Nanocrystalline Zeolites A: Synthesis and Heavy Metal Adsorption
Heavy metals in water and wastewater are important toxic pollutants. Removal of heavy metals from wastewater by adsorption is an effcient process. Nanocrystalline zeolites A has been synthesis from clear solution at temperature 150 0C which contains tetramethylammonium (TMA) cations as a organic template, aluminum tri-isopropoxide (Al(OiPr)3) as aluminum sources and Ludox LS as silica sources. The products were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to identify the structure and particle size. After 3, 4 and 5 day synthesis times, nanocrystalline zeolites A were obtained with 146 nm, 421 nm and 691 nm particle sizes, respectively. The synthesized zeolite A was applied for some metal adsorption and the results show that the nano crystal samples are well performanced. The removal efficiency for Cr and Pb could be 30% to 75% depending on the initial concentration and temperature. The adsorption isotherm on Cr and Pb were determined from Langmuir and Freundlich equation. The equilibrium sorption capacities (qe) from the Langmuir equation were 285.71 mg/g and 312.51 mg/g at 30 0C and 344.82 mg/g and 384.6 mg/g at 45 0C for Cr and Pb, which are much better than natural zeolites. Kinetic adsorption parameter analysis of nano zeolites A shows that the pseudo first order kinetics would be better for fitting the dynamic adsorption of both Cr and Pb cations.