Date of Award

December 2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Nidal Abu Zahra

Committee Members

Marcia Silva, Benjamin Church, Junjie Niu, Peter Hinow

Keywords

Adsorption, Heavy metals, Ion exchange, Water

Abstract

The estimated average blood lead level for the population younger than 5 years in the United States is approximately 100 times higher than ancient background levels, indicating that substantial sources of lead exposure exist in the environment. This research is focused on the removal of lead from water with a functionalized zeolite. Functionalization improves adsorption behavior to achieve adsorbent materials with high capacity and stability with potential multiple re-uses.

The lead sorption from water onto an Australian zeolitic mineral (clinoptilolite) unmodified and modified with sulfide-based reagents is investigated with batch and fixed bed column experiments. The effect of solution pH, functional groups’ concentration, and competing ions are studied on the adsorption behavior. Functional groups stability and particles regeneration are also examined. The idea of functionalizing zeolite with sulfides for the removal of lead is able to develop a unique adsorbent material. The use of reactive sulfides attached to zeolite is a novel development.

The functionalized zeolite was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). The reactivity, sorption kinetics behavior, and retention isotherms for lead were determined to permit modeling and design of processes for optimum contaminant removal.

The significance of this research work is realized by its ability to create an engineered mesoporous-macroporous medium for lead adsorption by incorporating the functionality into the natural zeolite; this is accomplished using sulfides-based reagents. Sulfide-based reagents are ideal candidates for heavy metal remediation applications because of their soft basic frameworks, which should show increased affinity toward softer Lewis acids. The functional design and data analysis are significant to the scientific community, and are fundamental for the water industry, as they provide the knowledge necessary for developing next-generation water filtration media using zeolite materials.

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