## 1 Introduction  
Safe and readily accessible water is vital for everyone, whether it is used for drinking, domestic use, food production, or amusement purposes. Better water supply and more hygienic and improved management of water resources can improve countries' state of health and living. A shocking increase in toxic metal contaminants over the last few decades has caused several problems for biotic organisms and ecology [1]. The harmful contaminants in the water have detrimental effects on marine life and make the water unsafe for consumption by humans. Polluted water contains bacteria which cause diseases such as diarrhea, cholera, dysentery, typhoid, hepatitis A, and polio [2; 3]. Various research activities have been conducted to generate techniques for extracting toxic ions and dyes, especially in the aqueous solution of hydrometallurgy, and hence to reutilize these ions. The methods of removing metal ions include filtration, chemical precipitation, electrocoagulation, neutralization, chelating ion exchange, and adsorption [4; 5; 6; 7; 8]. A volume of work has been conducted by researchers to extract these ions by utilizing various techniques and different low-cost adsorbents such as lignin, chitosan, clay, zeolite, activated carbon, polymeric adsorbents, chelating resins, etc. [9]. It is found from the literature that adsorption is the most favored method due to its simplicity, easy accessibility, cost efficacy, selectivity, and efficiency for the extraction of heavy toxic metal ions, dyes, and other pollutants [10; 11]. According to the literature, a chelating resin, compared with traditional anion and cation exchange resins, is more effective in removing pollutants and also overcomes the low selectivity of ion exchange resins [12; 13; 14]. Generally, adsorption of toxic ions is done by moieties present on the surface of the adsorbent [15; 16]. Moreover, chelating adsorbents can be produced by modifying the polymers with functional groups [17]. Chelating resins adsorb the toxic wastes present in the water on their surface through various chemical and physical attractions. New classes of synthetic permeable polymeric adsorbents have been discovered with adequate porosity, ample surface area, greater structural stability, and quick adsorption kinetics. A chelating agent is a type of ion exchange resin that is highly selective for anions or clusters of ions. They are capable of adsorbing ions through coordination interaction as a substitute for columbic forces in ion exchangers. Several chelating resins mentioned in published studies are synthesized by modifying polyacrylamide with different ligands such as polyethylene mine, amidoxime, acrylamide, dithiocarbonate, thiazoline, and amino acids [18]. Although there are several different composites and conjugates used for wastewater treatment, polyacrylamide has attracted great interest because of its exceptional properties such as environmental compatibility, commercial feasibility, high temperature resistance, and high tensile strength [19]. Polyacrylonitrile is an inexpensive raw substance utilized in fabric production units and is used in ion exchange substances in the form of beads due to their high porosity. Different varieties of polyacrylamide adsorbents are synthesized by mixing various monomers with acrylonitrile as a basic unit. It is a multipurpose polymer utilized to fabricate various products, including ultrafiltration membranes, hydrogels, hollow fibers for reverse osmosis, fibers for textiles, oxidized polyacrylamide fibers, etc. (Figure 1). Polyacrylonitrile fibers are the chemical initiators to form carbon fibers with good characteristics [11]. Among the various polymers used for toxic pollutant removal, polyacrylamide is highlighted in this paper because it contains a nitrile group (-CN) and can easily form different stable products after functionalization with other groups.