Award Date

12-2010

Degree Type

Thesis

Degree Name

Master of Science in Water Resources Management

Department

Water Resource Management

First Committee Member

Charalambos Papelis, Chair

Second Committee Member

Michael Nicholl

Third Committee Member

Vernon Hodge

Graduate Faculty Representative

Jacimaria Batista

Number of Pages

85

Abstract

As world population grows so does the demand for safe drinking water. Meanwhile water resources become increasingly scarce and quality of natural water decreases due to a combination of natural and anthropogenic factors. Industry and agriculture have become a premiere source of hazardous constituents, along with natural processes such as rock weathering and volcanic eruptions. Our ability to remove hazardous constituents from water depends on chosen technology and nature of contaminant. Sorption and ion-exchange have been widely applied for water purification. Natural zeolites have been widely applied in water and waste water treatment as ion-exchangers for removal of harmful contaminants from water. Most technologies that use natural zeolites are based on the unique cation exchange behavior of zeolites, thus making this sorbent limited to cation removal. Coating iron-oxide onto particles with natural affinity for cations (such as zeolites) and high surface area provides for an effective sorption media with the application for both cationic and anionic contaminants from water.


It was proposed that modification of natural zeolitized tuff according to techniques, previously tested on sand, would enhance anion removal capacity of the media and the coating would not adversely impact cation exchange capacity. Arsenic and strontium are commonly found in water supplies, and therefore are selected for this study to represent oxyanions and cations, respectively, in water systems. Natural zeolitized tuff was modified according to previously published techniques, and natural and modified particles were characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and cation-exchange capacity (CEC) was determined by ammonium saturation method. Sorption behavior of Ar (V) and Sr (II) was examined batchwise as a function of pH, ionic strength and the concentration of ion of interest. Residual concentrations of As (V) and Sr (II) in the solution were determined by GFAA and ICP.


Sorption studies revealed that application of iron-coating increased As (V) removal capacity of natural zeolitized tuff up to 100%, specifically in lower (1x10-6 M) concentrations and acidic pH. Iron-coating did not results in significant changes in cation-removal capacity as both natural and modified zeolitized tuffs showed similar cation-removal capacity in identical experimental conditions.

Keywords

Adsorption; Ion exchange; Iron-oxide coated zeolites; Iron oxides; Strontium; Water — Purification; Water — Purification — Arsenic removal; Volcanic ash; tuff; etc.; Zeolitized tuff; Zeolites

Disciplines

Environmental Sciences | Fresh Water Studies | Natural Resource Economics | Water Resource Management

Language

English


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