Synthesis and Characterization of Zeolite Y Encapsulated Metal Complexes and Surfactant Modified Zeolite Y for Removal of Pollutants

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa Universty


In this study heterogeneous catalysts were synthesized based on the encapsulation of iron(III), nickel(II) and copper(II) with complexes of N,N′-ethylenebis(salicylimine), mixed ligands of 2,2'-bipyridine and 1,10-phenanthroline and N,N′-disalicylidene-1,2- phenylenediamine ligands into zeolite Y supercage using ship-in-a-bottle method of synthesis. The catalysts were characterized by X-ray powder diffraction, BET surface area and pore volumes, Fourier transform infrared spectroscopy, electron paramagnetic resonance, thermo-gravimetric and elemental analysis. Computational studies based on Density functional theory (DFT) calculation are carried out on both neat complexes as well as metal complexes encapsulated into zeolite Y to investigate changes in structural parameters like bond length, bond angle and dihedral angle, energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), global hardness and softness value of the metal complexes upon encapsulation into zeolite. The results obtained from the physico-chemical analytical techniques showed that iron(III), nickel(II) and copper(II) complexes of N,N′-ethylenebis(salicylimine), mixed ligand of 2,2'-bipyridine and 1,10-phenanthroline and N,N′-disalicylidene-1,2- phenylenediamine ligands were successfully formed into zeolite Y supercage without affecting zeolite structure and properties of the metal complexes. Moreover, Density functional theory (DFT) calculations predicted that zeolite encapsulated metal complexes has higher reactivity compared to respective metal complexes. The catalysts prepared were found to be very effective in the removal of organic pollutants (i.e. azo dye, 2-phenyl phenol (OPP) and 4-chloro-3-methyl phenol (PCMC)) from synthetic wastewater. Interactive effects of four factors; initial hydrogen peroxide (H2O2) concentration, catalyst dosage, temperature and pH on the degradation of selected organic pollutants were determined. Experimental results showed that lower pH and higher temperature were optimal for complete removal of organic pollutants using the prepared catalysts. Moreover, increase in the concentration of hydrogen peroxide (H2O2) and catalyst dosage, beyond the optimum concentration had a negative effect attributed to the formation of hydroperoxyl radical (•OOH). This has a lower oxidation potential than the hydroxyl radical (•OH) and aggregation of catalysts, respectively. The extent of reusability for the catalytic oxidation of organic pollutants and the possible deactivation mechanism after successive reuse of each catalyst were studied. The possible intermediate product, degradation pathway and kinetic studies for oxidation of organic pollutants were also studied. Besides ion exchange zeolite have adsorption properties due to its large surface area and net negative charge. In this study the negative charge and hydrophilic surface properties of neat zeolite were modified by haxadecyltrimethyl ammonium bromide (HDTMA-Br) surfactant to adsorb both inorganic and organic pollutants simultaneously. The surfactant modification effect on the surface of zeolite was characterized using X-ray powder diffraction, FT-IR spectroscopy, scanning electron microscopy, BET surface area and pore volume, thermo gravimetric analysis, zeta potential and hydrophobicity measurements. The results of physico-chemical analytical techniques showed that a bilayer of surfactant-modified zeolite was successfully formed on the external surface of the zeolite. The surfactant-modified zeolite was investigated for the adsorption of acid blue dye and Cr(VI) in synthetic wastewater. The effects of adsorbent dosage, pH, temperature, time and initial pollutant concentrations were investigated in batch adsorption experiments. The correlation coefficient and the normalized standard deviation value showed that the experimental isotherm data fitted well to Langmuir and Freundlich isotherm models for acid blue dye and Cr(VI), respectively. The kinetic process is well described by pseudo second order kinetic model. The prepared catalyst and the surfactant modified zeolite showed good catalytic and adsorption capacities for removal of organic and inorganic pollutants from real tannery wastewater



Encapsulated Metal Complexes and Surfactant Modified Zeolite Y