Synthesis and characterisation of Zeolite/ ZnO nanocomposite for the removal of Rhodamine B from real textile wastewater

The release of dye wastewater from textile industries is of major environmental concern. In this work, a Zeolite/ZnO nanocomposite was prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and point of zero charge (PZC) analysis and evaluated for the removal of Rhodamine B (RhB) from aqueous solutions and real textile wastewater. The effect of contact time, pH, adsorbent dosage and initial dye concentration were studied using batch adsorption tests. The best condition was contact time of 20 min, pH 7, adsorbent dosage of 0.3 g, initial RhB concentration of 3.5 mg/L and temperature of 25 °C, which resulted in maximum removal efficiency of 74.95%. The equilibrium and kinetic data were well fitted to the Langmuir isotherm (R 2 = 0.991) and pseudo-second-order kinetic model (R 2 = 0.9986). The Langmuir separation factor (R L ) was found to be 0.717 indicating favourable adsorption process. The practical application of the nanocomposite was illustrated by the usage of textile wastewater where it showed an entire removal of the RhB at the original wastewater concentration of 0.339 mg/L and 87.74% removal at the spiking condition of 3.5 mg/L. The treatment technique also resulted in 99.16% and 91.45% reduction in electrical conductivity and total dissolved solids correspondingly. Moreover, the nanocomposite showed good performance for five regeneration cycles. The present work emphasizes Zeolite/ZnO nanocomposite as an efficient, reusable and low-cost adsorbent for treatment of textile wastewater.