2-Acrylamide-2-Methylpropane Sulfonic Acid Hydrogels; Preparation, Characterization, and Removal of Heavy Metals Pb2+ and Cu2+ from Wastewater

The aim of the study was the preparation and characterization of 2-Acrylamide-2-methylpropane sulfonic acid (AMPS) hydrogel with the intent to remove Lead (Pb2+) and Copper (Cu2+) heavy metals from wastewater. AMPS hydrogels were prepared by the free radical polymerization method at 70℃ for six hours. Potassium persulfate (KPS) was used as an initiator, and N,N’-Methylene-bis-acrylamide as a crosslinking agent. The swelling properties of hydrogels were studied in diverse conditions, such as temperature, ion strength, and pH. NaOH neutralized AMPS in 50%, 65%, and 75% w/w. AMPS monomer showed absorption by UV spectrophotometer at 229 nm. After neutralization, absorption was established at 203, 213, and 200 nm for 50%, 65%, and 75% w/w solution, respectively. This study showed a robust, complex formation between SO3- and Na+. The maximum swelling of AMPS hydrogels was determined as 16000% in 65% w/w NaOH and pH=7. The swelling behavior of hydrogels was studied at 25°C, 50°C, and 75°C. The maximum swelling was 220%, which was seen at 75°C. To evaluate the effect of ionic strength on hydrogel swelling, NaCl and KCl were used in different mol concentrations. In this research, the swelling properties in 0.00001M were more than 0.001M. FT-IR and TGA were used to characterize the structural and thermal properties. Atomic Absorption spectroscopy was performed to evaluate the removal of the heavy metals (Cu2+ and Pb2+) in wastewater. Morphologic investigation was studied by the Scanning electron microscopy (SEM) micrographs.