## 2 Materials and Methods
### Preparation and Modification of Zeolite Sediments  
The collected sediments were washed with deionized water (DI) to remove impurities, air-dried at room temperature for 48 h, crushed, and sieved to <0.1 mm particle size. The sieved zeolite sample was saved in an airtight acrylic container and tagged as NZ. Later, the NZ sample was treated with Mg/Al layered double hydroxides (LDHs) by following the coprecipitation method proposed by [PERSON] et al. [28]. Briefly, in a glass beaker, 0.01 M Al (NO3)3 and 0.02 M Mg(NO3)2 were mixed in 100 mL DI water, followed by the addition of NZ and LDH/NZ in a 3:7 ratio. The solution pH was adjusted to 11 using 1 M NaOH and 0.5 M Na2 CO3 solutions. The solution was shifted to a hotplate and mixed thoroughly at 80 \({}^{\circ}\)C for 4 h until a homogeneous mixture was obtained. Later, the solution was removed from the hotplate and was filtered by Whatman filter paper 42. The solid material was collected from filter paper, which was further washed three times with DI water to remove impurities. The collected solid material was oven-dried at 70 \({}^{\circ}\)C, grounded to a fine particle size, stored in airtight acrylic containers, and tagged as LDH-Z. The NZ also was treated with HCl, NaOH, and NaCl solutions of different concentrations by following the [PERSON] et al. [29] method to produce HCl-Z, NaOH-Z, and NaCl-Z. Briefly, in a conical flask, 5 g of NZ was mixed with 2 M HCl, NaOH, and NaCl solutions separately. The flask was placed in a bathtub, and it was shaken for 3 h at 75 \({}^{\circ}\)C, followed by centrifugation at 3000 rpm for 15 min. The supernatant liquid was discarded, and solid residues of sediments were collected, washed with DI water, filtered, and oven-dried at 70 \({}^{\circ}\)C for 48 h. Later, oven-dried sediments were collected and stored in an airtight acrylic container with separate tags for HCl-Z, NaOH-Z, and NaCl-Z. All the collected and modified NZ sediments (HCl-Z, NaOH-Z, NaCl-Z, and LDH-Z) were further grounded to micro- and nanosize particles separately. The dried particles of NZ and modified NZ were crushed and sieved to obtain the macroparticle size of \(<\)50 \(\upmu\)m. To obtain nanoparticle size of NZ and modified NZ, 10 g of dried NZ and modified NZ particles (\(<\)0.1 mm) were immersed in 1 L of DI water. The suspension was sonicated for 30 min (Ultrasonic sonicator Q700, Qsonica, Newtown, CT, USA) and left for gravity sedimentation for 24 h. Nanoparticles suspended in the upper 5 cm of the beaker were extracted using a siphon method. Later, more DI water was added to the suspension to make a final 1 L suspension volume, and the suspension was sonicated for 5 min. The cycle was repeated until large enough amounts of nanoparticles of NZ and modified NZ were collected. The collected nanoparticles were oven-dried at 40 \({}^{\circ}\)C and stored in tight containers until use. Table 1 describes a full list of the natural and modified sediments. Analytical-grade chemicals (HCl, NaOH, NaCl, Ca(OH)\({}_{2}\), Na\({}_{2}\)CO\({}_{3}\), NaOH, K\({}_{2}\)CrO\({}_{4}\), Mg(NO\({}_{3}\))\({}_{2}\).6H\({}_{2}\)O, Al(NO\({}_{3}\))\({}_{3}\).9H\({}_{2}\)O, NH\({}_{4}\)OAc, and HNO\({}_{3}\)) were purchased from local suppliers in Riyadh city and were used to modify NZ sediments and for further studies.