Competitive Adsorption of Cu, Ni, Pb, and Cd from Aqueous Solution Onto Fly Ash-Based Linde F(K) Zeolite

Abstract

The reaction of fly ash with a KOH solution was used to synthesize Linde F(K) zeolite, following which Fourier transform infrared spectroscopy were used to characterize the crystalline material. The competitive adsorption of Cu, Ni, Pb, and Cd onto this zeolite was subsequently studied in quaternary solution systems. The results show that the metal removal rates gradually increase with increases in the pH of the adsorption solution until reaching an asymptotic value. During the early stages of adsorption, the metal removal rate is very rapid, after which it gradually decreases. The overall adsorption efficiency order is Pb > Cd > Cu > Ni. The adsorption process is best represented by pseudo-second-order kinetics and an internal surface diffusion model. The primary adsorption process, which takes place between approximately 1 to 2 min and 40 min, appears to be controlled by internal surface diffusion.