## 3 Types of Adsorbents Made from Polyacrylonitrile
### Polyacrylonitrile in Ion Exchange Resins
(2010) examined heavy metals such as cobalt, strontium, and cesium released into water bodies through radioactive industries and removed them by using an ammonium polydophosphate-polyacrylamideonitrile (AMP-PAN) adsorbent [49]. In a single and binary solution of metal ions, the competitive adsorption of Co\({}^{2+}\), Sr\({}^{2+}\), and Cs\({}^{+}\) by ammonium AMP-PAN was examined. The binary system of metal ions Sr\({}^{2+}\)/Co\({}^{2+}\), Sr\({}^{2+}\)/Cs\({}^{+}\), and Co\({}^{2+}\)/Cs\({}^{+}\) were synthesized by combining the similar metal concentration solution with an identical volume ratio for every metal. Binary metal adsorption performance was best explained by the Langmuir model. The Freundlich, Langmuir, and D-R models were best fitted to the adsorption records by using the non-linear regression system. The adsorption model demonstrated that AMP-PAN was more selective for Cs\({}^{+}\) ions and the maximal uptake values were 0.16 mmol/g, 0.18 mmol/g, and 0.61 mmol/g for Co\({}^{2+}\), Sr\({}^{2+}\), and Cs\({}^{+}\), respectively. Due to competition among metal ions in a binary system, adsorption of one metal ion was suppressed in the presence of another metal ion. Alkali metals (Na\({}^{+}\)) inhibited the adsorption of cesium and calcium ions and diminished the adsorption of cobalt ions onto AMP-PAN. Adsorptions of Co\({}^{2+}\), Sr\({}^{2+}\), and Cs\({}^{+}\) onto AMP-PAN in the vicinity of surfactants were quite dissimilar. The presence of cationic (OTMA and HDTMA) and anionic (SDBS and SOBS) surfactants diminished the adsorption of Co\({}^{2+}\), Sr\({}^{2+}\), and Cs\({}^{+}\) onto AMP-PAN. However, the presence of non-ionic surfactants (Tween 80 and Triton X-100) did not decrease the adsorption. The zirconium-manganese oxide/polyacrylonitrile (Zr-Mn oxide/PAN) composite was synthesized in another study and used to remove Sr\({}^{2+}\) ions from wastewater [50]. Here, zirconium-manganese hydrous oxide was used as an inorganic active ion exchanger to prepare composite spheres. Zr-Mn mixed oxide powder was obtained through the co-precipitation method and then blended with polyacrylonitrile (PAN) to produce Zr-Mn oxide/PAN composite spheres. The adsorption process was carried out with an initial metal ion concentration of 20 ppm at pH 7.7 and a temperature of 324.2 K. The adsorption of Sr\({}^{2+}\)metal ions was investigated at concentrations ranging from 20 to 200 ppm, and the results were explained using Freundlich, Langmuir, and D-R models. Hydrous manganese dioxide-polyacrylamideonitrile (MnO\({}_{2}\)-PAN) spheres were chemically prepared and used for the removal of radio-contaminant cesium-137 from metal ion solutions [51]. Inductively coupled plasma was used to study manganese and other elements such as carbon, hydrogen, and nitrogen, determined through the CHN elemental analyzer. MnO\({}_{2}\)-PAN adsorbent showed thermal stability up to 583 K and had a crystalline structure. [PERSON] et al. (2011) developed a novel method for the modification of the surface of \(N\)-chlorosulfonamidated polystyrene through activators recovered by electron transfer and atom transfer radical polymerization (ARGET ATRP) methods [52], achieved by the use of ferric trichloride anhydrous (FeCl\({}_{3}\))/iminodiacetic acid (IDA) as a catalyst, L-ascorbic acid (VC) used as a reductant, and \(N\),\(N\)-dimethylformamide (DMF) as the solvent. Polyacrylonitrile was bound to the surface of polystyrene and the cyano moiety of the PAN-g-PS polymer was treated with hydroxylamine hydrochloride to introduce amidoxime (AO) groups in the PAN chain. The amidoxime moieties were efficient for the extraction of Hg\({}^{2+}\) ions from solutions. Adsorption phenomena were also investigated in binary metal systems such as Hg\({}^{2+}\)-Pb\({}^{2+}\), Hg\({}^{2+}\)-Ag\({}^{+}\), and Hg\({}^{2+}\) -Cu\({}^{2+}\), with the results indicating that resin exhibited selectivity for mercury ions.