Biomaterial Database

Photooxidation of 2,4-dichlorophenoxyacetic acid by ferrous oxalate-mediated system. 2004

Y Kwan, and W Chu

Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong. joanna.kwan@polyu.edu.hk

The photodegradation of a herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by ferrous oxalate/UV/H2O2 was studied. Ferrous oxalate, the more photoactive and reactive species, was found to react faster with hydrogen peroxide for hydroxyl radical production than ferrous ions under UV irradiation. About 2.9 times greater rate enhancement was found with the addition of 0.3 mM oxalate than that of a solution containing 0.1 mM Fe2+ and 1 mM H2O2 in the presence of UV light at 253.7 nm. The kinetics dependence of hydrogen peroxide concentration and initial solution pH were also investigated. A threefold increase in peroxide concentration could accelerate the removal of 2,4-D and nearly complete the reaction in 30 min of illumination. The initial decay rate of 2,4-D treated by ferrous oxalate/UV/H2O2 accelerated from 0.0029 to 0.0034 s(-1) and the overall removal of the starting material increased from 78% to 99.9%. The 2,4-D transformation at lower initial pH had higher reaction rates than that at higher pH and different reaction mechanisms were identified. The efficiency of the herbicide decomposition was retarded 2.6 times and 9.6 times as initial pH increased from 2.8 to 5.1 and 9.0, respectively.

UI	MeSH Term	Description	Entries
D010070	Oxalates	Derivatives of OXALIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that are derived from the ethanedioic acid structure.	Oxalate,Ethanedioic Acids,Oxalic Acids,Acids, Ethanedioic,Acids, Oxalic
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010777	Photochemistry	A branch of physical chemistry which studies chemical reactions, isomerization and physical behavior that may occur under the influence of visible and/or ultraviolet light.	Photochemistries
D006540	Herbicides	Pesticides used to destroy unwanted vegetation, especially various types of weeds, grasses (POACEAE), and woody plants. Some plants develop HERBICIDE RESISTANCE.	Algaecide,Algicide,Herbicide,Algaecides,Algicides
D006861	Hydrogen Peroxide	A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.	Hydrogen Peroxide (H2O2),Hydroperoxide,Oxydol,Perhydrol,Superoxol,Peroxide, Hydrogen
D014466	Ultraviolet Rays	That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.	Actinic Rays,Black Light, Ultraviolet,UV Light,UV Radiation,Ultra-Violet Rays,Ultraviolet Light,Ultraviolet Radiation,Actinic Ray,Light, UV,Light, Ultraviolet,Radiation, UV,Radiation, Ultraviolet,Ray, Actinic,Ray, Ultra-Violet,Ray, Ultraviolet,Ultra Violet Rays,Ultra-Violet Ray,Ultraviolet Black Light,Ultraviolet Black Lights,Ultraviolet Radiations,Ultraviolet Ray
D015084	2,4-Dichlorophenoxyacetic Acid	An herbicide with irritant effects on the eye and the gastrointestinal system.	2,4-D,2,4-Dichlorophenoxyacetic Acid, Ammonium Salt,2,4-Dichlorophenoxyacetic Acid, Lithium Salt,2,4-Dichlorophenoxyacetic Acid, Potassium Salt,2,4-Dichlorophenoxyacetic Acid, Sodium Salt,Monosan,2,4 Dichlorophenoxyacetic Acid
D018508	Water Purification	Any of several processes in which undesirable impurities in water are removed or neutralized; for example, chlorination, filtration, primary treatment, ion exchange, and distillation. It includes treatment of WASTEWATER to provide potable and hygienic water in a controlled or closed environment as well as provision of public drinking water supplies.	Waste Water Purification,Waste Water Treatment,Wastewater Purification,Wastewater Treatment,Water Treatment,Purification, Waste Water,Purification, Wastewater,Purification, Water,Treatment, Waste Water,Treatment, Wastewater,Treatment, Water,Waste Water Purifications,Waste Water Treatments,Water Purification, Waste