The coal gangue obtained from Shanxi Coal Mine in Jinzhong district, taking about 2 kg of coal gangue and bringing it to the laboratory. First, the samples were washed with distilled water, to remove the surface soil, dried in a drying oven at 105˚C for 5 h, and then stored in a desiccator. For well-known of coal gangue chemicals materials using XRF Al₂O₃ (29%), SiO₂ (56%) exist in the form of quartz, kaolinite, and also contain a small amount of Fe₂O₃, K₂O, Na₂O, SO₃, TiO₂, other (15%). Sodium hydroxide (NaOH), nitric acid (HNO₃), Lead chloride (PbCl₂), Copper (II) nitrate trihydrate (Cu(NO₃)₂・3H₂O) and Cadmium chloride monohydrate (CdCl₂・H₂O) were all analytically pure. Use an analytical balance to weigh 1.343 g, 3.821 g and 1.79 g and of Lead Chloride, Copper(II) nitrate trihydrate and Cadmium chloride monohydrate dissolved in 1000 mL of deionized water to obtain 1000 mg/L of Pb²⁺, Cu²⁺ and Cd²⁺ solutions for use. Zeolite was synthesized using NaOH. This study was conducted using deionized water with a conductivity of 2.7 *s/cm.

For Preparation of NaX_zeolite first Coal Gangue powder is obtained by crushing raw coal samples and passing them through a sieve with a mesh size of 120 after crushing, to obtain a homogenous mixture, 5 g of Coal Gangue powder were mixed and ground in a mortar for 15 minutes with a 1g amount of NaOH(s). In the muffle furnace, Coal Gangue powder was activated and unburnt carbon was removed by placing the homogeneous mixture in the crucible and placing it under an air atmosphere at 800˚C for 2 hours. As soon as the fused samples had cooled to room temperature, they were ground into a powder, dissolved in a solution of 100 mL deionized water, stirred for 15 minutes, and crystallized under 90 degrees around 24 hours, respectively. Before characterization and adsorption experiments, the product was separated through vacuum filtration several times with deionized water until pH reached natural.

This experiment was carried out in the Microbiology Laboratory, Taiyuan University of Technology, Taiyuan, Shanxi China. The main equipment used included to determine the Pores and specific surface area of the NaX_zeolite is using the Brunauer-Emmett-Teller (BET) method. The chemical composition of NaX_zeolite samples was examined by X-ray fluorescence analyzer spectrometer (XRF). Fourier transform infrared spectrophotometer (FTIR, PerlnElmer, L1600400 spectrum TWO FT-IR, UK), used for the functional groups on NaX_zeolite. A scanning electron microscope (SEM) was used to examine the morphological structure of the NaX_zeolite, in addition, total metal concentrations in the simulated wastewater were determined using the (PerkinElmer Analyst 400) atomic absorption spectrometer.

In this research 100 mL of Pb²⁺, Cu²⁺ and Cd²⁺ solutions with a mass concentration of 200 mg/L was accurately pipetted into a conical flask as simulated wastewater. Investigation of the effect of adsorption of dosage, Simulated wastewater was first treated with different masses of NaX_zeolite (0.03, 0.05, 0.1, 0.2, 0.4 and 0.5 g), put the conical flask into the constant temperature shaker, at 25˚C shaking for 60 min, After the adsorption, the samples were taken after pass through a 0.45 μm filter paper and determine the Pb²⁺, Cu²⁺ and Cd²⁺ concentration. The effects of pH on the adsorption of heavy metals exanimated with different pH values 3, 4, 5, 6, 7, 8 and 9 respectively. Use 0.1 mol/L of HNO₃ and 0.1 mol/L NaOH solution to adjust the pH of simulated wastewater. The effects of temperature on the adsorption heavy metals was shaken at 15˚C, 25˚C, 35˚C, and 45˚C for 180 min. After the adsorption is over, the Pb²⁺, Cu²⁺ and Cd²⁺ samples concentration was detected after filtered with 0.45 μm. for effect of time on adsorption of heavy metals increase the time from 5, 10, 20, 30, 40, 60, 75 and 90 minutes shaking at 25˚C. pH5 for Pb²⁺ and pH6 for Cu²⁺ and Cd²⁺, 0.2 g of the prepared NaX_zeolite, 150 rmp use for all those experimental processing. In the adsorption isotherm test, 10 mL of 50, 100, 250, 200, 250, and 300 mg/L Pb²⁺, Cu²⁺ and Cd²⁺ solutions were accurately pipetted into a conical flask as simulated wastewater, for accurately weighed using an analytical balance, 0.2 g of the prepared coal gangue-based NaX_zeolite was added to the simulated wastewater, and then the conical flask was placed in a constant temperature oscillator, and the adsorption was carried out at room temperature of 25˚C for 60 min. The concentration of Pb²⁺, Cu²⁺ and Cd²⁺ ware detected after filtered with 0.45 μm filter membrane, and the experiment of each adsorption condition was repeated twice. Concentration of metals ion ware detected by the atomic absorption spectrophotometer The Pb²⁺, Cu²⁺ and Cd²⁺ adsorption capacity and removals was calculated by Equations (1) and (2):

R = C o − C e C o × 100 (1)

q e = C o − C e M × V (2)

q_e (mg/g) is the Pb²⁺, Cu²⁺ and Cd²⁺ adsorption amount by adsorbent. C₀ (mg/L) and C_e (mg/L) represent the initial and after adsorption Pb²⁺, Cu²⁺ and Cd²⁺ concentration in solution, respectively. V (L) is the solution volume, and m (g) stand for the mass of adsorbent. R is removal percentage.

The coal gangue and the obtained molecular sieve XRD images (Figure 1) were analyzed, and it was found that the main components of coal gangue were quartz, kaolinite and mica. However, the diffraction peaks of quartz, kaolinite and mica are no longer contained in the XRD image of the alkali melt, indicating that after alkali melting, the quartz, kaolinite and mica structures in the coal gangue have been destroyed and transformed into soluble ones. Aluminosilicate,the obtained product contains some impurity peaks, but at 2θ = 20.2˚, 26.3˚, 46.1˚, 38.26˚, 73.2˚. There is an obvious FAU diffraction peak near 04˚.

It can be seen from the SEM image in Figure 2 that the surface of coal gangue is rough and has a lamellar structure. Kaolinite is a silicate with a layered structure, and mica is also an aluminosilicate with a layered structure. The SEM results

and the XRD results of coal gangue can confirm each other. In the SEM image of the synthesized product, the octahedral structure with uniform particles and complete structure can be clearly seen, and its size is about 5 μm, which is the structural shape of NaX_zeolite.

In the infrared spectrum of the product, the bending vibration bands of the T-O (T Si or Al) bond appear near 490 cm⁻¹ - 520 cm⁻¹, The −OH group appears near at ranges 3380 cm⁻¹ - 3460 cm⁻¹, the C-H appears near at ranges 1020 cm⁻¹ - 1050 cm⁻¹, the C=Cappears near at ranges 1900 cm⁻¹ - 1600 cm⁻¹ but it Changed a bit on their violent included, the =C-H group appears near at ranges 760 cm⁻¹ - 780 cm⁻¹ (see Figure 3). These characteristic bands are consistent with the infrared characteristic bands of typical NaX_zeolite, indicating that the prepared materials have the typical framework structure of NaX_zeolite.

By using BET, the specific surface area and porosity of the NaX_zeolite and coal gangue analyzed. coal gangue surface area is about 238.1 m²/g, the total pore volume is 0. 212 m³/g, the specific surface area and NaX_zeolite molecular sieves synthesized 380.1 m²/g total pore volume is 0. 211 m³/g, synthesized by low-grade kaolin.

Isothermal Langmuir, Freundlichand Temkin models for well-known adsorption of Pb²⁺, Cu²⁺ and Cd²⁺ by NaX_zeolite. 0.2 g of the prepared NaX_zeolite was added to the simulated wastewater with Pb²⁺, Cu²⁺ and Cd²⁺ mass concentrations of 25, 50, 100, 150, 200, 250 and 300 mg/L, respectively. The adsorption was carried out with shaking at 25˚C for 60 min. After the adsorption is over, the concentration of Pb²⁺, Cu²⁺ and Cd²⁺ was measured after filtered with 45 μm filter paper. It can be seen from Figure 8 and Table 1 that The adsorption effect of NaX_zeolite on heavy metal ions is closer to Langmuir model. The correlation coefficient of the Langmuir model (R² = 0.99, 0.983 and 0.978) for Pb²⁺, Cu²⁺ and Cd²⁺, greater than the correlation coefficient of the Freundlich model (R² = 0.838, 0.859 and 0.78) for Pb²⁺, Cu²⁺ and Cd²⁺, and the correlation coefficient of the Temkin model (R² = 0.935, 0.879 and 0.886) for Pb²⁺, Cu²⁺ and Cd²⁺. According to the fitting results in Table 1, the separation coefficient RL was calculated. at different initial concentrations The RL of Pb²⁺, Cu²⁺ and Cd²⁺ is between 0 and 1, It shows that the adsorption of Pb²⁺, Cu²⁺ and Cd²⁺ NaX_zeolite belongs to preferential adsorption, has a strong affinity. The maximum saturated adsorption capacity of Pb²⁺, Cu²⁺ and Cd²⁺ by coal gangue-based NaX_zeolite reached 87.33 mg/g, 87.95 mg/g and 88.57 mg/g. There is a strong relationship between the adsorption capacities of different metal ions and the chemical properties of the element and

the adsorbent.