Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.

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Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry

Fundamental principles and application of heterogeneous photocatalytic degradation of dyes in solution

Advanced oxidation process-mediated removal of pharmaceuticals from water: A review.

Steam reforming reactions will play a key role in new applications of synthesis gas and in a future hydrogen economy. The aim of this review is to provide a coherent description of the catalysis of the reforming reactions. The review is not comprehensive. The first section deals with the applications of synthesis gas and hydrogen and the various synthesis gas technologies. The optimum choice of technology depends on the requirements of the gas composition and the scale of operation. Two examples are included for illustration: synthesis gas for gas-to-liquid plants and hydrogen for fuel cells. The steam reforming process is described in the second section with emphasis on the role of the catalyst and problems related to carbon formation. The third section is a summary of the empirical evidence of the catalysis of the reforming reactions. The methods of characterization are discussed, and data representing sintering, activity trends, and promotion are summarized. The fourth section is a description of the mechanism based on a combination of empirical knowledge with recent data from studies of well-defined surfaces, in-situ high-resolution electron microscopy, and calculations based on density functional theory. The central concept is the role of surface defects as the source of reactivity and the nucleation centers for whisker carbon formation.

Hydrogen and Synthesis gas by Steam- and CO2 reforming

Synthesis and photocatalytic activity of ferrites under visible light: A review

Over the past few decades, a high number of pharmaceuticals have been detected in surface, ground and drinking waters. This contamination comes from domestic sewage, livestock, hospitals and chemical-pharmaceutical industries. Typical examples of these pollutants are the fluoroquinolones - powerful antibiotics used in human and veterinary medicine. The presence of fluoroquinolones in the environment can pose a serious threat to the ecosystem and to human health due to their high consumption globally: in 1998, around 120 tons were produced. Even at low environmental concentrations, antibiotics stimulate bacterial resistance. The consequences of the presence of fluoroquinolones in the environment are not fully understood, but are known to be toxic to plants and aquatic organisms. Approximately 85% of the fluoroquinolones present in influents can be removed by conventional wastewater treatment plants, but the removed fraction is frequently accumulated in the sludge, which is sometimes used as fertilizer, representing an additional input route into the environment. The removal of fluoroquinolones by biological treatment is ineffective, and it is believed that only advanced oxidation technologies are able to destroy these emerging pollutants.

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Environmental contamination by fluoroquinolones

Photo-Fenton degradation of wastewater containing organic compounds in solar reactors

The degradation of polyvinyl alcohol (PVA) by the photo-Fenton process was studied in laboratory scale, with aim of investigating the effect of process conditions on the polymer degradation rate. The experiments were based on a complete factorial design for the amounts of Fe(II) and H 2 O 2 added to water solutions of PVA of different concentrations. The degradation rate of the organic compounds was monitored along the time in discontinuous experiments by analyzing the dissolved organic carbon concentration (DOC) in the solutions. Under adequate conditions more than 90% of the DOC could be degraded in the process. Depending on the initial DOC concentration and the amounts of Fe(II) and H 2 O 2 added an insoluble phase is formed, which can be separated by mechanical methods, thus favoring the removal of organic contaminants in the treatment of industrial wastewaters containing PVA. The interpretation of the experimental results was based on the fitting of neural network models for predicting solid phase formation, and DOC concentration along the reaction time.

Antonio Carlos Silva Costa Teixeira

Papers

Environmental contamination by fluoroquinolones

Photo-Fenton degradation of wastewater containing organic compounds in solar reactors

Study on the photo-Fenton degradation of polyvinyl alcohol in aqueous solution

Deactivation of steam reforming catalysts by sintering: experiments and simulation

Correlating the chemical and spectroscopic characteristics of natural organic matter with the photodegradation of sulfamerazine.