Removal of Fe (II) Ions from Aqueous Solutions Using Highly Biopolymer Nanocomposite: A Green Adsorbent Surface

Abstract

Biopolymers are characterized by their three-dimensional polymeric networks, high hydrophilic properties, affordability, physical and chemical stability, non-toxicity, and exceptional ability to absorb water and other substances. In this work, the adsorption capacity of an inexpensive, biodegradable adsorbent, poly (AAC-co-AM) hydrogel, prepared by the free radical polymerization method, was studied for the removal of heavy metals such as Fe (II) ions. Several analyses of the hydrogel were performed, including FESEM, TEM, and XRD. The effects of various conditions on the adsorption process were investigated, such as hydrogel weight, Fe (II) ion concentration, equilibrium time, and adsorption isotherms. Iron ion adsorption increased from 77.25% to 97.91% as the weight of the hydrogel increased from 0.01 to 0.1 g/50 mL. However, the adsorption capacity decreased from 29.14 to 233.33 mg/g at a fixed Fe (II) ion concentration of 30 mg/L, an equilibrium time of 1 hour, the temperature of 25 °C, and a stirring speed of 150 rpm. As the equilibrium time increased, both the adsorption efficiency and removal percentage rose. In addition, increasing the weight of the poly (AAC-co-AM) hydrogel led to an increase in the removal percentage. The results revealed that the adsorption efficiency of poly (AAC-co-AM) hydrogel was 55.62 mg/g with a removal percentage of 92.78% at pH 7, a dose of 0.1 g/50 mL, an equilibrium time of 1 hour, an Fe (II) ion concentration of 30 mg/L, and the temperature of 25 °C. Beyond this, the adsorption efficiency began to decrease. Finally, the adsorption equilibrium was studied using the Langmuir and Freundlich isotherms. The data were best described by the Freundlich model.