Adsorptive Removal Of Organic Pollutants By Magnetic MOFs And Metal Based Mesoporous Silicas

This dissertation presents efforts to develop novel sorbents for adsorptive removal of organic dyes and sulfur containing compounds from commercial and simulated fuels.For cationic dye removal,uniform magnetic Fe₃O₄@MIL-100?Fe?core-shell microspheres were fabricated for the first time by a facile one-step hydrothermal strategy in which Fe₃O₄ microspheres not only act as core for MIL-100?Fe?shell but also play a role as an Fe metal precursor for Fe₃O₄@MIL-100?Fe?core-shells.The magnetic microspheres were uniform in size and highly superparamagnetic.The shell thickness was easily controlled by changing the reaction time.The adsorption process of MB followed Langmuir isotherm and pseudo-second-order.The thermodynamics of adsorption was analyzed to be spontaneous and exothermic.High adsorption capacity,good recyclability and superparamagnetism made them a good candidate for MB removal from waste water.For adsorptive desulfurization of simulated and commercial fuels,Ni based metal organic framework and mesoporous materials were synthesized.Nickel nanoparticles?<2 nm?,using Ni?NO₃?₂.6H₂O as nickel source up to 20 wt%were confined in MIL-101?Cr?cages for the first time by ultrasonic assisted IWI impregnation.Ni-MIL-101?Cr?exhibited enhanced sulfur adsorption capacity because of high surface area,excellent pore structure,high dispersion of nickel species,and the acidic sites on the surface.The adsorption of thiophene over Ni-ML-101 followed Pseudo second-order kinetics and Langmuir model.One-pot H₂-reduction synthetic strategy was developed for Ni⁰-based SBA-15 for adsorptive desulfurization of fuels.Ni?NO₃?₂·6H₂O as a nickel source was directly introduced into as-synthesized SBA-15.The subsequent reduction strategy allow Ni?NO₃?₂·6H₂O conversion to NiO,template P123 removal and reduction of NiO to Ni⁰ in a single step.In contrast with calcined SBA-15,as-synthesized SBA-15 provided confined spaces between template and silica walls for insertion of nickel assembly and 30 wt%nickel species with Ni⁰ were well-dispersed confirmed by XRD,TEM and Uv-DRS analysis.Severe aggregation of nickel species occurred outside pores in calcined SBA-15.This new strategy was more facile and Ni⁰ yield was enhanced to 75%calculated from XPS spectra.The synthesized materials were efficient in adsorptive desulfurization due to strong acidity and showed good reusability.Single-step H₂-reduction strategy was also successfully applied for the synthesis of Ni⁰ based KIT-6.This technique significantly improved the dispersion of nickel species than calcined KIT-6 due to existence of abundant silanols and confined spaces.Thus,template removal,decomposition of nickel precursors to NiO and reduction of NiO to Ni⁰ all occurred in one-step.Chloride,acetate and nitrate salts of Ni were used as precursors and it was found that along with as-synthesize KIT-6 support,nickel precursors also played a significant role dispersion of nickel species due to shielding effect of their capping anions along with hydration extent.Breakthrough tests showed that Ni-KIT-6?NO₃^-?can capture maximum 0.195 and 0.12 mmol.g^-1 of sulfur from model fuel and FCC gasoline,respectively.Thus,nickel precursors,synthesis strategy,and state of supports played an active role for the improved sulfur adsorption capacity of adsorbents.