Graphene oxide enhanced hydrogel as an adsorbent for effective removal of methylene blue

When used to treat printing and dyeing effluents, the existing hydrogels have the following problems: limited mechanical strength, slow adsorption rate, and poor reusability. Therefore, a simple one-pot method was used to prepare poly (acrylic acid-2-acrylamide-2-methyl-1-propanesulfonic acid)-g-sodium alginate/graphene oxide (P(AA-AMPS)/SA-GO) composite hydrogel, which was analyzed by Fourier transform infrared, scanning electron microscope, confocal laser scanning microscope and Brunauer–Emmet–Teller method. The mechanical properties, swelling ratios and adsorption performance of the composite hydrogel were determined in detail. The results show that the composite hydrogel has a porous structure and excellent mechanical properties. The maximum elongation at break and tensile strength can reach 803% and 104.8 kPa, respectively. When the GO content is 1.2%, the swelling ratio and methylene blue (MB) adsorption capacity are the highest, 54.9 g/g and 486.5 mg/g, respectively. The external conditions have a significant effect on the adsorption performance of the hydrogel. When the adsorption conditions are as follows: the adsorption temperature is 25 ℃, the amount of hydrogel is 0.1 g, the pH is 8, and the initial concentration of MB is 500 mg/L, the highest removal efficiency of MB is 98.1% in 90 min. Coexisting ions can inhibit the removal of MB. The adsorption model fitting and kinetic analyses show that P(AA-AMPS)/SA-GO follows the Langmuir adsorption model and belongs to single-layer adsorption. The adsorption kinetic model study shows that the gel fits the quasi-second-order kinetic model, with chemical adsorption as the primary and physical adsorption as the auxiliary. The P(AA-AMPS)/SA-GO hydrogel has a remarkable adsorption effect on methylene blue wastewater and can be used as an efficient adsorbent for wastewater treatment.