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 celcius, 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.