Microporous nanocrystalline NaA zeolite prepared by microwave assisted hydrothermal method and determination of kinetic, isotherm and thermodynamic parameters of the batch sorption of Ni (II)

Sorption of Ni (II) was well investigated and elucidated using nanocrystalline zeolite NaA (nNaA) synthesized by microwave assisted hydrothermal method, in which sodium metasilicate and sodium aluminate were applied as silica and alumina source. The synthesized zeolite was well characterized using various analytical techniques such as XRD, FE-SEM, FTIR and N2 adsorption-desorption isotherm. The influence of effective parameters such as pH, contact time, adsorbent dosage, initial concentration and temperature was optimized using batch adsorption method. The obtained optimized values for initial pH (2-8), contact time (0-150 min), adsorbent dosage(0.05-0.15 g), (50-2000 mg/L), temperature (298, 318 and 333 K) were 6, 60 min, 0.1 g, 100 ppm and it was found that the adsorption capacity increases with increase in temperature hence the process is exothermic in nature. The obtained equilibrium data were well fitted and found to be in good agreement with the Langmuir isotherm model type 1 (R2 > 0.99) with maximum monolayer adsorption capacities (qm) around 94.339, 131.578 and 185.185 mg/g at 298, 318 and 333 K, respectively. Thermodynamic parameters such as δ G, δ H and δ S reveal the spontaneous and exothermic nature of the adsorption process under natural conditions. Hence it can be concluded that the developed zeolite i.e. nNaA has potential application as adsorbent for rapid removal of Ni (II) from the solvent phase of aqueous solution.