Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery.

Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 μg/L while being magnetically recoverable.

Investigations of photochemical transformations of aqueous mercury: implications for water effluent treatment technologies.

Photochemical transformations of mercury were studied to determine its potential as a treatment mechanism to reduce mercury laden waters to trace concentrations. In this study, aqueous solutions of mercury nitrate in deionized water were exposed to UV irradiation and a gas purge. The impacts of purge gas (including rate and bubble size), UV irradiation wavelength, initial mercury concentration and time on mercury removal have been studied.

Removal of trace level aqueous mercury by adsorption and photocatalysis on silica-titania composites.

Silica-titania composites (STCs) were applied to trace level mercury solutions (100 microg/L Hg) to determine the degree of mercury removal that could be accomplished via adsorption and photocatalysis. STCs are a porous, high surface area silica substrate (> 200 m(2)/g), manufactured using sol-gel methodology, impregnated with TiO2 nanoparticles. The performance of this material along with its precursors, silica and Degussa P25 TiO2 were compared.

Photocatalytic degradation of methanol using silica-titania composite pellets: effect of pore size on mass transfer and reaction kinetics.

Nanostructured silica-titania composites (STC) synthesized with varying pore sizes (45, 134, and 299 angstroms) were tested for the removal of methanol from a humid air stream. The STC pellets were characterized for surface area and pore size distribution and tested in a packed-bed photocatalytic reactor for methanol removal and oxidation. While the pore size distributions for all STC were unimodal, STC with larger average pore sizes exhibited a broader pore size distribution.

Development of a regenerable system employing silica-titania composites for the recovery of mercury from end-box exhaust at a chlor-alkali facility.

The release of mercury to the environment is of particular concern because of its volatility, persistence, and tendency to bioaccumulate. The recovery of mercury from end-box exhaust at chlor-alkali facilities is important to prevent release into the environment and reduce emissions as required by NESHAP (National Emission Standards for Hazardous Air Pollutants). A pilot-scale photocatalytic reactor packed with silica-titania composite (STC) pellets was tested at a chloralkali facility over a 3-month period.

Improvement of thermal reactivation of activated carbon for the removal of 2-methylisoborneol.

Rapid small-scale column tests (RSSCTs) were employed to evaluate the impact of the dissolved oxygen (DO) concentration in the water used to create steam on the reactivation of spent granular activated carbon (GAC) using three novel thermal reactivation procedures: steam-curing, steam-curing with ramped temperature, and steam pyrolysis reactivation. Evaluation of the physical properties of the reactivated carbon showed a change in mass and volume loss with a change in DO. Performance testing of the carbons for removal of the taste- and odor-causing compound 2-methylisoborneol (MIB) showed that MIB uptake generally increased as the DO concentration decreased.

Removal of methanol from pulp and paper mills using combined activated carbon adsorption and photocatalytic regeneration.

Methanol is one of the major hazardous air pollutants emitted from chemical pulp mills. Its collection and treatment is required by the Maximum Achievable Control Technology portion of the 1998 Cluster Rule. The objective of this study is to investigate the technical feasibility of combined adsorption and photocatalytic regeneration for the removal and destruction of methanol.

Magnetically agitated photocatalytic reactor for photocatalytic oxidation of aqueous phase organic pollutants.

A magnetically agitated photocatalytic reactor (MAPR) has been developed and assessed for oxidation of phenol. The MAPR uses a titanium dioxide composite photocatalyst with a ferromagnetic barium ferrite core. The catalyst motion was controlled with a dual-component magnetic field.

Adsorption enhancement mechanisms of silica-titania nanocomposites for elemental mercury vapor removal.

A novel nanocomposite that combines high-surface area silica with the photocatalytic properties of titania has been developed that allows for effective capture of elemental mercury vapor. The adsorption capability of the developed material has been found to improve after periods of photocatalytic oxidation. In this study, the mechanisms for adsorption enhancement were identified.

Enhancing activated carbon adsorption of 2-methylisoborneol: methane and steam treatments.

This research investigated methods for tailoring a commercial, lignite-based granular activated carbon (GAC) to enhance its adsorption of 2-methylisoborneol (MIB) from natural water. Tailoring efforts focused on heat treatments in gas environments comprising steam and/or methane, since these gases can alter GAC pore structure and surface chemistry. Heat treatments that combined methane and steam enhanced MIB adsorption considerably, causing a 4-fold improvement (over untreated GAC) in fixed-bed adsorption performance relative to initial MIB breakthrough.