## 3 Types of Adsorbents Made from Polyacrylonitrile
### Polyacrylonitrile in Hydrogels

Table 1: Performance overview of various polyacrylamide-based adsorbents. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**S. No.**} & \multirow{2}{*}{**Adsorbent**} & \multicolumn{2}{c}{**Maximum Adsorption**} & \multicolumn{2}{c}{**Initial**} & \multicolumn{2}{c}{**Optimum**} \\  & & **Capacity/Contact Time** & **Concentration** & **pH** & **Reference** \\ \hline \multirow{2}{*}{9.} & Chitosan-coated & \multirow{2}{*}{Acid Blue-1368 mg/g/7200 min} & \multirow{2}{*}{250 ppm} & \multirow{2}{*}{-} & [95] \\  & polyacrylamide nanofibru & & & & \\ \hline \multirow{4}{*}{10.} & Copper-iron & \multirow{4}{*}{Reactive blue 19: 99.9\%/60 min} & \multirow{4}{*}{6.0/ 0.20 g} & \multirow{4}{*}{-} & [110] \\  & bimetallic-modified & & & & \\ \cline{1-1}  & polyacrylamideonitrile & & & & \\ \cline{1-1}  & nanoffibrous & & & & \\ \cline{1-1}  & membranes & & & & \\ \hline \multirow{4}{*}{1.} & Magnetic Co–Fe & \multirow{4}{*}{Cd\({}^{2+}\): 87 mg/g/7–20 min} & \multirow{4}{*}{100 ppm} & \multirow{4}{*}{6.0} & \multirow{4}{*}{[115]} \\  & nanoparticle containing modified & & & & \\ \cline{1-1}  & microgel & & & & \\ \hline \multirow{4}{*}{2.} & Graphene & \multirow{4}{*}{Cu\({}^{2+}\): 381.14 mg/g/147 min} & \multirow{4}{*}{2 mM} & \multirow{4}{*}{-} & [123] \\  & polyacrylonitrile 3D & & & & \\ \cline{1-1}  & double network & & & & \\ \cline{1-1}  & hydrogels & & & & \\ \hline \multirow{4}{*}{3.} & Amidoximated & \multirow{4}{*}{UO\({}^{2+}\): 640 mg/g gel} & \multirow{4}{*}{650–1850 ppm} & \multirow{4}{*}{4.0} & [18] \\  & polyacrylonitrile /N- & & & & \\ \cline{1-1}  & vinylimidazole & & & & \\ \cline{1-1}  & hydrogel & & & & \\ \hline \multirow{4}{*}{4.} & Amidoxime & As\({}^{5+}\): 333.3 mg/g/ 1480 min & \multirow{4}{*}{1–500 ppm,} & \multirow{4}{*}{17} & \multirow{4}{*}{[117]} \\  & p(AN-co-APTMACI) & Cr\({}^{3+}\): 26.7 mg/g/720 min & & & \\ \cline{1-1}  & hydrogels & Cr\({}^{6+}\): 1111.13 mg/g/900 min & & & \\ \hline \multirow{4}{*}{5.} & Cassava starch-g- & Pb\({}^{2+}\): 72 mg/g & 80 ppm & \multirow{4}{*}{8.5} & [118] \\  & polyacrylamideonitrile & Cu\({}^{2+}\): 76.6 mg/g & 124 ppm & & \\ \cline{1-1}  & hydrogel & Ni\({}^{2+}\): 86.5 mg/g & 196 ppm & & \\ \hline \multicolumn{4}{c}{FIBERS} & \multirow{4}{*}{1.} & Amidoxime-modified & Cu\({}^{2+}\): 52.7 mg/g/5760 min & - & [67] \\  & polyacrylamideonitrile fibers & Pb\({}^{2+}\): 263 mg/g/5760 min & \multirow{4}{*}{0.2 g} & \multirow{4}{*}{[72]} \\ \cline{1-1}  & polyacrylamide/thioamidated & Cr\({}^{3+}\): 37.9527 mg/g/60 min & & & \\ \cline{1-1}  & polyacrylamideonitrile fibers & Hg\({}^{2+}\): 18.05 mg/g/60 min & & & \\ \cline{1-1}  & Polyacrylonitrile & Cu\({}^{2+}\): 28.56 mg/g/60 min & & & \\ \cline{1-1}  & nanofibers & Cu\({}^{2+}\): 215.18 mg/g/4320 min & & & \\ \cline{1-1}  & Amidoxime & Fe\({}^{3+}\): 221.37 mg/g/4320 min & \multirow{4}{*}{-} & [74] \\  & polyacrylamideonitrile & Cu\({}^{2+}\): 215.18 mg/g/4320 min & & & \\ \cline{1-1}  & chelating nanofibers & Fe\({}^{3+}\): 221.37 mg/g/4320 min & & & \\ \hline \multirow{4}{*}{4} & Aminated chelating & \multirow{4}{*}{Hg\({}^{2+}\): 657.9 mg/g} & \multirow{4}{*}{20–2000 ppm} & [68] \\  & fibers & & & \\ \cline{1-1}  & Aminated & & & \\ \cline{1-1}  & polyacrylamideonitrile & Pb\({}^{2+}\): 520.0 mg/g/300 min & - & [105] \\ \cline{1-1}  & nanofibrous mats & & & \\ \hline \multirow{4}{*}{6.} & Polyacrylonitrile & Cd\({}^{2+}\): 0.23 mg/g/60 min & \multirow{4}{*}{5 ppm} & \multirow{4}{*}{[85]} \\  & /boehmite nanofibers & & & \\ \cline{1-1}  & & _E. coli_ = 97.37\% & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._