Removing diazo direct red 81 using chitosan/zero-valent iron nanocomposite from aqueous solutions and process Optimization

A simple and rapid approach based on chitosan/zero-valent nanocomposite (CS-nZVI) was synthesised for efficient removal of diazo Direct Red81 from aqueous medium.This nanocompositewasidentified and characterised by Field Scanning Electron Microscope (FSEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy(FTIR). The effect of different parameters such as contact time, adsorbent dosage, pH, initial concentration of dye, and temperature were examined. The highest removal efficiency was about 97% at an adsorbent dosage of 0.2 g L-1, contact time of 12 min, pH = 7, and the pollutant concentration of 10 mg L (- 1). Also, the highest removal value of real sample (Textile effluent) was 85%. Langmuir and Freundlich adsorption isotherms were examined that was better matched to the Freundlich adsorption isotherm model with R-2 = 0.9082. The Pseudo-first-order and Pseudo-second order kinetics were also investigated which was understood that it follows Pseudo-first-order kinetic with R-2 = 0.9602. Finally, thermodynamic study in different temperatures, which showed that The reaction is spontaneous and endothermic.