Preparation and Characterization of Acrylamide-۲-Methyl Propane Sulfonic Acid (AMPS) and Acrylamide (AAm) Hydrogel, and Its Applications in Removal of Heavy Metals (Cu۲+, Pb۲+)

The current research aimed to absorb heavy metal ions (Cu۲+ and Pb۲+) from wastewater. The hydrogel of acrylamide (AAm) and acrylamide-۲-methylpropanesulfonic acid (AMPS) was prepared in different molar ratios of feed compositions (۱:۱, ۱:۲ and ۱:۰.۲۵) 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 ۷۰°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 ۷, considering the non-Fickian state. The Cu+۲ and Pb+۲ 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 ۰.۹۵۸۸ for hydrogel in ۱:۲ [or M۴(Cu۲+)] 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 ۰.۹۶۸۵ and ۰.۹۱۸۶ for Cu۲+ and Pb۲+ adsorption, respectively.

کلیدواژه ها:

Bifunctional Hydrogel ، Swelling properties ، heavy metals ، adsorptive removal ، Atomic absorption spectrometry