Synthesis, characterization and properties of hydrogel based on acrylic acid composite for removal of cadmium 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: 2023-02-27 Accepted : 2023-02-27 Published : 2023-02-01

Keywords: hydrogel, Adsorption, Synthesis, Free Radical polymerization, Cadmium ion,

Abstract :

The hydrogel of Poly (Acrylic Amide - Acrylic Acid)/ Chitosan (PAM-AA/CTS) synthesized via free radical polymerization of Acrylamide and acrylic acid as monomers also added chitosan, using MBA as a cross-linking agent and KPS as initiator at 60 °C. FTIR and TGA spectroscopy were used to characterize the hydrogel. The FTIR results before and after absorbing Cd (II) reveals the presence of a broad absorption band in the range of 3190 - 3513 cm-1, where the O–H band overlaps with the N–H band, shows the presence of carboxylic and amines functional groups. Additionally, bands between 1743 and 1679 cm-1 suggest the presence of carbonyl bonds, and also, the sample was heated under an atmosphere with 10 °C.min-1 between 25 °C and 1000 °C. Though heating the hydrogel in ranges from 270-430 °C causes 50% mass loss that may be due to the pyrolysis of the carboxylic acids and amines groups. Hydrogel composed of PAM-AA/CTS efficiently removes heavy metals from aqueous solutions. Using the isotherm models of the Langmuir and Freundlich and those findings indicates that the potential is relatively high; however, the Langmuir equation does detect a good correlation with the Cd2+ ion. The maximum sorption capacity was determined to be 31.5 mg/g. Langmuir isotherm provided the best explanation for the current outcome. Thermodynamic analysis shows that the adsorption of Cd2+ is endothermic. These results show that hydrogels are effective, affordable, and ecologically acceptable materials for removing Cd2+ ions from aqueous solutions.