## 4 Influential Factors in Fluoride Adsorption
### The Effect of Adsorbent Mass on the Removal of F\({}^{-}\)  
The optimal concentration of the adsorbent material for fluoride removal depends on several factors, including the specific adsorbent material used, the initial concentration of fluoride in the water, and the desired level of fluoride removal. Table 5 presents an overview of F\({}^{-}\) removal studies by adsorption considering the influence of adsorbent mass. According to Table 5, it is evident that the concentration of the adsorbent material directly influences the efficiency of fluoride removal in the adsorption process. Elevated concentrations of the adsorbent material can enhance the number of active adsorption sites and expand the available surface area for fluoride adsorption. Nevertheless, excessively high concentrations may result in overcrowding of adsorption sites, leading to a reduction in efficiency due to mass transfer limitations. Additionally, the economic aspect plays a crucial role, as the cost of the adsorbent material may pose limitations on determining the optimal concentration. The balance lies in optimizing the concentration of the adsorbent material for fluoride removal, considering the specific conditions of the treatment process. Striking this balance is crucial not only for efficient removal but also for ensuring economic feasibility, especially in large-scale applications where higher concentrations may incur substantial costs. Therefore, \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Adsorbent Materials** & **Mass (g L\({}^{-1}\))** & **qe (mg g\({}^{-1}\))** & **Removal (\%)** \\ \hline [PERSON], [PERSON], and & & & \\ [PERSON] [28] & Iron nanoparticles impregnated via green technology & 2.5 & 1.44 & 90 \\ \hline [PERSON] et al. [17] & Silver and iron oxide (3:1) & 0.5 & 20 & 100 \\ \hline [PERSON] and & & & \\ [PERSON] [52] & Crystalline titanium dioxide powder & 25 & 153.5 & 75 \\ \hline [PERSON] and & & & \\ [PERSON] [4] & Zr impregnated in cellulose matrix & 10–12 & - & - \\ \hline [PERSON] and & & & 17.4 & 69.4 \\ [PERSON] [4] & Banana peel powder heat treatment & 1 & 26.3 & 81.3 \\  & Banana peel powder coated with calcium & 1 & 39.5 & 82.6 \\ \hline [PERSON] et al. [51] & \begin{tabular}{c} Tea residue as a support for hydrated aluminum oxide \\ Tea residue as a support for hydrated aluminum oxide \\ and anionic polyacrylamide \\ \end{tabular} & 1.2 & 7.43 & 89.7 \\ \hline [PERSON] et al. [53] & \begin{tabular}{c} Tea residue as a support for iron oxide \\ Tea residue as a support for aluminum oxide \\ Tea residue as a support for silver and iron oxide \\ \end{tabular} & 8 & - & 30 \\ \hline [PERSON] et al. [84] & Mesoporous alumina (Al\({}_{2}\)O\({}_{3}\)) modified with CaO & 0.4–2 & - & 90 \\ \hline [PERSON] and & & & 1.48 & 90 \\ [PERSON] [15] & \
\begin{tabular}{c} Mesoporous alumina \\ Mesoporous alumina \\ \end{tabular} & 3.0 & 1.38 & 56 \\ \hline [PERSON] and & Mg, Mn, and Zn impregnated in powder carbon & & \\ [PERSON] [15] & activated via ultrasound assisted sintese & 1 & - & 96 \\ \hline [PERSON] et al. [87] & Immobilized modified activated alumina & 10 & 0.48 & 95 \\ \hline [PERSON] and & & & 10.91 & 98.2 \\ [PERSON] [88] & & & 2.3 & 92 \\ \hline [PERSON] and [PERSON] [89] & Fe and Ce (IV) bimetallic oxide compound & 0.5 & - & 94.73 \\ \hline [PERSON] et al. [29] &
\begin{tabular}{c} Magnetic compound with Fe\({}_{3}\)O\({}_{4}\) nanoparticles \\ encapsulated in Zr (IV) net and polyacrylamide \\ \end{tabular} & 6 & - & 95 \\ \hline [PERSON] et al. [73] & Zr (IV) immobilized in sodium carboximetilcellulose & 8.0 & - & 90 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Overview of F\({}^{-}\) removal studies by adsorption considering the adsorbent mass. a thoughtful consideration of the optimal concentration is essential for achieving effective fluoride removal while managing economic constraints. [PERSON] et al. [17] applied masses of an iron nanoparticle-based composite adsorbent ranging from 0.5-5.0 g L\({}^{-1}\).