Synthesis And Characterization Of Zeolite Y Encapsulated Metal Complexes And Surfactant Modified Zeolite Y For Removal Of Pollutants

In this study heterogeneous catalysts were synthesized based on the encapsulation ofrniron(III), nickel(II) and copper(II) with complexes of N,N′-ethylenebis(salicylimine),rnmixed ligands of 2,2'-bipyridine and 1,10-phenanthroline and N,N′-disalicylidene-1,2-rnphenylenediamine ligands into zeolite Y supercage using ship-in-a-bottle method ofrnsynthesis. The catalysts were characterized by X-ray powder diffraction, BET surfacernarea and pore volumes, Fourier transform infrared spectroscopy, electron paramagneticrnresonance, thermo-gravimetric and elemental analysis. Computational studies based onrnDensity functional theory (DFT) calculation are carried out on both neat complexes asrnwell as metal complexes encapsulated into zeolite Y to investigate changes in structuralrnparameters like bond length, bond angle and dihedral angle, energies of the highestrnoccupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO),rnglobal hardness and softness value of the metal complexes upon encapsulation intornzeolite.rnThe results obtained from the physico-chemical analytical techniques showed thatrniron(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-rnphenylenediamine ligands were successfully formed into zeolite Y supercage withoutrnaffecting zeolite structure and properties of the metal complexes. Moreover, Densityrnfunctional theory (DFT) calculations predicted that zeolite encapsulated metal complexesrnhas higher reactivity compared to respective metal complexes.rnThe catalysts prepared were found to be very effective in the removal of organicrnpollutants (i.e. azo dye, 2-phenyl phenol (OPP) and 4-chloro-3-methyl phenol (PCMC))rnfrom synthetic wastewater. Interactive effects of four factors; initial hydrogen peroxidern(H2O2) concentration, catalyst dosage, temperature and pH on the degradation of selectedrnorganic pollutants were determined. Experimental results showed that lower pH andrnhigher temperature were optimal for complete removal of organic pollutants using thernprepared catalysts. Moreover, increase in the concentration of hydrogen peroxide (H2O2)rnand catalyst dosage, beyond the optimum concentration had a negative effect attributed tornthe formation of hydroperoxyl radical (•OOH). This has a lower oxidation potential thanrnthe hydroxyl radical (•OH) and aggregation of catalysts, respectively. The extent ofrnreusability for the catalytic oxidation of organic pollutants and the possible deactivationrnmechanism after successive reuse of each catalyst were studied. The possiblernintermediate product, degradation pathway and kinetic studies for oxidation of organicrnpollutants were also studied.rnBesides ion exchange zeolite have adsorption properties due to its large surface area andrnnet negative charge. In this study the negative charge and hydrophilic surface propertiesrnof neat zeolite were modified by haxadecyltrimethyl ammonium bromide (HDTMA-Br) surfactant to adsorb both inorganic and organic pollutants simultaneously. The surfactantrnmodification effect on the surface of zeolite was characterized using X-ray powderrndiffraction, FT-IR spectroscopy, scanning electron microscopy, BET surface area andrnpore volume, thermo gravimetric analysis, zeta potential and hydrophobicityrnmeasurements. The results of physico-chemical analytical techniques showed thatrna bilayer of surfactant-modified zeolite was successfully formed on the external surfacernof the zeolite. The surfactant-modified zeolite was investigated for the adsorption of acidrnblue dye and Cr(VI) in synthetic wastewater. The effects of adsorbent dosage, pH,rntemperature, time and initial pollutant concentrations were investigated in batchrnadsorption experiments. The correlation coefficient and the normalized standardrndeviation value showed that the experimental isotherm data fitted well to Langmuir andrnFreundlich isotherm models for acid blue dye and Cr(VI), respectively. The kineticrnprocess is well described by pseudo second order kinetic model. The prepared catalystrnand the surfactant modified zeolite showed good catalytic and adsorption capacities forrnremoval of organic and inorganic pollutants from real tannery wastewater

Get Full Work

Report copyright infringement or plagiarism