Development of Zeolite/ BI2O3 nanocomposite for removal of Rhodamine B dye from wastewater

Abstract

This study focused on the synthesis of a zeolite/bismuth oxide nanocomposite for the removal of Rhodamine B dye from wastewater. The synthesis of the nanocomposite was achieved through the sol-gel method, followed by thorough characterization using various techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD), dynamic light scattering (DLS), point of zero charge determination, and surface resonance analysis. The optimization conducted through a batch process involved a comprehensive investigation into various parameters to assess their influence on Rhodamine B dye removal efficiency. The results revealed that the optimum conditions for maximum removal efficiency (100%) were achieved at pH 4, an initial dye concentration of 0.5 mg/L, an adsorbent dose of 0.55 g, a contact time of 10 minutes, and a temperature of 25 °C. The isotherm study revealed that the adsorption behaviour of Rhodamine B dye onto the zeolite/Bi2O3 nanocomposite followed the Freundlich Isotherm Model with a correlation coefficient (R2) value of 0.9953, suggesting a favourable adsorption process. Additionally, the kinetic model analysis indicated that the pseudo-second-order model best described the adsorption kinetics, implying a chemisorption mechanism. Furthermore, the thermodynamic analysis provided valuable insights into the spontaneous and endothermic nature of the adsorption process. The negative values of ΔG° indicated the feasibility and spontaneity of the adsorption, while the positive ΔH° indicated an endothermic nature. The negative value of ΔS° indicated a decrease in the randomness at the solid-liquid interface during the adsorption process. The zeolite/Bi2O3 nanocomposite was then used to test its efficiency in removing Rhodamine B dye from real wastewater samples. The percentage of Rhodamine B dye removed by zeolite/Bi2O3 nanocomposite was 98.12% of wastewater sample. This study, therefore, suggests that zeolite/Bi2O3 nanocomposite is a promising absorbent for the removal of Rhodamine B dye from aqueous solutions and wastewater samples.