Search

The focus of the study is on the optimization of variables influencing the removal of Cd(II) ions using colloidal particles based on 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol (Br-PADAP) functionalized on Mesoporous Santa Barbara Amorphous-15 (SBA-15). The Br-PADAP-functionalized SBA- 15 mesoporous silica was synthesized and utilized as an adsorbent for removal of cadmium ions. By means of thermogravimetric analysis, transmission electron microscope, Brunauer, Emmett, and Teller, and CHNS analysis, the structural and physicochemical properties of the SBA-15 and its complex with Br-PADAP were characterized. The effects of different variables such as pH, amount of sorbent, temperature, and contact time on the adsorption of Cd(II) ions were examined. The highest adsorption capacity of the adsorbent was found to be considerable (5,000.0 mg g–1) by using the functionalized material. The reusability of the resulted composite is found for more than six cycles. The negative value of ΔG along with the positive value of ΔH shows that the cadmium adsorption on Br-PADAP/SBA-15 is a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

In this study, polyaniline/Fe3O4(PAni/Fe3O4) magnetic nanoparticles were synthesized and used as an adsorbent for the removal of Reactive Red 198 (RR 198) from water. Scanning electron microscope was used for determining morphology and size distribution of the prepared nanoparticles. The size of magnetic nanoparticles Fe3O4was characterized by Transmission Electron Microscope. The formation of magnetic nanoparticles Fe3O4, was confirmed through X-ray Diffraction Technique. The chemical structures of the products were investigated with Fourier transform infrared spectroscopy. Effective parameters on the removal of RR 198 such as pH, dosage, and time were investigated and optimized. At the optimum situations the pH, dosage, and time were 5, 0.8 g l–1, and 90 min, respectively. For determining the type of adsorption isotherm, Temkin, Langmuir, and Freundlich adsorption isotherms were used. The results revealed that Langmuir isotherm adequately met the experimental requirements. According to the Langmuir model, PAni/Fe3O4magnetic nanoparticles sorbents exhibited the highest RR 198dye adsorption capacity of 45.454 mg g−1. Kinetic analyses were conducted using pseudo-first and second-order models and the regression results showed that the adsorption kinetics was more accurately represented by the pseudo-second-order model. Thermodynamic parameters such as changes in Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were calculated. The negative values of ΔG°and the positive value of ΔH°(257.068KJ/mol) and ΔS°(104.590 J/mol K) show that the RR 198 adsorption on PAni/Fe3O4magnetic nanoparticles was a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]