## 3 Adsorption of Model Compounds by Eggshell Biocomposite Adsorbents  
After characterization of the different ESP biocomposites, they were used to treat wastewater containing organic pollutants shown in Table 2, whereas various adsorption studies are highlighted in Table 3 that showcase the utility of these biocomposites as adsorbents. The literature covered on the usage of ESP and its composites as adsorbent materials for pollutant removal in solid-liquid adsorption system were categorized into three distinct groups. The following studies [7, 20, 21, 35, 46, 48, 49, 50, 51, 52, 53, 59, 62, 63, 64, 67, 69, 71] were considered for the adsorption of different dye molecules and other organic pollutants onto ESP and its composites. Adsorption of anions and oxyanions onto ESP adsorbents were summarized [23, 24, 42, 43, 44, 54, 55, 56, 57, 58, 60, 61], while for studies including the adsorption of metal ions sorptions [23, 36, 37, 38, 39, 41, 61, 68, 70, 72, 73]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Common/IUPAC Names** & **Molecular Structure/Mass/Chemical Formula** \\ \hline Styryl pyridinium dye, & \\
2-(phenylethyl) pyridinium chloride & \\ \hline Methylene Blue, MB, & \\ Urelene blue, provay blue, & \\
3,7-bis (dimethylamino)-phenothiazzin-5-ium chloride & \\ \hline Rhodamine Blue, RhB, Basic violet 10, Tetraethylhodamine 610, & \\
9-(2-carboxyphenyl)-6-(diethylamino) & \\ xanthen-3-ylidene-diethyllazanium chloride & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Types of pollutants and their chemical structure. \begin{table}
\begin{tabular}{c c} \hline \hline
**Common/IUPAC Names** & **Molecular Structure/Mass/Chemical Formula** \\ \hline Congo Red, CR, Direct red 28, Benzo congo red, & \\ Disodium-4-amino-3[4-[4-(1-amino-4-sulfonatonapphthalene-2-yl) diazenylphenyl] phenyl] diazinyl-naphthalene-1-sulfonate & \\ \hline Eriochrome Black T, EBT, Mordant Black 11, Solochrome Black T, & \\ Sodium; 3-hydroxyl-4-[(1-hydroxynaphthalen-2-yl) diazenyl]-7-nitronaphthalene-1-sulfonate & \\ \hline Acid Orange, AO7, & \\ Orange II, Acid Orange A, Sodium; 4[(2-hydroxynaphalen-1-yl) diazinyl] benzenesulfonate & \\ \hline Acid red nylon 57, AN57, C. I. Acid Red 57, & \\
6-Amino-5-[[2-[(ethyl phenylamino)sulfonyl] phenyl] & \\ azo]-4-hydroxynapthalene-2-sulphonic acid & \\ \hline Methyl red, & \\ C.I. Acid Red 2, & \\
2-[(4-(dimethyl amino) phenyl) diazinyl] benzoic acid & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c} \hline
**Common/IUPAC Names** & **Molecular Structure/Mass/Chemical Formula** \\ \hline Reactive yellow 145 dye, Tetrasodium; 7-[2-(carbamoylamino)-4- [[4-chloro-6-[3-(2-sulfonatooxyethylsulfonyl)] \\anilino]-1,3,5-triazin-2-yl] amino] phenyl] diazinyl] & \\ naphthalene-1,3,6-trisulfonate & \\ \hline Remazol Brilliant Violet 5R dye, RBV-5R, & \\ Reactive Violet 5, & \\ Trisodium; 5-acetamido-hydroxy-3-[[2-hydroxy-5-(2- \\ sulfonatoxyethylsulfonyl)] phenyl] diazenyl] & \\ naphthalene-2,7-disulfonate & \\ \hline Malathion, & \\ Carbophos, mercaptothon, 2-[(diamethoxyphosphorothioyl) \\ sulfanyl] butanedoate diethyl & \\ \hline Phenol, Carbolic acid, Phenic acid, hydroxybenzene & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._As shown in Figure 6, a known dosage of ESP biocomposite was applied to treat a known concentration and volume of pollutant, along with mixing for a specified time. After reaching equilibrium during the adsorption process, the adsorbent was centrifuged or filtered for analysis in order to isolate the residual pollutant solution from the solid phase adsorbent. The experimentally obtained values of the initial adsorbate and residual adsorbate concentration were used to calculate the uptake based on Equations (1) and (2).