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Thermodynamics parameters calculated for the examined dyes. Table 2 endothermic, which favors the greater adsorption capacity at higher temperatures [46].

Table 2 Thermodynamics parameters calculated for the examined dyes. Table 2 endothermic, which favors the greater adsorption capacity at higher temperatures [46].

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Cilinoptilolite natural zeolite (about 6g) was firstly washed with DI water and dried in oven. Secondly, it was dispersed in tetramethyl ammonium chloride solution (250 mL, 0.40 mol/L) and ultrasonicated for 30 min to obtain an aqueous dispersion zeolite. Then two iron electrodes with 1cm x 1cm (anode) and 1cm x 4cm (cathode) di- mension and 0.20 mm thick were placed inside the solution and the distance between them was adjusted to 1 cm. The oxidation potential of 8 V was applied to the electrodes by a potentiostat / galvanostat and the reaction was carried out under ultrasonic irradiation at 90°C for 1h. Finally, an external magnetic field was used to separate MZeo. Finally, obtained MZeo was repeatedly washed with DI water and methanol and dried at 65°C.
Cilinoptilolite natural zeolite (about 6g) was firstly washed with DI water and dried in oven. Secondly, it was dispersed in tetramethyl ammonium chloride solution (250 mL, 0.40 mol/L) and ultrasonicated for 30 min to obtain an aqueous dispersion zeolite. Then two iron electrodes with 1cm x 1cm (anode) and 1cm x 4cm (cathode) di- mension and 0.20 mm thick were placed inside the solution and the distance between them was adjusted to 1 cm. The oxidation potential of 8 V was applied to the electrodes by a potentiostat / galvanostat and the reaction was carried out under ultrasonic irradiation at 90°C for 1h. Finally, an external magnetic field was used to separate MZeo. Finally, obtained MZeo was repeatedly washed with DI water and methanol and dried at 65°C.
Fig. 3. (a, b) SEM image, (c) EDAX of MZeo-HAP, (d, e) TEM images of MZeo-HAP. The functional group peaks of the compounds are observed in the figure. The bands observed at wavenumbers of 440 and 610cm 7! are ascribed to the Fe-O bonds in Fe304 MNPs (Fig. 4a) [32]. The Fig. 4b represents the MZeo FTIR spectrum. The band placed at 1100 cm™' is attributed to asymmetric stretching vibration of the Al-O-Si in the zeolite structure. Also, Al (Si)-O bending mode was observed with at 464 cm". To verify the presence of magnetic nanoparticles in the syn- thesized MZeo, the sharp band observed at 608 cm™ was due to the Fe- O bond. After modification of the MZeo by HAP, new bands were de- tected (Fig. 4c). In this spectrum, the bands at 567, 603, and 1032 cm-" clearly showed the formation of O—P—O bonds in the synthesized na- nocomposite which were related to the presence of the HAP in the adsorbent [33]. It is noteworthy saying that magnetic particles and zeolite could also be detected in the FTIR pattern of MZeo-HAP. XRD pattern of MZeo-HAP nanocomposite ranging (26) from 5 ° to 60 ° is depicted in Fig. 4d having numerous detectable peaks. All the peaks of synthesized nanocomposite are consistent with database of HAP (JCPDS No. 09-0432), clinoptilolite (JCPDS No. 39-1383) and Fe30, (JCPDS No. 19-0629) in the JCPDS-International Center for Diffraction Data file. According to the figure, diffraction peaks at 35.43
Fig. 3. (a, b) SEM image, (c) EDAX of MZeo-HAP, (d, e) TEM images of MZeo-HAP. The functional group peaks of the compounds are observed in the figure. The bands observed at wavenumbers of 440 and 610cm 7! are ascribed to the Fe-O bonds in Fe304 MNPs (Fig. 4a) [32]. The Fig. 4b represents the MZeo FTIR spectrum. The band placed at 1100 cm™' is attributed to asymmetric stretching vibration of the Al-O-Si in the zeolite structure. Also, Al (Si)-O bending mode was observed with at 464 cm". To verify the presence of magnetic nanoparticles in the syn- thesized MZeo, the sharp band observed at 608 cm™ was due to the Fe- O bond. After modification of the MZeo by HAP, new bands were de- tected (Fig. 4c). In this spectrum, the bands at 567, 603, and 1032 cm-" clearly showed the formation of O—P—O bonds in the synthesized na- nocomposite which were related to the presence of the HAP in the adsorbent [33]. It is noteworthy saying that magnetic particles and zeolite could also be detected in the FTIR pattern of MZeo-HAP. XRD pattern of MZeo-HAP nanocomposite ranging (26) from 5 ° to 60 ° is depicted in Fig. 4d having numerous detectable peaks. All the peaks of synthesized nanocomposite are consistent with database of HAP (JCPDS No. 09-0432), clinoptilolite (JCPDS No. 39-1383) and Fe30, (JCPDS No. 19-0629) in the JCPDS-International Center for Diffraction Data file. According to the figure, diffraction peaks at 35.43
Fig. 2. Synthesis scheme for MZeo-HAP nanocomposite preparation.
Fig. 2. Synthesis scheme for MZeo-HAP nanocomposite preparation.
Textual property of zeolite, MZeo, and MZeo-HAP nanocomposite. Table 1
Textual property of zeolite, MZeo, and MZeo-HAP nanocomposite. Table 1
Fig. 4. (a, b, c) FTIR of Fe304,, MZeo, and MZeo-HAP, (e) XRD and (d) VSM of MZeo-HAP.
Fig. 4. (a, b, c) FTIR of Fe304,, MZeo, and MZeo-HAP, (e) XRD and (d) VSM of MZeo-HAP.
Fig. 5. Nz adsorption-desorption isotherms for MZeo-HAP.
Fig. 5. Nz adsorption-desorption isotherms for MZeo-HAP.
Fig. 6. Schematic illustration for CR adsorption by MZeo-HAP via electrostatic attraction at low pH.
Fig. 6. Schematic illustration for CR adsorption by MZeo-HAP via electrostatic attraction at low pH.
Fig. 7. The effect of (a) pH, (b) pHzp- of MZeo-HAP, (c) contact time, (d) adsorbent dosage, (e) dye concentration and (f) temperature on adsorption efficiency
Fig. 7. The effect of (a) pH, (b) pHzp- of MZeo-HAP, (c) contact time, (d) adsorbent dosage, (e) dye concentration and (f) temperature on adsorption efficiency
Obtained parameters from studied isotherm models.
Obtained parameters from studied isotherm models.
Obtained parameters from PFO, PSO, and Elovich kinetics models.
Obtained parameters from PFO, PSO, and Elovich kinetics models.
Comparison of adsorption capacities of different adsorbents toward dye removal. Table 5
Comparison of adsorption capacities of different adsorbents toward dye removal. Table 5
3.12. Method validation Fig. 8. The comparison of MZeo and MZeo-HAP in terms of dye removal.
3.12. Method validation Fig. 8. The comparison of MZeo and MZeo-HAP in terms of dye removal.
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