Use of central composite design and surface modeling for cadmium (ii) ions removal from aqueous environment using novel modified layer double hydroxide

In this work, Zn۲Al-layered double hydroxide (LDH) that modified with Ponceau ۴R (E ۱۲۴) as food coloring, (Zn۲Al-LDH/Ponceau) was synthesized and characterized  using different techniques including, X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray (EDX) spectroscopy. Zn۲Al-LDH/Ponceau was then applied for Cd۲+ removal from aqueous solution. The response surface methodology (RSM) approach using central composite design (CCD) was applied to develop a mathematical model and optimize process parameters for Cd۲+ removal from aqueous solution using a chemically modified Zn۲Al-LDH/Ponceau. The optimal conditions to remove Cd۲+ from aqueous solution were found to be initial Cd۲+ concentration of ۷۶ mg.L-۱, pH value of ۴.۲۲, adsorbed amount of ۰.۰۴ g, temperature of ۳۰.۳ °C, and the contact time of ۴۶ min. The isotherm and kinetics and thermodynamics of the adsorption were investigated in detail. The obtained results suggested the adsorption of Cd۲+ onto Zn۲Al-LDH/Ponceau follow Langmuir isotherm and the kinetic data are in good agreement with the Elovich kinetic model. In addition, the results of thermodynamic parameters indicated that the adsorption process was instantaneous nature and exothermic.  

کلیدواژه ها:

Layered double hydroxide ، Cd۲+ adsorption ، Response Surface Methodology ، Central composite design