Ozonation of drinking water: part I. Oxidation kinetics and product formation.

Pharmaceuticals in STP effluents and their solar photodegradation in aquatic environment.

Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine.

Guidelines for Canadian Drinking Water Quality

Minerals and transitional metal oxides of earth-abundant elements are desirable catalysts for in situ chemical oxidation in environmental remediation. However, catalytic activation of peroxydisulfate (PDS) by manganese oxides was barely investigated. In this study, one-dimension manganese dioxides (α- and β-MnO2) were discovered as effective PDS activators among the diverse manganese oxides for selective degradation of organic contaminants. Compared with other chemical states and crystallographic structures of manganese oxide, β-MnO2 nanorods exhibited the highest phenol degradation rate (0.044 min-1, 180 min) by activating PDS. A comprehensive study was conducted utilizing electron paramagnetic resonance, chemical probes, radical scavengers, and different solvents to identity the reactive oxygen species (ROS). Singlet oxygen (1O2) was unveiled to be the primary ROS, which was generated by direct oxidation or recombination of superoxide ions and radicals from a metastable manganese intermediate at neutral pH. The study dedicates to the first mechanistic study into PDS activation over manganese oxides and provides a novel catalytic system for selective removal of organic contaminants in wastewater.

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Persulfate Activation on Crystallographic Manganese Oxides: Mechanism of Singlet Oxygen Evolution for Nonradical Selective Degradation of Aqueous Contaminants.

Ozonation of bromide-containing waters: kinetics of formation of hypobromous acid and bromate

For prediction of the rate with which organic compounds are oxidized and photoproducts formed in the aquatic environment by the /sup 1/O/sub 2/ route, the steady-state concentrations of O/sub 2/ in various waters were determined by using furfuryl alcohol as a trapping agent. Under noon, summer sunlight (Switzerland) in lake, river, and wastewaters, surface concentrations were (0.3-3) x 10/sup -14/ M /sup 1/O/sub 2/ per mg of DOC/L. Separation of natural aquatic organic compounds by gel permeation chromatography resulted in fractions showing little correlation between /sup 1/O/sub 2/ production efficiency and molecular weight, indicating that large macromolecular structures are not a prerequisite for the sensitization of /sup 1/O/sub 2/ formation. 26 references, 8 figures, 3 tables.

Werner R. Haag

Papers

Ozonation of bromide-containing waters: kinetics of formation of hypobromous acid and bromate

Singlet oxygen in surface waters. 3. Photochemical formation and steady-state concentrations in various types of waters