Highly efficient batch adsorption of anionic dye in wastewater using nanocomposite: Experimental and theoretical studies

Abstract

The adsorptive properties of the Erionyl Red (ER) dye on bentonite (B) intercalated with cetyltrimethylammonium bromide (HDTMA-B) were investigated using experimental and statistical physics methods. The dye was then taken up by the intercalated bentonite from a real water sample. After intercalation, X-ray diffraction analysis indicates an increase in HDTMA-B basal spacing to 15.2 Ả. Scanning electron microscopy images show the formation of large particles and many cavities. The results revealed that the material had high properties to adsorb organic molecules (greater than 99 %). The Langmuir-Freundlich model, described the isotherms, whereas the second-order model better captured the kinetic of dye adsorption. The maximum ER uptake observed was 478 mg g−1 at a temperature of 328 K. Reusability of nanocomposite showed stability, over five cycles. Thermodynamic analysis suggested spontaneous (negative ΔG°) and endothermic (positive ΔH°) adsorption processes. The statistical physics model was also used to estimate the orientation of ER adsorption on the material. The oxygens connected to the dye in the HDTMA-B structure played in particular an important role in the adsorption mechanisms of dye. This study combines experiment data with a theoretical approach to provide a new explanation for the mechanism. The removal of dyes from wastewater, in particular Erionyl red, is vital for the protection of the environment and public health. Nanocomposite appears to be an effective, durable, and environmentally friendly adsorbent for the removal of Erionyl red dye from synthetic solutions and real wastewater.