## 3 Environmental Applications of Organoclays
### Air Pollution
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Clay** & **Modifier** & **Methodology** & **Application** & **Efficiency** & **Reference** \\ \hline Laponite & poly(amido amine) dendrimers & & CO\({}_{2}\) gas and & 17 mg/g & [27] \\ Hydtralcite & G4.0 and poly(amido amine) & Cation exchange & NH\({}_{3}\) gas & 26 mg/g & [27] \\ Sericite & dendrimers G4.5 & & adsorption & & \\ \hline Montmorillonite & & & & & \\ (Portugal) & Amino acid & Cation exchange & CO\({}_{2}\) Removal & 0.8 mmol g\({}^{-1}\) & [142] \\ \hline \multirow{4}{*}{Bentonite (Canada)} & 3-amino-propyltriethoxysilane & & & & \\ (\(\gamma\)-APTES) & & acid activation & & & \\ 3-diethanolamino- & & chemical grafting & & & \\ (3-diEOH-APTES) & & & & & \\ \hline Montmorillonite & & & & & \\ Bentonite & Grafting with aminopropyl & & & & \\ Saponite & Diethylenetriamine organosilanes & & & 45.7 mg g\({}^{-1}\) (PEI) & \\ Sepiolite & Impregnation with & & impregnated & & 66.9 mg g\({}^{-1}\) (PEI) & [144] \\ Polygorskite & polyethylene phenoline & & & & 61.3 mg g\({}^{-1}\) (DT) & \\ (Spin) & Double functionalization & & & & 67.1 mg g\({}^{-1}\) (PEI) & \\ \hline Montmorillonite & & & & & \\ (Tunisia) & Acid treatment & Cation exchange & CO\({}_{2}\) Removal & 67.4 mg g\({}^{-1}\) & [145] \\ \hline Nanoclay & & & & & \\ montmorillonite & & & & & \\ (Iran) & & & & & \\ \hline Montmorillonite & & & & & \\ (China) & tetramethylammonium & & gaseous & & \\ (China) & & dry ball milling & & & \\ \hline Montmorillonite & & & & & \\ (Iran) & & & & & \\ \hline Montmorillonite & & & & & \\ (Iran) & Acid treatment & Cation exchange & & & \\ \hline Na- & & & & & \\ Montmorillonite & & & & & \\ (China) & tetramethylammonium bromide & high energy ball & Acetone & & \\ (China) & & milling & & Adsorption & \\ \hline Montmorillonite & & & & & \\ (China) & thermal treatment and & & & & \\ (China) & hydrochloric acid activation & & & & \\ \hline \end{tabular}
\end{table} 
Table 4: _Cont._decreased adsorption. Thus, montmorillonite with a 1700 modifier has a CRC of 3.88-7.14 compared to the 5.14 CRC with the montmorillonite with a 1100 modifier and the 11.7 CRC with the montmorillonite modified with a 500 molecular weight modifier. In the same year, [PERSON] et al., [133] used a low molecular weight dendrimer, like ethylene glycol, and found that at a lower loading availability of -OH, the group is higher and the adsorption of CO\({}_{2}\) improves. [PERSON] et al. [134] modified montmorillonite nano clay with polyethylenimine to provide sites for CO\({}_{2}\) capture. The CO\({}_{2}\) capture capacity was 7.5 wt% at atmospheric pressure and 17 wt% at 2.07 MPa pressure at 75-85 \({}^{\circ}\)C.  
[PERSON] et al. [135] modified bentonite clay with mono-, di-, and tri-ethanolamine to study the CO\({}_{2}\) adsorption capacity of bentonite clay. The CO\({}_{2}\) adsorption capacity was measured using a magnetic suspension balance. They found that the CO\({}_{2}\) adsorption amount was increased to 3.15 mmol/g compared to 0.93 mmol/g for the untreated clay. In a study conducted by [PERSON] et al. [136], diamine-modified montmorillonite clay was prepared by a water-based grafting method and applied for isothermal CO\({}_{2}\) adsorption. They found that the maximum adsorption capacity of modified montmorillonite is 2.4 mmol/g. [PERSON] et al. [137] used 3-aminopropyltriethodysilane to modify Na-bentonite in an ethanol-water mixture and an ethylene-glycol solvent mixture. They found that the ethanol-water mixture has a higher affinity for CO\({}_{2}\) than ethylene-glycol solvent mixtures with a retention efficiency factor above 16 \(\upmu\)mol/m\({}^{2}\). [PERSON] et al. [138] used laponite, sericite cationic clay, and hydrotalcite clay as anionic clays to adsorb CO\({}_{2}\) and found that cationic clay has the highest affinity for CO\({}_{2}\) adsorption. In addition, higher adsorption at 0.017 g/g of CO\({}_{2}\) was achieved by modifying it with dendrimers with cationic end groups. In 2016, [PERSON] et al. [139] and [PERSON] et al.