Laponite-AMPS/AA composite hydrogels for efficient removal of methylene blue (MB)

The aim of this study is to investigate the synthesis, characterization, and adsorptive properties of composite hydrogels that can be used to remove MB dye from aqueous solutions. Composite hydrogels were used to remove the MB from aqueous solutions. Composite hydrogels were synthesized by free radical polymerization of 2-acrylo-amido-2 methyl propane sulfonic acid (AMPS) and neutralized acrylic acid (70%-AA) as monomers in the presence of laponite clay (LAP). The composite hydrogels were characterized by FTIR, SEM and XRD. In composite hydrogels, the effect of monomer ratio and clay content on swelling and adsorption properties were also investigated. In the swelling behavior of composite hydrogels, it was determined that laponite acted as a crosslinker but was not sufficient alone. For this reason, chemical crosslinker was also utilized with laponite for increasing the stability and strength of the composite hydrogel. In the adsorption study for MB adsorption, it was observed that the adsorption capacities of the synthesized composite hydrogel were slightly lower or almost equal to those of the pure hydrogel. The capacities of composite hydrogels ranged from 900–1385 mg / g. It was determined that the higher the amount of AMPS present in the composite hydrogel the higher the amount of dye removed from the concentrated matrix medium of synthetic sea water at 1000 ppm MB. In addition, it was observed that increasing the amount of LAP resulted in some reduction in the adsorption time relative to pure hydrogel. This makes the hydrogel to be easily applicable in adsorption studies.