preparation and characterization of acrylamide-2-methyl propane sulfonic acid (amps) and acrylamide (aam) hydrogel, and its applications in removal of heavy metals (cu2+, pb2+)

The current research aimed to absorb heavy metal ions (cu2+ and pb2+) from wastewater. the hydrogel of acrylamide (aam) and acrylamide-2-methylpropanesulfonic acid (amps) was prepared in different molar ratios of feed compositions (1:1, 1:2 and 1:0.25) by the free radical polymerization method. potassium persulfate (kps) was used as an initiator, and n, n’methylene-bis-acrylamide was used as a crosslinking agent at 70°c for seven hours.  aam is a neutral monomer, and amps is a solid acidic monomer. strong complexes were obtained when two monomers with different molar ratios of feed composition were mixed. the complex was analyzed by uv-vis spectroscopy. the swelling properties of the prepared hydrogels were investigated at different ph values, temperatures, and ionic strengths. fourier transform infrared (ft-ir) and thermogravimetric analysis (tga) were used to study the hydrogels’ structural behavior and thermal stability. the diffusion phenomenon was investigated for the prepared hydrogels at a ph of 7, considering the non-fickian state. the cu+2 and pb+2 adsorption from wastewater by the prepared hydrogels at different mole ratios of a feed composition was investigated by atomic absorption spectrometry (aas). moreover, the morphology of the hydrogel was evaluated by scanning electron microscopy (sem). the surface adsorption fitting results indicated a higher correlation coefficient of 0.9588 for hydrogel in 1:2 [or m4(cu2+)] mole ratio of feed composition adsorption in both langmuir and freundlich isotherms. the evaluation of adsorption kinetics indicated a strong fit of the pseudo-first-order elovich model, evidenced by correlation coefficients of 0.9685 and 0.9186 for cu2+ and pb2+ adsorption, respectively.