## 3 Results and Discussion
### Characterization of the Zeolite Sediments
Various decomposition stages of zeolite samples were observed. The first degradation stage was found at 100-130 \({}^{\circ}\)C, which described the removal of water molecules by thermal treatment of zeolite sediments [48]. All tested sediments showed initial thermal degradation except for NZ-N, NaCl-M, HCl-N, and NaOH-M. The initial weight loss (first stage) described the dehydration of loosely bonded and physiosorbed water, while the later stage (second stage) of weight loss as a function of dehydration of zeolite samples was attributed to the desorption of strongly bonded water molecules with extra framework and ionic attachment [49]. Minimum weight loss (<10%) was found in these sediments (NZ-N, NaCl-N, HCl-N, and NaOH-N) up to a 400 \({}^{\circ}\)C increase in temperature, which showed strong bonding and adhesion of water molecules with zeolite particles and ample abundance of hydroxyl species. Also, these zeolite sediments (NZ-N, NaCl-N, HCl-N, and NaOH-N) showed strong stability up to 700 \({}^{\circ}\)C and witnessed minimum weight loss. The higher thermal stability indicated that the tested NZ and its derived sediments had strongly adsorbed water molecules on the CP mineral, which has strong structural stability and thermal resistance [50]. The presence of water molecules and CP mineral contents were also confirmed by the results of the XRD and FTIR analysis. An abrupt and quick degradation of sediments was observed at 800-900 \({}^{\circ}\)C, indicating a higher dehydration rate, affected by temperature increase. Surface area analysis of natural and modified zeolite sediments showed a significant impact of the difference in particle size (Table 4). All sediments with nanosize particles have significantly higher surface area against their microsize variants, and more than a 50% enhancement in surface area of nanosize sediments was noted against microsize particle sediments. The maximum increment in surface area was found in LDH-N (37.195 m\({}^{2}\) g\({}^{-1}\)), followed by HCl-N (36.145 m\({}^{2}\) g\({}^{-1}\)) and NaOH-N (35.146 m\({}^{2}\) g\({}^{-1}\)). The surface area of micro- and nanosize particles of modified sediments was found to be almost double that of the unmodified NZ sediments, which also confirms the successful modification of the employed sediments. Contrarily, the pore volume was reduced in nanosize sediments except for NaOH-N (0.112 cm\({}^{3}\) g\({}^{-1}\)), whose microsize variants have a smaller pore volume (0.067 cm\({}^{3}\) g\({}^{-1}\)). Likewise, pore size was also decreased in nanosize sediments, and LDH-N pronounced a maximum decrease in pore size of 50.36%, followed by a decrease of 48.73% in NZ-N and 45.80% in NaCl-N. Smaller pore volume and smaller pore size are obvious in materials with a higher surface area. Higher surface area and smaller pore size in LDH-N sediments indicated excellent surface porosity, which could be due to deeper incorporation of LDH particles with NZ particles during pretreatment [41]. It is expected that as the particle size of the zeolite sediment becomes smaller, more surface becomes exposed and, hence, the specific surface area increases. In addition, at a smaller particle size fraction, microporosity could increase, leading to the formation of additional internal surfaces that contribute to the increase in the total surface area of the zeolite sediment in the nanosizedfraction. A similar trend of increasing zeolite sediment surface area with smaller particle size was reported by [PERSON] et al. (2018) and [PERSON] et al. (2019). \begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Sample**} & **BET Surface** & **Pore** & **Pore** \\  & **Area** & **Volume** & **Size** \\ \hline  & **(m\({}^{2}\) g\({}^{-1}\))** & **(cm\({}^{3}\) g\({}^{-1}\))** & **(Å)** \\ \hline NZ-M & 9.1 \(\pm\) 0.1 & 0.023 & 101.328 \\ NZ-N & 20.8 \(\pm\) 0.2 & 0.027 & 51.947 \\ \hline \end{tabular}
\end{table} 
Table 4: Surface area and microporosity analysis of natural and modified zeolite sediments.