Thermodynamics and Kinetics of Heavy Metals Adsorption on Silica Particles Chemically Modified by Conjugated β-Ketoenol Furan

A novel adsorbent for heavy metals, functionalized with conjugated beta-ketoenol Furan, was fabricated using a simple heterogeneous method. The adsorbent design (SiNFn) was well analyzed and characterized by the techniques of solid state C-13 NMR, Fourier transform-infrared spectroscopy (FTIR), elementary analysis, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore sizes, and scanning electron microscopy (SEM). The new surface has good thermal stability determined by thermogravimetry curves analysis (TGA), and a good chemical stability investigated in various acidic and buffer solutions. The effect of various parameters on Cd(II), Cu(II), Zn(II), and Pb(II) adsorption, such as pH, concentration, temperature, competitive extraction, thermodynamics and kinetics studies, and extraction of metals from real water samples were investigated. The results indicated that the adsorption efficiency increases with increasing pH and follows pseudo-second-order kinetics. Adsorption was rapid as evidenced by equilibrium achieved within 25 min. The adsorption isotherm was better described by a Langmuir compared to a Freundlich isotherm equation. The thermodynamic parameters (Delta H degrees, Delta S degrees, and Delta G degrees) revealed that the adsorption was spontaneous and endothermic. The competitive adsorption exhibited high selectivity toward Cd(II). The new material was applied to the extraction of metals from two real waters: Touissit-Boubeker River and Giss River (Morocco) and shows efficiency and selectivity results especially for Cd(II).