# Ammonia Gas Adsorption in Fixed Bed and Fluidized Bed Using Bentonite Particles
## 4 Conclusions  
In this study, sodium bentonite was modified by a pillaring process with aluminum polyhydroxocations to improve adsorption performance for ammonia from air.  
The measurements carried out on the sodium bentonite showed that this type of clay can be subjected to the ammonia adsorption process because it can be agglomerated to form adsorbent particles. This material presents an acid-base character and the measurements showed the existence of acidic sites having high surface acidity values, being able to retain some molecules like ammonia.  
Surface chemical characterization results showed that the modification by pillaring led to an increase in basal spacing, specific surface area, pore volume and pore diameter of aluminum pillared bentonite, improving ammonia adsorption capacity.  
The ammonia adsorption kinetics were measured on sodium bentonite and on aluminum pillared bentonite with different gas-particle contact methods, and the ammonia adsorption capacity was calculated.  
Therefore, under fluidized bed conditions, sodium bentonite and aluminum pillared bentonite particles exhibited superior adsorption capacity compared to a fixed bed. In a  
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**No. of Cycles**} & \multicolumn{2}{c}{**Sodium Bentonite Particles**} & \multicolumn{2}{c}{**Aluminum Pillared Bentonite Particles**} \\ \cline{2-5}  & **mmol NH\({}_{3}\) Desorbed/g Bentonite** & \% & **mmol NH\({}_{3}\) Desorbed/g Bentonite** & \% \\ \hline
0. & 0.357 & 100 & 0.527 & 100 \\ \hline
1. & 0.245 & 68.62 & 0.464 & 95.44 \\ \hline
2. & 0.158 & 44.25 & 0.345 & 88.04 \\ \hline
3. & 0.062 & 17.36 & 0.268 & 50.85 \\ \hline
4. & - & 0.00 & 0.088 & 16.69 \\ \hline \end{tabular}
\end{table}
Table 4: Values of ammonia desorption capacity and desorption efficiency (%).  
fluidized bed, the mass transfer zone of the bed particles is higher due to the dynamic conditions by increasing the ammonia-particle surface contact. In these conditions, the aluminum pillared bentonite particle bed is saturated very quickly after 100 s and the optimal value recorded for ammonia adsorption capacity is 0.945 mmol NH\({}_{3}\)/g.  
The ammonia adsorption performance is very good for the bentonite pillared with aluminum polyhydroxocations and presents advantages of a simple pillaring process with low cost of preparation, which has very great application in air depollution.  
Conceptualization, G.M. and A.-M.G.; methodology, G.M.; software, C.V.J.; validation, G.M.; formal analysis, N.P. and V.A.A.; investigation, N.P. and V.A.A.; resources, I.D.N.; data curation, G.M. and A.-M.G.; writing--original draft preparation, A.-M.G. and A.-M.R.; writing--review and editing, G.M. and A.-M.R.; visualization, I.D.N.; supervision, C.V.J. and I.D.N.; project administration, I.D.N.; funding acquisition, A.-M.R. and I.D.N. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.  
The authors are grateful to [PERSON] and the entire team from Clermont University (ENSCCF), GePEB axis, for the technical support in carrying out the kinetics experiments.  
The authors declare no conflicts of interest.