Synthesis, characterization and properties of hydrogel based on acrylic acid for removal of zinc ion from wastewater

Subject Areas : Iranian Journal of Organic Chemistry

Arman Samadzadeh Mamaghani ¹ , Mohammad Reza Manafi ² , Mohammad Hojjati ³

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Received: 2023-02-26 Accepted : 2023-02-26 Published : 2022-11-01

Keywords: hydrogel, Adsorption, Synthesis, Heavy metals, Free Radical polymerization,

Abstract :

This research investigated the PMA-AA (maleic acid/acrylic acid) hydrogel, which was synthesized by free radical polymerization of maleic acid / acrylic acid as monomers, using MBA as a Cross-linking agent and (NH4)2S2O8 as an initiator at 60 °C. FTIR and TGA spectroscopy were used to characterize the hydrogel. The FTIR results showed a large absorption band at 3000 cm-1 due to the stretching vibration of OH of AA and MA carboxylic functional groups. The absorption band of the C=O group at 1706 cm-1 in PMA-AA hydrogel disappeared with loaded Zn2+ ions. The C=O stretch frequency at 1631 cm-1 in PMA-AA hydrogel moved to 1629 cm-1; these variations in IR frequency indicate that hydrogel absorption is a chemical process. Hydrogel results showed no weight loss up to 155 °C free hydrogel but at 190 °C, suggesting the decomposition of the hydrogel backbone. This rapid weight loss for hydrogels loaded at 330 °C demonstrated an enhancement in the thermal stability of the hydrogel adsorb the heavy metals. It was determined that the concentration, temperatures, and time of the adsorption and adsorption capacity were studied in detail. The maximum sorption capacity was determined to be 239.89 mg/g. Langmuir isotherm provided the best explanation for the current outcome. The pseudo-second-order kinetic model well-represented sorption. Thermodynamic analysis shows that the adsorption of Zn2+ is exothermic. PMA-AA hydrogel loaded with Zn2+ ions desorbed was shown excellent regeneration performance and maintained 99.30% adsorption capacity after four adsorption–desorption cycles.