. Through interfacial covalent and pi-pi interactions, TAFePc was loaded onto GO layers with a high loading ratio, and GO@TAFePc was exfoliated and uniformly dispersed in the matrix. With increasing GO@TAFePc hybrid content, the pore size increased and a loose network structure was formed for the hydrogels, while the specific surface area rose significantly by using the hydrogel in a dye removal process, the removal rate of methylene blue (MB) increased sharply with contact time, reaching 98% in the presence of H2O2 with good reusability, and high removal efficiency was achieved for different dyes. The large surface area of the hydrogel was beneficial for MB adsorption. Meanwhile, under catalysis of TAFePc, a large amount of high activity center dot OH was produced by H2O2 so as to degrade the MB molecules rapidly. Therefore, the MB degradation process for the composite hydrogel was ascribed to a dual adsorption/catalytic degradation mechanism. (C) 2020 Society of Industrial Chemistry