Study on the Preparation and Adsorption Properties of Sodium Alginate Graft Polyacrylic Acid/Graphite Oxide Composite Hydrogel

Sodium alginate graft poly acrylic acid/graphite oxide (SA-g-PAA/GO) composite hydrogel is prepared using potassium persulfate (KPS) as an initiator and N,N '-methylenebisacrylamide (MBA) as a cross-linker by solution polymerization. The composite hydrogel has been characterized by means of infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Adsorption behavior of acid fuchsin (AF) and sunset yellow (SY) onto the composite hydrogel is investigated in detail. Maximal adsorption amount of AF and SY is 86.9 and 77.5 mg/g (1.484 × 10–4 and 1.713 × 10–4 mol/g), respectively, under the condition that GO is 0.02 g, initial concentration of dye solutions is 1000 mg/L, mass of SA-g-PAA/GO is 0.2 g, adsorption time is 24 h, and the temperature is 25°C. The adsorption amount AF and SY is 28.9 and 28.5% higher than that on SA-g-PAA graft copolymer which is prepared without GO. GO serves as cross-linking agent during polymerization and the interaction between GO and SA-g-PAA is intermolecular hydrogen bonds. The adsorption of AF and SY conforms to the Redlich–Peterson equation and Langmuir equation, respectively. The kinetic models of both AF and SY conform to the quasi-second-order kinetic equation.