Comparative Sorption Studies of Dyes and Metal Ions by Ni/Al-Layered Double Hydroxide

摘要

Anionic clay Ni/Al Layered double hydroxide (Ni/Al-LDHs) with M²⁺:M³⁺ of (4:1, 3:1, 2:1 and 1:1) ratios were synthesized by co-precipitation method from nitrate salt solutions. The synthesized LDHs were characterized by thermo-gravimetric analysis, Fourier transform infrared spectroscopy, X-Ray Diffraction, Energy Dispersive Spectroscopy/Scanning Electronic Microscopy and Thermogravimetric spectroscopy. The effects of contact time, temperature and initial concentrations on the adsorption of lead, copper, congo red and methylene blue were investigated to optimize the conditions for maximum adsorption. The experimental data from the batch adsorption studies were subjected to equilibrium studies using Langmuir, Freundlich, Temkin and Dubinin-Kaganer-Radushkevic isotherms and found to be consistent with physical adsorption. The results from the thermodynamic studies also indicated, that the adosprtion of dyes was endothermic while that of metal ions was exothermic.